Had to replace PTFE, now going backwards, print not sticking?  

RE: Had to replace PTFE, now going backwards, print not sticking?

You'll see a lot of recommendations to try washing the bed with kitchen soap and plenty hot water, letting drip most of the water off and then drying with a clean paper towel to remove any grease your acetone wash might have let stay on it. I've had good results with that method myself. It's worth trying. In your case, repeated cleaning with acetone if done properly (a clean paper towel each time, washed hands or gloves) would probably have not left much on.

If that doesn't help, think about what has changed: Could any contaminants (eg. silicone oil, bearing grease) have stained the PEI sheet? Do the results change if you squeeze the filament more to the plate? Is the filament fresh, and what temperature is it on 1st layer? Is the 1st layer printed slowly enough?

RE: Had to replace PTFE, now going backwards, print not sticking?

You mention acetone, but have you done a simple dish soap wash and IPA wipedown?

Definitely get your Live Z down some more as that should help some. What do you have the value set to right now?

Check your PINDA height to make sure it is correct. 

RE: Had to replace PTFE, now going backwards, print not sticking?

Thanks @gnat @vojtech-p6 - you've both confirmed this is what the "print not sticking" looks like 🙂  I had relied on acetone I'll try the dishsoap method -- I assume with only a mild amount of soap... I'll have a look 😉

Z-axis is currently -0.75 --- I wanted to set this properly but couldn't get the calibration sheet to print correctly.

The settings I am running seemed to work before I took the head apart to replace the tube.  I am comfortable everything has gone back together ok. Since I am using the calibration sheet from a gcode, I haven't resliced it... and it worked before.

In terms of my settings;

• layer height 0.28
• 1st layer 0.38 (nice and thick)
• max speed 60mm/s  /  1st layer 25%
• bed temp is 60 deg c

I'll report back after the "water play" 🙂

RE: Had to replace PTFE, now going backwards, print not sticking?

Just plain dish soap with no scents or stuff for your hands. Use warm to hot water. Make sure you dry it with a lint free towel and do not touch the surface. 

Based on what I see, I'd bump the Live Z to -1 and work from there. 

My original value was -1.6. when I rebuilt for the S upgrade, -0.75 was the magic number, and I had to rebuild this weekend for a jam and the new value is -1.5. So just cause you had a known value before the rebuild doesn't mean it will be the same after a rebuild. 

RE: Had to replace PTFE, now going backwards, print not sticking?

Posted by: m3w19

• 1st layer 0.38 (nice and thick)

If that is on the 0.40 mm nozzle, then that's beyond what is considered the 'safe range'. The maximum recommended layer thickness for a nozzle is 80% of its diameter, so for a 0.40 mm nozzle, one shouldn't use layers thicker than 0.32mm. And even then, first layer is special. When debugging issues, I'd fall back to the standard 0.20 mm first layer.  If you look at Prusa's profiles for the 0.4 mm nozzle, they all have a 0.20 mm first layer independent on whether further layers are 0.05 or 0.30 mm.

And then I'd make sure the Z offset is right. As @gnat states, it changes everytime you reassemble the printing head, and most importantly re-mount the PINDA probe, because the Z offset is the difference between the PINDA detection plane and the tip of the nozzle. If any of them moves compared to the other, the Live Z offset needs to be adjusted.

RE: Had to replace PTFE, now going backwards, print not sticking?

Thanks

these settings were all from before the tube reset...

so after water play, I have a some work to do.  I noticed one side was continuing to look dirty (sort of film / oil / something) but the other side looked good.  testing with Side 2, the calibration sheet print fine, and I was able to refine my z-axis - thanks @gnat, I knew the z-axis would need to change, particularly as it was a NEW nozzle and not just a tube change... which is why I was pulling my hair out that I couldn't get the calibration sheet to even print... my first pass of the calibration sheet

wasn't too far off - started at -0.6 (top), through to -0.715 (bottom)  I think there is more work there but it is getting better.

and ... I was able to print a dragon reasonably cleanly

This was using the Slic3r 3D system settings for the MK3s - so no changes on layer height / 1st layer etc.

Clearly, side 1 is covered in something that dish soap, acetone, IPA isn't cutting through easily... now I have proven the printer itself is fine, I can go back to cleaning.  

RE: Had to replace PTFE, now going backwards, print not sticking?

More aggressive than kitchen soap are kitchen degreasers. Most will handle mineral oil and better ones can even handle silicone oil. They make removing persistent contamination of the PEI easier.

Beyond that, there's somewhat nastier chemicals like toluene and perchlorethylene, both usually available in home improvement stores near the paints department. They dissolve silicone oil well. But I recommend using them outside (for ventilation) and with rubber gloves on. Particularly perchlorethylene can sensitize the skin and cause rashes that never go away.

If a kitchen degreaser won't work and you don't want to get involved with the chemical solvents, there is always scrubbing the surface with a mild abrasive, like a 3M Scotch-Brite 7445 hand pad (recommendation of @bobstro ). Best while you have the degreaser on it. If you can't get the 7447's, then a fresh, never used, "no scratch" kitchen scrub sponge will work well, too. They'll leave the surface matte, but prints will stick like never before. An acetone wash is recommended afterwards (with a fresh cleanroom wipe) to remove any remaining PEI dust.

RE: Had to replace PTFE, now going backwards, print not sticking?

A few cleaning recipes...  In all cases, do the soap and water wash last to remove what the others leave. Except the smear test: it is useful to see if alcohol rinse or the acetone scrub left anything behind. If you use a quart or liter of either chemical, probably not, but if you're like me and use under less than one cc for cleaning the bed, then chances are good soap and water can get the bed a bit more clean. 

Hot Water wash: often, as needed
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.

Alcohol rinse: every few prints
Once in a while, an alcohol rinse is helpful to remove PLA residue. It does not remove finger oils.
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.

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. If you see any streaks, the bed is dirty and needs a wash.

Acetone wash: infrequent
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.

RE: Had to replace PTFE, now going backwards, print not sticking?

I use Windex followed by 98% IPA on one of my printers, it works well. With my old Prusa MK2 I had great success with UHU glue stick applied to a tired PEI bed sheet. I bought up a lot of E3D's stock of Glue Stick, when they sold it.  It can cope with several prints, before being washed off with water.

RE: Had to replace PTFE, now going backwards, print not sticking?

Oops IPA followed by Windex for PETG on my CR10.