PEI print bed surface experiments

[techstorage]

In an abundance of caution, I applied Kapton Tape over the small Via Holes on the Hot Bed. I know that the Via's are coated and the chances of a short are remote BUT I put Kapton Tape over the Via Holes in the Hot Bed.

Thanks Nitewatchman, I agree with you on an abundance of caution... I think I will follow your lead.

[mhackney]

After getting some advise from a member who I will not name but his initials are Michael Hackney

Ok, I got a chuckle out of that!

Once you calibrate Z, print a single layer, peal it off and measure it with a mic or even a good caliper. It should be whatever your layer height is.

[Holy1]

I have been struggling with just the opposite problem. My ABS parts have been stuck so tight that I could not get them off the PEI with damage.

After getting some advise from a member who I will not name but his initials are Michael Hackney, I have learned that the problem I was having has everything to do with the first layer. As I have gotten my bed and calibration flatter, I have tended to make the first layer thinner and really squished in. Now after some experimentation based on the advise, I have decided that the thin tight layer is almost impossible to remove. So I went to a thicker layer that was looser or more humped up and got no adhesion at all using the same temps.

So after playing with the ranges, I have settled on this which seems to compromise. Z=0 set on the surface, the nozzle tip is set using a 0.004" feeler gauge above the glass, the nozzle lowered an additional 0.1mm to -0.1 on the LCD display and Z-zero set there. I am printing at a 0.1mm layer height and the first layer is set to 0.22mm. Heated Bed temp is set to 75C, for large parts it is set to 85C. Parts now release with minimal effort and a slight amount of white stress area where it was attached.

I believe that given the other parameters level, cleanliness, and temperature are under control, the biggest factor concerning adhesion is the thickness and squishing of the first layer.

Thanks for passing along the tip Nitewatchman. Is there a special club you have to join to get this type of help? I seem to have no luck getting any type of response to any problems I post from any of the "seasoned" forum members.

[bvandiepenbos]

Brian, I use 1500-2000 grit sandpaper to prepare the surface all the time. This does result in a matt finish on the part.

I thoroughly wet sanded my PEI with 1000 grit then wiped with windex wipes and now ABS parts are sticking great again. Thanks!
happy. happy. happy.

now, if the canola oil will fix my E3D v6 PLA Jams I will be golden!

[mhackney]

Good to hear.

So I am concerned about E3D v6 jams. I have been running for 1000s of hours since I made the nozzle mod (that the V6 nozzles have now) with ABSOLUTELY NO jams of any kind - and I do not use Canola.

[techstorage]

Mhackney, what is your retraction value set to for PLA prints?

After my last jam I searched out my setting and it was 5.4 mm. I lowered it to 2mm and have started this canola oil dip.

[mhackney]

1.5 mm retract at 20mm/s. Ideally, you'd like to be able to specify a retract and a separate advance rate.

[mhackney]

I've written a lot (in my build thread) about the effect of fast retract / advance with PLA due to its thixotropic nature. I call it "hydraulic jamming" and I suspect it is the culprit that is biting folks. You need a slow advance after retract (20mm/s). If you could do a fast retract and then a slow advance, that would be ideal but we can't do that in today's slicers. I've manually optimized some of my production gcode files to do this though with no ill effect and even better/less string and blob problems.

[techstorage]

Thanks for the info, I see your point... when I manually unclogged my extruder, it felt like it had suction moving the filament till the end popped out the jam. I will slow down my retraction rate with the distance.

[bvandiepenbos]

Michael,
I run 4-5 mm of retract @ 50-80 speed.
That very well could be some of my issue, I need to try 1.5mm @ 20mm
I remember your post about that now that you mentioned it, I had forgot.

btw, the canola oil did help jams and starvation, but I suspect a print with many retracts would still jam.
Another issue we discovered last night at the Makerhive meeting is the drive roller was intermittently slipping unless we manually forced more pressure on the pinch feed bearing.
The PLA is harder than ABS so I bet it takes more pressure to bite into it.


If the slicer would use different retract vs. return feed rates that would be great.
Along those same lines, I have wished for a long time for a way to specify a time "dwell" before and/or after retraction. I think that would give finer control over start-stop of plastic flow at just the right moment. In other words, pause before moving in X & Y. Does that make any sense?
Much like our engraving machine has a adjustable dwell time to allow cutter sufficient time to reach full depth before moving in X & Y to engrave. Also dwells at end of cut to allow cutter enough time to reach safe z clearance height before moving to next letter. The machine Z spindle movement is air driven so controller does not know when proper Z position is reached.

Have you experimented with the 'wipe-while-retract' setting in slic3r ? seems to help sometimes, but not always.

