X and Y Layer Shifts

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NF6X
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X and Y Layer Shifts

Post by NF6X » Tue Aug 02, 2016 5:09 pm

I'm confining my posts to the Getting Started forum for now, because I'm a brand new M2 owner and still going through the new user learning curve. I hope this is the right category for this post.

After printing a calibration square on my new printer and finding that it came out really close to the expected dimensions with the out-of-the-box parameters in Simplfy3D, I decided to crank out a functional trial print overnight and then get back to fine-tuning calibration later. So I took a Raspberry Pi case that I had previously printed successfully on my Monoprice Mini + Cura, dropped it into Simplify3D on my Mac, started off the print, and went to bed. I think that the Simplify3D parameters were pretty close to default; I had played with some of them to get my single-wall test print, but then I attempted to set things back to default settings.

This morning, I popped the print off the bed. Everything seemed well-adhered. Then I noticed that the print had layer shifts in both X and Y axes. I didn't carefully examine the orientations of the pieces vs. their skirts before noticing the problem, but no asymmetry jumped out at me before popping off the parts. I set the pieces back on the bed for these pictures. The skirts are still stuck in place in their original positions.
IMG_3785.jpg
IMG_3784.jpg
IMG_3787.jpg
I can think of a number of possible causes for these layer shifts: Steppers missing steps? Pieces shifting on bed? Computer feeding the printer went wonky? Travel speeds set too high? Slipping belts? Cable came loose during shipment? I can't rule out printer trouble, computer trouble, or user trouble just yet. :)

The belt tensions both feel about right to me. I had the printer connected to my MacBook Air, being fed directly from Simplify3D. I plan to add an OctoPi (that's what this case print is for) to the mix later, but I'm keeping things simpler until I get more experience. I have not yet installed my Dual Extrusion upgrade kit, and I'm using the black PLA filament that came with the printer.

I have to head off to work, so I won't be able to try anything else until tonight. I'll have my laptop with me, so I should be able to pull up the Simplify3D parameters that were in effect while i'm at work. Can any of y'all suggest the most likely culprits for me to begin investigating?

P.S.: Prints made with black filament aren't the easiest things to photograph clearly!

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Jules
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Re: X and Y Layer Shifts

Post by Jules » Tue Aug 02, 2016 5:22 pm

Looks to me like maybe the edges warped up a bit, the nozzle hit it, and got out of alignment. (Most common cause of that kind of misalignment happening.)

(Hard to tell in the photos though - you'd have to get down at eye level and see if you have a little separation from the plate there.)
IMG_3787.jpg
You could try some hairspray on the next print to keep it locked down.

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NF6X
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Re: X and Y Layer Shifts

Post by NF6X » Tue Aug 02, 2016 5:48 pm

Note that all of the pictures were taken after removing the parts from the bed, and the specific one you annotated with arrows doesn't have the prints sitting anywhere near their original location and orientation on the bed, and their back ends are resting on the still-stuck skirts. That being said, I certainly can't rule out lift-up and shifting on the bed, and I didn't pay close attention before popping the parts off the bed this morning.

I printed on clean (?) Kapton, with the original Kapton film that came pre-applied on the bad. I did have lift-up when printing the test bracelet, with its very small bottom surface area. I have a PEI sheet on order, and I have some purple glue stick and a can of Aquanet that I haven't tried yet.

On my next attempt to print this model, I'll examine everything closely before removing the parts from the bed. Maybe I'll be able to measure the skirt gaps around the parts to detect any evidence of horizontal shifting. Heck, maybe I'll even point a video camera at the bed to do a post-mortem! After thinking about it all in the shower, shifting on the bed does seem like the most likely culprit.

BTW, Jules, I did discover that your favorite plastic scoring tool very easily tears thin Kapton film. :( All the more reason to get a sturdy PEI sheet on there in place of it! I figure I'll just alter the Rev. E corner clip design for 0.062" more height, so I can clamp down the glass + PEI without needing to notch the PEI corners. The plastic scoring tool did work very nicely on the sturdy Buildtak I have on my previous printer, which erred in the too-much-adhesion direction.

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Jules
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Re: X and Y Layer Shifts

Post by Jules » Tue Aug 02, 2016 7:19 pm

Uh-oh! Sorry to hear that - I use it on the PEI which will stand up to a chisel. My bad! :roll:

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NF6X
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Re: X and Y Layer Shifts

Post by NF6X » Tue Aug 02, 2016 7:41 pm

Don't feel bad! It's my own fault for not expecting that to happen. After all, I work with Kapton tape all the time in my electronics-related job and hobbies, so I should know better. Anyway, I view that factory-applied film as training wheels while I'm figuring out which approach to settle on through experimentation.

Say, once I have the PEI sheet applied, which do you think I'm more likely to want to use in a pinch: bare glass, or Kapton? I'll need to decide whether to keep the Kapton on the back side of the glass+PEI sandwich or not. I suppose I can put off the decision by affixing the PEI on the bare glass side, since I can always peel off the original Kapton more easily than applying new Kapton.

BTW, I pulled off the skirt from last night's print before I headed out the door to work. I noticed that the two passes had a nice gap between them, so my bottom layer clearly isn't dialed in right. That makes it seem even more probable that my print failure last night was just caused by imperfect adhesion. And that makes it something that will probably go away quickly with better calibration and better surface preparation.

I also remember being quite impressed by how quickly the M2's bed and head change direction and accelerate vs. my cheap starter printer. I suspect that the higher acceleration and jerk that the M2 is capable of makes good bed adhesion even more critical vs. many other printers. This printer's good rigidity probably translate to higher accelerations being experienced by the part compared to "floppier" printers. Neat stuff!

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Jules
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Re: X and Y Layer Shifts

Post by Jules » Tue Aug 02, 2016 8:10 pm

I tell you, once I put the PEI on, I never felt the need to use either bare glass or Kapton again. Stuff's awesome. (But it shouldn't matter - whichever one you prefer if you want to leave it on there for a while.)

Matter of fact, since you do know what you're doing already - you might want to just bypass the PEI on glass and look into the MIC6 plate with PEI. It's the closest thing to Nirvana there is, and it's a one time purchase. Damn near indestructible, and so perfectly flat, and great at distributing heat all the way across the bed.

viewtopic.php?f=10&t=3450

Insta is thinking about taking orders for a new batch of MIC6 plates, I think. He was asking if anyone was interested the other day. (He only does them in batches, due to the time factor. Check the last post in that thread and see if anyone else is interested.)

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NF6X
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Re: X and Y Layer Shifts

Post by NF6X » Tue Aug 02, 2016 9:39 pm

Jules wrote:Matter of fact, since you do know what you're doing already
That is high praise coming from anybody on this forum!
Jules wrote:you might want to just bypass the PEI on glass and look into the MIC6 plate with PEI. It's the closest thing to Nirvana there is, and it's a one time purchase. Damn near indestructible, and so perfectly flat, and great at distributing heat all the way across the bed.

viewtopic.php?f=10&t=3450

Insta is thinking about taking orders for a new batch of MIC6 plates, I think. He was asking if anyone was interested the other day. (He only does them in batches, due to the time factor. Check the last post in that thread and see if anyone else is interested.)
I've seen MIC6 plates mentioned in the forum, but I don't understand what they are yet. I'll go read up on them. Thanks!

wmgeorge
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Re: X and Y Layer Shifts

Post by wmgeorge » Fri Aug 05, 2016 10:44 pm

I will vote for the PEI sheet and proper set up. Mine has been on for about a year now, granted I do not print a lot, but it works great.
Retired Master Electrician, Commercial HVAC/R,CNC Router

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