eccentric turning

OK that makes sense. I'll put some thought into gearing down the spindle. toothed belt reduction might even be the way to go on this machine, perhaps 2:1 or 3:1 is enough. The larger lathe could be converted but would need big motors!

The cutters I'm planning to make are only 3/4 to 7/8" diameter for watch and clock work so not as much torque is needed for machining these.

Another neat thing to try with the eoffsets would be to pump both x and z axis simultaneously to perform Guilloche or Rose Engine turning.

Peter_Cassar wrote: OK that makes sense. I'll put some thought into gearing down the spindle. toothed belt reduction might even be the way to go on this machine, perhaps 2:1 or 3:1 is enough.

What model of lathe is it? There are possible solutions.

See, for example the epicyclic back-gear here: www.lathes.co.uk/latheparts/page4.html
Or this solution:

It's a German designed Optimum 2004 see -> www.machineryhouse.com.au/L687

It's back end looks similar to the lathe in the video you linked too. Nice thing about these lathes is the tapered gibs and hardened bed for a machine made in China it has a few bells and whistles. I scrapped all the screw cutting stuff because it was a let down , no back gear or tumbler reverse. I'll open it up again and see what sort of reduction drive I can squeeze in.

I have my suspicion that "German Designed" means "rip off of the Emco"

www.lathes.co.uk/emco/page2.html

You're probably right, it looks very similar. It's probably one of the better products coming out of that country in this market for the money though.

I just tried it out and successfully produced a hexagon in 5/8" brass bar. I realised that the lathe already has the reduction belt drive and bottom speed is 30rpm with useful torque . I think I might look at a larger reduction by fitting different pulleys to get down to 15rpm. 12 sided polygon yields a following error in X at 30rpm . I'd like 12 tooth cutters.

As it is I think I can produce a 6 tooth cutter with form relief , this is far better than fly cutting. I will look at a pre gashed blank to see how cutting goes but a solid blank may be OK and gash after.

This really simplifies a lot of mechanical complexity.

I have been enjoying this, making relieved gear hobs was on my list of things to try, you have proved the concept out,

I think that I will probably try using lincurve and cunning scaling to generate an asymmetrical form, but this is looking like it can work.