Unheated build surface for ABS

I've been experimenting with different unheated build surfaces for printing ABS. HDU foam works quite well, but unless you have a pretty thick piece, the top surface shrinks and causes the foam to warp when you print on it. The higher density foam is also rather expensive. I've now tried a few prints on 1/32" thick phenolic (McMaster XX grade). I've sanded the surface to expose some of the paper core fibers and then coated it with a film of ABS juice. Prints seem to stick pretty well and come off cleanly with the help of a razor blade. The phenolic sheet I'm using is thin enough that you can flex it and peel off a part once you get an edge liberated.

Has anyone else tried this? I'm quite new to 3D printing and am wondering what kind of trouble I'm liable to run into using this approach. I'm really hoping I can avoid an heated build platform.

-Jeff

thick acrilic sheets, slow printing with abs, and raft support are how we use to do it before heated beds. if you want an easy way out that does not cause your setup to be pricy, then invest in a heat lap. place it about 1 foot or so away from the bed.

here is one link to the subject here:
[en.wikipedia.org]

One thing is for sure. its been all done before.....

Thanks for the old-school wisdom.

How much of the job of the heated bed is for keeping the part stuck down, and how much is for combating other sorts of warping and distortions? In otherwords, If I can keep parts stuck down without any heat, how much do I have to worry about other problems like delamination as the rest of the part cools? Mostly, I'm trying to understand what all the issues are.

Worst case, though, it sounds like I can just use a heat lamp...

honestly with all the variables in play, it was hit and miss. heated bed solved so many issues i never went back to non heated bed with abs, or hdpe. pla was a real treat for the reprap printers. pla allows non heated surfaces.

for heated bed some people would add disks or leafs to the abs prints.

... some years ago I've seen some 'gripping tables' for foam-milling, where the bed was equipped with some thousand retractable thin needles, punching into the material for holding it in place but retracted when finished to release it.

'Thousands' needles won't be doable, but maybe a bed with really small screws (e.g. M1, 1mm diameter) from below, maybe in a square-array every 5mm, with a hole around, so the raft can bind with the thread will hold big pieces down? ... it would be a piece of work to release all catched screwas after finishing, but could be worth a try

In professional metal laser sintering something similar is done with an array of thin breakaway support structures (representing vertical needles or trees), connecting the building base (or subsequent surface) and overhangs ...

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Viktor
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Call for the project "garbage-free seas" - [reprap.org]

Well, I don't really know the science behind warping except it seems to me that the further the layers get from the bed, the quicker they cool and shrink which presumably causes the print to bend upward. Keeping all the layers at the same temp while printing and allowing them to cool at the same rate seems to be the Holy Grail of perfect ABS prints..... So, who has the answer?

i believe the people at pp3dp (as much as it pains me to say) may have hit the nail on the head, they use a perforated board which is essentially a piece of pcb with a few thousand holes in it, and the first layer of the raft extrudes a bit more,
i've been looking at having 200x200 sized piece of the same thing done for the prusa heated bed, but so far no-one wants to touch it,

somthing i've noticed is that the warping in abs on a heated platform doesn't actually start until the object gets taller than a certain amount, (around 5mm for me) i think if you can heat a chamber up to the full 110 to 130 you should be able to print just about any object in abs

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