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Why does this happen at the same spot?  

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ametwalyhsgca
(@ametwalyhsgca)
Active Member
Why does this happen at the same spot?

I've printed this twice and these kind of things seem to happen at the same spot for some odd reason. I wipe down my steel sheet with Iso 99% alcohol usually but its a weird issue for the fact that it tends to always happen at the same spot every time. Everything else lays down perfectly fine and sticks to the bed flawlessly. I am using the Prusa 3d filament with the MK3S.

(2nd object starting from the left)

Temp is 215C and 60C bed.

Originally this was at an extrusion multiplier of 1, but i noticed there was gaps in the lines of the initial layers so i increased extrusion multiplier to 1.1 The lines are a bit better, but this issue was the same even before the extrusion multiplier increase. Everything else is pretty much the same prusa profile for the MK3S. 

Printing at .3mm height (Draft) with .2mm initial layer.

 

Posted : 27/07/2019 12:17 am
Dave Avery
(@dave-avery)
Honorable Member
RE: Why does this happen at the same spot?

time to give it a soap and water wash. IPA cant remove everything . wash the plate with plain Dawn dish detergent - make sure it doesn't have additives like hand softener. then rinse real well and dry with a clean paper towel. without touching the surface re-install and heat to finish drying.  

Posted : 27/07/2019 12:34 pm
--
 --
(@)
Illustrious Member
RE: Why does this happen at the same spot?

Yep - for what ever reason people use alcohol. Alcohol picks oils off the fingers and smears it on to the bed in a micro fine invisible layer.  And heavy finger prints are not removed unless you use a LOT of alcohol.

Soap and water works because you are using gallons of water to wash and rinse; not drops.

Do NOT use kitchen scrubbers. Use FRESH paper towels that are NEW and fresh off the roll to scrub and a new paper towel to dry. Handle the bed by the edges, never touch the print surface.

With alcohol, a bed will look clean, but isn't.  After I remove residues using alcohol or acetone, I wash in soap and water as the last step in maintenance.

Alcohol wash: every few prints

  • Gloves recommended.
  • Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils well.
  • Pour a 5 cm puddle of 91%+ alcohol in the middle of the bed, with clean hands use a fresh paper towel to scrub the bed. Wipe up all the alcohol.

 

Acetone wash: infrequent
            (Not recommended for USE on Powder Coated sheets, but some find it necessary)

  • Pour a 2 cm puddle of acetone on the bed, scrub it around with a fresh paper towel. It will evaporate fast as you clean. This step removes PEI oxides that form over time and with heat, and improves PLA adhesion to a like new state.

 

Hot Water wash: often, as needed, and after any of the above
            (not recommended for daily use on Powder Coated sheets)

  • Handle the bed only by the edges.
  • Wash the bed in hot water, use a fresh paper towel as a wash cloth, with a few drops of plain dish soap (Dawn, unscented, no anti-bacterial, etc.).
  • Rinse well in hot water - if you have very soft water, rinse a bit longer.
  • Dry the bed with a fresh paper towel.
  • Handle the bed only by the edges.
  • Place bed on printer.

 

Streak test: when contamination is suspected

  • With a fresh piece of paper towel, and very clean fingers, dampen the towel with 91%+ alcohol, and wipe the bed side to side moving back to front, like you're painting it with alcohol. The alcohol should be thin enough on the towel it quickly evaporates from the bed. If you see any streaks, the bed is dirty and needs a wash.
This post was modified 5 years ago by --
Posted : 27/07/2019 7:22 pm
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