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IanW
27th April 2004, 03:20 PM
I was asked for details of my threading jig in another thread, so I'm posting it here. Because I can't attach more than one image to a message, I'll have to do this in several posts, so here goes: Section 1
All threading starts with a tap – once you have that, you can soon make a jig for your router which will thread any wood you can feed to it. There are quite a few possibilities. Metal taps would certainly do the job, but wood threads work better with fewer threads per inch than metal, for a given screw diameter. Taps specifically for wood aren’t easy to find, unfortunately. If you are a dab hand on a metal lathe, you could make one for yourself – mild steel is perfectly ok for threading wood. About 6 threads per inch is good up to one inch diameter screws, and 4TPI is better for larger diameters. Here are a couple of other solutions:
1. I saw this in an English magazine about 12 yrs ago, and had to try it. Pull the guts out of an old brass water tap – the style that didn’t use O-rings to seal the shaft. Cut a slot down the centre of the threaded part at the end, then chuck it in your drill-press or wood lathe. Spin it slowly towards you, and use a file to taper the end for starting. Because the threaded part is so short, you can’t allow much lead-in, unfortunately. Relieve the threads a bit on the side of the slot opposite the cutting edge, and you have a tap which will thread wood quite well. The only problem is that the thread is a little fine, but the clamps I made with my tap from a tap are still in regular use.
2. I wanted 2” and a 1 ½” taps, so made them by turning up a wooden blank, then chasing a suitable thread on them. After tapering off the thread, I drove in a bunch of 12G and 14G screws in a spiral pattern, which were clipped off and filed into cutters to match the profile of the thread behind them. It actually works, but it’s hard to make enough room in front of each cutter to allow chips to clear. You must back out after each half to ¾ turn to clear it. Slow going, but it does a good job in woods up to medium hardness, such as Mountain Ash.
Both taps are shown in the picture, along with two steel taps; a home-made 1 inch, and a factory made ¾ inch.

IanW
27th April 2004, 03:25 PM
Section 2.
Once the tap part is solved, you need some way of making screws. The easiest way is to use a router with a simple jig as shown. Two pieces of wood are squared and screwed together. One is then drilled to the major screw diameter, the other to the minor diameter, and tapped. Cut a generous access hole in the bottom for a 60 deg. (or whatever matches the thread profile of your tap) veining bit and plane the tapped piece down until you can position the bit just to the right of the beginning of the first thread.
The jig is shown opened, with the veining bit taken out of the router, and placed in the approximate position to cut thread.

IanW
27th April 2004, 03:28 PM
Section 3.
Clamp the tapped piece to your router base, and adjust the height and position of the bit, so that as it cuts a groove in your blank, this feeds onto the thread, and pulls the screw in at the correct pitch as the router cuts more thread. Now screw the piece with the guide hole back in position, and you’re ready to go. It takes a bit of practice to feel the bit bite as you feed in the blank, and start the thread cleanly – you may need to back out and trim off the daggy bit of thread, but once you have it feeding cleanly, you should be able to screw it in easily with the tips of your fingers as the thread is cut – if it binds, either your blank is too big, or you have the cutter a bit off – adjust accordingly.

silentC
27th April 2004, 04:18 PM
Excellent stuff, Ian. Keep it coming!

I especially like the router jig. If you had something threaded at the right pitch to begin with, you could make the tap this way and then go from there. I suppose there must be old things around somewhere that have a decent 1" to 2" thread that could be used. I think that would be a better result for me than trying to chase the thread on the tap by hand.

journeyman Mick
27th April 2004, 10:44 PM
Great stuff Ian, one of these days when I have the time (yeah, when?) I'll give this a go.

Mick

bitingmidge
27th April 2004, 11:08 PM
Ian,

Great stuff...saved me asking the question!

From your experience would it be possible to get a satisfactory result by filing notches and tapering steel bolts and nuts of these sorts of dimensions?

I have often tapped smaller diameters in timber and MDF using this method, but figured the thread would be too fine at the larger scale.

I guess for the cost of a 35mm nut and bolt it won't cost much to find out!

