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Antimix
(@antimix)
Estimable Member
Attach & Detach strategies

Hello,

when I printed in PLA, I always used the smooth sheet at 60°. I have several rolls of PLA, not only Prusament, and I noticed that other PLA are prone to not attach to my smooth PEI sheet, so I got the habit to always have hairspray on the sheet to improve the adherence.

At the end, the hairspray  is always on the sheet, even when I use Prusament, since I do not spend time to clean and wash the sheet.

Recently I was trying to print a calibration object from MakerMuse to test how my MK3 was reliable. This time I decided to handle it as a challenge, and completely clean the PEI sheet and print it without hairspray. 

I always had the following settings for PLA:

  • 1st layer Nozzle temp (higher) 210° - Others 198°C
  • 1st layer bed temp (higher) 60° - others 40°

I realized that my PLA (unbranded) did not stick at all in this condition (without spray), so I have to set the following values in order to stick:

  • 1st layer Nozzle temp (higher) 218° - Others 215°C
  • 1st layer bed temp (higher) 80° - others 60°
  • LCD PANEL SPEED : 45% (otherwise it was stripping away the PLA from the bed (during the 1st layer) while moving the nozzle.

In this configuration the MK3 was able to print perfectly using my unbranded PLA and stick on the PEI sheet, without any hairspray or glue.

The Clearence Tower test is basically a vase cylinder, with a small rounded real surface on the bed. What happened is that after 15 minutes, suddenly I heard a "krack" and the tower detached from the bed in the mid of the print. I fortunately was there  and I stopped the print where it was starting to do a spaghetti print.

I started to think to what happened and here is the reason for the topic:

May be that setting two different temperatures for the bed, (the 1st layer to the others) causes to the PLA a thermal stress and contraction due to temperature change, and causes the detachment ?

The habit to have a lower temperature for the other layer come probably from the early times where the power supply and bed were not so good so in order to avoid the wear of the components there was the habits to set a lower temp for the bed.
 
So, I reprinted with bed temp of 80°C for all the layers to check if it was true. And...
...yes it was , this time I got a perfect print, no detachment.

- What do you think ? Do you also use different PLA / PET temperatures for the bed ?

Regards

Posted : 26/11/2021 6:10 pm
Spinnetti
(@spinnetti)
Eminent Member
RE:

I found much to my dismay that when I first got my MK3, nothing would stick any better than my old cold, unprepared bed on my printrbot and there was no way after spending all that money I was going to use glue, hairspray or anything else on it. After much experimentation, what works for me is first to "condition" the sheet when its new - a fairly furious scrubbing with 150-200grit or so sand paper and/or scotchbrite and then wash with soap and water. Every once in a while, I hit it with sandpaper again (one of those foam block sandpaper things) then wipe down with windex. Between "treatments", I don't do anything. Just print. using 65 deg. bed temp (and leave it at that temp the whole print) and the parts just pop off on their own when the bed cools. Almost never have adhesion issues anymore, and when I do, a quick sand and windex puts things back in order - takes 30 seconds tops. The sandpaper doesn't seem to hurt the coating any, just makes it grippier. With a clean sheet, it still looks new several years later with no sign of degradation (still haven't used the other side of the sheet yet). I'm printing right now, with a big flat part that fills 2/3 of the bed and it stuck perfectly. The top surface is amazing - Not using ironing and its nearly perfect with barely visible print lines.

This post was modified 2 months ago by Spinnetti
Posted : 28/11/2021 12:48 am
Antimix liked
jsw
 jsw
(@jsw)
Noble Member
RE: Attach & Detach strategies

I've printed quite a few brands of PLA, both name brands and off-brands, and I really have not found any difference between the adhesion of Prusa(ment) and most other brands of PLA on either the smooth or textured sheets.

The times I've needed some adhesion boost is mostly when doing break-away supports with small footprints using PLA, where the ends of the 'square waves' will curl upward.  I almost always use Layerneer (which some claim is repackaged hair spray) but sometimes Kores glue stick.

I mostly use the Layerneer with ABS and PC Blend and sometimes PETg, where it will serve as both an adhesion booster and a release agent.

Only rarely do I find any reason to use any temperatures (or any other settings) that vary from the defaults, and for PLA I always use the default of 60/60 on the bed.  I agree that changing this may introduce some dimensional issues, but PLA is said to have less shrinkage than ABS.

The only filament that I can think of that I've found to really need a change are the various metallic filaments from Mika3d, and for those I've had occasional jams which go away when I goose the nozzle temp 5-10 degrees up from the 215/210 defaults (on Prusa).  I've found this to be more important on my other printer (Ultimaker S5) which, for some reason, defaults to a nozzle temperature of 200 for PLA using Cura.

Posted : 28/11/2021 7:48 am
fuchsr liked
Dan Rogers
(@dan-rogers)
Noble Member
Yikes and welcome.

