On Monday 01 June 2015 06:41:50 andy pugh wrote: > On 1 June 2015 at 11:09, Mark Wendt <[email protected]> wrote: > > Crikey! That's a beast! One can never have too much power. ;-) > > It's probably the most rigid 10x20 lathe ever made, but I was rather > hoping for a discussion of the best way to control speed under CNC > rather than a discussion of the lathe itself :-)
Well, since the variator changes speed quite slowly unless you want to skid the cones, which might damage them, I would go for a small stepper, geared way down, and cobble up something in hal to drive it to the desired rpms at a rate it can follow. If its in good shape, I'd expect it to be reversable by the computer as fast as you could do it manually. In that regard, how does it stop, by coasting or under vfd control? If it coasts, I think I would rig a psu to feed the motor dc, converting it to an eddy currant brake system, which should cut the stop time to 1/3rd or less of just letting it coast. That would make a G33.1 usable I'd think. I used some hal trickery to detect when it had almost stopped, and only then allowed the reverse signal to propagate to the drivers, which I preset to zero speed so that the accelleration curves would be obeyed as it sped up in the opposite direction. I used a retriggerable timer watching an encoder phase to detect when it was nearly stopped and therefore safe to apply the reverse polarity power. That also controlled the DC application. Lots of those ice cube relays clacking in and out. Some of my famous 400 line hal file. ;-) Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
