Which Tap & Die set to purchase?

[FenceFurniture]

I need to purchase a fairly simple Tap & Die set to use for odd jobs. I will need Imperial as well as Metric, and just in the common sizes, although it would be very useful to add a specific size on demand.

I imagine that I would be using them mostly on Mild Steel, but I guess there would be enough occasions where I wouldn't be able to determine what the steel is (I need to put a thread on this particular rod so as to fit an M8 nut - who knows what the rod is).

Looking at the McJings site, they have a fairly good selection, (https://mcjing.com.au/categorybrowser.aspx?categoryid=50)and a few questions come out of that:
HSS or High Carbon steel? It doesn't have to be fantastic for the amount of use it will get, but "lasting for more than one use" is desirable (I've experienced Chinese steel in drill bits - never again)
When it comes to Imperial there are a few different thread options in BSW, UNC, UNF etc. Is BSW the standard "garden variety"?
Are the McJings T&Ds of reasonable quality? If not, what would you recommend?
Looking at the Metric versions there, the seem to have two different pitches for quite a few of the diameters (e.g. M6 can be either x0.75 or x1). Is it the larger pitch that would be regarded as the standard?

Any and all pointers and help appreciated.

[chambezio]

Hi Brett. You have pushed your boat into uncharted waters.
I like you wanted to be able to clean-up existing threads or cut the occasional new thread. My thinking was along these lines...I have a Toyota- metric threads. I have a Commodore- Imperial and Metric? then there is the WWII Jeep- Imperial.
OK Imperial. Common useage is UNC UNF BSW (I will be shot down in flames here,you watch)
UNC this would be the most common AND it also is VERY close to BSW ....except for ½". They are not compatible but everything underneath is The "C" is for course thread
UNF This is for Fine threads The Jeep has a lot of them and engineers like fine threads too. They can be handy but coarse threads are more prevalent
METRIC these have fine and coarse as you have already found.

I have bought a Metric Set from M3 to M12 these were both fine and coarse

I also have a set with UNC and UNF from eighth up to Half inch. The graduation were by one sixteenth.
All the sets are Carbon Steel. If I am doing a specific job requiring multiple threaded parts I will buy HSS for that job with a long term view to may be end up with a HSS set
Carbon Steel would be good enough for occasional use. As far as brands went...No "recognised brands" but I bought what looked alright. These were all Ebay jobs and so far they have been OK. Though a M12 die split while I was cutting a thread once. The metric set I have has 3 taps for each button die. They are "start", "middle", and "bottom". which is handy some times. The cost, from memory, was around $40. You should also buy some good quality lubicant. My favourite is Trefolex but at the moment I am trying Tap Magic.
So concludes the walk through Tap and Die lesson.

[variant22]

I need to purchase a fairly simple Tap & Die set to use for odd jobs. I will need Imperial as well as Metric, and just in the common sizes, although it would be very useful to add a specific size on demand.

I imagine that I would be using them mostly on Mild Steel, but I guess there would be enough occasions where I wouldn't be able to determine what the steel is (I need to put a thread on this particular rod so as to fit an M8 nut - who knows what the rod is).

Looking at the McJings site, they have a fairly good selection, (https://mcjing.com.au/categorybrowser.aspx?categoryid=50)and a few questions come out of that:
HSS or High Carbon steel? It doesn't have to be fantastic for the amount of use it will get, but "lasting for more than one use" is desirable (I've experienced Chinese steel in drill bits - never again)
When it comes to Imperial there are a few different thread options in BSW, UNC, UNF etc. Is BSW the standard "garden variety"?
Are the McJings T&Ds of reasonable quality? If not, what would you recommend?
Looking at the Metric versions there, the seem to have two different pitches for quite a few of the diameters (e.g. M6 can be either x0.75 or x1). Is it the larger pitch that would be regarded as the standard?

Any and all pointers and help appreciated.
I have had more success with HSS than Carbon. I tend to break carbon steel taps quickly. They are usually the cheap ones. I have broken a few Bordo carbon taps so I no longer buy them. Ebay UK is a really good source for high quality taps at prices cheaper than you can buy local import junk. I have had nothing but good experiences with Dormer, ESC, Guhring, Yamawa and Nachi taps. I had a Europa blow up a couple of weeks ago, so I do not really rate them. I have moved from standard taps to Spiral taps. I have much more success with them cutting a clean thread and also going straight. I have also had near zero breakage.

BSW is British Standard Whitworth. Probably not what you want for Imperial unless your dealing with old British machines/cars. UNC is Unified National Coarse, and UNF is the Fine pitched Imperial. Generally cheap Bunnings bolt packs come in UNC. We are metric, but for some reason they stock mainly Imperial. :doh:

M6 x 1 is generally what I have come across. I can't say I have seen an 0.75 M6 bolt. No doubt they exist. Just not in my realm.

Generally speaking as far as Metric goes, all Japanese cars run metric bolts. I have found the thread is almost always fine pitched. That said my milling machine clamps are all metric and coarse thread.. make of that what you will.

I have also not had luck purchasing tap & die sets. I find it is cheaper to just purchase them one by one. The quality brand sets tend to go for serious money.

[BobL]

Looking at the McJings site, they have a fairly good selection, (https://mcjing.com.au/categorybrowser.aspx?categoryid=50)and a few questions come out of that:
I have a few of theirs and found that they don't stand up to repeated use but then again they are fairly cheap. The headaches come when cheap ones get blunt and break in a hole and then you really start swearing.
I found out I was wearing out a Mcjing 3/16" tap after about a dozen holes in 12 mm steel and after that the breakage rate went up. I must have broken half a dozen before I went to the CTC taps in this size.


HSS or High Carbon steel? It doesn't have to be fantastic for the amount of use it will get, but "lasting for more than one use" is desirable (I've experienced Chinese steel in drill bits - never again)
The HSS won't chip or break as easily as Carbon Steel.


When it comes to Imperial there are a few different thread options in BSW, UNC, UNF etc. Is BSW the standard "garden variety"?
More or less.


Looking at the Metric versions there, the seem to have two different pitches for quite a few of the diameters (e.g. M6 can be either x0.75 or x1). Is it the larger pitch that would be regarded as the standard?
Standard for some things and not standard for others.

With T&D sets you basically get what you pay for.
Cheap sets tend to
- be made out of cheaper steel so the taps are shorter so they won't break as easily. Sometimes the taps are too short and the shanks are too fat so they can't continue cutting into the hole and limit the length of thread that can be cut
- come with smaller (1") thin non-adjustable size dies, these make the thread cutting hard to start. its is really useful to be able to make the thread a little bit looser or tighter as required.
- come with handles that are usually too small, hard on the hands and go sloppy really quickly.

A good set
- have a couple of different size comfortable handles to suit the size of taps and dies
- will have 3 taps for each thread (a starter tap, a plug, and a bottoming tap) eg HAND TAP SET - 3 PCS - METRIC #G63 (http://www.ctctools.biz/servlet/the-391/METRIC-Coarse-Starter%2C-Plug/Detail)
- have larger thicker adjustable dies that are nice and tapered so they are much easier to start and form the thread in a much more reliable manner.

I have lots of odd and sods or P&N and Suttons and some unknown brand Japanese ones that are very good and have on occasion even made my own tap from a die and VV when I needed a wierd size.
The sets I have include
- a small set of smaller sizes of BSW from Mcjing. I have replaced most of the common sizes with with the triple sets (starter, plug, and bottoming) from either McJing or CTC tools.
I have two metric sets I bought from H&F one is a smaller cheap set of carbon steel, the other is their larger metric set in Alloy steel (https://www.machineryhouse.com.au/T014) which is much nicer to use.
I recently bought a set of BSP taps I bought from CTC tools in moly steel and these work well.

