Thread box tutorial
Alright, A while back I said I was going to do a thread about how I hand cut Vise screws and nuts. After a bunch of real life stuff getting in the way, I still haven't completed that tutorial, and will have to get around to doing carving another one to get pictures for it.
Since I am not sure when I will get around to it, I figured I would post the more "production" way to cut the threads.
I do not have pictures of all of the process, but will document it best I can.
The first step is to make the tap.
This is for screw 2 1/4" in diameter, 2 TPI (approximately)
1. Stock for tap
Acquire a blank about 12" long, 2" in diameter, or 1 65/64ths. Make sure you have a good strong head for a handle, and that the blank is strong enough to withstand extreme pressure without splitting.
Layout a 2 tpi spiral on the blank. First, draw a line length-wise on the shaft. Mark it every half inch. Then, take a long piece of paper and make a 1/2 strip of it, and wrap the strips around the shaft, lining them up with your 1/2" marks.
(You can do this more accurately with a little geometric arithmetic and more lines evenly spaced on the shaft, but I have found that you can do this with enough accuracy by eye.)
3. Cut Spiral
Once you have your spiral laid out, it is time to cut a saw kerf along the spiral. Using a stair saw, back saw or whet ever you so choose, cut a kerf along the spiral. Make this relatively consistent in depth. (I use a cheap gents saw with a board bolted to the blade as a depth stop.)
Continued. . .