Hi, I did several jobs before practically without issues, mostly plastic, some aluminum. I recently put my MPCNC to a new table and did some test runs and found several problems:
Some bearings connecting the gantry and Z axis have only a very light touch, how important are they? Should they all make a good contact? I think now it has some unwanted slack and the Z is not as rigid as it should be.
This leads to a quite severe chatter during the cut. When I apply pressure to the Z axis with hand the chatter is mostly eliminated.
The test cut was in soft plastic, with a 6 mm single flute bit at 9500 rpm.
I tried feeds from 100 to 1000 mm/min with no improvement.
Also the rollers do not have a perfect fit, some of the bearings are touching the stainless steel tubes rather gently which again adds to some slack. I have the original ones with aluminum motor mounts.
The table should be OK, I measured all the distances between legs and it is within 1 mm difference.
Some info about the build:
Working area 460 x 340 mm so on the small side.
Z travel 70 - 100 mm depending on the bit length.
Electronics - Arduino CNC shield with GRBL and bCNC, with endstops - this works great BTW.
All parts sourced/printed locally.
Also what is the max bit diameter you are using? I worked with 2-4 mm before and now I tried a 6 mm single flute and the machine went crazy… Is it too much for it to handle?
I will try to reassemble the whole thing and maybe reprint some parts when I have some time, just wanted an opinion on what to look for and avoid possible problems.
Thanks for any suggestions, I can upload some pics later if it would help.