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sajawors

Bending / Cracking / Warping during "tall" jobs.

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Just as the title suggests (I'm not sure what to call it). When we do longer jobs (taller jobs, really), we see this repeated bending up of layers that creates separations fairly regularly up multiple sides of our objects. We tried printing at a higher temperature (270 up from 255) and enclosing the U3E with a cardboard box to keep heat from escaping, but it's still happening, which leads me to believe that either lack of heat isn't the cause, or we haven't committed far enough, but I don't want to break anything by making it hotter. 

 

Does anyone even know what to call this so I can search more myself? I tried cracks and warping but didn't find anything about this particular issue. 

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I would if someone would like to send me a roll of it. 😛

 

The folks I'm working with have like 8 rolls of ABS they're wanting to use for this project. We have a list of about 50 objects that we need 4 each of, so they're not exactly looking to go buy all new material. We have *A* roll of PLA, but it's already spoken for in one of those objects. I suppose we could print what we needed from that roll next and then use what's left to print something tall... 

 

In the meantime, any other ideas as to what might actually be causing this specific problem?

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I never print with ABS, so I am not the guy to ask. But, I am also thinking substituting PLA for ABS may not be a great idea for a variety of reasons. But for basic strength, I love my TPLA.

 

But, I also get what you mean with the supplied stuff, and getting clients to change their ways is like pulling teeth.

 

@gr5 is very good with ABS type issues. I have tagged him to add his bona fide opinion on this matter.

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The cracking is caused by insufficient layer bonding.  The layer being laid down is not hot enough to melt the layer below.  Or it melts it but only along a 0.1mm line and you need much better bonding/adhesion.

 

1) You need to cover the front and the top of your UM3 to get the air temp up to 35C.  Just use a gallon ziplock or saran wrap and for the top use a box - the type for copy paper is perfect (no cutting needed, no taping needed - it just fits on top perfectly.

 

2) You need to lower the fan speed.  Play with fan speed on UM3.  For my UM3 (yours is likely different) 10% fan speed is identical to 100% so cura's suggested 50% fan speed is rather stupid.   I use 3% fan speed with ABS on my UM3.  30% on my UM2s.

 

3) Bed should be at 105C minimum.  This is how you solve the other issue (the lifting corners) combined with consider using pva juice or ABS juice (google abs juice) and use the brim feature.  Brim makes a large difference.  I recommend 110C bed temp.  This is impossible to reach without covering the front and top.  ABS gets soft at 99C so if the glass isn't above this temp it will warp off the bed instead of relieving the shrinkage forces.  Much more about all this on my video.

 

4) Raise nozzle temp.  I don't recommend messing with this as the UM suggestion works well.  ABS is very difficult to pick the nozzle temp.  To cold and you get bad layer adhesion and "cracking".  Too hot and you get clogs.  ABS at even just normal printing temps but left for a few minutes at this temp in the nozzle will turn it into a horrible gummy clog.

 

5) Layer heights.  Some people say thinner layer is better as the nozzle is closer to the layer below to heat it.  Some say thicker is better as the mass of heat is enough to melt the layer below.  I don't know what the truth is as I haven't played with this much but try sticking with 0.1mm to 0.2mm if you don't want to experiment yourself.

 

For adhesion to the glass, in addition to the stuf in #3 above there are a lot more things you can do.  I mention them all in great detail in this long video but it's packed with information.  You might not need to watch the video but if brim, abs juice and 110C bed aren't enough then watch this video:

 

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I'm printing nearly only ABS and had a lot of struggling with it at the beginning.

All the tips from @gr5 are very important to consider for printing ABS. You could also try turning the fan completely off (0%) and reducing your speed.

For me actually thick layers at a high temperature work the best for strong bonding and no clooging (245°C / 0,3 mm layer height / 0.8 nozzle).

When all your material is used up, I would give alternatives a try. I have made great experiences with the UM CPE and just the standard Cura settings.

Maybe buying a roll of that or the before mentioned Tough PLA is worth the investment instead of wasting all the bought ABS on failed prints 😉

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