Difference in cut size along X axis. Can anyone help me?

[MauricioBachega]

I have a problem with my machine, it is cutting with different sizes along the X axis, I have already checked the mirror alignment and it is 100%.
I was working with a cut of 2 pieces from the side of the other, the first is in the exact size, the second one was 0.6mm bigger.


The difference between them.


I decided to make a test during the entire table (1300mm) making 3 squares and see the difference in measurement.



The difference

The bigger the piece, the bigger the difference.
I work with absolute coordinate, the reference of the machine is on the top-right and my workpiece start on the top-left.

I decided to do another test only in the middle of the machine with Current Porition to see if it was a problem in the RDWorks coordinate and the problem continued, the piece got bigger.

Regardless of the coordinate system or position in RDWorks, the problem remains the same on the machine (at the left (0 to 25cm), the size is perfect, more to the right above 30cm the pieces is larger)

To prove it, I made a ruler with strokes every 10 mm over 400mm, until the 250mm the strokes remain the same, above 250mm it starts to get bigger.


I use RDWorks 8 and the controller board is RUIDA.

Has anyone had the same problem or know what it might be?

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[Dean448]

As for the 10mm ticks along the X axis... I would adjust the X axis pulses per unit setting in the controller.
I would test fire and move each axis to its range and change this setting until the controller matches the scale.
It’s difficult to see when pulses per unit is off over 10mm but much easier at maximum range.


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[MauricioBachega]

The machine is well calibrated, I made a 1000x1000 square and set the pulse per unit of X and Y.

The problem is that it changes the measurement along the X axis

[Dean448]

So you verified that 400mm move on the controller matches 400mm on the scale. But 100, 200 and 300mm do not match?


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[MauricioBachega]

I did this test over the 1300mm

This is the 1300mm calibration in X


26 50mm rectangle
A---Z


The Results


As you can see, as I said, from 0 to 250mm the measurement is much smaller, but after the 5th square (250mm+) you can see that the measurement stabilizes, the most amazing thing is that in total the cut was 1300 perfect, so the measurements vary within those 1300mm.

Looking at this test, it seems an irrelevant difference (0,2mm), however if I cut two squares of 200mm
The first one will be 0.6mm smaller and that is quite a difference in the assembly of a box for example.

[Dean448]

Ok. I have a theory but it’s pretty detailed
The lens stands off the work by at 50mm. The mirror on the x axis must allow the beam to be directed 90 degrees to the wood. If the angle changed slightly the beam moves from where it was supposed to go. You can do the math. 0.3 wouldn’t take much.
Not sure how you would measure something like this but all the mechanical parts need to be tight and straight.

In the end these units aren’t that exact. I tried using my machine to cut wooden gears and gave up due to the burned and tapered surface. The wood isn’t perfect either. You may want to repeat the test using a thin acrylic


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[OZOZ]

I have a same problem. Can anyone help us?

[Medjed]

Had same problem while ago... Struggled for months without solution... Then some guy came to my workshop, took the calliper, fix it on 100mm exactly and start to measure and compare teeths on belt. On some sections distance was uneven...

STRECHED BELT!

Bought new one for 20€, change it in 15 minutes and solved problem...

Hope it will work for you...