Let me introduce you both to the third phase of machine calibration - the delicate art and quasi-science of live-z dousing.  Of course I say dousing in jest - unless you are in CA (cough cough).  But if you, gentle reader, have experienced what either of these gentle-folk  here in this thread are describing then there is a seat for you in Live-Z school - hosted here, live each week, in the threads on these forums.

Pull up a chair - learn that calibration STARTS with the piece of paper, moves on to initial calibration and ... oh, yes, that's right... this is where a lot of folks snooze off during the first day in a printers life so that darn PEI sheet takes the brunt of the blame.

Live z - the exciting new series, will help you - never sand the snot out of a new PEI sheet to get PLA to stick again.  Never goop up another sheet with ungodly mixes of joy and release in the name of making vanilla PLA stick on that DAMN benchy again ...

Live Z.  Be there.   Every day.  Here.  Prusa forums.

Posted : 28/11/2021 7:49 am
Chris Laudermilk, StanHD, burtronix and 2 people liked
jsw
 jsw
(@jsw)
Noble Member
RE: Attach & Detach strategies

I've found that doing rigorous Z calibrations really helps with overall quality and consistency of the prints, particularly on the textured sheets.

The test prints (I prefer the 3x3 squares as shown below) give a much better picture of Z calibration than the built-in one-square method, plus, if needed, they will show when additional left/right and front/rear compensation might be needed.

For the smooth sheets I'll tune things for the best oval squish factor, but for the textured sheets I've found that the sweet spot is where the 'brush strokes' of the filament bead just disappear into the texture.

Posted : 28/11/2021 7:58 am
fuchsr
(@fuchsr)
Noble Member
RE: Attach & Detach strategies

Live-Z school - hosted here, live each week, in the threads on these forums.

Okay Dan, you have secured my vote for "Best Post of the Year"!!!

Hair spray? Sanding? What's next? The Iron Maiden? The Comfy Chair? I'd say, in 99% of cases proper Live Z adjustment does the job without any of those instruments from the days of the Spanish Inquisition. 

And of course, now there's the satin sheet, which in my hands feels like being in a league of its own. Works out of the box, without any shenanigans, with any filament I've thrown at it. (Okay, okay, you need glue stick as a separating agent for TPU). I just finished four days of printing large rectangular objects almost the size of the steel sheet, not a trace of dreaded warping, with just the naked satin sheet.

 

Posted : 28/11/2021 12:52 pm
Antimix
(@antimix)
Estimable Member
Topic starter answered:
RE: Attach & Detach strategies

I switched my paradigm. Till now as many of you, especially for laziness, I used hairspray for everything (and sometime glue), since it worked for everything, and I did not have to wash the sheet any time. But recently I decided to "Back to The Standard", and have the printer to work with the standard Smooth, Textured, Satin sheets untouched.

  • After having carefully cleaned the SMOOTH and TEXTURED sheets, I will use them only without spray or glue
  • I will play around only on 1st layer calibration, Filament Temperature, and Bed Temperature
  • Only if all this fail for a specific model or material....
    I will use my cheap Chinese metal raw sheet full covered with glue or hairspray. This because I don't want to mess any more the expansive Prusa sheets covered with other materials. I purchased the cheap metal clone just for this purpose (Glue,Tape,Hairspray)

Basically, in the cases where it is the GLUE that allows a material to attach (or detach), and so it is mandatory the contact between the filament and the glue/hairspray, I will use those filaments ONLY on the metal Chines sheet without any specific coating. I could even use old good Blue Tape if required, but only on the Chinese sheet. I mean, if glue MUST be between TPU and the bed to avoid destroying the plate, why use the precious texture, Smoot, or Satin sheets ? Just a clone metal sheet full of glue it is enough.

Regards

 

Posted : 28/11/2021 4:41 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Attach & Detach strategies

I have Prusa Mini for over six months now. I don't really print a lot (not daily, that is) and I only printed PLA and PETG so far (ASA is waiting on shelf for it's use).
For PLA I use smooth sheet, and for PETG textured sheet, and I never used any stuff on them -adhesion is just perfect all the time. I can read many times "what glue or spray should I use" and I just keep wondering. Ok, I can understand that there might be special filament types, which maybe require some "adhesion help". But other than that, Prusa flexible sheets are worth every cent.

[Mini+] [MK3S+BEAR]...
Posted : 28/11/2021 5:52 pm
cwbullet
(@cwbullet)
RE: Attach & Detach strategies

I agree with the above.  Your live Z or Z offset is likely off.  With PLA, I never need hair spray.  I will use it on a rare occasion with difficult-to-stick prints or in order to promote removal (filaments that are too sticky).  I suggest you spend some more time getting your printer dialed in.  Remember each sheet needs a different Z offset or live Z.  

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Chuck H
3D Printer Review Blog...
Posted : 28/11/2021 6:23 pm
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