Problem with rear side of Test Cube
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is your bed level? looks like the nozzle is closer on one side of the print than the other. a bad first layer can make trouble for the rest of the print in abs, especially if you are printing small items with short layer times. I would try leveling the bed so the first layer looks perfect and printing 2 test cubes instead of one to give each layer enough time to cool off before the next layer hits. I forgot to ask how ridged is your carriage? is there any play or slop in any direction?
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Fredrick, it has printed.
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@dmbgo said in Problem with rear side of Test Cube:
Fredrick, it has printed.
I think you may just be seeing ABS shrinkage.
You do have a bed adhesion issue on one section and I imagine you can see that.
If you have some PLA perhaps print the same object and see what you get.
Have you got any PETG you could try? It's a good alternative to ABS and it doesn't have the kind of shrinkage issue that ABS has.
Frederick
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@antlestxp,
The bed isn't level atm, the bed is usually level though, I just wanted to get the disk printed before it was too late for Fredrick.I will now try printing 2 x test cubes at once, since, as you say it might be caused by the print failing to cool fast enough.
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@dmbgo said in Problem with rear side of Test Cube:
I will now try printing 2 x test cubes at once, since, as you say it might be caused by the print failing to cool fast enough.
You don't want ABS to cool fast - that exacerbates the shrinkage issue. That's why I said to print this test with no layer cooling.
Frederick
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Thanks Fredrick, I do have some other filaments somewhere, and your model has shown me that the printer is capable of printing well, if the conditions are right. I as using ABS, since I thought that if I could get that to print well, everything else should be easy.
Thanks for your help. -
I think that before embarking on anymore tests, I will put the printer back in its thermal home. I only had it out to solve other issues, which are fixed now.
Once it is back, I'll level the bed properly and let you know how it goes.Regards David Maher
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Oh, and as far as rigidity goes @antlestxp , I have modified the printer and added fairly heavy steel cross pieces on the Y axis and installed rectangular steel bracing pieces into the existing frame. You can see the front cross piece in the photo of the printer above. The standard Black Widow looks quite different.
If you think I need to go further, please let me know.
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@dmbgo said in Problem with rear side of Test Cube:
I think that before embarking on anymore tests, I will put the printer back in its thermal home. I only had it out to solve other issues, which are fixed now.
Once it is back, I'll level the bed properly and let you know how it goes.I check this site on a regular basis so if you include @fcwilt I will get alerted to your posts.
I will not be at all surprised if ABS prints fine with the enclosure.
If you haven't researched PETG I think you should check it out.
This was posted on ALL3DP.COM:
PETG is stronger, more durable and it prints better. It's also available in transparent colors. ABS is only necessary if you absolutely need the 100°C temperature resistance or its ability to be glued and painted. Otherwise, it's difficult to justify the printing difficulties involved
Frederick
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Thank you, it sounds like excellent advice!
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@fcwilt
Well the printer is finally back in its thermal enclosure, there was a bit of a hiatus getting it done, whilst I was doing other things.
Sadly the symptoms are unchanged. The thermometer on the enclosure says the the internal enclosure temp is around 30C (86 F). I think this should be warm enough to print ABS? -
@dmbgo said in Problem with rear side of Test Cube:
Sadly the symptoms are unchanged. The thermometer on the enclosure says the the internal enclosure temp is around 30C (86 F).
I have seen articles that suggest 110C. I have seen those that suggest 70C to 90C.
If any of those are correct then 30C will be much too low.
Frederick.
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That's a pretty high temperature for the enclosure, more like a bed temp. I can try it with a higher temp though.
I also have a Prusa MK3, which has an enclosure as well. It prints ABS fine (no curling / lifting) just using the heat generated by the bed. Do you think I should raise the enclosure temp to see if there is any change?
I've also bought a stock of PETG now, but haven't tried it yet. If the problem still occurs with PETG does that indicate that it is not caused by the ABS per se?Regards David Maher
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@dmbgo said in Problem with rear side of Test Cube:
That's a pretty high temperature for the enclosure, more like a bed temp.
I found another article which suggests 60-70.
I never tried ABS after reading the issues with it and went right to PETG and others. PLA actually is fine for most of what I print.
Frederick
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Thanks Fredrick,
I'll try the PETG and let you know. It might not be for a couple of days. -
@dmbgo said in Problem with rear side of Test Cube:
Thanks Fredrick,
I'll try the PETG and let you know. It might not be for a couple of days.Barring my dying unexpectedly I will be around.
Frederick
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@dmbgo you want to be above 60 for the enclosure but not to high if printing small parts. Goal is to have the layer cool just enough to start to become solid but not enough that it shrinks. You want to avoid using the fan because that will cool to rapidly. I will usually print multiple objects when I print abs. My enclosure usually hovers around 70 degrees. Did you ever try printing 2 objects to increase your layer times?
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@antlestxp
"@dmbgo you want to be above 60 for the enclosure but not to high if printing small parts. Goal is to have the layer cool just enough to start to become solid but not enough that it shrinks."To answer your last question first, yes, I did print 2 separate test cubes about 250mm apart, to see if the extra time for layers to "set" helped - it didn't, the issue remained unchanged.
I'm fairly sure now that it's not being caused by a shrinkage issue. I have, in the past, successfully printed objects in the same enclosure using ABS with similar settings.
in a day or so, I will try using PETG with its recommended settings to see if the issue is ABS, or happens with all mediums, as @fcwilt suggested.
