Stuart Stevenson wrote: > Gentlemen, > I am a happy camper. > Jeremy came in my office with a quiet voice to give me a report on how the > Cinci cut the big plate with all the holes with a +-.002 location tolerance. > I thought OH NO we have problems. He then smiled and said it nailed all the > holes. There was one dimension out of tolerance. A hole to hole location of > +-.001 on a distance of between 25 and 26 inches. It was -.0015 or .0005 out > of tolerance. This is in the realm of temperature causing the tolerance > fluctuation. I think maybe the design is a little tight toleranced as quite > a number of the holes are bolt holes. Bolt holes with a +-.002 location > tolerance are a little overdone. Jeremy said he thought this is the only > machine in the shop that could do these parts. What an endorsement of EMC2. > I heard someone say you cannot make a silk purse from a sow's ear but I am > not so sure anymore. > Yeah, somebody's nuts. I'm glad you are fighting these insane tolerance battles, not me! Sure, you press your palm against the middle of this piece for 5 minutes and there's no WAY it can stay within that tolerance over a span of 26 inches!
As top the "sows ear", well, good iron is still good iron. > The Enshu is basically done. It is ready to make parts. This afternoon I > was looking at how to get an encoder on the spindle. After removing the > spindle cover and finding it would be a major undertaking to mount and > connect an encoder we started looking at the spindle drive. The spindle > drive is a full servo with feedback from the spindle motor. Instead of > encoder feedback it has resolver feedback. This feeds directly into the > spindle drive. Reading the manual lead us to check a few pins with a scope. > We found encoder A and B pulses on two pins and an index pulse on another > pin. This will allow feedback into EMC and give me control of the spindle as > an axis. I will be able to drive the spindle as an axis with the MPG. > I am not sure exactly how I want to control this. > I will be able to read the index pulse after every gear change to orient the > encoder to the spindle. > If there are gears between the spindle and motor, then you have a backlash problem when the spindle reverses. Check out http://pico-systems.com/bridge_spindle.html to see how I put an encoder on a spindle that was almost impossible to find any other way to do it. This has worked reliably for six months, so far. These sensors are intended for use inside auto transmissions, so they should stand up to oil bath gearboxes in machines, too. Jon ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
