Polycarbonate build plate…. No bed heat Success!!!
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Personally before printing I would run a bunch of mesh leveling routines on both the clear and white with different clip positions, then compare the results of the two. Your test earlier showed better results with the clear than the white but that could change after changing up clip placement. The cup of the clear sort of acts to your advantage because you cannot clip the middle of the bed…. though once sorted you might find that is the reason the prints end with cups because the clear is following the shape of your bed so the white, might work better.
Your wet sanding job looks great btw, that sheen before from the 120 is what I was talking about.... when the sheen comes back things start to stick too well and its time to resand... I try to have my sanding such that I rarely have to remove the clips to remove a print.
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After using 8 clips (2 front, 2 back, 2 left, 2 right) the leveling is… exactly the same xD
I will need to redesign the Z bed attach to allow me to add an adjustment screw… anyway, for the moment, I will need to rely in the RRF mesh algorithm to compensate this....
I will do some print tests and let you guys know.
Thanks!
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It seems, most of the mesh levelling problems could be avoided by using a thick base plate ( glass/mirror suddenly is a good option ) and a thinner PC sheet?
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Quick update.
Not sure if you're following the PrecisionPiezo thread, where I posted some accuracy testing I did, as I found something quite interesting IMHO. I'm obtaining an accuracy of 0.002mm doing 36 tests over the same point, which is awesome, however, if I do it after homing, I was obtaining a deviation of 0.07Xmm (70 microns) from the Z homing test. This caused that the first layer sometimes was too low (and squished the filament) and sometimes was too high (and it didn't stick for the circles). I tried several things for Z homing (home X, Home Y, move slowly to Z, G30, Home Z again), and during several tests I got a better deviation (around 10-15 microns from the Z Homing heigh) and a mean of 0.002 for the testing in the same point. I still need to do more testing to be confident about the repeatability of the measures, but this explains why I got some of my issues with PETG, where I was unable to un-stick it (too close from the bed!).
Last night I printed another PrecisionPiezo support mount (in my trusty PLA), using the white (flattest) PC sheet, and this is the result:
I just had a couple of minutes this morning to check the print, but so far, my impressions:
- Circles and details in the first layer were perfectly printed, with some under extrusion (more about this in the last bullet point)
- It was really easy to remove, the bigger one I was able to remove by hand, for the low height ones, I just bended a bit the sheet and both came off perfectly
- I couldn't observe any warping/cupping, but I will check it closely when I get home tonight.
- I couldn't see elephant foot either, but I will do more tests with different Z offsets.
- I've detected that I'm having under extrusion problems after retraction… I've checked and my bowden tube is a bit too short after I setup the new sensor, and is a bit tight, so I'm gonna replace it for a bigger new tube. I've also observed that my acceleration/speed settings are the default ones and seems to be too low for my setup, compared with the settings I used to have in marlin before, so I will adjust that too and test again.
I will do the adjustments and report back, but the problems with the extruder may explain my low performance printing PETG, meanwhile the defective sanding I did and the random Z homing heigh can explain why I wasn't able to remove sometimes the part (60-70 microns is "nothing", but can be the difference of a squashed PETG impossible to remove and a good one).
Cheers!
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@CaLviNx:
It seems, most of the mesh levelling problems could be avoided by using a thick base plate ( glass/mirror suddenly is a good option ) and a thinner PC sheet?
I am using mirror polished ceramic floor tiles 12mm thick silicone heater underneath (if i need heat) and a 3mm pc sheet held down with button magnets and that seems to keep everything flat enough.
That sounds like a sweet setup, can you post pics of how its done?
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Quick update.
Not sure if you're following the PrecisionPiezo thread, where I posted some accuracy testing I did, as I found something quite interesting IMHO. I'm obtaining an accuracy of 0.002mm doing 36 tests over the same point, which is awesome, however, if I do it after homing, I was obtaining a deviation of 0.07Xmm (70 microns) from the Z homing test. This caused that the first layer sometimes was too low (and squished the filament) and sometimes was too high (and it didn't stick for the circles). I tried several things for Z homing (home X, Home Y, move slowly to Z, G30, Home Z again), and during several tests I got a better deviation (around 10-15 microns from the Z Homing heigh) and a mean of 0.002 for the testing in the same point. I still need to do more testing to be confident about the repeatability of the measures, but this explains why I got some of my issues with PETG, where I was unable to un-stick it (too close from the bed!).
Last night I printed another PrecisionPiezo support mount (in my trusty PLA), using the white (flattest) PC sheet, and this is the result:
https://s20.postimg.org/ykbxijjul/PP1.jpg
https://s20.postimg.org/4460keybh/PP2.jpgI just had a couple of minutes this morning to check the print, but so far, my impressions:
- Circles and details in the first layer were perfectly printed, with some under extrusion (more about this in the last bullet point)
- It was really easy to remove, the bigger one I was able to remove by hand, for the low height ones, I just bended a bit the sheet and both came off perfectly
- I couldn't observe any warping/cupping, but I will check it closely when I get home tonight.