If I was starting over again I would just get the basic sizes in triple sets from CTC.

One thing to invest in is a small tub of trefolex cutting compound. Its expensive but it will save a lot of heartache

[Big Shed]

I find the cheap alloy/carbon steel sets pretty useless, OK to clean up an existing thread and perhaps for tapping in aluminium but that's about all.

About 90% of my thread requirements are metric so I bought this H&F HSS metric set of taps

T019 | 29 Piece - HSS Hand Tap & Drill Set | machineryhouse.com.au (http://www.machineryhouse.com.au/T019)

and bought the separate matching metric dies. It is very useful to have the correct drill sizes with the taps.

I have also bought a few of the common Whitworth sizes and the odd UNC or UNF size as required, all in HSS.

Once you break off your first cheap tap in a work piece you are "cured" of buying cheap taps, or at least you should be.

+1 on the Trefolex, although it is getting harder to get, but definetely using a tapping fluid.

[RayG]

Hi Brett,

Dormer are excellent, Sutton are good, Greenfield are up there.... don't buy sets.. get them as you need them, taps usually come in sets of 3.. plug, taper, bottom..

I've got mostly hand taps ( straight flutes ) but I'm seriously thinking of gradually going over to spiral taps, probably Dormer.

Ray

PS.. Most of the hardware/fastener places around here now carry "Goliath Brand" taps... they seem ok for the few I've used..

[FenceFurniture]

Thanks very much to all for the replies, there's a lot of good info there. Will check all those links later on.

Thanks again. :2tsup:

[Stustoys]

I've got mostly hand taps ( straight flutes ) but I'm seriously thinking of gradually going over to spiral taps, probably Dormer.
I think spiral taps are really meant for machine tapping at something less than full thread........but there are also gun taps (which are also called spiral pointed). Gun taps have smaller flutes as they push most of the swarf forward.



"Goliath Brand" taps... they seem ok for the few I've used..
I'd say their taps are at least as good as Suttons.
"Our comprehensive range of quality HSS Taps & Dies are all manufactured in Birmingham, England"
Just stay away from their tapwrenches and diestocks. They are just nasty*

Stuart

*Unless the ones I bought are knock offs

[variant22]

I think spiral taps are really meant for machine tapping at something less than full thread........
Stuart

Can you please clarify what you mean by "less than full thread"? The spiral taps I use (Dormer/Gurhing/Yamawa) all tap full threads well. Great for blind holes as well as all the way through. They tend to look more like a bottoming tap. They cut the thread right close to the bottom of a hole. I found that the threads are also nice and tight, but this might be more of brand issue than the type of tap. They also seem easier to get straight when hand tapping, but I am not sure why as they should theoretically be worse.

I noticed that a discussion over on PM about hand taps has members referring to them as "yet to be broken" or "broken taps". Which I tend to agree with. Spirals draw the material out of the hole whereas normal taps tend to gum up and end up binding and breaking. I have had them break doing the 1 rotation, 1/2 reverse. More often than not (for me) they break on the reverse where it tries to break the chip.

Here is a nice link on some of the different tap styles: Tap Guide, Styles , Chamfers, Markings, Symbols, Technical, Thread Forms, Tap Thread (inch) Limits and Dimensions (http://www.newmantools.com/taps/styles.htm)

302421

[RayG]

I think spiral taps are really meant for machine tapping at something less than full thread........but there are also gun taps (which are also called spiral pointed). Gun taps have smaller flutes as they push most of the swarf forward.


Does tapping with a battery drill qualify as machine tapping... :)

I thought the main difference was that spiral taps don't need to be reversed to break the chips. I can't think why they wouldn't be suitable for hand tapping.

Ray

[variant22]

Does tapping with a battery drill qualify as machine tapping... :)

I thought the main difference was that spiral taps don't need to be reversed to break the chips. I can't think why they wouldn't be suitable for hand tapping.

Ray
I think that the thought is that spiral taps are not as tapered as standard hand taps. So the thread is cut much earlier and potentially easier to get the thread off square. I find the opposite to be true. The thread starts earlier so it is easier to see if it is going off square and straighten it up before it is too deep. I would rather straighten when the tap is at the top of the hole, not way down the bore as with a hand tap..

For the record, I am not sure if my M8 Europa was more a casualty of the clutch in my tapping head than the strength of the tap. That said they are almost the same price as Dormer/Gurhing/Yamawa etc, but, and it is a big but, they have no COO on them... so my money is going to the name brands with the first world COO.

[nearnexus]

I sat back and watched this thread with interest, to see what comments came forward.

I suppose it boils down to : are you using or working on/with, older threads or new stuff?

If it's the earlier option, then you really have no easy fix.

My father was a GM mechanic and I have almost unlimited bolts/nuts from those days, plus various metric stuff salvaged from gear - all different pitches.

I have metric and imperial taps and dies in BSW, SAE, metric coarse/fine, and some UNC and UNF.

It's never enough for all contingencies.

If buying all new bolts then just go with the common metric in coarse or fine, or both.

As for taps, HSS is the way to go without a doubt.

Rob

[Stustoys]

Can you please clarify what you mean by "less than full thread"?
60-80% (I dont have the range of drill sizes needed to play that game so my tapping drills are normally on the tight side)


Does tapping with a battery drill qualify as machine tapping... :)
ummm no not exactly.........I would have thought you'd have made yourself a torque limited stepper motor setup with auto reverse. :)


I thought the main difference was that spiral taps don't need to be reversed to break the chips. I can't think why they wouldn't be suitable for hand tapping.


Not "unsuitable", "less suitable". Spiral taps just arent as strong. As I remember it, most taps(hand tapping) are broken by bending not torque(how they work that out I have no idea and I cant find a link to back it up).

I think that the thought is that spiral taps are not as tapered as standard hand taps. So the thread is cut much earlier and potentially easier to get the thread off square. I find the opposite to be true. The thread starts earlier so it is easier to see if it is going off square and straighten it up before it is too deep. I would rather straighten when the tap is at the top of the hole, not way down the bore as with a hand tap..


In a perfect world you would start out square and not have to straighten things up(a great way to break taps).....but most of us dont live in a perfect world :)

[variant22]

I think spiral taps are really meant for machine tapping at something less than full thread........
60-80% (I dont have the range of drill sizes needed to play that game so my tapping drills are normally on the tight side)

Can you please post a reference? Assuming we are talking about the same thing, I have not seen a separate drill size chart for spiral fluted taps. They seem to use the same sizes as hand taps.

[issatree]

Hi Brett,
Have just come back from Aldi's, & I saw a set there.
Never took a great deal of notice, looked up their Cat. but there was nothing there.
My guess wood be that it maybe up to ½"- 12mm.

[FenceFurniture]

Thanks Lewis.

[Oldneweng]

Hi Brett,

Dormer are excellent, Sutton are good, Greenfield are up there.... don't buy sets.. get them as you need them, taps usually come in sets of 3.. plug, taper, bottom..

I've got mostly hand taps ( straight flutes ) but I'm seriously thinking of gradually going over to spiral taps, probably Dormer.

Ray

PS.. Most of the hardware/fastener places around here now carry "Goliath Brand" taps... they seem ok for the few I've used..

I think you are allowed to buy the "sets of 3.. plug, taper, bottom." Just don't buy complete sets of taps/dies etc is probably what Ray means.:D

Dean

[Pat]

Brett, for casual use, have a look at garage sales. I have picked up a drawer full of P&N & others over the years.

I even managed a 500ml container of Trefolex Cutting compound for the princely sum of $2.00.

