Woes of ABS and part warping

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691175002
I print almost exclusively ABS. With the brands I've been using the build chamber must be >45c and <50c. I have a vent at the top of my enclosure that is partially blocked by a piece of cardboard. I leave a multimeter thermocouple in the chamber and open/close the vent to adjust temperature.

In my experience there is really no way to reliably print ABS if the chamber is <45c. I used to play with ABS juice and other tricks, but even if you keep the first layer in place the print will just delaminate somewhere else and you end up chasing your tail trying to improve layer adhesion while maintaining crisp print quality.

I print on bare Kapton at 95c and scale my parts up to 100.6% to compensate for shrinkage. The parts pop off the bed themselves as the bed cools.

How do you heat the printer volume? I am finding that the bed by itself isn't doing it, I still leach heat out. Oh, BTW, thanks for the 100.6% thing, that can be useful...
What temperature do you heat your hotend to and what ABS brand do you use? All of those things affect what happens.

Thanks,
DLC

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691175002

(I wish slicers would let you define a per-filament scaling factor because sometimes I forget to print ABS at 100.6%. I mean I could change my firmware steps/mm but that screws up prints in other plastics and is a pretty dirty hack that could have other consequences.)

Slic3r makes it easy to have multiple config files for different filaments.

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dlc60

So even though the part was stuck like set concrete to the bed, the corner STILL LIFTED, just not nearly as much.

Adding frog's feet (just round pads) several layers thick to the corners will help keep them stuck to the bed. You can also put some ABS juice on/around the perimeter after several layers have printed.

As the previous poster indicates, 31C is too low a chamber temperature to print ABS reliably. If you are relying solely on the bed heater to heat the chamber, you probably need to double-glaze the chamber to improve the insulation.

The only times I have printed ABS parts higher than about 10mm, I put 2 plastic bags over the entire printer to enclose it. One plastic bag wasn't enough, it needed the air gap between the two bags to provide enough insulation. I can't remember the exact temperature that the chamber reached but it was in the 40s.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I think you are correct. My efforts do not insulate well enough to heat the interior. I put "mouse ears" on my print and it stays mostly flat, but still curls. I get cracks in the main body too AND I have to chisel the part off of the BuildTak, Ahh!!! I may have to dedicate a machine to JUST do ABS and put it in an oven to temperature control it. I thought that putting walls all around would work, it doesn't, you need more than breeze walls and they obviously need a decent "R Value" to even work. Breeze walls work fine for stuff that is a couple of cm's high, but more than that takes extraordinary effort it appears. I will try the "second bag" trick the next time I have a big part to print. Five hours is a long time to wait to find out your print didn't fly.

My last print attempt stuck VERY well, didn't curl too much, and had cracks, but not too large.
But...
I ran out of ABS about 2/3 through the print. Sigh.

Oh, if anyone out there uses BuildTak, what do you do when removing a part pulls "dimples" in the surface? Is there any way to get it flat again or do I just have to pull it off and burn another $10 to replace it?

Thanks,
DLC

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etfrench

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691175002

(I wish slicers would let you define a per-filament scaling factor because sometimes I forget to print ABS at 100.6%. I mean I could change my firmware steps/mm but that screws up prints in other plastics and is a pretty dirty hack that could have other consequences.)

Slic3r makes it easy to have multiple config files for different filaments.

So does Simplify3D, you just have to remember to select it...

I know you can change basic settings like extruder and bed temperature on a per-filament basis, but I haven't seen an option to scale the STL per-material.


My enclosure is a glued/taped monstrosity made from 3/4" insulation foam and will hit ~60c with just the bed and extruder if left closed and unattended for several hours.

I intend to include some means of controlling the chamber temperature on my next printer but if you also run a heated bed it is not obvious as to whether the chamber will need active heating or active cooling (or both). Stratsys machines print into a temperature controlled chamber and do not use a heated bed at all, but I don't know if that is ideal for materials like PLA.

I think large printers should be well insulated because dumping hundreds of watts of heat into the surrounding area for days at a time will get expensive (and/or make the room very uncomfortable).

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dlc60

Oh, if anyone out there uses BuildTak, what do you do when removing a part pulls "dimples" in the surface? Is there any way to get it flat again or do I just have to pull it off and burn another $10 to replace it?

Thanks,
DLC

Don't use BuildTak. I could not get a sheet of BuildTak to last for even one roll of filament without forming dimples on the surface. Buy a sheet of .75 mm (or thereabouts) PEI and some 3M 468MP adhesive transfer tape to stick it onto the bed. Works better than BuildTak and will last a very long time. Applying the 468MP transfer tape to the PEI sheet without bubbles can be a bit of a chore though.

You can also buy PEI with the adhesive sheet already applied from here Ultem PEI sheets.

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xyze

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dlc60

Oh, if anyone out there uses BuildTak, what do you do when removing a part pulls "dimples" in the surface? Is there any way to get it flat again or do I just have to pull it off and burn another $10 to replace it?

Thanks,
DLC

Don't use BuildTak. I could not get a sheet of BuildTak to last for even one roll of filament without forming dimples on the surface. Buy a sheet of .75 mm (or thereabouts) PEI and some 3M 468MP adhesive transfer tape to stick it onto the bed. Works better than BuildTak and will last a very long time. Applying the 468MP transfer tape to the PEI sheet without bubbles can be a bit of a chore though.

You can also buy PEI with the adhesive sheet already applied from here Ultem PEI sheets.

I see what you mean- trial and error using BuildTak can get expensive. Finding a height that sticks, but not too much, is all trial and error...
Thanks for the recommendation.

As for ABS, it is just too difficult to make large parts without it taking over my workspace with special exhaust hoods and heat chambers. I am going to see what I can do with PETg. I will find out just how tough it is in the meantime.

Thanks,
DLC

I print ABS all the time and the key thing realy is a chamber temperature of >=50C.
A PEI sheet is the best surface i found so far, in my latest setup i use it with magnetic foil on the heatbed and magnetic and PEI foil together as the removable print surface. It is flexible and can be peeled of easily after printing.
Edit: there is one material that is very similar to ABS, except it does not warp nearly as much. Check for Green Tec from Extrudr

Edited 1 time(s). Last edit at 10/11/2017 06:37AM by Srek.

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I hear what you are saying. For me PLA is for "art" pieces and toys, figures.

My current favorite is PETG. It is harder and more flexible than PLA as well as higher temperature tolerance. It is not as flexible or tough as ABS, but the lower shrinkage compared to ABS means it is far, far easier to print without extraordinary measures. I also love its glossy finish.

I have found my new filament! It may be more stringy than the other filaments, but it totally suits my needs right now.

DLC