- I couldn't see elephant foot either, but I will do more tests with different Z offsets.
- I've detected that I'm having under extrusion problems after retraction… I've checked and my bowden tube is a bit too short after I setup the new sensor, and is a bit tight, so I'm gonna replace it for a bigger new tube. I've also observed that my acceleration/speed settings are the default ones and seems to be too low for my setup, compared with the settings I used to have in marlin before, so I will adjust that too and test again.
I will do the adjustments and report back, but the problems with the extruder may explain my low performance printing PETG, meanwhile the defective sanding I did and the random Z homing heigh can explain why I wasn't able to remove sometimes the part (60-70 microns is "nothing", but can be the difference of a squashed PETG impossible to remove and a good one).
Cheers!
I actually ended up with a situation like yours last night but I have too many variables in the fire and more testing needs to be done to be sure…. but heres the jist of what happened.... i upgraded to the lastest version of S3D .... loaded up a new roll of Taulman Blueprint... yes my bed is getting a little shiny but there were a lot of variables at play here too that the surface wouldnt account for how bad it was.... my extrusion was suddenly out of whack and i couldnt get it right before i gave up for the night... also my z was a bitch to get correct even with babystepping.... three failed prints all with the same exact issue.... complete welding to the bed, parts near impossible to remove.
I will do some more testing this evening to see if i can get to the bottom of what causes this.
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I've upgraded S3D too, although I won't use it until I fix all my issues, just to avoid the too many variables problem =_=, and then I will print couple of parts using both just to compare… I'm curious about the new bridging stuff, as in my experience, bridges in S3D were a mess compared with cure or slic3r...
Cheers
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Okercho, can you try printing an object with a large, flat base, to see if the "cupping" is still present? I suggest a 150-200mm circular profile, extruded a couple mm tall. In my experience, it is these types of prints that show the cupping the most. Especially hollow structures, eg the bottom surface of a hollow cylinder, where the surface area on the bottom occupies a large portion of the bed.
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I'm planning to do a case for the PanelDue7" in PETG once the extrusion problem is fixed, with that we should be able to check if the warped/cupping problem is still present… Hopefully I would be able to do during this weekend and let you guys know.
Cheers
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@bot:
Okercho, can you try printing an object with a large, flat base, to see if the "cupping" is still present? I suggest a 150-200mm circular profile, extruded a couple mm tall. In my experience, it is these types of prints that show the cupping the most. Especially hollow structures, eg the bottom surface of a hollow cylinder, where the surface area on the bottom occupies a large portion of the bed.
When you say that the stresses transferred to the print from a cupped bed held flat will result in a cupping effect in the print or do you mean a warping effect in the print (reversed effect)
I ask this because the photos he posted looked like warping not cupping. and just want to make sure we are all on the same page.
I planned on printing a large 180x180 square (my bed is only 200x200) just ran into some other issues i have to get sorted first… the objects he printed before were confirmed to be smaller objects like the ones i was printing without issue.
I am not saying that the effect you have noticed is non existent... i wont know until i print a larger object.... but that after what i seen last night he has some other issues to get sorted before making a conclusion about any warping or cupping.
When he can print without other issues... then a determination about cupping can be made.
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My PEI bed, if left un-clamped, but oriented the way it is on the build plate, has a concave top, and a convex bottom – IE the edges of the PEI plate curl upwards. When clamped down, the plate is flat to about 50-100 microns. When printing, eg, a large hollow cylinder with a diameter that occupies a large part of the build plate, the print adheres fine entirely through the print. The edges of the circle are touching the build plate, as well as the middle of the circle. However, when the print is removed, there is a noticeable convex surface on the bottom of the print. If you now place the object (cylinder) on the bed, the center of the circle is touching the build plate, and the object would have a tendency to rock around. IE there is a "bulge" on the bottom of the print, approximately equal to the curvature of the print surface when unclamped. The warping does not occur during the print, seemingly the PEI "holds" the print down enough to resist this -- but when the part is removed, the condition presents itself.
It's easily fixed by heating up the bottom of the part, and pushing it flat against a surface plate. It's odd, and I'm wondering if the phenomenon I sometimes see is the same as was described here.
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Gotcha so basically the cupping of the plate then shows itself as warping when the part is removed. Well its hard to say at this point because the objects that I have printed do not show this effect albeit they were only up to 80mm but his parts were small as well.
