Wooden screw threads.

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I notice you are working the screwthread "dry", have you ever pre-soaked the dowel in BLO beforehand to see if this gives a better surface fininsh to the threads? I know When I make threads by hand BLO helps give a much better finish as well as making it easier to move the threadbox

Droogs, soaking the dowel with oil works well (on many woods) with the traditional threadbox, but in my experience it doesn't do a lot for you when using high-speed cutters. The swarf can stick together & gum up the works quick-smart. That may not occur with the OP's amazing setup as the business area is more exposed, but it certainly does with my more Heath-Robinson threading jig. Waxing & polishing the blank can help to make it run through the jig more smoothly, but I usually don't bother:
Threading jig.jpg


I've been making & using wooden threads for more than 35 years and made at least a half-dozen different styles of taps, but I always use the above setup for threading, mainly because of the bone-hard woods we have to contend with in Oz. A traditional cutter blunts after a few turns in many of our woods, but a carbide router bit will cut miles of thread without complaint.

The screw on the tail viseof my work bench has been doing yeoman service for over 30 years & shows no sign of flagging - I think it will see me out.

I made myself a portable bench a few years ago & just for fun, I made all of the vises entirely of wood:
Bench under.jpg


The guide rods on the front vise are she-oak (Allocasuarina torulosa), which is a very hard, tough wood. I was a bit concerned about how they would fare given I live in a climate with extreme humidity swings, but so far they have been fine. I think I've waxed them once since I assembled the vise nearly 5 yeas ago.

It's been to a couple of wood shows & had lots of interest & requests for plans (difficult to oblige when I just made it up as I went along!). At home it usually sits in a corner so I can use the twin-screw vise for cutting dovetails & tenons (after clearing off the junk that inevitably accumulates on it!). I made the undercarriage so the top sits about 150mm higher than the surface of my main bench, which makes it very comfortable for these operations:
Twin-screw vise.jpg


(Looks a bit tall & spindly, but the wood it's made from is forest red gum (Eucalyptus tereticornis), which has a density close to 1.2, so it's rather hefty for its size & sits pretty solidly!)

One of my other uses for wooden threads is for making handscrews - I have a wall full of them & couldn't live without them.
handscrews.jpg


You can probably gather that I like wooden screws too..... :)
Cheers,
Ian
 
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I am very jealous, I wish I had access to some of the woods you can get just for the purpose of making clamps of all types. Fantastic vises btw. I've done plenty of screws but all by handbox. What you say about probable clogging of the threadbox at high rpm makes a lot of sense if the wood is "sticky".

Have to say it has never even crossed my mind to use a router with a threadbox, nice JOF there :). I would really love to make a Jara and broze infil smoother one day
 
The OP's building of a lathe from wood and using it to cut wood threads is inventive and ingenious but since other methods are under discussion wood threads are easily cut on a table saw once a suitable blade is made. It works on the same principle as a traditional thread box or a router jig. #11

Pete
 
Yes, Inspector, somewhere back in the mist of memory I remember seeing a jig used with a TS. It's the high-speed cutting you want, & how you achieve that doesn't matter a whole lot, as far as the finished thread goes. But I suspect it would cost a fair amount more to buy a saw blade & have it ground to match your desired thread profile.

I would also venture the router jig is quite a bit easier to set up. With the guide-piece removed, you get a clear view of the cutter, and I can usually get it positioned first try for larger threads (unless I'm showing someone else how easy it is!)
b cutter in position.jpg


Of course with the guide piece in place, you can't see the cutter, so you just have to work by feel. If you get a good start, the screw should be easily rotated into the jig with finger pressure, but if you are doing a batch, you get tired of that pretty quickly, and it's handy to use a crank :
Crank.jpg

A plunge router is a good choice for this job because you can de-plunge & make it easier to back the screw out when it's finished

Droogs, we do have some excellent woods for making screws down here. But some of our hardest woods don't make good screws, they can be too brittle & the threads tend to break away under load. One of the reasons I have so many hand screws is because I'm just curious about how different woods work as screws (anything will take decent internal threads across the grain, even pine can make a good nut) I have to admit that one that's up there with any of the best is Apple, which should be available to you. And it's one that threads very nicely with the traditional threadbox, lovely clean threads that are as tough as boots....
:)
Ian
 
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Actually Ian the blade was cheap. It was in the late 80s and I had a couple blades I got from a junk bin and a local saw doctor re-toothed it for a few dollars a tooth. I had a second one sharpened for chamfering but I wish I had it done with rounded teeth for coving. Hindsight eh. ;) Most important thing is to keep an open mind so different methods can develop and possibly flourish.
Pete
 
Do you have to consider the direction of the grain when cutting a thread in wood? it feels like the crest of the thread would not be well supported?
 
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