I try to mill a circle, but … it isn’t a circle !!!
It’s a oval “circle” … why ?!
Has anyone an idea ?
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Hmm… Lots of possibilities.
Your clamps didn’t hold and your stock moved?
Your design software messed up?
Your slicing software messed up?
Your bit is bent?
Tell us more! The people here are really helpful, but they need lots of info from newbies like you and me to be able to really help us.
Start with, what tools you used. Luban? Other design software? How did you get the gcode to your snapmaker? All of that kind of stuff.
The forum will get you straightened out pretty quickly.
All is tight mounted.
Nothing is bent.
Design and slicing is clean.
I use an 1.4mm flat end mill.
A 3mm hole has not the dimesions 3x3mm, but 2.92x3.2mm – it’s oval.
The 2.5 mm carbon plate is mounted tight.
I use to generate the g-code, Fusion360 and then SnapMaker Luban to send to the machine.
arrg… I can’t upload a g-code file 
Not letting new members upload gcode or images is pretty annoying. That’s pretty much the first thing a new member is going to attempt. You should unlock the permission in a few days, but I don’t remember exactly how long. In the mean time, you can post links to iCloud, Google Drive, Dropbox, etc.
For simplicity, can you try generating the same circle in Luban? It’s not the best piece of software, but it does remove some variables (like, was Fusion configured correctly for the SM).
Does the linear module the CNC is attached to feel loose? The bracket that comes out of it that is? Not necessarily the mounting but the bracket that the head mounts to itself from inside the module
It only takes minutes, you just have to meet the following criteria:
- Entering at least 5 topics
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From here: Understanding Discourse Trust Levels
It’s intended to get new members to search and read existing threads before starting their own.
gcode files have to be zipped to be uploaded.
0.1mm (each direction) could easily be explained by slop in the linear modules (backlash). If you gently push the head you should be able to feel it rock a bit side to side if that’s the issue - it’s only .1mm though it’s not much.
In the short term that could be corrected by prefixing M425 X0.05 Y0.1 F1 S0 in your gcode (or something like that, determined with testing to verify roundness). Long term you’ll need to a) get support to replace your modules or b) follow sdj’s guide on opening up and tightening the roller tensioning mechanism: Excessive play in x-axis linear module bracket - #9 by sdj544
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Thanks for the link! I always wondered how Tone was able to create that wiki of links.
Share pictures of your machine please.
From front at bed level and from front at height of z towers looking down at minimum.
-S
Did you solve it? I tried to mill a 3.4 mm hole and it ended up looking like a square
I used the G-code:
“G2 I0 J-1”
what are you cutting, a plastic case?
Use a “center cutting” end mill to pierce that, should come out round.
Providing the work is sufficiently clamped/sturdy. Vibrations will cause problems too. Like cutting something with a Dremel tool the bit grinding against a thin wall will cause resonance in the part. Creative jigging helps.
Nice tips overall!
But I just found out that G2 and G3 are prob. not supported yet in the software… So I have to use another post processor like Fusion to solve my problem.
same issue here. I tried to cut out a circle with a diameter of 85mm. But the result is oval in shape. the x-axis is 85mm wide but the y-axis is 86.5mm wide - 1.5mm off! everything is brand new, the 5 linear modules and the 200W CNC Module I have only just installed! I have installed the latest firmware and the updated luban.
I tried to cut the circle directly via luban and also generated through Fusion 360 - both times the circles were NOT perfectly round… 
so frustrating!
I believe there is an issue with the CNC gcode generator where it doesn’t use G02/G03 arc statements to draw circles. I attached a gcode file that I created with Luban where I drew a circle and made two cuts each going 1mm deep. I exported the gcode and opened it with Notepad++. You can see where it uses G01 X,Y defined segments to create the circle. I edited by hand and added another circle with 3 cuts .5mm deep each pass. For the circle I added manually I used G2/G3 CW/CCW arc statements. You can import this into Luban and/or run it. Please take all precautions if you run this on your machine. It “should” work.
I take no responsibility for any damage that may be caused by using this file, I am no expert. Use at your own risk.
Luban_vs_Manual Radius.cnc (20.3 KB)
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