[mhackney]

Brian, WOW! That very well could be it! Slow down to 20mm/s and see what you think. You could reduce the retract distance too. I like a retract that is 2X the bore length - that seems to be a goo ballpark. I've read many accounts about Canola oil helping. I think it's putting lipstick on a pig

Yes on the drive roller too, I discuss this in my thread also. The sharp teeth actually leave a ridge on the PLA due to its hardness and incompressibility. I could feel these snag on the ends of the PFTE and PTC fittings as I pushed the filament manually after it went through the extruder. I cleaned mine up with some 400 grit sandpaper to reduce the "tooth" (or is it "redooth the tooth"?)

I agree about the retract settings and it does make sense to have a configurable dwell. I think that's why I like KISS results so much, if you look at the gcode and watch the print, it has an ever so slight pause.

Yes and KISS has that too. KISS implementation is "cleaner" (no pun intended since it's a wipe!) It depends a lot on part geometry.

[bvandiepenbos]

could dwell be added with a post process script?

[mhackney]

Yes, absolutely

[626Pilot]

I know the manufacturer was planning or is making a 12" disk for the Rostock. I got one of these and it worked very well. I have it on the printer now in fact.

When is that going to be a thing?

[mhackney]

I thought it was already available.

[nitewatchman]

I am still waiting on the Gecko Plate and roll of filament.

[Rando]

I've written a lot (in my build thread) about the effect of fast retract / advance with PLA due to its thixotropic nature. I call it "hydraulic jamming" and I suspect it is the culprit that is biting folks. You need a slow advance after retract (20mm/s). If you could do a fast retract and then a slow advance, that would be ideal but we can't do that in today's slicers. I've manually optimized some of my production gcode files to do this though with no ill effect and even better/less string and blob problems.

If you can't beat the slicer,...

When you did the manual modifications, was there something you searched for in the GCODE file that landed you where the change needed to be made? Sorry, I'm only conversant in the format of the code, not the semantics of the actual codes yet. So, I'm wondering if I was to search for, say, a string corresponding the the retraction action and then add code to just wait a moment, we could make a simple post-processing script for people to experiment with.

Que?

[mhackney]

Rando, the extruder movement is an "E" parameter in the gcode like this: G1 E11.7596 F1200

There are 2 ways to specify E movement - absolute or relative. I use absolute which basically is like saying go to X then go to Y then go to Z. Relative is like saying go forward 3 steps, go forward 2 steps, go forward 5 steps. In KISS you can pick this in Printer->Firmware->Firmware Type. The other slicers have similar options.

The F1200 is the speed. You can't tell by looking at one line of code if you are extruding or retracting in absolute mode, you need the context of the lines before or after (you can in relative mode since retracts are a negative (-) movement. The F1200 is the speed in mm/min (not mm/sec that you set in KISS' retract speed). So, for a 20mm/s retract, that's 1200mm/min in the gcode. In KISS you'll see this:

G1 X10.53 Y-4.3 E34.4869
G1 X9.9 Y-4.24 E34.5078
G1 X9.17 Y-3.51 E34.5422
G1 X9.02 Y-3.93 E34.5569
G1 X9.15 Y-4.06 E34.5628
;
; 'Destring/Wipe/Jump Path', 0.0 [feed mm/s], 20.0 [head mm/s]
G1 X9.15 Y-4.06 E34.5628 F12000
G1 E33.0628 F1200
G1 X9.15 Y-4.06 E33.0628
G1 X9.15 Y-4.06 Z3.2 E33.0628 F12000
;
; 'Solid Path', 0.7 [feed mm/s], 20.0 [head mm/s]
G1 X6.8 Y2.82 E33.0628
G1 X6.8 Y2.82 Z0.2 E33.0628
G1 E34.5628 F1200
G1 X5.04 Y4.58 E34.6456
G1 X4.47 Y4.58 E34.6644
G1 X5.97 Y3.08 E34.735

See the line in bold red. This says "travel to the X-Y position while extruding to 34.5628mm of filament (the extrusion speed was set many lines before and does not have to be specified on every line of code).

I have no idea what the blue line does, it seem superfluous to me. Anyone know?

The bold green line is your retract - notice that the E value is less than the E value on the red line since it is absolute positioning. The speed is 1200mm/min or 20mm/s.

The best blue line also seems superfluous, perhaps these create a small delay? I haven't tried stripping them to see what happens.

The next line is the Z lift

Jump ahead to the bold orange line - this is the advance to counter the retract and it is at 1200mm/min. If I wanted to change that to 40mm/s I would just set to F2400.

KISS is pretty regular and everywhere you see a line of gcode that is just positioning the extruder it is an advance.

[626Pilot]

I thought it was already available.

It's not on their site, and the smaller round one is sold out.

[JFettig]

so, back to PEI stuff for the PEI thread

I've been printing on the smooth side, its been hit or miss as far as getting things to stick, and when it sticks it sticks HARD. 85C and the parts are lifting, 90C and they're next to impossible to remove. What I am finding is that every time I print on a raft(really thick wide bottom layers with gaps) it doesn't ever lift and it always comes off easily. I haven't started using sand paper yet.

