Wooden Thread Profiles

[Ray Gardiner]

Very cool... are these too much work to consider making them for order???

Hi Jamie, Short answer, yes, too much work. (and I'm supposed to be retired!) It's a pity that all the commercially available ones are the wrong profile.

But they aren't hard to make, see if you can find a local engineering firm and give them a drawing/sketch. Show them some pictures as well.

Hi George,
I have a 12x36 taiwanese lathe, (It looks like the Grizzly G4003). 3 phase motor retro-fitted with VFD and DRO. Don't know if it would have enough power to do 3 tpi though.
2" 01 drill rod from victor.net is about $4 per inch, I just used mild steel. You can get hydraulic tubing in sizes that would be suitable, that's probably the cheapest option.

Regards
Ray

[Chris Vandiver]

Here is a related link(hopefully it works);
http://www.workbenches.se/verkstadsbilder.php

Look at the botoom right hand photo.

[jamie shard]

Hi Jamie, Short answer, yes, too much work. (and I'm supposed to be retired!)

Ha, I thought so! It's beautiful work and beautiful work always seems so simple when you look at the final product.

[seth lowden]

Very coincidental- I was going to post a link to the youtube video on that site, Chris. I will instead post the link to the English version. The video is kind of cool. I have been interested in these benches for a while, since someone posted about his on Badger Pond.

http://www.workbenches.se/en/index.php

I do not have extensive experience, but on my 100+ year old commercially made bench, the screw has 60 degree threads, and I have not seen any antique taps that are not 60 degree. Looks like they were all filed with a triangle file to me, not a square file.

[george wilson]

Seth,look into the Diderot encyclopedia,written in the 18th.C.. You will see proper wood thread forms in drawings there. Some things declined in the 19th.C.,and I'm afraid wood thread forms were among them. Having a thread in wood that is thicker at its bottom,and not as tall proportionately to metal threads is perfectly logical,given the relative ease with which wood can chip out or shear off as compared to metal.

[Johnny Kleso]

Can you buy some high grade threaded acme rod and carbonise it ?

[Ray Gardiner]

Thanks for that link Seth,

I will repost the image here.. Interesting thread box.

Attribution.. The above image is from http://www.workbenches.se/en/index.php

The next one is a Peugeot Freres tap and thread box from Peter McBride 2" 3.5 tpi


I hope Peter doesn't mind me reposting them here.

The third one is a custom made 2" 4 tpi made for IanW.

Image thanks to IanW.

And just to round out the references here are a few companies offering vise kits with wooden screws.

http://www.bigwoodvise.com/index.cfm
http://www.lakeerietoolworks.com/sho.../1?shop_param=

All the commercially available screws, taps, and thread boxes (that I have found) are 60 degree profile, not 90 degrees as they should be...
that's not to say they wont work well and last a long time, and, 60 degree threads are fine, but 90 degree is a bit better.

The other conclusion, is for a 2" diameter thread 2 to 4 tpi seems to be the range.

Hope that helps someone else looking for similar info.

Regards
Ray

[george wilson]

3 tpi is ideal for a 2" screw. These size threads are large enough that they have the width to not shear off easily,even at 60º. That is the size and thread that I made for years for all the workbenches at Williamsburg. They got worn out every several years,and I had to keep making them.