Thanks for the info,

Regards,

P

IanW
28th April 2004, 08:40 AM
Midge - yes, using a bolt or coach screw is another alternative tap solution. As you say, it's a question of getting a coarse enough thread. I've tried coach screws - right pitch, but the sharp, fine lands aren't so ideal. I think by the time you get into 2" in Whitworth, it gets down to something like 4 or 5 TPI. I don't get as mystical about it as some, but a wooden screwed tail vise is fun to make and works so well, you'll be pleased you made the effort. When well-made and waxed, wood screws run very smoothly and satisfyingly.
If you are wondering about strength and durability - I've been using one vise for close to 20 yrs, and it shows no sign of wear. I have stripped a couple of badly-made clamp jaws, and had the thread on a few screws crumble because the material was faulty or simplly unsuitable, but we have dozens of woods here that make excellent threading material.
Later tonight or early tomorrow I'll post a couple more bits on clamp-making - no tiime just now...
avagooday

IanW
28th April 2004, 11:29 AM
OK - I managed to find a couple of minutes to fiddle with these, so here are the short primers on clamp-making as promised.
1. Handscrews.
Making wooden clamps is pretty straightforward. Some of the woods I’ve tried successfully for screws are: Casaurinas, Acacias, River Red gum, Red Stringy, Bush Cherry (Exocarpus), Red Penda, and others I can’t think of right now. Some exotics like Apple and Desert Ash turn and thread very well if you can get your hands on them. I turn the blank in one piece, and make the shaft a loose fit. In general, wood threads need to be a bit sloppy compared with metal, to cope with seasonal movements.
Scraps of just about anything make jaws, but softer woods will be less likely to mar work. Even Radiata pine will do, and certainly meets the criterion of being soft. None of the dimensions is critical, but each has an effect on the function. I’ve settled on three ‘standard’ sizes. The most useful size for the sort of work I do most uses ¾ inch screws with about 300 mm of thread. Jaws around 200-250 mm long and 50 mm deep give you a maximum clamping distance of around 200mm. Clamps this size can apply a surprising amount of pressure, more than enough for any adequately-made joint, but if you want more squeeze, just apply more clamps.
The 1” diameter screws are used for clamps with 300mm long jaws, and a total clamping capacity of a little over 300mm, while my little ½” jobs have jaws about 125-150mm long and open to hold about 100mm.
These clamping capacities are also pretty much the practical limit of the material as the screws are easy to break when working at maximum capacity. Well-made threads do not strip easily, but you will bend and snap the bottom screw if you tighten jaws much off parallel, but with a modicum of care and attention, you soon get used to them. About the only time I have busted clamps in the last 12 yrs is when the dog knocked over a piece of work bristling with clamps and snapped of several of the exposed ‘pusher’ screws.
Make jaws as wide as you can, not only for strength but to minimise bruising of work pieces. One jaw has both holes tapped, the other has a shallow hole at he top (inside) for the ‘pusher’ screw, and the centre hole is the full diameter of the screw.
When assembled, handscrews are opened and closed quickly by holding both handles firmly, flipping the whole thing towards or away from you, then ‘pumping’ as if you were working bicycle pedals to keep unscrewing or closing. (It’s easier to do than explain!)

IanW
28th April 2004, 11:30 AM
2. Bar clamps
Sash (bar) clamps are a very useful item, but are a bit more fiddly to make than handscrews. If you want the travelling jaw to open when you unscrew it, you need some way to capture the end of the screw in the jaw. This is most easily done with a couple of tongues which mate with a groove turned in the end of the screw, held in place by the side covers. I’ve shown this with the side cover off in the second pic, and a screw end from another clamp above. The side covers also have guides which ride in grooves in the bar to keep the jaw aligned as you tighten it. Glue the guides on in-place, then take the sides of and put a few counter-sunk screws in from the inside to reinforce them.
A couple of strategically-placed dowels reinforces the headstock (next pic).
The loose side arrangement for the rear jaw keeps the face vertical to the bar as it is tightened (last pic). The threaded pin is a bit elaborate – a simple dowel would suffice.
The clamp shown has a bar of Bull Oak – a bit of overkill – any good (i.e. not too splintery!) hardwood will do fine, sized accordingly to the length. I’ve only made them up to about 600mm opening, using 1 inch screws. I’m ‘getting around’ to making some whoppers with 1 ½” screws and maybe 1800mm capacity, someday.

