Is there any provisions for backlash compensation in the SB control software?
Is there any provisions for backlash compensation in the SB control software?
No there isn't. It really isn't a good idea either and falls under the category of, "You can't fix hardware problems with software." But that doesn't stop people from trying.
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I did a bunch of reading on it last night. What I was able to figure out from a few forums is to get your machine right. Then try and pick up a few more thousands by backlash compensation. But you think is not a great solution either way? It seems to be pretty widely used and accepted. I'm with you though...seem kind of like a giant band-aid. I was just thinking if I could dial it in it might help pick up .003-.005" in tolerance. Just something to play with if it were available. Thanks as always for your hard earned insight.
Erik
This was interesting.
https://machmotion.com/blog/what-is-...-to-correct-it
"backlash compensation" - I don't think so! There are some great posts on here discussing keeping things properly tuned and replacing worn parts (IE pinions etc). I had an instance awhile back with some china end mills that were not cutting to my liking and what I discovered was a lot of 'bit flex'. Symptoms were similar to what I would expect from backlash but turned out it was in the bit itself. My machine is over 10 years old and I cut mostly cheap HD ply, so it gets a lot of long run use. The replaceable parts are cheap, quick to change, make my machine a good wood working tool. Russ
AKA: Da Train Guy
Thank you for the feedback guys.
A Shopbot is 'reasonably' tight and backlash free when you measure .003-.007" of play in any one axis. I'd recommend getting a good dial indicator set up and measure everything including gantry AND table deflection when you press down on them with moderate force. There comes a point where you can't get a bolt together machine any tighter and you just have to do the best you can or look at other options. The gearboxes themselves will show .004- 006* in many cases when new.
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Slightly off topic....Brady...5 yr old Desktop....Any time frame to replace anti-backlash nut on Z-axis, and spring for spindle support?
What are indications of the need to replace?
LIKE the one piece older Desktops with welded frame, and machined Y-rail area...vs. the new bolted together for my applications.
Sorry for the off topic....and appreciate any info/threads Brady(Thanks in advance).
scott
scott P.
2013 Desktop/spindle/VCP 12.0*
Maine
Scott, What kind of play have you measured on your machine?
I don't have a lot of good things to say about plastic lead nuts when real ballscrew/nut combos can be had for dirt... They are fine if you don't cut over 2 IPS in most cases on these machines.
High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com
OK,OK......THIS week I'll buy a dial indicator set Brady
Still pretty tight on second passes, BUT Z seems to drop a hair on every RR(5 RR's will eliminate a light pencil mark on wood).
Was just wondering if those years of cutting buttons at low Z had stretched the spring.
I'll get some hard numbers when indicator(and steel plate?) come in.
Sorry I asked the question without any numbers Brady
scott
scott P.
2013 Desktop/spindle/VCP 12.0*
Maine