# Thread: x and y axis: cut a square but not perfectly right angledd

1. ## x and y axis: cut a square but not perfectly right angledd

Hi
I cut a square and measured the opposite angles to be 90.5 degrees and 89.5 degrees so the square is slightly skewed by .5 degree
I am assuming this is a mechanical issue and am wondering if anyone else gets this problem and how you adjusted the axis to resolve it.

rabbit 3040 laser

2. Yes, it is a mechanical issue. One of the axis is not at 90 degrees to the other. Most likely the beam (gantry) is the problem.

It can usually be corrected by loosening the idler (non driven side) bearing and moving the head back and forth so it aligns and then carefully tightening the block again without inducing any torque and twisting it out of alignment.

I would also check that it is repeatable before you do this as it could be due to friction if the idler side isn't able to move freely. If this is the case you'll chase your tail trying to correct the problem.

Zax.

3. Hi,

My machine has a similar problem - it doesn't cut to scale and the axes are slightly skewed. However, by far the simplest solution I've found is to scale and skew/shear the CAD file before sending it to the machine - an easy matter to do in any CAD program. This is what I've done and have been making square, dimensionally-correct parts ever since.

Check the scaling by getting the laser to mark lines at what it thinks are (for example) 10cm intervals. Then simply measure the actual distance between the marks and you know how much to scale by.

Shear/skew is trickier. Best I've found is to cut two identical squares (around 10cm on an edge) from cereal packet. Flip one about the vertical axis, then place it on top of the other one. Align the bottom edges. If the axes are squint, then the top corners will be out. Try skewing it 0.1 degrees or so one way and see what effect it has.

As an example, my "preparation" prodcedure is: scale by 0.9875, skew/shear by 0.36 degrees to the right.

Hope that helps.

Lindsay

4. Thanks zax15uk, I have not been brave enough to make the adjustments at the moment as I am in the middle of some jobs, but that sounds like it will be the solution.

As for scale, imajeenyus, there is a software solution for scale problems within newleydraw which I use to adjust the parameters. I cant remember exactly where it is but it is under properties.

• imajeenyus,

As geekinesis suggested in NewlyDraw you can adjust the V and H DPI under the Device tab to correct for sizing issues.

You should never need to adjust your design to compensate for mechanical or software issues.

Zax.