Hi, I've been making a wood box but I've discovered an issue.

Hi, I’ve been making a wood box but I’ve discovered an issue. I designed the box with symmetric measures, but when after finish the job, you can observe a little difference between X edges and Y. I measured all edges, and I’ve compared with the design, and the problem is in “Profile Outside” job (You can see pictures). I try to run some calibration patterns and all of them show me that the machine is OK, the motors, ball bearings, belts, electronics etc. I run the same design but using “engrave and a pen” (see pictures and measures) like a bit to see the plot, but these plot is perfect according with the design. I’ve thought that maybe it can be a CAM software error. What do you think?
CamBam + Shapeoko 2 + GRBL + ChiliPeppr + Makita + Bosch 1-1/4 4 flute

Silly question, but did you make sure your dremel or spindle is perpendicular to the mill’s table? Mine was tilted in forward for a little while.

Sounds similar to what Frank Hermann was talking about when he had a similar setup. The video he posted this morning shows he moved to a different style machine the 3040 and now he has perfection.

Yeah, short story is blame the belts.

You should be able to strum the belts like a guitar string. Not too high of a pitch though.

Yes, that’s the problem i run it. Ok, you can do some tricks. Change the outsidediameter in you Cambam tool. I.e. You use Tool Nr3 with 3mm, then change the Outside diameter to 2.9mm and try to mill a pocket with i.e. 8x8mm. measure it and change your OD for a perfect result. To change the steps/mm in GRBL makes no senses, cuz the long distances are mostly not correct. Hope this helps.

Thanks for your suggestions. The strange is that the pocket milling is perfect but the profile outside has the problem. If it was the belt tension, you couldn’t see the perfect finished at the pocket job.

@Camilo_A_C I know, u have to calibrate ur machine. This is why u mill a pocket and measure its realy 8mm or only 7.8.

Is the pocket doing climb milling and the contour doing conventional? Or vice versa? Also, so the two operations have different depth of cut or fees rates?

@Frank_Graffagnino The two operations have different depth of cut but same feed rate. Pocket contour is conventional.

@Frank_Herrmann Why in one job in this case a pocket, the measures are correct, but in another job (the profile) in the same gcode file generated by Cambam, the measures are wrong using same feed rate,spindle rpm and bit? see: http://i.imgur.com/PJk1tkv.png

@Camilo_A_C please send me ur cambam file.

Offcourse!! check your email. Thank you.

Hmm, your cambam file looks good. I guess your Y-Axis are not correct calibrated. The tool outsidediameter are 6.35mm. that’s correct? Please mill a X:5mm and Y:50mm pocket and measure the inside from this pocket if this realy 50mm …

Ok, I try it tonight. Thanks. The tool is 1/4inch, but file measures are in mm.

i suppose the different depth of cut could definitely make a difference… especially if the one with the problems is the deeper one.