The correct drill bit for the tap is also helpful, you can ream out a hole if it is a smidge tight, but you are in a world of woe if the hole is oversized for the tap.

[Ueee]

Hi Brett,
I looked at the Aldi tap sets when they were here a few weeks back. They are metric only, carbon steel made in China. I wouldn't be holding my breath.

I'm with most of the other guys, buy good ones as you need them. Or buy a cheap and nasty set, and buy good replacements for the ones you break. That way you only buy the ones you really need.

UK ebay is your friend!

Ew

[cba_melbourne]

Brett,

a set of inexpensive but well made Japan made carbon alloy straight taps and unsplit dies can be an excellent starter kit. Not sure if you still can get them. They look like this set and used to cost about $120 each for a metric set.

You soon find out which taps or dies you use most, and will buy these as fully ground brand name spiral point HSS. You soon learn which materials are better cut with a set of three taps. And you soon discover that blind holes are best cut with spiral flute taps that eject the chips upwards.

These are two places that I recommend to buy good brand name taps from at reasonable prices (some of these taps are unused old stock, but who cares if they are good):
cncpoorboy toolstore items - Get great deals on items on eBay Stores! (http://stores.ebay.com.au/cncpoorboy-toolstore/TAPS-AND-THREADING-TOOLS-/_i.html?_fsub=1256164014&_sid=190812284&_trksid=p4634.c0.m322)
jow1995 items - Get great deals on METRIC, BSW items on eBay Stores! (http://stores.ebay.com.au/jow1995?_trksid=p2047675.l2563)

Do not forget to buy a set of drills to go with the taps. The correct size drill is very important. You cannot just use a drill set of 0.5mm increments, if you try you break taps or make threads that strip out quickly. You need to buy the proper size.

You also need some good 90 degree countersinks if you want to properly tap holes. Just using a larger drill to countersink is not very satisfactory.

Over time you will also want to buy better quality wrenches. Used ones of good brand name and made of steel are a far better choice, than new ones with cast body that come with cheap sets and break just from looking at.

You also need something to guide your taps when hand tapping. Easy to make your own from some scrap metal. But look at these for inspiration:
Complete SET OF 6 Guides BY BIG Gator Tools TAP AND Drill Guides | eBay (http://www.ebay.com.au/itm/Complete-set-of-6-guides-by-Big-Gator-Tools-Tap-and-Drill-guides-/110911868063?pt=LH_DefaultDomain_0&hash=item19d2dccc9f)

For steel use something like lard to lubricate taps, for Aluminium use WD40. Or buy some tapmatic fluid or similar commercial product. Taps stay longer sharp and break less if generously lubed.

Australia is now metric, like most of the world. You may be best off starting with a metric tap/die set, unless you need to work on an old car (new cars are largely metric even if made in the US). If you work with water/air/oil pipes you may need a few sizes NPT taps/dies. In general, I try to rather substitute metric threads for imperial ones, rather than buy imperial taps that I only use for one job and then never again.

Chris

[Stustoys]

Can you please post a reference? Assuming we are talking about the same thing, I have not seen a separate drill size chart for spiral fluted taps. They seem to use the same sizes as hand taps.
You mean a chart with drill sizes for straight flute, spiral flute and spiral point? nope, I doubt there is one. Though to quote your link which says the same sort of thing only backwards. "This gives the spiral point tap more cross-sectional area, which means greater strength, allows higher tapping speeds, and requires less power to drive."
As I said its not a case of "you cant do that!" just more likely to break something.
With a three tap set and to tight a hole you can go taper, int, bottom, taper, int, bottom......... Its a little on the slow side though lol :D

Stuart

[Combustor]

Amen to Pat's comment above. Haunt the garage sales, swap meets and fleamarkets. Much of the stuff from deceased estates etc.will be quality brands, some long gone, but excellent. You can re-sharpen dull taps with a small stone on a Dremel tool or similar. Just undercut the leading edges of the flutes slightly till they feel sharp again. Dies will take the same treatment if you have a small enough stone. Older tap and die holders are usually much better than most of the stuff I have seen lately. For my vintage machinery restorations I have picked up at auction sets of Whitworth/BSF taps an dies to 1" , BSP pipe dies and guides, UNC/UNF sets, and a Metric assortment in addition to various Morse Taper drills. They are out there, keep looking! Combustor.

[Kiwibrucee]

Hi, I found it very helpful to have a copy of the engineers black book or something similar on hand when buying stuff on epay, I discovered the hard way there are a few "non standard" thread pitches out there that pop up, often you think you have a bargain, when upon closer inspection you have ended up with an orphan.
It lists all the correct drill sizes too.
I find a set with the correct size tapping dills included was great as its not that easy to get he odd drill sizes needed individually without going to a specialist store.
Sutton Heritage 26 Piece Metric HSS High Speed Steel TAP Drill SET T901HM26 | eBay (http://www.ebay.com.au/itm/Sutton-Heritage-26-Piece-Metric-HSS-High-Speed-Steel-Tap-Drill-Set-T901HM26-/221285988131?pt=AU_Tool_Parts_Accessories&hash=item3385ac3723)

Regards
Bruce T.

[FenceFurniture]

Thanks for the next batch of answers - more great info and advice. Stuff I would never have considered!

[Ueee]

Bruce T's comment also reminded me of something else, you can get oversized (and probably undersized) taps for tapping before heat treatment etc. They are of no use for normal work though.
My local shop has sets of Guhring gun nose taps and matching drills, i think they are M5,6,8,10,12. Top quality HSS, about $130 from memory. Considering the list price on a Dormer M12 is about $60 thats pretty good value. You will find better on ebay though.

Ew

[BobL]

More advice :) get yourself a copy of the #12 Workshop Practice series "Drills, Taps and Dies" by Tubal Cain.
Just the tables in the back are worth it.

[DSEL74]

In relation to imperial I generally find Whitworth the most common. So i guess it depends on what your working on.

My suggestion would be to go to super cheap or equivalent and buy a $50 set, which will be fine for brass, aluminium and soft steel and see what you use then replace those with a qood quality HSS ones.

There are also number sizes and tap drills often (even for metric) come from a different standard of sizing.

I'd also get my tap wrenches etc from swapmeets and garage sales for good quality at cheap prices, so go for round dies as they are more common than hex. The other things is buy a few sets of thread pitch gauges, they look like feeler gauges with teeth. This will allow you to know what tap or die you need for an existing mating part.

[Master Splinter]

The Aldi set also happens to have correctly* sized drill bits and a thread gauge...so for $25 it's not a bad start.

*apparently...I haven't checked 'em against Machinery's Handbook specs.

[cba_melbourne]

*apparently...I haven't checked 'em against Machinery's Handbook specs.

Not the most authoritative source of information about metric threads. The machinery Handbook is an excellent American Hadbook. But as such it describes the current (early) American implementation of the metric ISO system. It is a bit like in the early days of metrification in Australia, when clearances under bridges were signposted as 3.657m (12 foot). You end up with things like designers using rather exotic metric threads, like M7 and M3.5.

[Master Splinter]

...But Machinery's Handbook has the overwhelming advantage of being easily and freely available...

[Stustoys]

Metric tapping drill size is thread size minus pitch. Works for imp threads to I'm told if you can be bothered with the maths.

Tapping drill size isnt critical anyway(assuming you arent talking about production or chasing the last 10% of strenght). I normally use to small a drill, so tapping becomes much harder... but I know I'm being pig headed doing it... but then I have the time.
Tapping Torque Vs Thread Strength :: Tapmatic (http://tapmatic.com/tapping-questions/tapping-torque-vs)

Stuart

[BobL]

Metric tapping drill size is thread size minus pitch. Works for imp threads to I'm told if you can be bothered with the maths.
This method will produce holes that are generally too tight and can lead to broken taps.

