SpeechlessCalm
Plastic
- Joined
- Mar 29, 2023
Many years ago I inherited an old lathe, I set her up during early COVID lock-down, and have been experimenting since. She’s a fairly basic treadle-drive ‘ornamental’ style from ?mid 1800s. I cannot confirm a manufacturer - there are no markings at all - but the main headstock spindle is Holtzapffel #3 threaded (which I only recently learned here).
The lathe has a sliding headstock type of thread chasing assembly, and I am trying to find information on how – exactly – to use it to cut threads. I'm wanting to build an adapter to allow me to fit the eccentric chuck mount (photo 1) to my modern wood turning lathe.
My question, relating to how this assembly is used, is primarily whether the thread is cut with a single pass or, if not, do the multiple passes rely simply on the follower / master engagement geometry to ensure subsequent deeper cuts align perfectly with previous cuts.
Even better, does anyone know of contemporary manuals / instructions for this – not so common – type of screw cutting assembly?
p.s. I'm sure you have worked it out from my question but I am not a machinist at all. I hope what I am asking makes sense.
Photo 1 shows the headstock assembly with eccentric chuck attachment foremost and thread chasing assembly to the rear/right.
Photo 2 shows the thread chasing assembly. Rotating the lever releases the main spindle and brings the threaded ‘star’ follower up to engage the master threaded ‘drum’. That engagement drives the headstock spindle laterally as it rotates. Each of the two stars has 7 concavities, six threaded and one blank. There are 12 drums, one matching each thread on the stars, that can be fitte
Photo 3 shows the threaded follower stars elevated so as to engage the appropriate master-threaded drum.
The lathe has a sliding headstock type of thread chasing assembly, and I am trying to find information on how – exactly – to use it to cut threads. I'm wanting to build an adapter to allow me to fit the eccentric chuck mount (photo 1) to my modern wood turning lathe.
My question, relating to how this assembly is used, is primarily whether the thread is cut with a single pass or, if not, do the multiple passes rely simply on the follower / master engagement geometry to ensure subsequent deeper cuts align perfectly with previous cuts.
Even better, does anyone know of contemporary manuals / instructions for this – not so common – type of screw cutting assembly?
p.s. I'm sure you have worked it out from my question but I am not a machinist at all. I hope what I am asking makes sense.
Photo 1 shows the headstock assembly with eccentric chuck attachment foremost and thread chasing assembly to the rear/right.
Photo 2 shows the thread chasing assembly. Rotating the lever releases the main spindle and brings the threaded ‘star’ follower up to engage the master threaded ‘drum’. That engagement drives the headstock spindle laterally as it rotates. Each of the two stars has 7 concavities, six threaded and one blank. There are 12 drums, one matching each thread on the stars, that can be fitte
Photo 3 shows the threaded follower stars elevated so as to engage the appropriate master-threaded drum.