I think its important to eliminate these other issues first. What is odd about his heightmap and print issues is if you look at the height map even when clamped down it shows the middle cupped upward and the edges downward but then the exact reverse effect after printed, I wonder if the bed is passing this along to the PC plate as well because his raw bed heaightmap is similar. I do not see this on my height maps (waiting on a piezzo to arrive for better accuracy) or prints but we will see with larger ones.
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Hi there,
Yesterday I edited the config.g to change acceleration and jerk for my extruder, as it was low compared with my previous settings in marlin. So far, it seems that it's not under extruding, at least, with the couple of parts I've printed in PLA.
However, I tried again with PETG… and failed again, I'm not sure if my PETG is just crap or there is something I'm not doing right... an image worth more than 100 words:
This is with my 3DCPI PETG @ 245 degrees with 0 at the bed, the skirt didn't stick to the bed, but the part sticked so well that I had tons of problems to remove it. Layer height was 0.1 and Z offset AFAIR 0'25 o 0'27. First layer seemed ok, but after a couple of layers you can see the result.
I have another PETG, from Prima Select, and it was even worse, I wasn't able to even stick the filament to the bed… the filament started to create little blobs in the nozzle, and I had to stop the print. I tried with several temperatures between the recommended range, and a bit low too, with no success... I'm looking forward to receive the rigid.ink PETG, if that fail too, I will start thinking on not using PETG anymore, it's only creating frustration and the results are not worth it.
I printed another part in PLA, with a BQ filament (I don't like this filament, so I'm using for non-important parts), the part is 105mm long, and came out pretty much OK, no elephant foot, gorgeous first layer (I really like the finish of the PC in the bottom layer) and I was able to remove it by bending just a bit the PC sheet, so quite happy about that, seems that the offset I'm using (0'11mm with the precisionPiezo) is the right one. I couldn't check the cuping/warping, as I looked it before coming to the office, I will check it tonight.
BTW, the effect you mention for the center of my bed I think is because my bed is too large (300x300), I have a little screw in the middle of the bed to push up a bit, seems that I will need to adjust it too, I may forgot about doing it.
Cheers
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Thats the effect I am seeing right now orkercho, i will let you know when I have a chance to troubleshoot (the filament)
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Okercho,
I just wanted to show you that I am able to reproduce what you are experiencing. But more testing needs to be done before i can draw a conclusion.
This was with a freshly sanded build plate. The part on the left was printed and easily removed just by sliding a scraper underneath. It did not show any signs of cupping. For that print I used a known working roll of PETG it was Taulman Guidl!ne I have also printed Taulman TechG (petg) and Rigidink Petg without issue.
The second one showed warping after flexing the plate… as you can see it was difficult to remove breaking the part in the process. This was with a roll of Taulman Bluprint which is a high temp petg printed at 290
I am not yet ready to blame a bad roll of filament as i need to do more testing (extrusion issues and horrid first few layers) i want to see if different settings will resolve those issues before coming to a conclusion but it is looking like a filament issue.
Its just going to take some time because i will need to keep resanding until i get it right. I will report back when i know more.
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So here are my findings and conclusion. Clear PETG has a tell tale that you do not see in your colored PETG. When clear PETG gets too hot it gets a lot of micro bubbles giving it an opaque white look instead of a translucent appearance.
I remembered this when extruding into air and seeing it come out clear at 5mm/s then i remembered i had lowered all of my jerk and accell settings to match a post that deckingman had made during his testing of pressure advance. I was already slicing at 75mm/s with no reductions in speed for any features accept first layer.
So i raised my accel and jerk settings a lot and increased first layer speed to 80% though 70% is probably better then reprinted with the Taulman Blueprint….
The print popped right off as i tapped it with a scraper.
On the left is the new print, on the right is the failed print from before.... as you can see as the print got to smaller features and slowed down the PETG started breaking down and becoming opaque.
I think it is safe to say you are seeing the same thing, your filament is spending too much time in the hotend or you need to lower your temps if speed is not a factor
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These findings also seem to make a good case for using clear filament to calibrate your printer because they give you a clue when settings are negatively impacting the filament through overheating.
Looks like I have some more tuning to do
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I've read about polycarbonate build plates before and the tenor was, the parts often stick too good. Maybe it's the sanding, that makes all the difference? Would it work with shotblasting too? I guess it depends on the stuff you shoot at it?
Where did you get the POM filament from? ( Why do they offer it, when it is "known" to be unprintable? )
I've made these 2040-sliders from PTFE, but POM would be much better I guess.Motedis sell POM Filament http://www.motedis.com/shop/3D-Filaments/3D-Filament-POM-175mm-05kg-Made-in-Europe::3540.html
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This surface works really well.
ABS printed on 80 C heatbed from https://www.thingiverse.com/thing:1504207
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Is that the PC Bed material?