The other commonly use ROT is Bolt Size - 10% of bolt size, but both are only ballpark figures

The Tubal Cain (TC) book recommends 5.35 mm holes for a 60% or loose fit down to 5.1mm for an 85% (tight) fit - the "British Standard" sizes are 5.3, 5.2 and 5.1 mm
So the -10% rule (5.4 mm) is too loose and the Size - Pitch rule (5 mm) will be too tight

M8 (1.25) TC recommendation is 7.2 mm for a 60% fit down to 6.9 mm for tight fits.
-10% rule (7.2mm) is on the loose side and Size - Pitch (6.75 mm) is too tight.

M10 (1.5) TC recommends between 9.2 and 8.6 mm. -10% rule is OK but Size - Pitch (8.5 mm) is too tight.

M10 (1.25) does not have an entry in TC but all sizes can be worked out using a formula on P92 of the TC book.

Diameter of bolt - 1.083*Pitch * % flank height/100

The % flank height is ~10% greater than the engagement, so a 60% engagement is around 50% flank height.
This will allow you to work out what ever you want.

[Stustoys]

This method will produce holes that are generally too tight and can lead to broken taps.
Isnt that what I said?:p Though you shouldnt break taps....... it just might takes ages, no cordless drills:D. Likely doesnt do they taps any good either. Did I mention I can be pig headed?

The thing is most tapping drill charts use those sizes...........as we said they are really to tight for normal use on steel. But cast iron can tap like butter, as can Aluminium, plastic is anyones guess..........so I guess that maybe why the err on the tight side.

There is a lot to it, deep holes normally use larger drills........ but it all depends what you are after.

Stuart

[FenceFurniture]

Thank you chaps for your continued discussion and debate - very enlightening, as always.

A few Qs have come up as a result. I just had a close look at some of my threads (various common bolts) and they all have a 60° profile, as I expected once I thought about it. Is this always the case (apart from specialised threads)?

I presume that the distance between the threads is referred to as the pitch (i.e. the wavelength). What is the depth of the "V" referred to as, and what is the incline of the thread referred to as please? The depth of the "V" would be the pitch multiplied by Tan 60°. I remember back in High School Tech Drawing that the teacher explained Starter Motor threads, with multiple parallel threads for strength at the increased incline which is to enable rapid movement lateral movement per revolution.

Thinking about an M6x1 thread for example, I understand that one revolution of the nut will advance it by 1mm (very useful for jigs etc), and an M6x0.75 will advance by 0.75mm, and that lead me to something else I've noticed - backlash (specifically on hand planes :((). If the nut that the thread advances though is fixed then any backlash would have to be only from the threads not mating correctly, and because the pitch must be the same for the thread to actually work, then this backlash would have to be from one of the threads not being at 60° wouldn't it? Obviously if the device that is holding the nut has some play then that will introduce it's own backlash, and I suspect that is what is responsible for it in planes, but in other nut & bolt combos I do notice it from time to time (which is where the different angle thing in the profile would have to come in). I guess that is what also creates the "chatter" that is too often found when spinning down a nut at speed.

[Big Shed]

A few Qs have come up as a result. I just had a close look at some of my threads (various common bolts) and they all have a 60° profile, as I expected once I thought about it. Is this always the case (apart from specialised threads)?



No, BSW - British Standard Whithworth is 55 degrees, see here

British Standard Whitworth (BSW) Thread Form (http://www.boltscience.com/pages/screw4.htm)

[FenceFurniture]

Thanks Fred. It was an eyeballed 60° :U.

[Michael G]

If the nut that the thread advances though is fixed then any backlash would have to be only from the threads not mating correctly, and because the pitch must be the same for the thread to actually work, then this backlash would have to be from one of the threads not being at 60° wouldn't it?

No - if the nut thread is too large or the bolt thread too small (for example instead of a nominal 6mm major diameter it's 5.8*) then there will also be slop in the threads which will manifest itself as backlash.

Michael
* If you measured a M6 thread you would probably find that the major diameter was less than 6 anyway because of the manufacturing process

[cba_melbourne]

This method will produce holes that are generally too tight and can lead to broken taps.

I disagree. The method "Metric tapping drill size is thread size minus pitch" does give the proper standard drill size.

However, it is up to you to correct this drill size according to the many variables of the job at hand. This requires some experience and common sense. For example:

- It is up to you to decide how strong a thread you need/want for the particular job. The standard drill size is for a 75% thread depth. But for many applications, a thread depth od 60-70% is perfectly adequate. For example, a 100% thread specification is only 5% stronger than a 75% thread specification, BUT REQUIRES 3 TIMES THE TORQUE TO PRODUCE!!!
- the material matters. Mild steel and cast Iron and and Brass etc will work best using the standard drill size (say for M6 5mm drill). Whereas tough materials such as S.S. and and better steel grades need a slightly larger drill (say for M6 5.1mm drill). And extremely tough materials like Aluminium-Bronze may need a 5.2mm drill for M6, else it will indeed be very hard to tap and if successful without breaking the tap the screw may bind in the threaded hole because the clearance is too small. Materials like soft Aluminium and some plastics tend to slightly flow when threading and need a larher drill size (say 5,1 or 5.2 for M6) - think of this a little bit like if you were using a thread forming tap instead of a thread cutting tap.
- the type of tap you use matters too. Have you noticed that the better taps come with colored rings around the shaft? These rings tell for which material the tap geometry and tap tolerance and tap coating has been optimized. You can use these taps on the material they were designed for drilling the standard size hole (here what the codes mean www.allenbenjamin.com/get_file.php?file=953 (http://www.allenbenjamin.com/get_file.php?file=953)). But if you are using generic all rounder taps, it is up to you to correct the drill hole.
- the quality of the tap you use matters too. Better taps are finely precision ground to a known dimensional tolerance (the tolerance is usually marked on the shaft or on the box). Cheap taps can have HUGE dimensional tolerances. A cheap, roughly finished only machined tap (possibly with some burrs left) is likely to require a lot more torque to cut than a fully ground/polished high quality tap. You are well advised to drill a larger hole than specified when using low grade taps.
- what will the threaded hole be used for? For example, a S.S. screw in an Aluminium hole exposed to the elements will want to seize, more so if the thread is a tight fit. Sure you should use an anti seize compound, but it will also help to drill a larger hole before tapping.
- are you cutting dry or with a lubricant? The hole can be choosen tighter if using a lubricant.
- a blunt/worn tap requires much more torque -- drill a larger hole or sharpen the tap or toss/replace
- are you properly countersinking the hole?
- are you using a guide or tapping freehand?
- tapping manually in a drill press or mill?
- how good are you at "feeling" whilst tapping? If inexperienced, better drill a larger hole.
etc etc etc - Chris

[BobL]

, , , , , , If the nut that the thread advances though is fixed then any backlash would have to be only from the threads not mating correctly, and because the pitch must be the same for the thread to actually work, then this backlash would have to be from one of the threads not being at 60° wouldn't it? . . . . ..

Backlash has little to do with the angles of the thread and happens when the male thread is too small in diameter for the female thread - so even though the angles are all same the Male "V's" are not protruding far enough into their female counterparts and is why backlash increases with use/wear.

This is where having adjustable dies is really useful.
Since making taps adjustable is somewhat tricky, generally the female thread is cut/tapped first.
Then the die is adjusted to to cut a thread that is too tight and the male thread is cut and tested on the female part.
The die is then adjusted accordingly and the thread cut until a satisfactory fit with minimum backlash is obtained.
It sounds like a lot of mucking around but once the die is set it will generally cut true for repeated threads relative to the tap.

