Thread: Which Tap & Die set to purchase?

Originally Posted by Big Shed

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

Originally Posted by cba_melbourne

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.
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

Originally Posted by Chief Tiff

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.

Originally Posted by Stustoys

Guess that makes me a clown then.
Stuart

Guess it makes me a clown as well Stuart

Phil

Originally Posted by cba_melbourne

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!)

Originally Posted by Steamwhisperer

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.

Originally Posted by Steamwhisperer

Guess it makes me a clown as well Stuart

Always room for one more

Stuart

Originally Posted by Steamwhisperer

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

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.

Ken I think the heat is giving my evil thoughts.

Originally Posted by Chief Tiff

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

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

Originally Posted by Chief Tiff

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.

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!

Originally Posted by Stustoys

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.

Originally Posted by Stustoys

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). 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.


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...

Ray

This is getting a little anal for a backyarder.

Originally Posted by Big Shed

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

Originally Posted by RayG

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

Plenty of room, all welcome.

Lots of shiny new things I hope?

Stuart

Brett

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

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

Hand Taps 004.jpg

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:

Hand Taps 003.jpg

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:

Hand Taps 001.jpg

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:

Hand Taps 002.jpg

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.

Hand Taps 005.jpg

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:

Hand Taps 2 003.jpg

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.

Hand Taps 2 001.jpgHand Taps 2 002.jpg

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 .

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

Regards
Paul