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Benchy breaking off the bed when almost done  

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dj_segfault
(@dj_segfault)
New Member
Benchy breaking off the bed when almost done

I just finished assembling my Prusa i3 MK3S last weekend.  To eliminate variables, I am only printing from gcode that came on the card with the printer. I had some problem with the Z axis first layer setting but I think I have that resolved. Sometimes the first layer doesn't stick at all, but generally it does.

I tried printing Benchy of course, watched it for about an hour, and left.  When I came back I saw this mess (I moved it before taking this picture)

Since then I tried printing some shorter things, and they worked OK (the Prusa logo was curled up a tiny bit on the left)

I then tried printing Benchy again, but watched it the whole time.  At pretty much the same exact point, I saw the model break free of the bed and move around.  This is probably what happened above which is why my first Benchy turned into an afro 🙂 

The first layer seemed to stick just fine and it stayed for about 2 hours before breaking off.  So I'm guessing the extruder bumped into it maybe? Again these are my first prints evar so I am still very much learning about the failure modes.

What are the likely causes of this in a repeatable manner, and what can I do to fix it?

Thanks.

Posted : 06/10/2020 3:18 pm
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(@)
Illustrious Member
RE: Benchy breaking off the bed when almost done

Fingerprints are the most common offense. 

Soap and water are the best way to clean the smooth print sheets. Alcohol can work, but requires finesse and a LOT of alcohol or a LOT of clean downy free rag. Soap and water is also required for the textured sheet, but the sheet must be heat dried after a wash - e.g., bake the sheet at 80C for a bit to get any moisture out of the texture.

That said - some people never get the textured sheet to work well with PLA. 

Posted : 06/10/2020 5:18 pm
dj_segfault
(@dj_segfault)
New Member
Topic starter answered:
RE: Benchy breaking off the bed when almost done

I tried again and it failed at the same spot, the roof over the cabin, so I started to suspect it was failing at that bridge.

I finally got it to print using glue stick on the bed.  I think I used too much though and will try my next model applying less.

 

Thanks

This post was modified 10 months ago by dj_segfault
Posted : 12/10/2020 3:58 pm
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(@)
Illustrious Member
RE: Benchy breaking off the bed when almost done

If soap and hot water didn't work to clean the sheet... PLA and textured sheets are sometimes not compatible. Many have purchased alternatives or the smooth PEI sheet for PLA. 

You can have a chat with Prusa about it. They will probably say there are no warranties on the print sheets, so buyer beware and all that. But try. They might comp you a smooth sheet.

Posted : 12/10/2020 6:37 pm
Peter M
(@peter-m)
Noble Member
RE: Benchy breaking off the bed when almost done

First layer needs to be pushing filament down into the powder coated bed, not to much, this will help with sticking.

Wash powder coated bed a few times with hot water and dish soap, this also helps with sticking.

If still fails:(and normally not needed)

First layer slower 10 mm

First layer hotter nozzle ,

Hotter bed.

Glue stick and other things you can buy for sticking.

Posted : 14/10/2020 8:23 am
cwbullet
(@cwbullet)
Illustrious Member
RE: Benchy breaking off the bed when almost done

Can you redo the first layer test and post and image?  Also, show the bottom of your prints.  

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Chuck H
3D Printer Review Blog...
Posted : 14/10/2020 9:14 am
Andrew D. liked
Andrew D.
(@andrew-d-2)
Active Member
RE: Benchy breaking off the bed when almost done

I agree with @charles-h13. 

 

Heres the link to the Knowledge base : https://help.prusa3d.com/en/article/first-layer-calibration_112364  

Posted : 14/10/2020 2:00 pm
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