[cba_melbourne]

> A few Qs have come up as a result. I just had a close look at some of my threads (various common bolts) and
>they all have a 60° profile, as I expected once I thought about it. Is this always
> the case (apart from specialised threads)?

Nowdays yes. Only some antique British threads had 55 degrees. It matters where you do restoration work. Nobody would use these threads on new products.


> If the nut that the thread advances though is fixed then any backlash would have to be only from the threads not
> mating correctly, and because the pitch must be the same for the thread to actually work, then this backlash
> would have to be from one of the threads not being at 60° wouldn't it?

The amount of backlash is given by the thread tolerance. In industry, male and female threads are both made to tolerances. Very much like shafts and bearings have tolerances. For example, a nut may have been made to 6H tolerance and a bolt may have been made to 6g tolerance and they will both be a loose fit to each other. Taps and dies can be bought to different tolerances.

In the home shop one rarely works to tolerances, one usually fits parts together. This is true for shafts/bearings and for nuts/bolts too. One adjusts the bolt diameter when threading in the lathe until a test nuts fits to ones feeling. Or one adjusts a split die until the nut fits.

[Big Shed]

> A few Qs have come up as a result. I just had a close look at some of my threads (various common bolts) and
>they all have a 60° profile, as I expected once I thought about it. Is this always
> the case (apart from specialised threads)?

Nowdays yes. Only some antique British threads had 55 degrees. It matters where you do restoration work. Nobody would use these threads on new products.



Whitworth may be "antique", but up until last year the majority of the nuts and bolts in Bunnings for example were Whitworth so a lot of workshops still abound with Whitworth bolts. I certainly wouldn't call them a "specialised" thread.

[Chief Tiff]

No, BSW - British Standard Whithworth is 55 degrees, see here

Metric and Unified are 60 degree threads. Unified are UNC, UNF and NPT (US pipe thread)

Whitworth threads are 55 degree; these are Whit, BSW, BSC (different name, same threads), BSF and BSP (English pipe thread)

The differing angles mean that they are NOT interchangeable even though the nominal diameters and threads per inch are the same; unless you are the type of clown who also "knows" that Philips screwdrivers can also be used in Pozidrive screws and that drill bits can be accurately reground by hand. Additionally, the roots and crests on Unified are cut flat where on Whit they are rounded. Basically, when you jam in a Whit bolt into a Unified thread it is effectively slightly oversized and ends up smearing its threads. Do this with stainless and you may encounter that wonderful phenomenon known as "galling". A quality set of thread pitch gauges in Unified, Whit and Metric (Starrett or Moore & Wright are tops) will enable you to physically see the difference between thread pitches easily.

Diameter minus pitch and diameter less 10%; these are ballpark figures. Buy a set of thread tables (like Zeus) or print them off from on line sources and post them around your metal work area. The big problem you'll find is getting the correct sized drill bits; most drill bit sets come in either 0.5mm or 1/64th". Not really suitable unless you're drilling out a hole with your hand sharpened bit to tap UNC to use with a Whit machine screw with a pozidrive head that almost fits your Philips screwdriver. In which case they're absolutely perfect. Buy Dormer drills; they come in 0.1mm increments and the basic HSS used to make them is harder than you will believe; until you have seen them drill out a stainless Whit bolt that had galled in a UNC tapped hole that first blunted Sutton HSS then Sutton cobalt bits.

Whitworth nuts and bolts were discontinued in the civilised world a few decades ago; eventually Australia will be dragged kicking and screaming into the 20th century and will also stop using them. Imperial pipe threads such as BSP and NPT unfortunately will still be around for a long time though. You'll find that most combined metric/imp sets are Unified.

To summarise:
1) Buy your taps in metric and Unified threads; only buy Whit if you absolutely must. Dormer, Goliath and SKF use superior HSS steel to Sutton or P&N.
2) Buy thread gauges in all three thread forms for easy thread identification.
3) Get a set of thread tables and buy the correct sized drill for each application. Dormer and SKF for drills.

[BobL]

I disagree. The method "Metric tapping drill size is thread size minus pitch" does give the proper standard drill size.

However, it is up to you to correct this drill size according to the many variables of the job at hand. This requires some experience and common sense. For example:

I agree, common sense and experience are extremely valuable.

Unfortunately I don't have much experience so I turn to a reliable source like the Tubal Cain book on Taps and Dies which I have found (unlike the Web) to be extremely reliable.

[Ueee]

Poor Brett just wants some taps and dies:D. Very good info guys.

To make this all easier try this program Machinists Calulator (http://members.shaw.ca/lnr729/shopcalc/WorkshopCalulator.html)

I have attached a screen shot from the last unusual threading i did, 5/8 18 UNF. It shows common drill sizes and their % fit, as well as theoretical drill sizes for any given fit. For us metal workers it will also give you measurements over wires etc plus other non thread related stuff.

Cheers,
Ew

[Stustoys]

unless you are the type of clown who also "knows" drill bits can be accurately reground by hand.

Guess that makes me a clown then. Out of interest how close to size does the hole need to be? perhaps we should be reaming them before tapping?


While Dormer drills in 0.1mm steps might be great if you had a few 1000 holes to tap at say 600 an hour(when you would mosy likely be using way less that full thread depth unless you happen to have an all singing all dancing tapping machine and by that I dont mean a tapping head in a mill or a cordless drill:p). Its really a little over the top for your average guy in his shed. Though being a little over the top doesnt stop most of us.


Poor Brett just wants some taps and dies:D. Very good info guys.
:D Should we start on thread strenght of dia cut threads v roll formed?

Stuart

[FenceFurniture]

Crikey. I go down to the shed for a couple of hours and another bunch of posts. :2tsup:


No - if the nut thread is too large or the bolt thread too small (for example instead of a nominal 6mm major diameter it's 5.8*) then there will also be slop in the threads which will manifest itself as backlash.Ah, yes, that'll do it. Thanks Michael.



>I just had a close look at some of my threads (various common bolts) and
>they all have a 60° profile, as I expected once I thought about it. Is this always
> the case (apart from specialised threads)?

Nowdays yes. Only some antique British threads had 55 degrees.I looked at M6, ¼" and 5/16". In my local hardware, would the garden variety Imperial threads be UNC? Or summink else? Reading another post it's a bit hard to know if they've changed or not in the last little while. One change I have noticed is that since a few months ago none of the local hardwares have a single brass wood screw to show between them. :~



Poor Brett just wants some taps and dies:D. Very good info guys.

To make this all easier try this program Machinists Calulator (http://members.shaw.ca/lnr729/shopcalc/WorkshopCalulator.html)Ah yup, that's about right Ew, BUT I'd rather find out this stuff before rather than after! It's all good.

Thanks for the link.

[cba_melbourne]

Whitworth may be "antique", but up until last year the majority of the nuts and bolts in Bunnings for example were Whitworth so a lot of workshops still abound with Whitworth bolts. I certainly wouldn't call them a "specialised" thread.

Yes for some obscure reason Bunnings still sells 55 degree Withworth fasteners - but notice this is only the hot dip Zinc plated variety for outdoor use. To buy a tap or die for these makes no sense, unless you can hot dip galvanize your workpiece afterwards. All other fasteners at Bunnings including high tensile and stainless appear to be either metric or American 60 degrees.

