Author Topic: XY Calibration (Resolved)  (Read 979 times)

ggallant571

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Re: XY Calibration
« Reply #15 on: March 26, 2022, 03:39:16 PM »
You examined the gcode from BCL to verify that there are no G02 or G03 commands? Just G01. I have a faint recollection of someone optimizing curves from small straight lines to arcs. Ralph is talented enough to do that.
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mdoolin

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Re: XY Calibration
« Reply #16 on: March 26, 2022, 05:58:27 PM »
Yes, entirely G01 except for M03 and M05 to turn the laser on and off.

mdoolin

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Re: XY Calibration
« Reply #17 on: March 28, 2022, 10:41:56 PM »
I figured it out.

It's not a software problem, it's hardware. The gantry wasn't square to the frame, so if you cut a rectangle you got a rhombus. That translated to an oval skewed on the diagonal.

The mounting plates for the gantry were 1/4" plexiglas. I had to replace one of the stepper motors at one point, and I think it got overheated and warped the plexiglas mounting plate. So I replaced them with 1/4" aluminum. See attached photo.

That almost solved the problem.

While it was much better, I still wasn't getting a consistent right angle when I'd cut a square. I added .002" shims under one side of the ends of the gantry pieces, and that got it closer. But still not consistently right.

Here's the trouble: I think there's enough slop in the tracks that it depends on where exactly the gantry happens to be sitting when the stepper motors are engaged. I found the I could cajole it into cutting a pretty good right angle by nudging one end of the gantry a bit one way or the other before engaging the stepper motors.

Not quite the precision I was hoping for, but I understand this is a hobbyist machine from which I'm trying to get pro CNC results. This small inaccuracy wouldn't be a problem for most users.

ggallant571

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Re: XY Calibration
« Reply #18 on: March 29, 2022, 08:46:53 AM »
Good to hear. Makes me wonder how bad mine is. My 3d printer has a similar non-square problem due to the placement of the belt pulleys in relation to the drive gears. It has a firmware compensation option. BTW - don't see any attached picture.
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mdoolin

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Re: XY Calibration
« Reply #19 on: March 29, 2022, 12:21:48 PM »
Sorry, here's the photo -

mdoolin

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Re: XY Calibration
« Reply #20 on: March 29, 2022, 12:25:13 PM »
Also, thanks for the recommendation of LightBurn. I didn't know there was a Mac version, and it looks pretty good so I'll try it out. And that site led me to finding the AtomStack 10w dual laser head, which I have ordered - https://www.aliexpress.com/item/1005003727779510.html?spm=a2g0o.store_pc_promotion.promotePruductList_2001992869252.5

ggallant571

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Re: XY Calibration
« Reply #21 on: March 30, 2022, 06:56:05 AM »
LightBurn is a commercial product with a 30 day evaluation free use period. LaserGRBL is opensource which I think is Windows only. Try both.


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mdoolin

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Re: XY Calibration
« Reply #22 on: March 30, 2022, 07:33:42 AM »
I just got LightBurn to work on my MacBook. It opens my Illustrator files directly, no more exporting as dxf. For that alone it's worth the $60! and it's so much more intuitive for me as a Mac user. So thanks again for the recommendation :)