Yes i think stuart is right, sometime ago in a similar discussion someone told me the same, the there are two different motors for turning or milling.
Well, the only question left then is if i can use spindle synchronised motion, at very low speed (10 rpm or less), and a mill in the X axis to make a lobe/cam shape? The finish process it will be as always in a cam grinder so the main problem is how to make a fast rough milling. Thanks again for your answer. Regards. 2010/5/5 Stuart Stevenson <stus...@gmail.com> > Gentlemen, > I have zero experience with these machines. I have watched machines such as > this. It appeared to me as if the spindle 'changed' gears between the > turning and milling operations. I assumed a worm drive was > engaged/disengaged for the different cutting requirements. > Just saying. > Stuart > > On Wed, May 5, 2010 at 10:57 AM, Andy Pugh <a...@andypugh.fsnet.co.uk > >wrote: > > > On 5 May 2010 15:47, John Kasunich <jmkasun...@fastmail.fm> wrote: > > > > > Just because a particular motor works well driving the spindle > > > in lathe mode does NOT mean it will be even close to good enough > > > for direct drive positioning. > > > > A good point, I have only been discussing what is technically possible in > > EMC. > > > > I am fairly sure that various lathes do exactly what is being > > proposed, but how much such spindle drives cost is something I could > > not even speculate on. > > This machine does it, it also looks quite expensive :-) > > http://www.youtube.com/watch?v=JZcFMjLmjZc&feature=related > > > > <thinking aloud> > > > > I would guess that there is a risk of the flute-frequency setting off > > oscillations in the controller. > > > > For the proposed application (rough-milling cams) the rotary stiffness > > requirements might not be all that exacting. > > > > I suppose in principle, with a fast-enough X axis and enough low-speed > > spindle torque you can machine cams with a conventional turning > > operation and spindle-synchronised motion. > > > > I think this might be one of those applications where a small-budget > > proof-of concept might be a good idea, though the problem here is that > > it might be something where you need the expensive stuff (high torque > > servo, high-count encoder) to make it work. > > > > > Good PID tuning might be able to reduce the steady state error, > > > but when an individual flute of a spinning end mill applies a > > > brief force to the axis, the axis will move. Only after it moves > > > will there be a position error that the PID can use to drive the > > > axis back to the proper position. > > > > I wonder if a Resolver (and high-resolution interface electronics) > > might be a better bet than an encoder? > > > > > > > http://www.analog.com/en/other-products/militaryaerospace/ad2s80a/products/product.html > > > > Is a 16-bit converter and claims +/- 2 arcmin resolution. on 50mm > > diameter material I think that is 0.015mm (0.0005") tangential > > resolution. Say 4 counts to produce a PID response and it is probably > > good enough for end-mill roughing a cam with live tooling, but not for > > some other operations you might think of. (I am imagining the cutter > > axis at right angles to the spindle axis and on the same plane, the > > stiffness requirements with the axes parallel strike me as more of a > > challenge) > > > > -- > > atp > > > > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > -- > dos centavos > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
