Ruida machine calibration issue

Hello,

Thank you so much for all the helpful information in this forum!

I am having some trouble with my Ruida Laser, the bed is 900x600mm.

When I cut a rectangle through Lightburn, the sides are not at exactly 90 degrees from each other. For instance, when I cut a 600mmx400mm rectangle out of a larger piece, I can not flip the cut piece over and fit it back into the larger piece because the corner angles seem to be slightly acute or obtuse.

The following was performed based on the instructions found here: How are steps calibrated?

I have already calibrated X and Y as well as I could with a meter stick by eye. A 600mm length cut was 600.5 mm, so I updated that, and a 550mm appeared to be 551mm by height, so I updated that.

What am I missing?

Thank you!

By updated, do you mean going into the vendor settings and adjusting the step length?

Thanks for your reply! Yes, that is what I meant by updated.

My guess is that the problem is that the bed is not perfectly level. The bottom left corner is about 1mm lower than the other corners.

I’m using slats, so there’s no obvious low tech way to raise the corner, like if I were using the honeycomb bed or any other one piece bed.

Is there a software solution?

Thanks!

Nothing come to mind other than layers of card stock on that corner as a shim.

I will ask how you did your measurement checks. To do it properly, you need to cut as large a square as possible. The larger the square / rectangle the better your calibration. When you input it, put a dashed line down the middle to fold on to check your skew while you are at it.

Thanks so much, Dave!

I’m using slats at the moment, but if I were using a one piece bed (like a honeycomb one), that low tech solution would work perfectly!

I didn’t have anything longer than about 620mm, and the bed is 900x600, so I cut rectangles defined as 600mm (which, after cutting, measured 600.5) and 550mm (which came to 551).

I’m crossing my fingers for a software solution so that I don’t have to make a solid bed for the slats, but I think that might be the next thing I try.

Thank you!!

Use old wrapping paper cut from the back. It’s what I use for my 500 x 700 bed check. And don’t forget to check the skew while you are at it. Too many people assume their machine is square.

There isn’t, not with a DSP controller - most of them only handle 2D moves, and some (like Ruida) will allow Z moves in between, but not a coordinated XYZ move, which would be required to do software-based leveling like 3D printers do.

Thanks so much, Oz, that’s really helpful!

Yes, that’s true, Dave! My machine is not square at all!

About the wrapping paper cut from the back, can you say more about that? I’m not following yet. Thank you!

I’ll try.

For my 500 x 700 bed, I don’t have paper to cut a rectangle that large. but she had several old rolls of wrapping paper she was going to toss out. I use it for various testing. the primary reason I snagged it was for the squareness and dimension test. You can see those pics on my google page.

I did a 350 x 550 rectangle with the dashed line down the center. I don’t remember by how much, but it was off on my first test. I entered the 350 drawing dimension and the measured cut length in the Y axis step length adjustment window. Did the same for the X measurements, and retested. If I remember right, I had to tweak the X by a couple mm on the second test.

Then you fold the paper in half, as pictured in the second squareness test. You can see mine is off by a little over 2mm across that 350mm cut length. That is my skew error. basically my squares aren’t quite square, and my circles aren’t quite round. The bigger the circle / square, the more pronounced the error. As my Y drive axle is behind my laser tube, and I don’t do inlays and such, it will probably be there until I have to change laser tubes.

The key for accuracy is to do as large a squareness check as you can. The closer to your max bed size, the more accurate your correction will be.

Hope that makes sense.

Hey Dave,

On a side note, do you have pressure regulators in your air assist rig from your pics? It looks like the low/ high pressure setup from Russ’ air assist head kit, and the part with the blue handle would be the regulator? Do you have a link to where to source that part?

Not in that picture. And the blue handle valves are ice maker shut off valves. The valve with nothing connected to it is for air for acrylic block burn tests so I don’t have to mess with the lines to the nozzle. The bypass valve is my engraving bypass. It barely blows bubbles in a cup of water, you can see them in the accompanying video.

Of course, that is all out the window now from the looks of it. Through a video from another user, I am playing with high pressure air, in the 20 - 40 psi range, to keep my Premium MDF cuts clean. If it does what it’s supposed to, and individual tests seem to indicate so, I will have to look at a new set up. Ideally an ultra low for engraving, a low for acrylic, and a high for the MDF. The switching and such via solenoid or physical valve has yet to be decided.

The mod list just keeps growing and growing and growing…

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