Just why hot dip galvanised Withworth fasteners are still so popular in Australia I do not know. Maybe it is because imported stainless steel fasteners are so overpriced here? Maybe someone knows? Chris

[Steamwhisperer]

Nowdays yes. Only some antique British threads had 55 degrees. It matters where you do restoration work. Nobody would use these threads on new products.
I normally agree with the majority of what you say Chris but saying "nobody"?? Ummm, I do. Almost everything I make at home (at least) has the Whitworth form.
Saying "Only some antique British threads had 55 degrees.", is correct for American threads as well. Even the American Standard Square Thread has a modified form with a 10 deg included angle.That could almost be confusing. :D
They also do Acme, Butress etc. I am stretching this a bit I know as it's obvious you are talking about the 'V' form but I had to say something :D:D


Whitworth nuts and bolts were discontinued in the civilised world a few decades ago; eventually Australia will be dragged kicking and screaming into the 20th century and will also stop using them. Imperial pipe threads such as BSP and NPT unfortunately will still be around for a long time though. You'll find that most combined metric/imp sets are Unified.
Gees Chief Tiff, you make it sound like the Whitworth thread form is almost the worst thing to happen to mankind.


Guess that makes me a clown then.
Stuart

Guess it makes me a clown as well Stuart:D:D

Phil

[Big Shed]

Yes for some obscure reason Bunnings still sells 55 degree Withworth fasteners - but notice this is only the hot dip Zinc plated variety for outdoor use. To buy a tap or die for these makes no sense, unless you can hot dip galvanize your workpiece afterwards. All other fasteners at Bunnings including high tensile and stainless appear to be either metric or American 60 degrees.

Just why hot dip galvanised Withworth fasteners are still so popular in Australia I do not know. Maybe it is because imported stainless steel fasteners are so overpriced here? Maybe someone knows? Chris

Sorry, have to disagree with that. It was not only the hot dipped galvanised ones, also the standard zinc plated ones. Just try and put a UNC nut on one of the Bunnings (and Mitre 10 and most Oz hardware store) zinc plated bolts and you will find that the thread form is different.

I have had Whitworth taps and dies since Adam was a boy, showing my age here I guess.

In fact until the last year or so you couldn't buy most metric bolts and nuts in a "normal" hardware store you had ot go the specialist bolt places (where most bolts are way cheaper anyway - even the Whitworth ones!)

[Stustoys]

Almost everything I make at home (at least) has the Whitworth form.
And a good thread form it is to. Though granted it doesnt matter for what I make I'm told its better when subjected to fatigue due to the radius at the thread root. Which according to one of my books has been reinvented by the USA as mil spec 8879C for that very reason.........but we are heading out of my depth.



Guess it makes me a clown as well Stuart:D:D

Always room for one more :)

Stuart

[Chief Tiff]

Gees Chief Tiff, you make it sound like the Whitworth thread form is almost the worst thing to happen to mankind.



Not at all; Whitworth was the first common thread with specific standardised sizes; it was a logical and desperately needed outcome of the Industrial Revolution.

It also had a couple of drawbacks: they were notorious for shaking loose under vibration and the shallow angle with rounded root/crest radii were a little awkward to make cutting tools for. A 60 degree angle lends itself to production tooling; this made Unified easier and cheaper to make so naturally it overtook Whitworth. Even in the UK if you want Whitworth threads you have to specifically ask for them as the only market is vintage machinery and very idiosyncratic applications;eg the tripod mount on a camera is still 1/4" whit. General purpose hardware is all metric.

I seriously don't understand why there is such a plethora of whitworth on the market. We appear to be the only country still using it and I get the impression it's down to purely reluctance to accept change. As an example of utter stupidity a couple of years ago I took delivery of a brand new air compressor for work and had to initially pull it apart to mount it in a truck. It was "made" by a very well known Australian seller of industrial compressors; of course the only Australian component was the air receiver and associated fittings. Maybe. Anyway, the compressor itself came from China and used Unified fasteners. The diesel engine that span it came from Italy and was therefore all Metric. No prizes for guessing what thread form was chosen for all the fasteners etc that mounted the whole shebang together.

WRT to drills; the initial hole for tapping obviously has a tolerance depending on diameter, but for say M6-M10 0.1mm either way is too much. The tapping drill for an M8 is 6.8mm; a 6.5mm is way too small and is a pig to cut the thread with and a 7mm gives you a crap sloppy fit. So you need a 6.8mm drill bit. Or a hand sharpened 6mm bit in a hand drill :p

[Toggy]

Well one day I am going to make up a project and make my own taps and bolts in a a 7.5 tpi or or .5tpi or other strange thread.. Just to send some poor mug around the twist in the future when he tries to match it; and because my lathe will do it.:D

Ken I think the heat is giving my evil thoughts.

[Stustoys]

WRT to drills; the initial hole for tapping obviously has a tolerance depending on diameter, but for say M6-M10 0.1mm either way is too much. The tapping drill for an M8 is 6.8mm; a 6.5mm is way too small and is a pig to cut the thread with and a 7mm gives you a crap sloppy fit. So you need a 6.8mm drill bit. Or a hand sharpened 6mm bit in a hand drill :p
Who said anything about 6.5mm? 8-1.25=6.75 try 17/64 and see how you go.
Not so sure 7mm would give to a "crappy sloopy fit"(in fact it shouldnt, the thread form would still be the same. just the thread depth would change. If the app is correct 7mm would give you 73.90% thread depth which is more than good enough for most applications.

Stuart

[Big Shed]

I seriously don't understand why there is such a plethora of whitworth on the market. We appear to be the only country still using it and I get the impression it's down to purely reluctance to accept change.


It is probably a result of the notorious reluctance by Australian manufacturing companies to invest in new machinery. The company that produced Whitworth bolts here in Oz probably imported those machines pre WWII from the UK and saw no reason to invest in new machinery, until they lost their market to Chinese manufacturers who did invest in new machinery.:roll:

A classic case of this was British Tube Mills in Adelaide, established with used machinery imported from the UK pre WWII and run until the 1980s without replacement, when they closed down because they couldn't compete with imported tube from China made on all new machinery that didn't break down 10 times a day and used 1/10 the labour!

How do I know this?

My son did his F&T apprenticeship there and finished (luckily) the year they closed down. He reckoned it was like working in a museum!

[BobL]

Who said anything about 6.5mm? 8-1.25=6.75 try 17/64 and see how you go.
Not so sure 7mm would give to a "crappy sloopy fit"(in fact it shouldnt, the thread form would still be the same. just the thread depth would change. If the app is correct 7mm would give you 73.90% thread depth which is more than good enough for most applications.
Stuart

I assume we mean M8 (1.25) mm ?
If so I agree.

I use a fair few M8 (1.25) bolts in projects and 7 mm seems to work perfectly well for me, even in Al unless it is thinner than about 3mm and then I use 6.9 mm bits.
FWIW for M8 (1.25) Tubal Cain recommends drill sizes of 7.2 mm for 60% coverage, through to 6.9mm for 80% coverage.
I picked up a few M8 (1) all thread rods a while back and have used some of this stuff for fixing for which I usually use 7.1 mm drills.

[RayG]

Guess that makes me a clown then. Out of interest how close to size does the hole need to be? perhaps we should be reaming them before tapping?


While Dormer drills in 0.1mm steps might be great if you had a few 1000 holes to tap at say 600 an hour(when you would mosy likely be using way less that full thread depth unless you happen to have an all singing all dancing tapping machine and by that I dont mean a tapping head in a mill or a cordless drill:p). Its really a little over the top for your average guy in his shed. Though being a little over the top doesnt stop most of us.


:D Should we start on thread strenght of dia cut threads v roll formed?

Stuart

Sorry for the late membership application, been sweltering at a blacksmith clearing sale.. but any are there any vacancies left in the clown club?... :)

Oh... and roll formed are stronger because... :D

Ray

[pipeclay]

This is getting a little anal for a backyarder.