[teoman]

Rando, the extruder movement is an "E" parameter in the gcode like this: G1 E11.7596 F1200

There are 2 ways to specify E movement - absolute or relative. I use absolute which basically is like saying go to X then go to Y then go to Z. Relative is like saying go forward 3 steps, go forward 2 steps, go forward 5 steps. In KISS you can pick this in Printer->Firmware->Firmware Type. The other slicers have similar options.

The F1200 is the speed. You can't tell by looking at one line of code if you are extruding or retracting in absolute mode, you need the context of the lines before or after (you can in relative mode since retracts are a negative (-) movement. The F1200 is the speed in mm/min (not mm/sec that you set in KISS' retract speed). So, for a 20mm/s retract, that's 1200mm/min in the gcode. In KISS you'll see this:

G1 X10.53 Y-4.3 E34.4869
G1 X9.9 Y-4.24 E34.5078
G1 X9.17 Y-3.51 E34.5422
G1 X9.02 Y-3.93 E34.5569
G1 X9.15 Y-4.06 E34.5628
;
; 'Destring/Wipe/Jump Path', 0.0 [feed mm/s], 20.0 [head mm/s]
G1 X9.15 Y-4.06 E34.5628 F12000
G1 E33.0628 F1200
G1 X9.15 Y-4.06 E33.0628
G1 X9.15 Y-4.06 Z3.2 E33.0628 F12000
;
; 'Solid Path', 0.7 [feed mm/s], 20.0 [head mm/s]
G1 X6.8 Y2.82 E33.0628
G1 X6.8 Y2.82 Z0.2 E33.0628
G1 E34.5628 F1200
G1 X5.04 Y4.58 E34.6456
G1 X4.47 Y4.58 E34.6644
G1 X5.97 Y3.08 E34.735

See the line in bold red. This says "travel to the X-Y position while extruding to 34.5628mm of filament (the extrusion speed was set many lines before and does not have to be specified on every line of code).

I have no idea what the blue line does, it seem superfluous to me. Anyone know?

The bold green line is your retract - notice that the E value is less than the E value on the red line since it is absolute positioning. The speed is 1200mm/min or 20mm/s.

The best blue line also seems superfluous, perhaps these create a small delay? I haven't tried stripping them to see what happens.

The next line is the Z lift

Jump ahead to the bold orange line - this is the advance to counter the retract and it is at 1200mm/min. If I wanted to change that to 40mm/s I would just set to F2400.

KISS is pretty regular and everywhere you see a line of gcode that is just positioning the extruder it is an advance.

So basically if you set your retracts to fast,
Waht your post processor should do is this:

Find G1 Exxxx (where Exxxx is larger than the precious line and modify that line to change the F value.

Also optionally add delay?

[mhackney]

so, back to PEI stuff for the PEI thread

I've been printing on the smooth side, its been hit or miss as far as getting things to stick, and when it sticks it sticks HARD. 85C and the parts are lifting, 90C and they're next to impossible to remove. What I am finding is that every time I print on a raft(really thick wide bottom layers with gaps) it doesn't ever lift and it always comes off easily. I haven't started using sand paper yet.

Yeah, too many threads here and there! There's another discussion on retracts on the Canola oil thread and one somewhere else so I can't keep track.

I assume that you are printing ABS at that bed temp? I've been printing a lot on the glossy side the last 3 weeks for some special projects (fly reels I'm sending to Field & Stream and some other folks) and I've found it is more sensitive than the mattes side to first layer height. With the matte, I sand the surface gently and the PLA or ABS sticks very well at lower temps. You can't sand the glossy side and keep it glossy! I print ABS at 80°C bed and make sure my first layer truly is .2mm thick (for my normal .2mm layer height). Tweak up your Z by .05mm and test and see if you can find that sweet spot.

Yesterday I replaced my arms with the TrickLaser carbon rods with ball ends (the mag ball ends have been failing with my Kraken system). When I was done I thought I had calibrated Z height but the first print was as you describe, not sticking to the glossy side of the PEI. I raised the Z by .08mm and now I'm in business again.

[626Pilot]

What we could really use is a slicer that slows down/backs out the filament while it's still finishing the final few millimeters of the line. The reason it blobs is that it stops and retracts, but the retract doesn't come soon enough because the filament is still being pushed out the nozzle due to thermal expansion. If the retract could be made to start sooner, it would overcome the oozing from thermal expansion.

[mhackney]

"Wipe" can actually address some of that. My hotness and system are so well tuned that a premature retract would cause a starved line. I don't get blobbing any more. Eliminate back pressure and you eliminate blobbing. Reducing the bore of my .4mm nozzles to .75mm eliminates a lot of back pressure.

[teoman]

Back pressure could also be caused by tiny amount of water in filament.