I've been messing around for ages with old gears and cogs to make another pen mill that can be used on my metal lathe and cut metal as well. I only wanted a hexagon shape with a slight twist - about 60deg.
I couldn't get the ratio high enough with the bits and bobs I had and eventually came up with this idea.
It is nothing more than an indexable jacobs chuck. The long chrome arm slides up ( or down ) the ramp, turning the mandrel while the cross slide of the lathe is moved.
The aluminium collar with the threaded studs is changeable for different designs ( pentagon, octogon etc )
I didn't realise it at the time but with the ramp parralel to the mandrel, the rotation of the blank is not linear. No biggie as I can spin at an angle till I get it correct.
The aluminium is from an office wall partition.
I've only tried it on this piece of red PR so far. On the weekend I'll try ali, then some stainless. I'm pretty pleased with the result and it was real easy to make:biggrin:
I couldn't get the ratio high enough with the bits and bobs I had and eventually came up with this idea.
It is nothing more than an indexable jacobs chuck. The long chrome arm slides up ( or down ) the ramp, turning the mandrel while the cross slide of the lathe is moved.
The aluminium collar with the threaded studs is changeable for different designs ( pentagon, octogon etc )
I didn't realise it at the time but with the ramp parralel to the mandrel, the rotation of the blank is not linear. No biggie as I can spin at an angle till I get it correct.
The aluminium is from an office wall partition.
I've only tried it on this piece of red PR so far. On the weekend I'll try ali, then some stainless. I'm pretty pleased with the result and it was real easy to make:biggrin: