Frugal doweling and threading

[Sam Takeuchi]

While shopping for a wood tap and die set, I came across a pretty interesting website on how to make wood tap and die from cheap readily available hardware. It is in Japanese (original page here (http://www10.ocn.ne.jp/%7Ekouzou/page166.html)), but here (http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=auto&tl=en&u=http%3A%2F%2Fwww10.ocn.ne.jp%2F%7Ekouzou%2Fpage1 66.html) you can view it via Google Translate. Bunch of how to videos on the page, too. I know it's not anything new, but it might be of interest to some people. Definitely cheaper than $45 commercially available doweling and threading set, plus there's more sizes to choose from, too.

As for me, I don't have an angle grinder. Might be doable with Dremel with enough grinding wheels...

[Andrew Gibson]

that is pretty cool. However, it is my understanding that the strength of wooden threads comes when they are triangular in shape, not square like the ones made on the site.

If you check out Roy underhills site on PBS he has an episode of the woodrights shop on how to make a traditional thread box, you just have to buy the tap.

Edit, here it is. http://www.pbs.org/woodwrightsshop/video/2700/2704.html

[David Keller NC]

If you would like to make a traditional tap and die for wooden screws/nuts, Roy Underhill has an excellent explanation of 2 different methods in his latest WoodWright's Shop book.

One note about the Japanese page & method (and also about the commercially-made taiwanese T&D sets available from Woodcraft and others). Generally, you will have a very difficult time finding a machine screw with coarse enough threads to serve as a tap for wooden nuts (and therefore the screw). I have the 1-1/2" taiwanese set, and whil they are very well made and work well, at 6 tpi, the threads are just too fine to be generally usable to make miter jacks, vises, veneer presses, etc... Ideally, one would want about 3-4 tpi 90 degree profile threads for this purpose.

[Sam Takeuchi]

Definitely these aren't the ideal threading tool for sure, but for many applications I can see wood screws made from machine screw/bolt quite usable. I can see many use for those skinny wood bolts (like M10 size) in musical instrument making, either part of jigs or for clamping, too.

After I saw this page, I went looking for a tap and die in Japan (I'll be over there soon), the cheapest wood tap and die I could find was $86 for 25mm screw (appr. 1"), about $100 for 32mm (1-1/4") and 38mm (1-1/2") ones. The same thing sold at Woodcraft for $43 to $45. I think if I had to pay that much, I could understand why someone would want to make their own tap and die.

[David Weaver]

Yeah, super set of youtube videos. Basically anything you can find that's metal now that's got a bolt and longer nut is a target for a thread box.

I'd like to get some of the older thread boxes and taps, but I have only seen one sell, and it was $100, and I wasn't fast enough to get it.

Heard from a knowledgable source not long ago that 90 degrees for triangular threads in wood, and a good way to do it is with a jig for a router. Would finally give some of us a good reason to use a router.

[george wilson]

Both Davids are correct: Wood threads are 90º,not 60º like metal threads,and need to be much more coarse than metal threads.

The OLD threading sets that Woodcraft sold back in the 60's were correct in coarseness. The ones available now are not.

A few years ago the bookbinder's shop in Williamsburg ordered a stitching frame clear from Scotland,hoping it would be better than an American product(is there an American product?) It had the usual too fine looking treads on its 1" diameter upright posts. I THINK they were about 6 threads per inch. the base was made of MDF. It simply wasn't fit to be used in an 18th.C. setting. They came wagging it to me. I don't know why they just didn't ask me to make them one in the first place,instead of wasting museum money on it.

I happened to have one of those old Woodcraft taps laying in my tool cabinet. It was rather miserable: I know it was cast,from iron or steel I couldn't tell,and the threads were hand filed for sharpness. It was radically tapered,and would have not been easy to guide through a hole easily. I turned its shank more true,and chucked it in the tailstock of my metal lathe and tapped the 4 maple discs needed for the stitching frame. The tailstock kept the old tap straight.

To cut the threads,we had made a roughly welded up affair to hold a router body in the tool post at 45º in the lathe. I cut some beautiful,clean threads in 1" maple rods,4 tpi..

The stitching frame was infinitely better than the imported piece of junk,which would have been more at home in someone's home bookbinding hobby shop. I did not bother to take a picture.



In the bookbinder's shop,there is an old,large standing press that was made many years ago,I don't know where. It had a 6" diameter screw with square threads in wood. The threads had snapped off at the roots over the years. Jon and I some years back,had made a replacement screw and nut with the correct 90º thread form,which will last many,many years. I think I already posted a picture of it,but will post it again soon. It,too,was cut using the same router in the lathe setup I just described. This lathe we had was very unusual: It could cut incredibly coarse threads,for what reason I don't know. It could cut a thread 10" from crest to crest!!! I'd never need to cut a thread that coarse,but it could have come in handy for making Jacobean twists!