Making a tap for wood

[AndyT]

Quick update on this.

After playing about with some more experiments, using different scraps of wood and different sized preliminary holes, I found I was getting a very sloppy fit. This is the reason why:

I'd made the tap 1/16" of an inch oversized.

So, it was back to the lathe, being pleased that I hadn't changed the way it was set up, or removed the end holes in the tap. A few passes with a file while the work was spinning removed enough material from the diameter, but that left teeth that were too shallow. I managed to line up a cutter, with the leadscrew set to work at the right tpi, and follow the original angle close enough. I really don't think I would have been able to do this with a powered lathe or a finer thread. As it was, I was able to pull the lathe round by hand, scraping away on one side of the thread, to deepen the teeth.

A few passes and it felt like it would work, and it does.

Sharp eyed readers will notice the addition of a cross-bar and retaining screw as well.

Now I could use the tap and box combo to make something, but I'll put that in the Projects, as it's wood, not metal.

 

[MusicMan]

Nice one, Andy!

 

[xy mosian]

Good save Andy.
xy

 

[woodfarmer]

A simpler way (lazy me) is to use over size round bar.
suppose you want a one inch tap. 25mm
use a 1 and a half inch round bar, mark the centre and scribe a 7/8 inch circle.
centre pop a few times around this scribed circle then drill holes. 4 equidistant is about right. Hole size not really critical 1/4 to 3/8 about right.
Now turn down the bar to 1 inch, you have your flutes and because the centres are inside the 1 inch diameter they will be a bit off set and will give a good cutting edge.
Cut your thread.. and you have a tap with not too much work.

suggest you make a wooden dummy one first to get the feel of what happens.

regards

hope this is of use to you

 

[woodfarmer]

I forgot to say, turn a taper at the start of the tap

 

[AndyT]

Thanks for the suggestion, but in this case I was also looking for something I could make with a bit of steel from the assortment of oddments I already have. Not always the easiest option and I didn't explain that in the original post.