AlexS
28th April 2004, 07:37 PM
Ian,
Thanks for that excellent information...make me want to give it a go.

echnidna
28th April 2004, 08:18 PM
Great tools Ian.

What did you finish them with?

IanW
29th April 2004, 08:25 AM
Echidna,
Oil 'n' wax.
The wax is the essential bit - stops glue from sticking to bits you wouldn't want it to. I give them a yearly waxing (every three years or so!), paying most attention to the threads, which I do with a toothbrush. This keeps them running nicely, and prevents any accidental glue drops from doing damage. As I said somewhere above, a drop of glue in raw threads will produce a pretty powerful joint!. All my clamps are overdue for some TLC, I'm in the middle of a move, which requires building a new w'shop. As always, it is taking much longer than anticipated.......
Cheers,

bitingmidge
29th April 2004, 07:10 PM
Here is a link to the only page I have been able to find on the Web with any useful non-commercial information:Cutting Wooden Threads (http://www.ilovewood.com/alburnam10.htm#Threads)

The whole site has a number of areas which may be of interest, go to

ilovewood.com (http://www.ilovewood.com/) and check out some of the links...the above is found in the Alburnam's Archives section.

Cheers,

P

gatiep
29th April 2004, 09:05 PM
Has anybody here tried the Hamlet or Sorby thread chasing tools for woodturning?

Thanks
Cya
Joe

bitingmidge
12th July 2004, 05:11 PM
Has anybody here tried the Hamlet or Sorby thread chasing tools for woodturning?
I guess that's a no! :D

Hey IanW (or anyone else that's knows ).....what's the best method of making dowels for threading?

I have found a few options, involving setting up large scale pencil sharpeners, and belting timber through ever decreasing holes drilled in steel, but was wondering if turning was an option (Now that I have a lathe!!).

Is it feasible to build a router jig to make this quick and easy, or is there some other way?

I am talking 3/4" to 1 1/2" threads, with the bigger ones at about 600 long, the smaller probably 450 Max.

Thanks,

P

Sturdee
12th July 2004, 06:18 PM
Is it feasible to build a router jig to make this quick and easy, or is there some other way?

I am talking 3/4" to 1 1/2" threads, with the bigger ones at about 600 long, the smaller probably 450 Max.


Yes there is.

Patrick Spielman in one of his books on routing describes a homemade jig that he built to do that. Try your library, if they don't have it I could get a copy of it for you.


Peter.

IanW
13th July 2004, 08:50 AM
Midge,
Yeah, I turn them. I'm a reasonably adept spindle turner, so I can do it pretty quickly, but it took me a few hours to master turning long, whippy spindles for the 3/4" clamp-screws when I first tried it. However, it's a good way to learn, and if you ever wanted to get into chair making, you'd have a flying start. As to chasing threads, it's easier than you might think, for short lengths like container lids, but pretty difficult to do over a long length like a bench screw. (I'm much to tight to even think of buying chasing tools, though - you can make them very easily if you really wnated to do it).
What you really need is a suitable TAP - that's the essential item, and once you have that, you can make a router jig for threading screws in something under 10 minutes. This system beats the pants off the old traditional threading tools, which turn their noses up at most of our semi-petrified timbers.
Y'know, it's hardly worth getting into threading unless you really get the bug like I did a few (20?) yrs ago and just want to try out everything that looks threadable. Since you only want a few screws to use for your bench and make some (lots of?) clamps, it's probably better to bribe somebody like me with a coupla stubbies and an afternoon of your one-liners, and make enough to do what you want plus a couple of spares!?
The hardest part is getting hold of suitable taps, unless you have a friend who's a dab hand on a metal lathe - which is how I come by mine - :D
The next hardest job is finding nice dry bits of suitable wood for the larger screws. There are lots of good threadable woods, but some are hard to dry in bigger chunks (like she-oak, for e.g.).
My suggestion is to go with 2" for your tail vise, though I have used 1 1/2" successfully on smaller benches.
If you're getting really serious about this, PM me and we should be able to work something out.
Cheers,

bitingmidge
13th July 2004, 09:00 PM
Sturdee,

Thanks, I have checked and our local library stocks all Spielman's books...have you any idea whether it was a router or lathe one? Doesn't matter, I'll get around to them all eventually!


