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Prints become more spaghetti - first later failed  

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cerw
 cerw
(@cerw)
New Member
Prints become more spaghetti - first later failed

Hello

We have our Mk3 over year and it never had any major issue, in last few week most prints starting to fail, so I did recalibrate the whole thing, and the 1st and 2nd point seem to always manage to touch the paper? the 3 and 4 seem fine? Anyway the LCD just said turn the printer off, but not how to fix this? so i just hold it there and the calibration finished. What is the right way ? 

 

When I redid first layer, the print looks really bad, Z-Live can only go to negative and just makes it worse? And the whole lines seem like the printer is drunk?  Can anyone help?

 

Thanks

Petr

 

 

Posted : 23/05/2019 1:40 am
RH_Dreambox
(@rh_dreambox)
Prominent Member
RE: Prints become more spaghetti - first later failed

When I redid first layer, the print looks really bad, Z-Live can only go to negative and just makes it worse?

Yes, Z-Live should be a negative value. The larger the negative value is, the smaller is the distance between the nozzle and the bed.
Your image shows that you should increase the negative value because the nozzle is too high.
If filaments adhere poorly to the bed, you can also clean it with detergent and hot water (no chemicals).

Bear MK3 with Bondtech extruder

Posted : 24/05/2019 12:16 pm
bobstro
(@bobstro)
Illustrious Member
RE: Prints become more spaghetti - first later failed

If you've been able to get the XYZ calibration to work, you need to get your Live-Z set correctly. It looks like you've tried, and are encountering problems. This is what the little square at the print of the Live-Z calibration should look like:

This can be caused or aggravated by two factors that need to work together well for successful prints. Even if you're dubious that these are the cause of your problems, they're 2 fundamental troubleshooting steps you need to complete to rule out the basics. Here's mama's tried and true copypasta recipe to get you going...

  • A dirty PEI print surface. Even if you don't think this is the cause, it's always a good idea to make sure your PEI surface is clean before trying any other fixes. Take it to the kitchen sink and give it a good dunk with Dawn (original formula, no vinegar or hand softener variants) dishwashing soap or your local equivalent (e.g. Fairy in UK). Use a clean paper towel to clean it off, and another to dry it. Avoid using any sponge or cloth that has been in contact with grease. Above all else, avoid touching the PEI print surface. Once it's good and clean, you should be able to use 91%+ isopropyl alcohol between prints, 100% acetone when that fails, and another dunk when acetone fails. Worst-case, use a 3M 7445 ScotchBrite pad or equivalent to give it a very light buff, but only infrequently.
  • If you have not already done so, try using Jeff Jordan's "Life Adjust" procedure for calibrating your Live-Z setting. It is much easier to use and understand than the on-board routine. In general, start high (less negative) and work lower (more negative) in large increments (e.g. 0.1mm) until the filament starts to stick on its own. When it's right, you should be able to gently rub it without it coming loose. Then start lowering (more negative) the level until there are no gaps between layers. When you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines without dislodging them. 
And above all else, avoid touching the PEI print surface.
Try those 2 steps. If you're uncertain of the Live-Z results, post pics here of the 75x75 print bottom and you'll get quick help. 
In the future, a good dunk with Dawn will restore both sides of your to like-new condition and is always a good thing to try when you encounter 1st layer problems. 
If you want more detail, I've consolidated my notes on Prusa PEI adhesion, bed cleaning, and Live-Z calibration
My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 24/05/2019 2:04 pm
cwbullet
(@cwbullet)
Member
RE: Prints become more spaghetti - first later failed

My Z drifts a little over time.  As it gets out of tolerance, I have found doing a first layer test is a good measure I need to adjust it.  The rectangle does not fuse well when out of tolerance.  

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Chuck H
3D Printer Review Blog

Posted : 24/05/2019 6:10 pm
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