Preventing warping

[samusi01]

Any thoughts on how to prevent warping? These were printed as illustrated in the second image, i.e., with a slight pitch and roll...

(edited to add:) Thickness on these is a max of about 1mm, somewhat less in the corrugations.

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[John]

we all go through this at one time or another ..  see this for some hints

https://3dprinterly.com/9-ways-how-to-fix-resin-3d-prints-warping-simple-fixes/

[Chris333]

Maybe stand them up while curing so the light hits both sides at the same time.

[wvgca]

i am not much help... have both filament and resin printers, but hardly use the resin one, too much cleanup and additional exposing work there ... plus i'm HO so the filament does good for that size of parts .. sorry

[samusi01]

@John

Thanks for the links. I'll try some of those tonight or tomorrow.

@Chris333

Those images were pre-curing... post curing is marginally worse. At least the alignment pins fit perfectly and function as intended.

[John]

A couple of things you can do to fix the existing parts -- after you have it cured .. run the piece under some hot water from the faucet until it becomes pliable - usually no more than 10 seconds - then immediately put it between two 3-2-1 blocks or other flat surfaces to let it cool .. you can also put it into the freezer for a few minutes .. that fixes these most often ..

I would also tilt those two pieces at 45 deg .. and add more supports on the backside especially around the edges .. those two items probably should have large supports on the corners and the bottom edge .. good luck...

What printer, resin and settings are you using?

btw .. what's the model and what should lit look like ..

[AlwaysSolutions]

Is there a reason everything is only "slightly" angled?  It may just be my eyes playing tricks on me with the perspective so ignore this if I'm seeing things.  I would print everything on that build plate straight up and down with no tilt except the roof piece on the left side.  One of the main purposes to angling your pieces is to lessen the pull forces on the model and fep during a layer change (by reducing the area of the model contacting the fep at any one time)  This lowers the risk of print failure.  Since your walls are only about a mm thick anyway, tilting would actually increase the contact area, albeit negligibly in this case. Anyway, that's just a side observation.

To the warping issue.  First, always let your prints completely dry before curing.  These resins can retain moisture and swell enough to cause issues with thin walls.  And since there is more material on the corrugation side the corrugation will expand slightly more than the other side, potentially causing a warp.  Allowing it to dry gives the piece a chance to stabilize into its intended shape.  Second, if it's still warped after curing, the hot water trick is how I'd go about trying to fix it.

Cheers -Mike

[Chris333]

I always dry my prints first. But some say you should cure while they are submerged in water. So 

[samusi01]

@John

Printer is an Elegoo Saturn 2 8k, using their 8k gray resin. Settings are what I presume are their recommended, from the Chitubox instance downloaded from their site, or from the USB drive that came with the machine. Don't recall which. I'll try the hot water bit... all images, first post and this post, are captured after the alcohol bath and drying but prior to any curing.

I did try another shot overnight, slightly more angled, with the complete structure (in this case, an unloading shed cover) as a single object as well. That turned out well enough, but some slight warping on the standalone walls still exists. I think if I added supports at the marked locations, that is the outer corners, it might help.

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@AlwaysSolutions

Your eyes aren't deceiving you: they are all slightly angled, as leaving them square to the build surface seems to result in either slightly wavy surfaces parallel to the build surface, peaking at the attach points, or else layer separation as I've not bothered to really dial in any settings. The out of the box settings in Chitubox have been handling things pretty well. I'll have to give the parallel option a try, or perhaps experiment with the skirt that Mr. Bussey uses. Except for a headhouse (not imaged due to it printing fine), all corrugations are double sided.

Sam

[Erock482]

Looking at your post print picture with the supports on, I would add more supports up the backside all the way to the top. that might help keep them in shape.

Alternatively, the soak in hot water and then weigh down to keep them flat while they cool works very well, I use that for flattening car floors that have gone banana shaped

[Lemosteam]

Assuming this model will be buried in the substrate of the landscape, I feel that the cross section at the top of the panel is causing this. if there were a "board" of the same thickness as the vertical ribs, I bet the warp would go away.

Also since these have minimal curvature, I would print them on the build plate, flat or vertically and remove any elephants foot or distortion by sanding them on a flat plate. 

Technically you could glue the whole model together in advance of curing using UV resin glue and then cure it as a completed model hoping that the added support structure would prevent the warping (but you might need a floor.

Just my thoughts, and it would print much faster as well.

[samusi01]

An update - tried the hot water bit first, without success. First pass was with the hottest tap water that I could generate. No change. Went back and microwaved a beaker of water - around 140F - and thirty seconds of dunking followed by 1-2-3 blocks didn't do anything. I may go back and retry, either with hotter water or a longer duration in the water. I did try printing directly off the build plate and that seemed to well. As can be seen below, there is some minor bloom around the base but nothing that can't be corrected. As time permits, I need to go back in and add internal structure on the bottom - supports for rails, etc. - and that should help if I want to give it a shot again when I get back home.

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[dem34]

Well, in my experience once its evenly warmed up you need to clamp the model for around 12-24h in the position you need before it actually holds the desired shape.

[samusi01]

That's substantially longer than I tried. I'll give it another shot, perhaps fifteen days or so worth of sitting.

Sam

[peteski]

While I have no experience with these resins, I know that 140 deg. F is way too cool to make polystyrene soft enough to change its shape.