Since you only want a few screws to use for your bench and make some (lots of?) clamps, it's probably better to bribe somebody like me with a coupla stubbies and an afternoon of your one-liners, and make enough to do what you want plus a couple of spares!?

Ian,
For what I have in mind it'll need a carton of Crownies and an afternoon of Ocean-Liners!

I'll get back to you in a month or so, or maybe catch up at the next Brisso Love-In!

Many thanks,

P

Wayne Davy
13th July 2004, 10:55 PM
Ian,

Great job on the instructions - you are an inspiration. I want to build myself a real nice workbench one day and intend to incorporate the traditional front and end vices with wood screws. (One day - sigh).

GregLee
13th July 2004, 11:20 PM
The Spielman New Router Handbook has the dowel making jig. It is at the beginning of Chapter 17 on page 201.

Here is a link to the book (http://www.skillspublish.com.au/BK09-06.htm)

I made the jig to make dowels for plugging screw holes and pinning mortises. Work well.

IanW
14th July 2004, 08:59 AM
Wayne, and Midge,
Sounds like a bench/clamp making bee could be in order in a month or three? My day job is going to have me running pretty ragged for the next few months, so I won't be as available as I would like to be, but I'm sure I could fit in an afternoon somewhere, helping to get a keen wood-threader started. If you can come up with suitable bits of wood, we can soon do something useful with them. I've found the most useful clamps for the sort of work I do to be the ones using 3/4" screws. They open about 200-250mm, which is about the limits of the material. That means you need about 300- 350mm for threading plus handle, say about another 100, so yep, 450mm sounds about right. (And about 30mm square or a little more for the handle). I've tried quite a few Eucalypts - Red Stringy and River Red Gum were good, most Acacias are excellent, She Oak and River Oak are also good (if you can get them dry in one piece!) and there are several other odd species that are really good like Bush Cherry (Exocarpus sp. - grows into bigger trees down south, the ones I've seen up here are pretty miserable specimens). For the jaws, anything goes, and the softer the better (almost) - the threads in side-grain are much tougher than the ones on the screw.

And Wayne - the sooner you build that bench, the sooner you'll ask 'why didn't I do it years ago?'. Yeah, I know, same reason I took 15 years to build the first 'real' bench - not enough bleedin' hours in a day. My first try at a serious bench had a 'travelling dog' instead of a tail vice, and that was such a revelation I immediately started plotting to build a second, with a real tail vise. That took only 5 years gestation, and it has now served me well for a good 18 yrs or so. I would have liked to incorporate a European style front vise, too - they have several advantages over the Record style, but they have one big disadvantage - the amount of space they take up in front. I've never had the luxury of enough space to contemplate having that great long screw sticking out the way it does. My stud days are well and truly over, but a bloke could still do some evil damage, there! So I've decided my next and final bench (which I'm going to make only because I have some great bits of hardwood that would be a pity to waste on anything else) will have a quick-action front vise as a compromise. To tell you the truth, I hardly ever use the front vise, anyway - more than 80% of the work I do uses the tail vise in one way or another.
OK - we can take this up later when the time is right...
Cheers,

the Padma
17th December 2008, 04:17 PM
once upon a Long time ago, in our distant future when electricity and routers didn't exist, treading dowels was done like this.... http://www.wgtoolco.com/sb.html

blessings
the
Padma

the Padma
17th December 2008, 05:41 PM
go here and see drawing on how to hand cut threads (not hard at all) and how to thread the nut (a bit of a hassle)

Blessings
the
Padma


http://books.google.ca/books?id=dDbKtdJAZU4C&pg=PA123&lpg=PA123&dq=wood+tap+and+screw+box&source=web&ots=6eVnttOCaI&sig=uB_6rUL3d7XszyhO0uyQ76CwRh8&hl=en&sa=X&oi=book_result&resnum=8&ct=result#PPA123,M1

silentC
17th December 2008, 08:17 PM
That's a blast from the past!