[Bushmiller]

Whitworth may be "antique", but up until last year the majority of the nuts and bolts in Bunnings for example were Whitworth so a lot of workshops still abound with Whitworth bolts. I certainly wouldn't call them a "specialised" thread.

Fred

And they are normally cheaper than the equivalent metric size. I had originally thought it was because they were clearing backlogs of stock, but it's been going on for twenty+ years now.

Regards
Paul

[Stustoys]

but any are there any vacancies left in the clown club?... :)

Plenty of room, all welcome.

Lots of shiny new things I hope?

Stuart

[Bushmiller]

Brett

You certainly have a knack of posting threads that move along quickly :). That's those that survive of course :rolleyes:. Anyhow I didn't come online to be mischievous :wink:.

I just thought I'd add my twopennyworth, which accurately sums up it's value. There is something missing in all this wealth of information.

I know.

There's no pictures :(. How do you expect me to understand what's going on without pictures. Even my two volume dictionary has pictures (Oxford Illustrated for duffers and other illiterates.)

This was my first set in the orange box plus a few extra taps and dies thrown in. It was a cheapie and is over thirty years old. I have damaged a few taps, mainly in the smaller sizes, but I think I was lucky and I wouldn't recommend anybody buy one of these. There is an exception to that if you are mainly cleaning up old damaged threads. The set was metric and included both coarse and fine metric up to 12mm

302640

The reason for fine threads is engineering. They are stronger than the coarse threads. As others have said, almost inevitably you come to do a specific job and you don't have the right tap or die. I keep meaning to buy a basic imperial set, but have never quite got around to it. Hence the recommendation to buy a basic set and then supplement as you need. Like this:

302641

As already stated these will normally come in sets of three, which progressively increase the amount of cut. I think those pictured are P & N.

More recently (ten years ago?) I decided to buy a larger general purpose set. This is it:

302642

It looks fine, good price (about $100 or so I think) but it has been something of a disaster. The larger taps and dies are reluctant to cut anything harder than Gidgee and this is what can happen to the smaller taps:

302643

That is not a spiral tap, but is has spiraled :((. The blank spots in the set above are where the taps broke. Carbon steel for this application only cuts cake.

So more recently again I invested in a HSS set. Small with just the common metric sizes and three taps to each dimension. Again about $100, this time from Carbatec.

302644

Much better. Then just buy extras as you need them, but that can be quite expensive. I should add that this is not a high end set, but in HSS it is adequate for my limited use.

An example of a custom buy was this from the McJing stand at the last WWW show in Brissy:

302647

30 x 3.5mm tap and die suitable for a lathe headstock. Still unused :-.

Finally this is a tapping drill. Really it was more about the drill than the application. Lesto made these in the fifties and early sixties before they were bought out by Bosch. (Lesto themselves were famous for pioneering the jigsaw). I rather like them and have two straight drills, a screwdriver and this tapping drill. They all look the same until you get to the business end.

302665302666

I haven't had the courage to use it in anger yet.

Ok, that's it. Everybody can have a read now not just the literary geniuses :D.

Got to get back and work on the cave. 1646hrs: It might have cooled down.

Regards
Paul

[cba_melbourne]

There was some more info on this older thread:
http://www.woodworkforums.com/f65/tap-die-sets-tap-magic-175791/

[cba_melbourne]

Out of interest how close to size does the hole need to be? perhaps we should be reaming them before tapping?
Stuart

The smaller the thread, the more accurate you need to size the hole. On sizes below M10 you can certainly feel a difference in torque required, for every change of 0.1mm in drill diameter. Once you go below M3, a change of 0.1mm can mean the difference between a tap breaking or not. I would say that if working on small scale workpieces and doing metric threads, a 0.1mm increment drill set up to 6mm is a necessity. From there up a drill set 6-12mm in 0.1mm increments is desirable, but if too expensive can be replaced by a 0.5mm increment set PLUS a small number of additional single drills in 0.1 increments to cover the ranges required for M8, M10 and M12 taps and a few 10ths above.

And yes you are right, one should indeed ream holes that are to be tapped with tapered pipe taps :D such as NPT for air and oil lines.

[Grahame Collins]

I need to purchase a fairly simple Tap & Die set to use for odd jobs. I will need Imperial as well as Metric, and just in the common sizes, although it would be very useful to add a specific size on demand.

I imagine that I would be using them mostly on Mild Steel, but I guess there would be enough occasions where I wouldn't be able to determine what the steel is (I need to put a thread on this particular rod so as to fit an M8 nut - who knows what the rod is).

Looking at the McJings site, they have a fairly good selection, (https://mcjing.com.au/categorybrowser.aspx?categoryid=50)and a few questions come out of that:
HSS or High Carbon steel? It doesn't have to be fantastic for the amount of use it will get, but "lasting for more than one use" is desirable (I've experienced Chinese steel in drill bits - never again)
When it comes to Imperial there are a few different thread options in BSW, UNC, UNF etc. Is BSW the standard "garden variety"?
Are the McJings T&Ds of reasonable quality? If not, what would you recommend?
Looking at the Metric versions there, the seem to have two different pitches for quite a few of the diameters (e.g. M6 can be either x0.75 or x1). Is it the larger pitch that would be regarded as the standard?

Any and all pointers and help appreciated.

Despite the extra cost ,HHS is the set I would be inclined go with as I do a bit of tapping in stainless less and carbon steel taps are really not up to work in stainless for any period of time. However it is your pattern of use that would dictate the purchase. If you are going to use them with a lathe, the type with a center make axial alignment an easy task.

Choose a name brand of a well known manufacturer. I would be looking a buying taps & dies as I needed them paying attention to the wrenches and handles as those from even some of the better brands have some bloody annoying characteristic. The adjustable tap handles are a pain in the rrse as the non adjustable side will unscrew.
If a set is better to your liking a set of Gear wrench taps and dies made in Taiwan are very good value around the $80 mark but be aware the dies are button dies -no slit in the die nut.The up side is the the handle system is superb.
I would include a pic but cook wants me to go out with her so maybe later.

Cheers
Grahame

cheers

[FenceFurniture]

There's no pictures That's great Paul - thanks very much for going to that trouble!

Yairs, it has moved along quickly hasn't it? Stacks of good info though. I suppose pipeclay is right in that there's a lot of info there for a backyarder to digest, but that's ok, I can just filter it when it goes into the rabbit hole, and retrieve when necessary.

Graham - yes a pic of your set would be excellent please.

[Ueee]

I suppose pipeclay is right

Oh god please don't encourage him!

Ew

[morrisman]

If a set is better to your liking a set of Gear wrench taps and dies made in Taiwan are very good value around the $80 mark but be aware the dies are button dies -no slit in the die nut.The up side is the the handle system is superb.
I would include a pic but cook wants me to go out with her so maybe later.

Cheers
Grahame

cheers

These the ones ?

Gear Wrench 40pc TAP DIE | eBay (http://www.ebay.com.au/itm/Gear-Wrench-40Pc-Tap-Die-/171058134213?pt=AU_HandTools&hash=item27d3dbfcc5)

[variant22]

These the ones ?

Gear Wrench 40pc TAP DIE | eBay (http://www.ebay.com.au/itm/Gear-Wrench-40Pc-Tap-Die-/171058134213?pt=AU_HandTools&hash=item27d3dbfcc5)
I have that exact set. I never use the taps or dies. I do however use the ratcheting tap wrench frequently. That alone is worth every penny of the $75 (inc postage) that you pay for the set.

[Grahame Collins]

Fence furniture,
Morrisman has posted the pic for us,ta Morrisman!

