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James Campbell
(@james-campbell)
Active Member
Help identify 1st layer issue

My printer was doing great, then I changed filament and it hasnt worked well since.  Things I have tried...

- Changed nozzle

- Changed Filament (on fourth roll all from different manufacturers

- Reduced hot end temp (was 215, now 205)

- Reran First Layer Wizard and even 100 x 100 first layer print

- Resliced File

Any ideas on what the issue may be and how I can solve?

Posted : 08/07/2021 10:04 pm
James Campbell
(@james-campbell)
Active Member
Topic starter answered:
RE: Help identify 1st layer issue

Posted : 08/07/2021 10:13 pm
Swiss_Cheese
(@swiss_cheese)
Noble Member
RE: Help identify 1st layer issue

Your sheet is dirty, Clean the sheet, not with IPA but with hot soapy water dry thoroughly with fresh paper towels and reprint.

 

Enjoy

 

Swiss_Cheese

 

P.S. I don't use the soap I rinse mine with an instant hot 100C water that I have at my sink, but the soap will help you desolve the oils on your plate if you don't have one.

The Filament Whisperer...
Posted : 09/07/2021 4:26 am
James Campbell
(@james-campbell)
Active Member
Topic starter answered:
RE: Help identify 1st layer issue

While that certainly helped with sticking (and I thought I was doing a good job with IPA), that doesnt seem to solve it...  Could it be a clog somewhere? (I just replaced the nozzle)... 

Posted : 09/07/2021 5:32 am
Diem
 Diem
(@diem)
Noble Member
RE: Help identify 1st layer issue

The bed is still dirty ... clean again.

Did you recalibrate your first layer Z after changing the nozzle?   It's hard to be certain from that picture but it looks like you are a little too low.

Cheerio,

Posted : 09/07/2021 12:10 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: Help identify 1st layer issue

@james-campbell

I think it is a combination of too dirty and the Z offset is off.  Can never be sure until the bed is clean.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 09/07/2021 12:26 pm
bobstro
(@bobstro)
Illustrious Member
RE: Help identify 1st layer issue
Posted by: @james-campbell

While that certainly helped with sticking (and I thought I was doing a good job with IPA), that doesnt seem to solve it... 

I'm going to give you the big info dump here just to get everything in one place...

Your underlying issue is bed adhesion. Bed adhesion should be strong enough to hold the print flat and securely against the forces of filament warping and nozzle friction. Filament should lay down cleanly on the PEI print surface and hold throughout the print.  If adhesion is poor, your print is likely to fail or have problems at higher layers. Common adhesion-related problems include:
  • Part warping or lifting along edges.
  • Bumping or knocking noises as the part moves under the nozzle.
  • Uneven vertical surfaces and bulges caused by print lifting and compression of overlying layers.
  • Spaghetti resulting from parts moving during printing.
  • The dreaded "blob of doom" caused by the part lifting and sticking to the nozzle as it extrudes filament.
There are 2 main causes of bed adhesion problems: cleanliness of the PEI print surface and Live-Z height adjustment. Even if you're dubious that these are the cause of your problems, they need to be addressed as 2 fundamental troubleshooting steps to rule out the basics:
  • 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. If it's a smooth PEI sheet, 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 (1200-1500 grit) pad or equivalent on smooth PEI to give it a very light buff, but only infrequently. If you've got a textured powder-coated PEI print surface, the official instructions are to use 91%+ isopropyl alcohol on it only. Rumors persist that some have had good luck getting started with these sheets by giving them a wipe with 100% acetone and a dunk with Dawn. Either way, there's no real warranty on these sheets. YMMV.
  • Incorrect Live-Z. 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 onboard routine and much easier to make mid-print adjustments accurately with. 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 you've got your Live-Z setting adjusted properly, you should be able to gently rub the extruded lines on the PEI surface without dislodging them.  Then start lowering (more negative) the level until there are no gaps between layers. You should not be able to peel the lines apart after printing, but the top should be regular. 
Remember that the effectiveness of a solvent such as isopropyl alcohol is going to depend on concentration and volume relative to the amount of grease you're trying to remove. 71% pads work... on very tiny amounts of grease. A squirt of 91% works better, but if there's a lot of grease, you need a lot more alcohol. This is why a wash under the sink with Dawn is so effective: There's a much larger volume of Dawn-and-water attaching to grease and rinsing stuff away instead of just moving the broken-down grease molecules around.
  
And above all else, avoid touching the PEI print surface.
 
Glue stick is NOT necessary for PLA on the PEI print surface. You paid the big bucks for a Prusa with a removable spring still sheet with PEI, so clean it up and take advantage of it. Save the glue stick for printing sticky stuff like PETG that might adhere too well. Even then, I only find I need glue stick when printing high-temp PETG at 260C+ temps.
 
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. If you want more detail, I've consolidated my notes on Prusa PEI adhesion, bed cleaning, and Live-Z calibration. Good bed adhesion should look something like this:
 
 
A bit of trivia - The reason higher concentrations of alcohol seem to be harder to find is that isopropyl alcohol is most effective against bacteria at roughly a 71% concentration. A bit of distilled water helps slow evaporation, making the alcohol more effective. If you're looking in pharmacies, that's why 91% and higher seem to be hard to find.
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 : 09/07/2021 5:56 pm
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