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Too much post curing shrinkage

Hi everyone,

I have been using the Formlabs curing station with provided recommended settings for white resin. However, I am observing significant shrinkage. Am I doing something wrong or the provided recommended settings are not reliable?

Thanks,
Mehrdad

How long you “dry” the parts after washing? I wash and let it dry until the next day, then cure if nessesary. Have no issues with bending or deformations since on Grey V4. No experience with White.

Rene,

Have you always let the parts dry for a day? I guess i have taken the part directly to the form cure after an hour a so of drying. Never attempted waiting a day

Don

Hey Don

Before I was kind of washing them and when they looked dry I cured them. But had issues with bending on some geometries. FL suggested drying longer as the resin soaks up some of the IPA. So now I just leave them over night before I do anything to them. But that is just because it fits in to our daily workflow. I don’t know exactly how many hours or so. And guess that would depend on the geometry as-well.

//René

Good to know. Started my 3L for the first time in a while today. Noticed the ever apparent clicking noise from the magnets. Safe to say i do not like that but hope it will get resolved with future updates.

Don

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Thanks for the response guys! I was not letting the print dry much before putting it in the curing station. I usually let is sit for 15 to 30 minutes before curing it. I don’t wish to wait days before curing the part. If i could wait that long, i would just put the part under the sunlight…

That being said, i was using a $100 curing station from creality before upgrading to formlabs wash and cure and I did not get any shrinkage. I believe the shrinkage is caused by the heating operation rather than UV light.

Honestly I am quite disappointed to get this result from such an expensive upgrade (which for me looks like a downgrade). I am going to skip curing with formlabs curing station until formlabs address the issue.

This is highly dependent on geometry, but yes, thermal cures WILL induce warp and on some geometries it can be very significant. I haven’t found a good solution around this other than curing without heat for longer periods of time.

AFAIK many other industrial materials from other companies (eg. 3D Systems) also require thermal cures but I’m not sure if they are any better in terms of warping - my suspicion is no.

If you do need to thermal cure for really thick parts, you MUST leave supports on when doing so and only remove supports after. This will greatly mitigate warp.

I was printing a large flat object in black V4 and had warping problems when printed flat. I ran tests of curing without heat and it made no difference… What fixed that warp was printing the part at a 45 deg angle to the build plate. I will have to try letting the parts dry a day but most of the time I’m in a rush to see the result.

I think the settings for Form cure give optimum strength.
This means using a temperature that is above the point where the plastic relaxes and it distorts.
There should be a table of settings for max strength without distortion too IMHO.

The cure station is not great: It could easily be programmed to dry parts, do a preliminary cold cure to keep shape, then do hot cure to optimise strength.
Instead it has a dial rotarion that backwards ( clockwise to decrease), which I find irrationally irritating!
I wish they had better software developers.

Do you leave support structures attached during curing? I find that helps prevent dimensional changes.

I’ve experimented with a cold then hot cure, doesn’t work. You still get deformation on some geometries because the cure temp is so close to the HDT.

Whenever you can, you should leave supports on. It makes it much more difficult to remove supports though.

In general, if you don’t need the full strength shown in the datasheet, curing for 3X the time without heat has been working well for me and does not result in warping. I tend to do this on thin geometries that are prone to warping. On thicker pieces it doesn’t matter as much.

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