I have a metal lathe.
I’ll just let that fact sink in for a minute
It’s a relatively small Chinese lathe sold by Harbor Freight long ago and purchased by me from Craigslist a while back.
I’ve had a lot of fun learning how to use it, and now it’s time to start putting my little machine shop to work: that’s right, it’s time to start making parts and tools to use in my machine shop.
It’s a standard design, with four sides that can each hold a cutter, and in theory you can rotate the holder to bring each of those cutters to the workpiece as needed. The problem is that cutters have different thicknesses, and they must be shimmed by various amounts to place the cutting tip at the correct height (exactly aligned with the center axis of the workpiece).
Finding and placing the shims is a pain, and I am rarely able to get the height just right.
So I decided to make a new tool post that could be quickly and easily adjusted.
I decided the best approach would be to start with the concept of a sliding/locking dovetail, and figure out the rest as I went.
First order of business: a big chunk of metal…
Then I drilled a smaller hole near the back of the tool holder (the opposite end from where the dovetail and piston would be). This is where I would place the cam that would move the piston and lock the dovetail.
Then I placed a piece of a washer between the shaft and one of the teeth of the lathe chuck to set it off-center and turned on the lath and cut passes between the marks on the shaft until the cutter was removing material all the way around the shaft.
Now I had a shaft with a cam (a camshaft) to move the piston.
I put the camshaft into place and them set the piston in the hole.
I rotated the camshaft until the piston was at its lowest point and then scribed a line.
Coming soon: Part 2 – The dovetail, the tool holders, and the camshaft handle