Need help calibrating

I’ve recently change out the bushings on the print head, but something is out of calibration, or out of whack. My prints aren’t printing correctly, they are out of shape.

After changing out the bushings I printed a part, but found that the round shapes were oblong. So I printed a 20mm calibration cube, found the calibration was off, made the calculation changes, input them into the firmware, then printed out a new 20mm cube, and it was right on the money.

I went back to making my parts to find out that the round shapes were still oblong. So I created a 20mm round x 20mm high part. Here is a pic of the 20mm round print. But it’s not round, it’s oblong or egg shaped. The shape dim range from 19.60mm to 20.75mm, and the height is right on the money.

Help, what did I screw up? How do I fix it? :open_mouth:

Thank you.

Round parts being oblong indicates that the belt in that direction isn’t tight enough. Usually the narrow portion is the direction that needs tightening. It can also be the belt pully, not the belt that is loose which will cause the same effect, but is harder to detect because the belt seems fine.

The narrow side is my X axis (left/right), and I’ve tightened it but still no luck.

Since this is all happened from when I changed out the smooth rod bushing, I’m wondering if the smooth rod installation is missing something. Should I go back and pull that assembly back out and start all over? Or could there be another adjustment I should check? Could my belt be wearing out?

Where do I go from here?

Also, I’m located in Southern California, any chance there is a service company in the area that works on these? I need to get it back up and running.

Looking at your picture, it looks like your X axis belt drive wheel is not quite flush/tight with the flat part of the X motor shaft. So you are getting a small flat surface on the left and right side of your round prints as it ‘turns’ the corner. AKA - very slight X axis sloppiness.

If you look at the sides of the printed model you will see a very small bump on the SW and NE corners of your printed part where the drive gear is wobbling on the flat.

Or at least that is what it looks like to me from the picture you posted.

I’m still having issues with my Mini. I’ve tightened the X-axis belt, and checked the set screw for the timing pulley, tightened the stepper motor mount screws, can’t see anything cracked. And it still creates prints like this.

I’m wondering if I should go ahead and replace the belt & timing pulley, just in case it one of them is the issue. How often does a timing pulley go out???

The attached pic is a top view of the hollow 20mm diameter part I’m using to resolve the issue. This time I stopped it more then half way thru the print. It’s set to 20% fill, so you can see where areas of the inner & outer walls don’t match up.

Any help you can offer would be appreciated, I need to get this machine back up and running.

If you cannot see visable belt wear damage (Frayed edges, missing belt teeth, cracked rubber, split belts, or similar) than the belkt does not need to be replaced. These are timing belts designed for engines that run much faster than 3d printers will ever get them moving. Unless the timing belt is cut to ribbons by improper allignment against a particularily sharp pulley, it is unheard of for them to wear out.

The pulleys almost never wear out. the main failure cause of them is setscrew related. The pulley body itself should be fine for the entire theoretical life of the printer unless you hit it with a hammer or step on it or something similar.

Maybe post a video of your printer printing a circle layer? we might be able to see something off from there. It definitly looks exactly like the “belt is too loose” issue. If the top of the picture is in the Y direction, I would say the issue is possibly with your bed motor, belt or pully, not your X axis. Its staying flat in the Y travel direction when it should be moving to finish the circle round if the top of the picture is towards the back of the machine.

I agree with Tim, and you can see that even the skirt has the sudden direction change. Check that your drive pulleys set screws are tight and lined up with the flat on the motor shafts on X/Y.

Thank you two for the input and suggestions. I hate to say, I haven’t even checked the timing pulley on the bed (Y-axis). I replaced the bushings on the print head, so I assumed my issue was with that part of the machine.

I check the bed timing pulley and belt and let you know.

Thank you!

I’m still missing something. I checked & tightened everything related to the bed, it’s mounts, it’s belt, it’s timing pulley, etc…

Here is a link to a video of it running. I hope someone can see something I’ve missed.

Thank you.

It kind of looks like the y axis pulley slipped slightly, like it wasn’t tight to the center of the flat spot of the motor shaft and can move slightly. But you checked that, so it must be something else. Maybe check for a loose Y axis motor cable? If there is an intermittent wire short for some reason that cuts power to one of the two pairs of motor coils it can cause the motor to lose most of its force for a second. You can check for that by carefully and safely putting some pressure against the top of the Y axis pulley while it is moving and seeing if it feels like it is losing drive force at any point, doing so in a manner that will not result in a finger removal. That or take the belt off the motor and run a test that way.

Aside from that, I’m not sure what to tell you. It is your Y axis, it is behaving like a slipping pulley or a looser belt or a failing Y axis motor driver. It’s possible this is an electronics board issue if the other things aren’t the issue.

ALso try pulling up and down on the Y axis motor shaft and see if it remains attached to the motor.

Your video shows that it is the X axis that has the problem. You will see the skirt has a flat left and right side and not a smooth curve.

Well I’m still having the same issues. I replaced the pulley on the X-axis stepper motor, and replaced the belt, but no luck. It seems to be getting worse, if it really is related to the X-axis only, could I have a stepper motor going out???

In the pic’s you’ll see that I still have flat areas on round parts, but now the parts swerve/sway when going in the Z direction. Also, I can actually see the print head jogging/stepping when making a diagonal pass. I uploaded a video of it to youtube, you can see it jogging/stepping on the longer diagonal passes.

I have to get this machine up and running, please help.

Thank you.