The thread I mean.

No, that still isn't clear :)

IanW
18th December 2008, 09:18 AM
That's a blast from the past!

The thread I mean.

No, that still isn't clear :)

I think I know what you mean. :;

Amazing how things come back to haunt us!

:U

ddeen
26th December 2008, 01:35 PM
Ian, thanks for this great thread. I would like to try it out. One thing I cant figure out is how you feed the wood to the router. Do you hold the router with one hand and feed the dowel with the other ? Sorry for the dumb question.

IanW
26th December 2008, 04:45 PM
Ian, thanks for this great thread. I would like to try it out. One thing I cant figure out is how you feed the wood to the router. Do you hold the router with one hand and feed the dowel with the other ? Sorry for the dumb question.

Ddeen, the router is clamped in my tail vise. That way I can twist the dowel in using both hands to keep a nice, even feed rate. You need to have the setup fairly secure. If you have a vacuum setup to remove the sawdust it helps, too.
Cheers,

mick foxall
7th January 2009, 02:44 PM
I was asked for details of my threading jig in another thread, so I'm posting it here. Because I can't attach more than one image to a message, I'll have to do this in several posts, so here goes: Section 1
All threading starts with a tap – once you have that, you can soon make a jig for your router which will thread any wood you can feed to it. There are quite a few possibilities. Metal taps would certainly do the job, but wood threads work better with fewer threads per inch than metal, for a given screw diameter. Taps specifically for wood aren’t easy to find, unfortunately. If you are a dab hand on a metal lathe, you could make one for yourself – mild steel is perfectly ok for threading wood. About 6 threads per inch is good up to one inch diameter screws, and 4TPI is better for larger diameters. Here are a couple of other solutions:
1. I saw this in an English magazine about 12 yrs ago, and had to try it. Pull the guts out of an old brass water tap – the style that didn’t use O-rings to seal the shaft. Cut a slot down the centre of the threaded part at the end, then chuck it in your drill-press or wood lathe. Spin it slowly towards you, and use a file to taper the end for starting. Because the threaded part is so short, you can’t allow much lead-in, unfortunately. Relieve the threads a bit on the side of the slot opposite the cutting edge, and you have a tap which will thread wood quite well. The only problem is that the thread is a little fine, but the clamps I made with my tap from a tap are still in regular use.
2. I wanted 2” and a 1 ½” taps, so made them by turning up a wooden blank, then chasing a suitable thread on them. After tapering off the thread, I drove in a bunch of 12G and 14G screws in a spiral pattern, which were clipped off and filed into cutters to match the profile of the thread behind them. It actually works, but it’s hard to make enough room in front of each cutter to allow chips to clear. You must back out after each half to ¾ turn to clear it. Slow going, but it does a good job in woods up to medium hardness, such as Mountain Ash.
Both taps are shown in the picture, along with two steel taps; a home-made 1 inch, and a factory made ¾ inch.

Ian, what do you use to cutthe matching threads? Tks.

IanW
7th January 2009, 08:48 PM
Ian, what do you use to cutthe matching threads? Tks.

Mick - a tap. Somewhere in the thread it's mentioned that you begin with a tap suitable for wood threads. Those are not easy to come by on their own, nowadays, so you may have a bit of a search, unless you have access to a metal lathe & know how to drive it...
Cheers,

QC Inspector
18th January 2009, 07:33 PM
A little over 3 years ago I posted on the Knots forum another way of cutting threads as an answer to making big threads. Turned out he was after a "screw" for a wall sculpture so my method wasn't what he was looking for. Rather than link to it I'll copy and paste from the notes I kept and re-post the pertinent info here so that the non-Knots members on this forum can view it. (If that's okay with you?).


