prints wont stick to smooth sheet  

RE:

Is your build plate spotlessly clean?  (Someone is bound to chime in to 'clean your plate and clean it my way.')

Has anything else changed?  Does your live Z calibration print stick adequately?  It might be helpful to post a photo of the underside of the 'flag' portion of the internal Z cal test print.

Do the first layers stick, with the print eventually breaking loose, or do the first layers fail to stick?

(Heresy, I know!) Have you tried an adhesion booster such as glue stick or Layerneer/Magigoo/etc.?

RE: prints wont stick to smooth sheet

I had fantastic adhesion prior to whatever has happened. I used glue stick usually.

Perhaps time to try the acetone refresh.

Cheerio,

RE: prints wont stick to smooth sheet

Posted by: @ian-l-2

I had fantastic adhesion prior to whatever has happened. I used glue stick usually.

"Whatever happened" could have been a change in z-offset for whatever reason. Try out what jsw suggested. 

If that is not the reason and z-offset is still spot on, then it can be the simple fact that print plates degrade over time. After 2 years that would not be uncommon. If a very thorough bath in detergent with scrubbing with a soft spongue doesn't help, a careful acetone refresh might. 

What glues stick are you using, regular ones (Kores and the like)? If so, try out Magigoo and equivalent. They enable much better adhesion and are much easier to clean off (simple rinsing with warm water). 

RE: prints wont stick to smooth sheet

A good bath with acetone (please use pure acetone, not a nail polish remover) can restore the sticky quality to the plates.

I've also heard of folks buffing the surface with very fine sandpaper, but I've never had to do this myself.

The only times I've had any issues getting something to stick is with small-footprint PLA prints, and PLA prints with break-away supports, as in those with small support footprints.  I've found that Layerneer really helps with those 'square wave' support footprints that tend to curl up.

I really think that a lot of the reports over the years of 'nothing will stick' are more related to a marginal Z calibration than to the knee-jerk conclusion of a dirty build plate.  Cleaning the build plate in those circumstances may result in just enough adhesion to make things stick, while allowing the Z error to remain.

RE: prints wont stick to smooth sheet

I agree with what youve just said,  its not the buildplate in my amatuer opinion. Both sides of the smooth plus the texture sheet wont stick.  Im thinking possibly an extrusion partial blockage or something .

Anyway lets see what a new nozzle does. Thanks for your advice

RE: prints wont stick to smooth sheet

well tried new nozzle...it wasnt that

next...?

RE: prints wont stick to smooth sheet

so here is an update.  Turns out my fan shroud was broken/ detached a bit and was collliding with the prints. took it off and everything is back to normal

time to print a new one

All buildplates failing at the same time is odd.  If acetone refresh doesn't work it's time to check the environment...

We usually assume that contaminents are human fingerprints, filament residue and PEI oxidants.

But if you are using aerosols in the same room, or spraying paint, laying fibreglass, arc welding ... anything that creates dust, smoke, spray... You get the idea. The bed needs to be clean.

heerio,

RE:

Can you post a picture of how the underside of the first layer calibration rectangle looks like?

RE: prints wont stick to smooth sheet

This is really reaching, but it might be worth a quick look-see sanity check to be sure nothing like this is happening.

I have not heard of this happening on a Prusa printer (yet?), but I have heard of it happening on an Ultimaker printer.

This is where the 'sounding', the equivalent of the dynamic Z probes by the Pinda, is off and the machine is actually extruding the bead in mid air, like above the build plate, and it is giving the impression that it is failing to stick.

You might take a VERY close look at the extrusion as the print begins.  Is it actually pushing the bead of molten filament onto the build plate, or is it simply depositing it in mid air, where it does not contact the build plate?

The only way I can envision this happening with the Prusa is with some kind of a Pinda issue, electronic or mechanical, but it might be worth looking into, as I've heard of it happening with other printers.

RE: prints wont stick to smooth sheet

I had the smooth give me some grief awhile back,

Try Dawn, and a nice fine, but aggressive scrubbing puff. non abrasive of course

put the sheet on a cutting board over the sink and scrub that bitch like it was a surgical implant.

then keep yo greasy piggies off it.

I find IA (80%)  not that great