Strange Drawing issue - everything on the left is taller than the right

Hey everyone! So my Dad and I just finished up our build and we are trying to make sure everything is working properly but when we try to draw the crown, a strange shift is happening where everything on the left side of our picture is slightly taller than everything on the right side of the picture. So in doing a little troubleshooting, we drew a “Square” by jogging the machine right 100mm, then up, left, and back down all 100mm. The “Square” is only 97mm from front to back (Along our y axis) and it is 100mm from left to right (Along our x axis). Anyone have any ideas as to what our problem could be? We are very puzzled. Attaching a picture of our shifted crown.




A picture of your build would help here. Was the square a square or a rhombus?

It is possible that one of the steppers is not working/connected and the axis is only being driven by one motor instead of 2. Did you check the pulleys to make sure they are all the same (should be 16 tooth pulleys), the set screws are tight, and the stepper motor connections are good?

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Also make sure your steppers are both plugged in. I had a similar issue and it turned out one of my Y axis steppers had unplugged (inside the drag chain) so the other one was pulling it along.

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Just to add a couple more pics. I have double checked the connections, and it appears all of the motors are working. When I jog it in a 150mm square the diagonal measurements are exactly the same. The Y travel loses 3mm over 150mm of travel. X travel isdead on 150.


That wouldn’t cause the crown issue. The drawing and square are two separate issues.

What hardware and electronics are you using?

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Thanks Ryan. I assumed if the y travel was consistently less than the x, maybe it would compound to the crown issues.

In any case we did get the full Rambo kit with dual end-stops.

Hmmm. The crown that was drawn was my Gcode found at the end of the crown page?

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Correct - we went through and followed the getting started guide using EstlCam, and then resorted to your gcode as the next step of troubleshooting to take out the variable of any settings that we may have had wrong (they all looked the same). The one heavy line at the bottom is a false start - so ignore that part.

If you are using my hardware, electronics, and gcode you machine should not be off by 3mm. Unless your pulleys are not on all the way.

Some pictures of your build will help me look for obvious issues.

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Okay - keep in mind we aren’t finished with cable management :-). Here are some overall pics along with a couple of the steppers up close. Let me know if there is anything else specific that would help. The frame looks crooked in the pictures, but is within 1/32 of an inch on the diagonals. Overall it seem to runs really smooth, and zeros out at the stops perfectly.

Okay nothing jumps out at me but I do see two things that could possibly cause issues.

1- The tension bolts that I can see seem to be very tight. I just looked over at my test bench it it doesn’t even have a nut on a few of them. You can tension it enough to not mover correctly.

2- The pulleys are on “backwards” which in itself does not mean failure but it puts the collar so close it can rub the steppers and bind.

#1 is a bigger concern but doesn’t explain why what is going on with your machine. The pen mount you are using isn’t the most accurate style and could be it as well. Just to be safe you should try mine, it is a quick print. Some of your locks do not have screws, that could cause wobble.

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This may not be it, but some of the pictures look a little too dark, almost as if the marker is really pushing on the paper. Are you starting the marker with it really pressing into the paper? When I use a pen, I think I set it to a height where when I drag the gantry, the pen will just write.

So maybe the marker is getting caught in the paper? Or is the surface underneath blemished somewhere? And it doesn’t look like this would be a problem as a lot of the details are clean, but is the marker securely attached to the toolhead, and the toolhead itself to the gantry/toolmount? Does the gantry wiggle if you try to drag it around?

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First - thank you everyone for your help on this. I went through and made sure the bolts were not too tight, and I will flip the pulleys around shortly. We actually started with your pen mount, and tried another one to see if the flex it it was causing our problem. I have put yours back on with the same results… However…

New information - I jogged it 5 times in a row along the Y axis (50mm each), and discovered that the total line was still 3 mm short. When I measured each segment I found out that the first one was 47mm, and the rest were all dead on 50. It seems like I read something about an offset, but don’t know where. I will keep looking now that I have this information, but thought I would post it to see if this clarifies anything.

Using my gcode, my pen mount, ball point pen, and 3 sheets of copy paper stacked up taped down on all 4 sides. Park the head with the tip of the pen just barely touching the paper. Barely.

Reset the control board.

Run my crown Gcode let me see a picture of the results.