A tip when threading wood

[george wilson]

If you will apply a liberal amount of mineral oil to the wood you are getting ready to run through a wood threading die,and let it sink in a while,it is very surprising how much better,cleaner,and less torn the threads will come out. the mineral oil will mostly be eliminated when the threads are cut,and does not look offensive. What does remain makes the threads screw together better,too. This still is not a substitute for a dull,or misaligned thread box. Do not use a drying oil,or your threading box will get all gummed up.

I used to make all of the replacement bench vise screws for the historic area,and found this really helped a lot. Those threads were 2" in dia.,and 3 threads per inch. We had an old German thread box and tap to do this with.

I cannot recall seeing this tip in any of the books out there,though it is possibly in one.

[David Keller NC]

George - Related to this, I've used denatured alcohol for a similar purpose. I got the idea from the practice of softening up end-grain before planing with it. Since a good bit of the screw thread is end-grain, it made sense that softening it up would make the tapping or threading easier, and it sure does.

[harry strasil]

The screwboxes I got from the old AMT site suggested a light oil before cutting the threads George.

[george wilson]

Looks like you guys are already on top of it!!

And now,everyone else who reads this will be in top of it too. I make my own threading tools,which I could post pictures of. One is a double thread box and two ended tap that does both right and left handed threads.

[Chuck Nickerson]

I'd like to see your self-made threading tools. I'm still using the Beall wood threader, and would like to move away from this router-based solution.

[Stephen Shepherd]

I have been cutting wooden threads for a couple of decades and have used linseed oil to lubricate tight screws with no problems. I then discovered that it was much easier to make them slightly undersize and threading was easy.

I wrote about it years ago here.

Cutting Wooden Threads (http://www.fullchisel.com/alburnam10.htm#Threads)

Stephen

[Jim Koepke]

George,

Count me in on the list of folks who want to see your threading tools.

I have been wanting to make some threading tools but have no idea where to start.

jim

[george wilson]

I'll post probably tomorrow. Right now,my wife is off for 2 weeks of abuse by French waiters. Mercy Buckets Madamoozle!! I am unable to sleep in most beds because of my back,so I stayed here.

Ammended. The pictures are up now.

[David Keller NC]

"I have been wanting to make some threading tools but have no idea where to start.

Jim - Do you have Roy Underhill's newest book? There's an extensive description of how to make wooden thread taps and threadboxes in the appendix. Covered is making a steel thread tap, but also a wooden thread tap. This last one might be more expeditious for a woodworker that's looking to tap a few threads of large diameter, but won't use the tool so much that it'll wear out.

I highly recommend this book - and it's cheap.

[george wilson]

My big cider screw is in one of his books. Wonder if it's that one? I make a type of tap that was around by something like 1820,if I recall. However,you have to have a metal lathe to make it. It is the best type of tap,I think. Some old type of tap used to be sold years ago. It looks like a big metal tap with big flutes,but the whole tap is very tapered. We had one at work. It was hard to thread a hole squarely with it. I think it was cast,too. It did work,at least. I think the Beale taps are much better than that old tapered tap.

[Jim Koepke]

Jim - Do you have Roy Underhill's newest book? There's an extensive description of how to make wooden thread taps and threadboxes in the appendix. Covered is making a steel thread tap, but also a wooden thread tap. This last one might be more expeditious for a woodworker that's looking to tap a few threads of large diameter, but won't use the tool so much that it'll wear out.

I highly recommend this book - and it's cheap.

Thanks for the tip. Guess there is a new book to put on my shopping list.

Just looked at Amazon and it looks like his latest book listed is Working Wood with Wedge and Edge, is that the one?

jim

[Robby Tacheny]

On the topic of wooden screws, do you think leg vise would work ok with 1.25" doweling threaded at 6tpi. I can't seem to find a lower tpi cutter and die, and I haven't been able to find any antique threading tools big enough.

The size above seems to be the best balance of available materials. I can't imagine that I would have it adjusted to less than 3/4" often, so for most tasks I should only have to make 6 to 8 spins.

-R

[george wilson]

1.25" is pretty small,and the thread needs to be more like 4 tpi in that size.

[Pedro Reyes]

1.25" is pretty small,and the thread needs to be more like 4 tpi in that size.

On that subject, the biggest available threading kit I can afford (have it already) is 1.5" and 6TPI, there are a few larger ones but the price jump is ridiculous making it prohibitive.

