Gantry not square

Does Lightburn have a means to square an out of square gantry in software? I am rather new to the software. My laser engraver is a DIY consisting of 2020 and 2040 extrusions. The frame is dead on square but I cannot get the gantry square by mechanical means. The error is about 3-4mm over 400 mm. Thanks!

You can select and manually skew a design, but aside from that, no.

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Thanks for the response. I can see how that would work…but I was hoping Lightburn had a one and done solution. Helpful though and I do appreciate it.

I’ll add my .02 It’s called a skew test. it’s a fairly easy test, but the solution is purely physical. It can be a PITA to take care of, but it’s a one and done kind of thing.

Set up the largest square / rectangle you can do in your machine, and put a dashed line down the middle. I used old wrapping paper. Cut it and then fold it on the dashed line. If the corners come out even, congratulations, your X is perpendicular to your Y. If they don’t, the mis-match is how far out of square you are. You adjust one end of your Y axis drive by that amount, and you are now square.

I was lucky, my skew was 2.8mm. My belt teeth were 2.5mm spacing. I loosened one end and hopped it one tooth. .3mm is less than my kerf, so I’m good.

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Thanks. Hopping the belt is what I have been doing…I just can’t seem to get it right. I will try the wrapping paper thingy…that should be easier than the 3-4-5 hypotenuse thing I have been doing. I appreciate your taking the time to respond.

Everybody has a slightly different way of doing things. Russ has a good video on getting your gantry square. My notes say it’s #89

Thanks for the help! I have a K40 but the gantry issue is on a DIY laser diode engraver. I will look at the video and see if there is anything I can learn from it. Thanks again.

When you say wrapping paper…do you mean like Christmas gift wrapping paper or something else?

I used old Christmas wrapping paper, my 80W has a 5070 bed, so I needed something large. It was headed for the trash anyway.

All to many assume that the calibration and skew check was done before their unit shipped, diode or laser. By cutting as large a square / rectangle as you can, and checking the actual cut against what it was supposed to be, you get the most accurate calibration. All too many try and do a 100mm or 200mm square and wonder why large projects are just a hair off. Same for the skew. The larger your cut piece, the more accurate your skew check will be. I had 2.8mm over 500mm. Imagine if I had done the same test with only a 100mm square.

I knew to make anything as large as possible for accuracy. I followed your advice with the Christmas wrapping paper…the issue was the paper wanted to curl…even somewhat after taping the ends down. So I cut the 350mm square with the dotted line down the middle…I actually did it three times…each time it worked out within 1mm. What started this is that I was burning an alignment grid onto the waste board and X and Y lines were not square…even after burning the Xmas paper they still don’t look square. I am going to burn a project and see how it comes out…the “look” of being out of square could be my glasses. Thanks for your advice and help…I do appreciate it.

LOL, Lasers, the never ending project!

Depends by what you mean by the gantry not being square.

If the gantry is physically square, then one of the drive belts/acme/ball screws is off. Usually they have some adjustment, but best to run it manually to the end stops, then loosen the connection - move it manually until its square then retighten. Most timing belt connectors have a screw you can tighten to allow movement, ball and acme threads are different, but the same applies - adjust so its mechanical square.

If the software outputs a square, then only a machanical issue can result in something not a square.

I’ve a different issue in that I’m using ball screws - due to the accuracy requirements, I’m using 2 drivers/servos with different calibration so that the gantry remains square even though there might be slight differences in screw pitch - I’m going to use a laser interferometer to measure each movement to ensure its always square. I LOVE eBay… Lol

You can measure across the diagonals of the square to check it’s square, obviously the measurement should be the same on both diagonals, this is the normal fabrication check when fabricating frames or anything that’s symmetrical.

Steve

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