Hi all,
Consider yourself prethanked for looking at this post! I appreciate any feedback assistance you might offer.
THE SETUP
Rhino/Visual Mill/Mach 3
MACHINE
Rebuilt by a friend (far away, so I can't throttle him) with Geckos etc, Digital Tool frame, servos, 3 1/4 PC router, belt drive
THE APPROACH
I cut a lot of 3/4" furniture grade plywood. I do that in essentially two steps.
1. 1/4" downcut spiral bit cuts to 1/4" depth.
2. 1/4" upcut spiral bit cuts to 1/2" then 3/4+ penetrating the piece.
Note: Downcut runs clockwise to the piece, upcut runs counterclockwise.
THE PROBLEM
The upcut runs cut slightly offset from the downcut, usually in one axis. In small parts spread across the table the offset grows incrementally. You can imagine the problems: dimensions, edge finishing, fitting ETC ETC ETC!
TESTS
I cut two squares to test the cut direction setup and the down/CW up/CC approach yielded the best results. Smallest step, square piece, 1/32 off in one direction. NOTE *** Never been trained on CNC. Just bought this thing from my buddy and started messing around. Don't know jack about Gcode and just work the VM the best I can. Is this CW/CC thing even right???
THOUGHTS
Is this a backlash problem? I've got belts, not a gearbox. But everything drives on tracks...
On the physical setup, I've tighted all excentrics, replaced the router (it was time), checked/matched belt tension as much as I am able.
Seems like the bits are driving off course, pulling out of line. It does seem fairly consistent in one axis, but inside and outside curves are problems.
NEXT STEPS
...that I've thought of: backlash compensation. Any clues on setting that up? Standard tests?
Is this electronic? Erf. The mind reels... Any thoughts appreciated.
Or, selling the router and getting out of the 'making stuff for people' business.
Your thoughts/comments are so appreciated. I am-out-of-my-gourd frustrated with this and it has been going on for too long.
THANKS!
DAN