So can this cut it? I've heard people say yes, but wanted to see your thought and perhaps alternate suggestions. I would like to have wooden screws for my vises (tail and leg)

/p

[Robert Rozaieski]

On that subject, the biggest available threading kit I can afford (have it already) is 1.5" and 6TPI, there are a few larger ones but the price jump is ridiculous making it prohibitive.

So can this cut it? I've heard people say yes, but wanted to see your thought and perhaps alternate suggestions. I would like to have wooden screws for my vises (tail and leg)

/p


I used the 1-1/2" kit on my twin screw vise and it has been working fine. I've tightened the screws awful tight, sometimes to the point that I think I'm probably over tightening them but I've yet to chip even a single thread. I'd say go for it.
http://www.sawmillcreek.org/attachment.php?attachmentid=93676&d=1217506572

[george wilson]

These modern made wood threading tools always make the threads too fine. I guess there isn't much you can do about it,though. Our 2" thread box was about 3 tpi,which was appropriate to that size.

Robert,I can't tell from the picture,but it is best to make a big wooden nut,and have the screw pass through your jaw,and into the nut(which is fastened to the back of the vise.)
That way,you can easily replace the nut when it gets worn,which is likely sooner than later with too fine a thread.

[Robert Rozaieski]

These modern made wood threading tools always make the threads too fine. I guess there isn't much you can do about it,though. Our 2" thread box was about 3 tpi,which was appropriate to that size.

Robert,I can't tell from the picture,but it is best to make a big wooden nut,and have the screw pass through your jaw,and into the nut(which is fastened to the back of the vise.)
That way,you can easily replace the nut when it gets worn,which is likely sooner than later with too fine a thread.
The entire bottom jaw can easily be replaced by unbolting it from the bench should it get damaged. It's also 2" thick so I don't expect to have any problems with it any time soon.

[Robby Tacheny]

In the screw world, I always thought more tpi was better. Its like finger joints for example. 1/4" finger joints aren't going to withstand shearing well if there are only 3, but if there are 30 on an 8 inch tall box, all of the sudden the thing is quite a bit more solid.

This is not an argument but more of a theoretical discussion. I thought the reason for not having too much TPI would be the fact that no one wants to turn a vise 10 - 12 turns to make one inch.

I realize that depth and the actual width of a single thread would make a difference too, but is the issue with the higher thread count the lack of strength due to the more shallow and less wide threads?

Thanks for the good info and don't let me steal this thread, I am happy to start a new one for this "theoretical discussion." I'll do it in the morning.

George Wilson, Thanks again for the great tip and advice!

-R

[george wilson]

Big threads were always used with wood. Not the same as steel. In steel,12 tpi is the strongest thread for large size nuts,like on presses. Next time any of you are in a museum,or flea market,and see old wooden clamps or linen presses,or other things with wooden screws,try to check the number of threads per inch. Wood doesn't have the shearing strength of metal,and the tips of threads are more easily (much more) easily broken,or crumbled away. We made stitching frames for the book bindery. There were 5 threads per inch on the 1" dia. screw shafts. The 12" cider press we copied from one in England had 6 threads per foot. Look back about 12 or 13 pages,and note the big threads on the cider press,and book press screw I posted. The 6" dia. book press screw had 1 thread per inch.

[Carl Maeda-San Diego]

I put oil on my dowel too before I cut the threads.... it was in the instructions. I have the Woodcraft screw box and tap. The quality is very cheap... it didn't even cut cleanly out of the box. I had to tinker with it to get it to cut smooth threads.
But yes, I would like to see how George made his.

[David Keller NC]

"Just looked at Amazon and it looks like his latest book listed is Working Wood with Wedge and Edge, is that the one?"

Jim - Yeah, that's the latest one. Frankly, all of them are excellent books, and are available in inexpensive softcover.

[David Keller NC]

On the topic of wooden screws, do you think leg vise would work ok with 1.25" doweling threaded at 6tpi. I can't seem to find a lower tpi cutter and die, and I haven't been able to find any antique threading tools big enough.

The size above seems to be the best balance of available materials. I can't imagine that I would have it adjusted to less than 3/4" often, so for most tasks I should only have to make 6 to 8 spins.

-R

Robby - While a bit counter-intuitive, the least expensive alternative for those looking to build and all-wood workbench with traditional, large-diameter, low thread count wooden screws are the screw/nut combinations from Big Wooden Vise. I think most would regard these as "not cheap", and they're not compared to mass-manufactured metal acme screws, but for someone that doesn't plan on making a few dozen big wooden screws/nuts over the next several years, it's cheaper than trying to make a tap and thread box that size.

You can also get something similar, though in a slightly larger diameter, from The Greenlake Clock Company.