Theyare the set I have, and look at the bloody price :o. I paid $80 and thought I got them cheap:doh:. After fritzing around with some of the standard tap and die handles the Gear Wrench set are a pleasure to use as the handle is made to fit both the the die unit or the tap unit, both of which snap in.

The handle has a reversible ratchet built in and looks and feels like a bit of quality kit.
It is a wholly metric set and there is a imperial UNC/ UNF one available as well.

The vacuum moulded box has the home aperture for each tap and die named so you know exactly where to put them back.

The woeful set I got from H &F around the same price, have the dies fall out when you close the box.

Grahame

[Ueee]

Of course you can buy just the wrench etc but it is more than the set Mike linked above. KD Tools 5 Piece Gear Wrench TAP AND DIE Adapter SET Sold AS Each | eBay (http://www.ebay.com.au/itm/KD-Tools-5-Piece-Gear-Wrench-Tap-and-Die-Adapter-Set-Sold-as-Each-/310839477271?pt=LH_DefaultDomain_0&hash=item485f7a0417)

Ew

[FenceFurniture]

Well Graham, by all accounts that would appear to be the way to go for a starter kit, and maybe add on a few imperials because I only really need a few sizes in them (1/4, 5/16, 3/8). More than likely I'd be doing them by hand as I don't run a conventional drill press (and they'll be few a far between as far as I can see).

What say the collective wisdom? To make it easy you could just give Graham's last post or Morrisman's post a "like".

[FenceFurniture]

Of course you can buy just the wrench etc but it is more than the set Mike linked above. KD Tools 5 Piece Gear Wrench TAP AND DIE Adapter SET Sold AS Each | eBay (http://www.ebay.com.au/itm/KD-Tools-5-Piece-Gear-Wrench-Tap-and-Die-Adapter-Set-Sold-as-Each-/310839477271?pt=LH_DefaultDomain_0&hash=item485f7a0417)

EwYes, it briefly crossed my mind to make variant22 an offer, until I realised just that!

Hmmm, :think: although I could buy the imperial set and have the handle and then pick up the metrics that are not used........surely the handles would be the same (either metric or imperial hole.....otherwise they'd have to make two different ones, which wouldn't make any sense)

[Bushmiller]

Correction.

Mr. Alzheimer let me down badly. The HSS set I purchased was from Hare and Forbes, not Carbatec ( Advertising executives of both businesses can PM me for bank details if they wish to voice their thanks in the time honoured manner :rolleyes:).

Having said all that, I suspect (but don't know), that equal deals are available out there and reading subsequent posts that would appear to be the case.

I have to say I am not up to speed on such things although I am not back in the dark ages. I did hear however that George V1 has passed on and some bird is on the throne.

Regards
Paul

[FenceFurniture]

Interesting. When you go to the Gasweld website the Metric set is still (http://www.gasweld.com.au/3886-gear-wrench.html)$63, but the 40 piece Imperial (http://www.gasweld.com.au/3885-gear-wrench.html) is $95. I guess that's because they make far fewer Imperials.

Looks like the Imperial set would cover what I need - UNC & UNF in the common sizes, but your comments are appreciated, as always.

[NCArcher]

I go past that particular Gasweld every time I go into Newcastle for work. :D
Give me a yell if you want me to pick something up.

[FenceFurniture]

Chaps, a couple of Qs on that Gasweld set:

I've looked and looked and I can't see what steel they are (and you'd think they would mention if it was HSS).
Maybe it's been mentioned in today's plethora of posts, but Graham when you say they are button dies, so no slit, what is the implication of this please?

Cheers
Brett

[Grahame Collins]

The dies with the slit in em ,make for adjustment of the cut thread.

Meaning you can make the cut male thread tighter or loose to custom fit the thread to the nut,within in a small range of course.

Yes are carbon steel but appear to be a good quality. I use the 6mm die on stainless rod all the time and its still cutting well after a year or so.


Here's some helpful stuff about dies

dies - ICS Cutting Tools (http://www.icscuttingtools.com/Dies.htm)


Grahame

[BaronJ]

Hi Brett,
Have just come back from Aldi's, & I saw a set there.
Never took a great deal of notice, looked up their Cat. but there was nothing there.
My guess wood be that it maybe up to ½"- 12mm.

I've just recently bought a set of those from Aldi. The tapping size drills in that set are HSS and are split point. The taps seem to be HSS as well but don't have any indication on them, neither have the dies.

Other than that I've only used one tap from the set, M4 in BMS. It cut easily and left a clean, sharp in appearance thread. Having said that I would buy taps and dies as needed for repair work. Any new work I will stick to metric.

[Toggy]

Geez Ewan, Ray Phil; you guys are just as warped as me.:D
I must be in good company.

Ken

[RayG]

This method will produce holes that are generally too tight and can lead to broken taps.

The other commonly use ROT is Bolt Size - 10% of bolt size, but both are only ballpark figures

The Tubal Cain (TC) book recommends 5.35 mm holes for a 60% or loose fit down to 5.1mm for an 85% (tight) fit - the "British Standard" sizes are 5.3, 5.2 and 5.1 mm
So the -10% rule (5.4 mm) is too loose and the Size - Pitch rule (5 mm) will be too tight

M8 (1.25) TC recommendation is 7.2 mm for a 60% fit down to 6.9 mm for tight fits.
-10% rule (7.2mm) is on the loose side and Size - Pitch (6.75 mm) is too tight.

M10 (1.5) TC recommends between 9.2 and 8.6 mm. -10% rule is OK but Size - Pitch (8.5 mm) is too tight.

M10 (1.25) does not have an entry in TC but all sizes can be worked out using a formula on P92 of the TC book.

Diameter of bolt - 1.083*Pitch * % flank height/100

The % flank height is ~10% greater than the engagement, so a 60% engagement is around 50% flank height.
This will allow you to work out what ever you want.

I disagree....

Just sticking with the M8x1.25 for this calculation,

Drill Size = Basic Major Diameter of Thread - [% of full thread * Pitch] / 76.98 ..... ( Black Book page 22 )

So for a M8x1.25 60% ( loose fit ) Drill Size = 8.0 - [ 60 * 1.25] / 76.98 = 7.0 mm not the 7.2 mm quoted above.. 75% fit gives the standard drill size of 6.8 mm

Tubal Cains recommended drill size of 7.2mm gives only a 50% engagement flank.

Regardless of his errors, I'd dispute the assertion that tapping for a loose fit is a good way to stop breaking taps, starting square and not bending the tap seem to be more sensible approaches.


Ray

PS... On re-read I see that we might be swapping %flank height for %engagement when referring to fit? PC might be correct, this is getting a bit anal for home workshop applications...

[BobL]

PS... On re-read I see that we might be swapping %flank height for %engagement when referring to fit? PC might be correct, this is getting a bit anal for home workshop applications...

Yep - that's what is happening - the BB and TC equations are the same if the same parameters are being used.

Warning - NERD alert!
These equations come from the ISO specification for the metric thread (see ISO metric screw thread - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/ISO_metric_screw_thread))
A 100% contact has the equation Drill size = Diameter of bolt - 1.082532*Pitch
A less than 100% contact, Diameter of bolt - 1.083*Pitch * % flank height/100
End NERD alert

Here is the TC chart I use - only a range of tapping drill sizes for the coarser threads are provided but any others can be worked out from the equation provided.

http://www.woodworkforums.com/attachment.php?attachmentid=302758&stc=1

[morrisman]

Hi

A theory : If your spindle or chuck ( therefore drill shank )has any amount of runout, then the drill chart figures would not mean anything ?

It may be worthwhile measuring your drilled hole to see if it is actually the size you are wanting ... the smaller sizes may need one of those expanding ball devices ( small hole gauges ).

Mike