Mini Lathe Unwanted Taper?

[ShagDog]

Think it's possible, but you probably have to do some tweaking, like alignment of the head stock. My LMS mini had a slight taper, but I managed to align the head stock a little better. Don't think it's at 0.0001"/inch though. Haven't measured it in a couple of years, but I'd be surprised if it was that good. Most of the time I don't need that level of performance!

Thanks. Great response. Exactly what I am looking for in that it is based on your experience with your mini lathe.

 

[ShagDog]

Yes and no.

With carbide tooling and a heavy cut you’re doing good at .003 over 3” on a 7” chineses lathe. In fact I would say that would be exceptional.

A good lathe in the same size range with a properly ground HSS tool bit might get you what your looking for, but that is wholly operator dependent.

Are you able to accomplish .0001" per inch on your Prazi's?

 

[tmenyc]

On my still new LMS 7500 (not your 7" but 8.5" and from the same platform) I'm getting a taper of approx .001" per inch of turned length, most at the first and last inches. However, the wobbling of the tailstock when it's moved along z closer to or away from the headstock could well be, and probably is, the cause; I need to take the time to figure out how to improve this, in the lathe or my operation of it. If it turns out that i need to consider the first and last inch as waste, that might not be the worst of all results.
My turning is mostly in delrin, using CCMT or a handmade HSS tool, running around 600 rpm. I use CCMT because it works so well on delrin, with 20-50 thou cuts. I use the HSS tool for fine cuts and finish.
Tim

 

[homebrewed]

On my still new LMS 7500 (not your 7" but 8.5" and from the same platform) I'm getting a taper of approx .001" per inch of turned length, most at the first and last inches. However, the wobbling of the tailstock when it's moved along z closer to or away from the headstock could well be, and probably is, the cause; I need to take the time to figure out how to improve this, in the lathe or my operation of it. If it turns out that i need to consider the first and last inch as waste, that might not be the worst of all results.
My turning is mostly in delrin, using CCMT or a handmade HSS tool, running around 600 rpm. I use CCMT because it works so well on delrin, with 20-50 thou cuts. I use the HSS tool for fine cuts and finish.
Tim

When I use the tailstock on my 7x12 I lightly tighten down the quill lock, to take out any play it might have.

 

[RaisedByWolves]

Are you able to accomplish .0001" per inch on your Prazi's?

Its certainly doable, but it really depends on if the job warrants it.

I'm using a particular tooling system developed for smaller machines. These are primarily HSS or Cobalt and with the proper grind it eliminates the amount of "Push" from the tool bit and can actually get a neutral or even some "pull" to counter the cutting forces.