My XY rectangles are showing a 0.5° shift in Y direction. Z is fine.

[dmckee 0]

While printing rectangular objects about 100 mm x 40 mm, I notice that the prints are shifted about 1 mm toward the rear of the machine (Y axis). The vertical Z axis shows no shifting and is perpendicular to the build plate. Beside belt tension and lubricating the slides what are some possible causes I can look at to resolve this?

[CarloK 203]

What printer brand and model?

[dmckee 0]

What printer brand and model?

 

Ultimaker2

Colorfabb PLA/PHA

Extruder 210 C / Bed 50 C / Flow 100%

Nozzle tip 0.4 mm

Layer 0.1 mm

Print Speed 60 mm/s

Travel 120 mm/s

[neotko 1,417]

Check this guide and also post a photo of the print. Most of the time one thing is a shift or leaning or skipping. Is important to post images because it could even be x/y out of square.

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide

Edited November 10, 2017 by Guest

[dmckee 0]

3dverkstan is my go-to solution source when I have a problem, but it fell short this time. View of part in image: Looking down at plate, long dimension is X-axis. Shift is 1+ mm.

[gr5 2,167]

Did you mess with jerk or acceleration settings on your UM2.  It's possible they are too high.  But more likely the problem is a loose set screw.

I know you probably already tightened your set screws but not enough.  You have to tighten the hell out of them.  If you use an L shaped allen wrench your fingers should HURT after.  You may need a break to save your fingers between each tightening.

The problem is most likely on the shortest belt - the one on the motor or the other end.  These are also the hardest to get to.

If you don't believe me and want to prove me wrong, use a sharpie (permanent marker) and mark the shaft and the pulley.  You'll see after a print like this it will have moved enough to know which pulley was the problem one.

It's not surprising at all that the problem starts at a certain height.  The accelerations involved to get this to slip are complex and will only repeat with certain geometries.

There is also a chance you messed with acceleration.  The defaults should be 5000mm/sec/sec for x and y acceleration and 20 m/sec for jerk.  If you have tinkergnome you can look at them directly I think.  Or if you don't you can download pronterface and connect to UM2 through USB and pronterface reads back these values when it first connects.  There are also gcodes to use through pronterface to adjust these settings.  You could lower jerk to 10 and acceleration to 1000 but that will just mask the problem.

It's also possible there is something wrong with the current setting. It should be around 1000ma for X and Y stepper. Again tinker marlin can check this or pronterface. But I doubt you messed with this.

MUCH MORE LIKELY IT'S A PULLEY SET SCREW.

Edited November 27, 2017 by Guest

[dmckee 0]

1>...jerk or acceleration settings

2>...more likely the problem is a loose set screw...on the shortest belt ...

3>If you don't believe me and want to prove me wrong, use a sharpie (permanent marker) and mark the shaft and the pulley.

4>It's not surprising at all that the problem starts at a certain height.  

Hey thanks for the response gr5. Let me respond to your suggestions.

1> I'm not a tweaker. When I have tweaked with settings in the past nothing good came out of it, and it just came down to time wasted. So jerk and acceleration settings are normal, but I will check.

2> What I'm going to do is loosen the set screws and rotate the shaft to a new position, giving the set screw a fresh piece of steel to bite into.

3> Marking the shaft is a great idea! Frankly it's the first time I've heard of it.

4> It sound like you have a misconception about the part build. In the picture the vertical axis (Z) is coming out of the picture. Imagine looking down through the top of the UM2 at the build plate and you would see the part just as it is pictured. I don't know if that affects your suggestions or not.

I'll run through these items and try it again after a meeting and we'll see what happens.

Thanks

[neotko 1,417]

I would check if the X/Y are properly squared. On umo this is done like this:

https://ultimaker.com/en/resources/20910-align-print-head

The part to just check doesn't exist on youmagine, only the other versions that 'click' on the shafts. But the process basically it's the same.

https://www.thingiverse.com/thing:38300

https://www.youmagine.com/designs/adjustable-axis-alignment-tool

https://www.youmagine.com/designs/ultimaker-xy-axis-square

[gr5 2,167]

4> It sound like you have a misconception about the part build. In the picture the vertical axis (Z) is coming out of the picture. Imagine looking down through the top of the UM2 at the build plate and you would see the part just as it is pictured.  I don't know if that affects your suggestions or not.

 

Oh.  mind blown.  Okay I guess maybe it's not a loose pulley after all.  I really need to see this from a few more angles.  Maybe the bottom view?  It looks like part of the part is straight and another portion is crooked?  That doesn't make sense - usually crookedness happens because the printer shifts a little on each layer.  But here it looks wrong on a single layer.  I'm confused now.

Did you look at this part in layer view by the way?  Does it look fine there?

@neotko's suggestion of tilted X/Y makes sense - except the bottom half of the part looks straight?  Or is it just a strange camera angle fooling me?  You can see the tilt easily by looking straight down and pushing the head to the 4 sides and looking at the two rods that go through the head and also checking if the end blocks hit at the same time when you push the head to an extreme.

Edited November 30, 2017 by Guest