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« on: July 14, 2008, 10:56:44 PM »
Carl,
Thanks for the pictures as it really helps just knowing it's not some 40 year old mill ( mine is !).
One thing mechanicaly woud be the attachment of the screws ball to the underside of the tables and if the bolting moves you will never get consistantcy. So thats something worth eliminating. This would also be more pronounced at higher travel speeds. I assume you can't rack your tables, when my friend installed his ball screws into same kind of mill
as yours is was a PITA as the anchoring of the nuts had to be just right with the gibs adjusted.
Just a comment on testing, namely keep your moves the same, ie. same pattern.
Reduce your velocity to 10, and keep the acceleration low and maybe make your moves always over say 3" square and accross the corners so you have the same pattern to judge against. It's just an inerita thing.
Just for kicks,lower your tuning, do a test, then do a test with the heavy vise removed. This can give you a glue if the nuts are moving.
Not an EE either, so excude if the lingo is off , in terms of noise traveling / being inductively coupled to other wires, the solution can be difficult and sometimes like black magic. If you find something like spreading wires makes a difference just play around with those wires and gage results. ....One thing at a time...... The electrical field around the wires will increase as as current, voltage, and of course frequency is increased. The field can build up over time and at some point could cause interference with a device. Sort of sounds like what would that one extra line of code do! Shielding will help this as it contains that field, neatly wrapping aluminum foil 100% around each cable is a quick shield without trying a different cable. Additioinaly just have the shield touching against the grounded box and not the stepper.
Just some thoughts,
RICH