Parts Cracking?

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Chris botha
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Parts Cracking?

Post by Chris botha » Sun Jun 08, 2014 12:33 am

Hey All,

I have been trying to print a phone case for my wife, in OEM ABS, WInbo ABS (2 temps, 230c and 250c) and the Ebay stuff (230C) and because the footprint on the machine is so small I cant get it to fit any other way than diagonally on its edge.

I have tried standard prints (all options default) and tried 0.15mm / FINE and also 0.3mm/Fast with supports etc..

I have tried 4 times to print this now, each time the exact same thing, it looks great, and its in one piece until you take it off the machine, once you start removing supports it starts cracking, in some cases along the growlines, but in other completely cracking even diagonally across the layers (so not delamination), see image for the kinda cracking I'm talking about

Any ideas here?

Image

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JuliaDee
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Re: Parts Cracking?

Post by JuliaDee » Sun Jun 08, 2014 4:12 am

I've never tried to print a phone case on edge like that, they're usually pretty thin and I print them laying down. I've had terrible splitting problems with electronics enclosures with 4mm walls on edge. I've printed quite a few lithophanes (natural un-colored Octave ABS) on edge, though (2.5mm thickness) and never had one split. An enclosure will almost certainly help reduce ABS splitting, and PLA will not split if you can find one (ColorFabb PLA+PHA, PolyPlus from PolyMakr, or pp3dp's new one) that will feed on the Up.

The issue of cracking across layer lines is pretty extreme; not sure I've ever seen that.

Chris botha
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Re: Parts Cracking?

Post by Chris botha » Sun Jun 08, 2014 4:21 am

Thats what I thought too.. doesnt seem to make sense unless there is extreme pressure in the build...

this is Winbo and Ebay filament attempts the OEM I stopped before it was complete as it tore itself free from the build platform and was cracked before it was even complete, the Red Winbo I tossed as well.

the other filaments the build finished perfectly, the object is in one piece until it cools, then these breaks occur.

Its worth noting that the red and Yellow Winbo have been printing other things perfectly..


I will look at PLA but from the heap of threads complaining about PLA temps and warping issues I have avoided it until now..

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JuliaDee
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Re: Parts Cracking?

Post by JuliaDee » Sun Jun 08, 2014 5:51 am

Chris botha wrote: I will look at PLA but from the heap of threads complaining about PLA temps and warping issues I have avoided it until now..
"Regular" garden-variety PLA will bring you nothing but pain and heartache imo (although Drew might disagree). Colorfabb PLA+PHA, PolyPlus, and the new pp3dp material are different, though. Colorfabb is a slightly flexible material that extrudes at a higher temp than straight PLA and I've used it without problems on the Up. Doesn't print super-clean but maybe that was just me. Anyway it's excellent for phone cases and is available in a ton of colors. Distributed in the USA by http://www.printedsolid.com. Polyplus prints very precisely and feeds without issue on the Up, I've tried it. It's new and color selection may be limited at first. Support removal can be tedious due to the fact that it tends to break off in many small pieces instead of one big one like ABS. I haven't tried the new pp3dp PLA but I assume it works, for obvious reasons :)

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DrewPetitclerc
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Re: Parts Cracking?

Post by DrewPetitclerc » Sun Jun 08, 2014 6:19 am

I have printed a lot of phone cases in both ABS and PLA, my solution was to split the model in half with a locking joint I could glue if needed, this way I could print 1 half at a time, flat side to build plate.
All of them range in wall thickness from 1.5mm up to 4mm and some even thicker with special designs.
See there:
http://www.thingiverse.com/thing:164598

Julia is right that I'm pretty fearless with most materials, the only one I have not conquered are the flexible ones, I hope to remedy this with a new barrel design and feed gear upgrade soon.

Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

roller
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Re: Parts Cracking?

Post by roller » Sun Jun 08, 2014 11:13 am

I'm with Drew - I usually go the option of dividing the case in two and it seems your existing print is giving the same hint by dividing itself ;) If you want to try PLA, I also love my ColorFabb PLA (with PHA). It works very well and is very reliable.

Printing a tall thin wall like that is often going to have a problem with cracking or lifting due to shrinkage - it's effectively the worst case scenario for ABS shrink. IT will be made even worse as we head in to winter. You may get away with such a print by building a heated chamber to surround your printer during the print. Any chamber will suffice, even a cardboard box over the printer though if you want something as a long term solution (many prints) I recommend keeping the vents at the base of the print open to the cooler air. But for a quick go through a cardboard box over the printer and do your print. I bring the ambient up to temp inside the box by charging it with a fan heater (or hair dryer) when I am about to start the print. I have pulled off many a tall thin wall this way.

Chris botha
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Re: Parts Cracking?

Post by Chris botha » Sun Jun 08, 2014 12:03 pm

Cool.. I will look at an enclosure as the creaking and rumbling noises are not helping my romantic life at all either... "hold on honey.. I think I hear a filament jam... ".. :lol:

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