I hope someone with more cnc experience can help me. I’m using the 200W CNC and Luban 4.13. My first test cut was perfect. Quick, easy, worked perfectly. It was a small section of a larger piece, cutting PCB. There are three tool paths. The first cuts gaps at .2mm, the second tabs at .8 mm and the third all the way thru the 1.3mm board in two .7mm passes. It was all correct in the test. Then when I ran the full piece, the first two paths were on, but the third pass buried into the material (I’d guess 1.5mm or so) and broke the bit as it tried to cut. I did the tool paths and everything and then ran it again. This time the first (.2mm) cut was perfect and the second cut buried itself into the work and base. The third time I tried restarting Luban and the machine, and this time the first cut cut way too deep. It’s like the machine is getting the wrong z, but when I check the G-code I see the correct (-.2, -.8, -.7 then -1.4mm) z distances, and when I home the bit it goes to the correct z height.
I have the quickswap and bracing kits and they are both active in the profile on Luban.
Not sure what the next step is… So any thoughts/advice would be appreciated! Thank you!
It seems you didn’t set your work origin correctly.
If you replace the bit (for example) you have to set your work origin in Z direction again to get the correct offset to your tooling path and work piece.
Yes, except I’m not replacing the tool. And I checked to see if it had slipped in the collet and it is where it I put it - back of mill flush with the back of the collet.
The weird thing is the that it will do the first or first and second cut right before plunging too deep, and it returns to the correct home position (lower left of work piece .1mm above surface) if I home it after it cuts too deep.
So Z set correctly, until my third attempt it cut initial path(s) correctly, and it homes to the correct position after the incorrect depth cut.
I’m baffled, especially as it seems to be a progressive error (1st try not until 3rd cut was it wrong, 2nd try wrong on 2nd path, 3rd try wrong on the first path), and when I look at the g code it all looks correct. Thanks!
From my first look it seems your toolpaths finally are at the same depth, so it seems you set the stepdown and or final depth of the different paths incorrectly.
Hi Fas, I’ve looked at the file you posted (not in Luban) and it appears to be correct to what you explained you programmed it to do. It’s using Absolute Positioning. One thing I did notice was that the header code thinks the Laser is attached…
;Snapmaker Luban 4.13.0
;Thu Aug 01 2024 16:8:31
; G-code for laser engraving
; Generated by Snapmaker Luban
; G-code START <<<
G90
G21
G0 Z80.00 F1500
G0 X13.20 Y151.14
G0 Z2.00
M3 P100
G1 Z-0.20 F200
I don’t use Luban so I don’t know if this is how it should be, perhaps someone with more experience of the software can offer some explanation.
It almost seems like your losing your Z height reference. I’d check to see if anything with your machine looks loose (Toolhead etc).
Also try breaking the program up into 3 seperate programs and Home the machine between each one to see if that helps.
That is a great idea. I’ll try running three different paths with a home between them. I’m also going to try running via the touchscreen rather than Luban.
And yes I saw the laser mention. I’m thinking that is a relic, since it works w the CNC. The touchscreen and Luban both recognize the 200w CNC is attached.
Just the .8mm cuts - using Luban I set the work origin and then homed the machine and then went to the work origin. All good. Started the job. Dug down thru the PCB just like before. Not all good. G-code of course looks right, sending Z to -0.80
OK, so I sent the job to the touch screen. Started it. First line went right (huzzah!) approx .8mm deep. Second line, no go - dug thru PCB into the waste board below like before.
So at this point I’m baffled. I am headed to a model railroad convention for the next week and a half (what I use the SM for most of the time is model railroading stuff) who I won’t be able to test anything.
I do notice that there’s about a .2 or .3 mm difference in height between the back and front, but that wouldn’t account for the ~.8mm difference between half way thru the pcb and digging into the waste board…
At this point I’m thinking maybe reinstall both Luban and the firmware, one at a time with testing to see if that helps? I’ll update this post mid-next week when I get back and have a chance to play a bit.
Hi Fas, that is very strange. When you have the chance could you post some photos of your setup on the bed of the Snapmaker and what “bit” you are using for the milling. Also have you the bracing kit installed etc. It sounds like you have excessive movement (play) in the bed but without any photos its difficult to know.
This is the first full milling I attempted, and you can see the .2mm gaps, and the .8mm tab grooves cut correctly. And the .7 cuts started correctly, but then it is almost like something slipped and it started digging deep.
Finally, this is the last cut I made. The furthest right cut was deep from a previous attempt, but you can see the .8mm gap is there after the deep cut ended when I stopped the machine. The two .2mm gap cuts barely scratched the surface (Z a bit too high) but then the left .8mm cut when all the way thru and then some.
A few more thoughts, do you see any bed wobble like this:
I don’t think this could be your issue but nobody knows:
Your tool sits tight in the collet, no movement in Z, right?
Your quick swap kit sits in the end position, no movement in Z, right?
Asking this because I have experienced these issues.
After it runs too deep I send the machine to the work origin and the z height is correct, so I don’t think it is slippage, altho the first time might have been slippage since I didn’t go to the work origin after that.
I don’t see wobbling. nothing so obvious that it would explain the serious missed z depth.
When I get home I think I’ll try reinstalling the firmware and see where that takes me. Thanks!
I’m away from my machine until next Wednesday. Once I get back I’ll switch the tool heads and then switch back hoping that will clear out anything that has gone wrong in the programming. If that doesn’t work I’ll reinstall the firmware. If that doesn’t work I’ll reinstall Luban. And if that doesn’t work - support ticket indeed!
I’ll let you all know what the upshot is once I have answers (or no answers after trying everything). Thanks - FAS
OK, so I’m back from vaca, and after a couple days of putting it off I finally get back to the SM and CNC. But first I had to laser cut something, so I swapped out the heads, laser cut, and then put the cnc back on. And it worked! perfectly. Just what it was supposed to do. So the secret seems to be if things get glitchy, swap out the heads and then try again!
