Thread: Making a large tap for wood threading

I did it with smaller bolts. I grind slots UP the length of the bolt. 2 or 3 of them is enough. Then taper the end a bit as well. Worked ok cutting a thread for me. Cutting the thread on the wooden bolts is the hard bit.

Actually, once you have a tap, making the thread box (die) is relatively easy. See this video from Roy Underhill.

Hi Mark,

This might help

https://www.woodworkforums.com/f65/ta...hreads-131552/

Stuart

I tried to make one of those with a 1/4 sq carbide lathe cutter but could not get it work properly. I'll be watching to try again. Hate failed projects. All mine did was chew the end of the dowel.

Nice one.

Let me be a little clearer. If I go to an engineering shop and ask them to make me one, what would be a reasonable price?

If we are talking about the beer economy, how many cases?

Shouldnt be hard but 1 or 2 threads per inch is bloody course! I wouldn't attempt it in my own lathe (but I would at work) go to an engineering jobbing shop they can turn your thread, mill the slots and put a square on the end for a shifter/wrench

If you get it made from good steel then it shouldnt need hardening

Originally Posted by _fly_

I tried to make one of those with a 1/4 sq carbide lathe cutter but could not get it work properly. I'll be watching to try again. Hate failed projects. All mine did was chew the end of the dowel.

Not surprised, you would have real trouble getting a sharp enough edge on carbide, the cutter for thread boxes should be a high carbon steel, like 01, and in any case it's tricky enough to set up a thread box like Sir Roy uses with the correct angles anyway....

The other thing, is that some wood threads nicely some doesn't.. wood with interlocking grain seems to thread better. Whatever wood you use, a bit of mineral oil will help the threading.

I made up an attachment to fit a router to the QCTP, and that works well.

Regards
Ray

There are other ways to make large wood threads. Here is a link to an old post I made in a thread (no pun intended ) a long time ago.

https://www.woodworkforums.com/f44/th...tml#post880362

Pete

Pete,

I've read all the threads concerning threads, so to speak...

That is an interesting method you have used but again it is predicated on having a tap to make the die.

So we are full circle back to the subject of this thread. (wow this is getting very confusing

Patrick, Two to three TPI is pretty normal for a wood bench screw of that size.

I'm going to call Coventry Fasteners and see if they can supply large bolts and the cost. Anybody got any other suggestions for a supplier?

Actually the tap is not needed to make the die when the threads are large. In pics 8 & 9 the "comb" was the only thing used to control the advance of the thread while cutting. Lay a bolt on a V-block, turning it into the tip of a pen and watch it move along. That is the principle used to make the big thread.

When you take the dowel and start the cut over the saw blade the newly started thread will engage the comb. It will control the advancement of the dowel until the cut is completed as long as the dowel is held against the comb and onto the saws mitre gauge, a sled, or box positioned over the blade.

The first threaded dowel was used to make the powered tap (pic 10) and then the first nut was made with it.

One of the advantages of using the "powered tap and die" is that you can thread wood that would normally be prone to tearing out. Another is the forces needed to turn them are greatly reduced in comparison to those needed to run a 3" tap into a hard wood.

Good luck with whatever you end up doing.

Pete

Originally Posted by markharrison

Nice one.

Let me be a little clearer. If I go to an engineering shop and ask them to make me one, what would be a reasonable price?

If we are talking about the beer economy, how many cases?

It sure wont be cheap I can point you to a guy who can help you out but he would probably still charge you a coupe a hundred .....sounds like 2-3 hours work but i can see it turning into 5 very easy

Pete, I get it now. I couldn't work out what picture 10 was.

Do you have a picture of the cutter you used in the "tap"? Any ideas where I might buy one?

Originally Posted by markharrison

Pete, I get it now. I couldn't work out what picture 10 was.

Do you have a picture of the cutter you used in the "tap"? Any ideas where I might buy one?

The cutter was from an old carbon steel set my father has and I don't have any pictures. It is like a mini shaper set of 3 wing cutters that can be placed on the little arbour that fits a router to make small mouldings and whatever comes to mind. There was a 60 degree cutter about 1/4 or 3/8 inch wide in the set that he picked to make the 4" dia x4tpi thread. I have never seen a set like it for sale anywhere.

The closest you can get to it now would be a Slotting or Rabbeting bit and it would need to be ground to the 60 degree profile by a sharpening service.

C1044 3/8" Rabbeting Bit, 1/4" Shank

The type of straight-line extension grinder I referred to. Look at the model 18220 or its Asian counterpart.

http://www.dynabrade.com/dyn10/conte...ch=die+grinder

The one my father used at the time was a Makita electric 1/4".

Makita Canada Inc

You have to get creative when breaking into uncharted territory.

Pete

Hi Pete, Mark,

The traditional (and better) profile for wooden threads is 90 degrees (60 degrees is fine for metal, but weaker in wood) , and you could use a router with a 90 degree V bit instead of the table saw with the same setup as Pete's.

I went for a router mounted on the QCTP with a V cutter.

[ame="http://www.youtube.com/watch?v=8fdaPFRv5ZY"]DSCN0072 - YouTube[/ame]

Regards
Ray