<style type="text/css"> <!-- @page { size: 8.5in 11in; margin: 0.79in } P { margin-bottom: 0.08in } --> </style> Threads can be cut very nicely on the table saw however. You'll need to make a jig, get a special blade made up, or use a molding head with the appropriate blades ground for it, and you will need a wood tap of some kind.


About 20 years ago when my father was living with me, (he is still alive), he was trying unsuccessfully to cut 1 ½ inch threads with the traditional thread box that I was never able to get to work. I said we should use a router, and he disagreed and said, "No the table saw's better because the larger diameter cutter will cut cleaner". I had a profile blade that came from a window factory, that was probably used for cope and stick work. I took it to a saw filer and had him put new carbide tips on, and grind a 60° angle on it. .......Then my father proceeded to play.


Photo #1 shows the blade that I had reground, a 4 inch diameter thread, and an off cut from a 1 ½ inch diameter one.


Photo #2 shows the blade in the table saw. It's about 7 ¼ inch in diameter and 3/8 of an inch thick. I don't remember the cost. But it wasn't all that outrageous, because it was something different, and he enjoyed doing it.


Photo #3 is of one of the jigs. The two blocks are for different diameter threads of 5/8 and a 3/4. They are at the angle needed to present the proper pitch to the blade. The jig is clamped over the “thread” blade to use, and is rotated 180° to select the other size.


Photo #4 is the bottom of the previous jig. As you can see, little time was wasted making fancy jigs. Only what was necessary to get the job done.


Photo #5 shows a portion of a second jig of 1 inch and 1 ½ inch diameter, with the latter in front of the blade.


<style type="text/css"> <!-- @page { size: 8.5in 11in; margin: 0.79in } P { margin-bottom: 0.08in } --> </style> Photo #6 is a bottom shot of the jig in photo five.


Photo #7 shows the jig over the blade with the unthreaded side towards the camera, and the threaded part of the jig on the far side. In use, with the jig centered and clamped over the blade, the dowel is started in the near side of the hole and turned against the rotation of the blade. The freshly cut portion of the thread engaging in the far side and drawing the dowel through. The blade is raised or lowered to control the fit of the thread as needed.


Photos #8 & #9 show some of what was used to cut the 4 inch thread. Since I don't have a jig for it, I believe it was done with the miter gauge using the “comb” to control the advance of the thread.


Photo #10 shows the “tap” used to cut the 4 inch threaded hole sitting behind it, the other sizes were cut with wood taps. It was a section of thread carved out to accept a quarter inch electric in-line grinder, that had a small 60° three wing cutter, positioned at the left end at the start of the thread. Way better than a tap for cutting large threads. If I were going to make one now. I would use one of the imported quarter inch, air powered, long nose die grinders. A simpler shape to carve out and smaller in diameter. Plus the airline fitting would rotate and not tangle as much as an electric cord does as the “tap” is advanced into the wood.


An Acme style thread may be possible, using a saw blade or dado blade in the table saw, and a slotting cutter in the grinder. I can't say for sure because we never tried it.

rhancock
23rd June 2009, 08:39 AM
For reference purposes to help those searching this topic, there's some more information in this thread (http://www.woodworkforums.com/showthread.php?t=91959).

Woodlee
23rd June 2009, 10:23 PM
Sturdee,

Thanks, I have checked and our local library stocks all Spielman's books...have you any idea whether it was a router or lathe one? Doesn't matter, I'll get around to them all eventually!


Ian,
For what I have in mind it'll need a carton of Crownies and an afternoon of Ocean-Liners!

I'll get back to you in a month or so, or maybe catch up at the next Brisso Love-In!

Many thanks,

P

Its in Speilmans New Router Hand Book ,I made one and made a few 1" and 1 1/8 jarrah dowells.
Bit of fiddling around but it works well .Need two people ,it makes it easier.

Although I was in a tearing hurry , a bit more time and thought it could easily be made into a one man operation.

Kev.