Durable Resin Deforming

Ever since we have been experimenting with the durable resin it seems to readjust or deform. The durable resin feels soft after the print is complete compared to the grey resin we normally use.
In the first picture the orientation I am holding the part is the orientation that it was printed. It was supposed to come out in a cylindrical shape, but towards the bottom it began to droop down.

These were from the print following the one above. The “drooping” seems to be happening when the print is almost complete just as the previous photo. We removed a lot of material to try and minimize it which worked better, but there was still some deformation.

Has anyone had any issues like this or have any experience / tips for printing with the durable resin?

I don’t know how your supports are set up but you may want to make sure you have ample support and keep them on until after your done post curing the part. The supports should help keep the part stable.

Durable is definitely one of the more difficult resin to work with. It doesn’t like thin walls, but too thick walls lead to large cross section area per layer which lead to high peel forces and deformation.

I haven’t found a way around that other than avoiding large parts and large cross section area, as well as finding a middle ground between wall thickness and the part being mechanically stable.

Hi Ken,

The supports were setup on the face my hand is holding and the top of the outside diameter all the way to the other end. The area where is is drooping is where the supports aren’t, but I cant put supports on that side anyways. The deformation happens before I even take it off the print bed and I don’t even have a chance to try and cure a good part.

Thank you.

Hi John,

What you said about the cross section area makes sense, because when we reduced the part down from the first print to the second print it definitely helped lessen the deformation. I think next I might try to print it more horizontal to the print bed. That way I can add some supports to the inside diameter to add a little more support to the bottom of the print. I’ll post some pictures after we print it in that orientation.

Thank you.

Do you have a pic of the setup in PreForm?
Thinking running the object more vertical might be better than horizontal… Horizontal may make it sag anyways and internal supports might be a pain to snip out.

Here is the orientation of the first print.

The second print was more vertical and still had the slight deformation.

Surprisingly the I.D. was big enough for me to get a fine grain piece of sand paper and wipe them all out. Since the material is soft the supports come off easier.

Sorry, the first print orientation picture didn’t load for some reason. Here it is.

That wall thickness should not sag. I am thinking the inner fill is way under exposed. typically on these machines the outer parameter of the slices is one exposure and the inner is exposed less. this creates a shell and reduces wear and tear on the pdms. If the inner exposure is too low the resin will just collapse down.

For kicks try a very thin tall test and you will see there should be less distortion if any. I would contact tech support and see if they can correct the settings for you.

you are printing a part with massive walls.

Durable is a very flexible material and its supports are not rigid- they bend like licorice.

I think you are seeing the sheer accumulating weight of the part try to pull the part down and to one side.
Is there a reason you are printing such a thick cylinder?

You can BUY nylon or Polypropylene in cylinders that size and simple drill the countersunk hole for a lot less and a lot faster.

This is the first time we have used the durable resin, so we were unaware of how the material would print. We reduced the size of it for the second print which helped out. Usually we do make our own masking in house with UHMW, but we are trying to utilize 3-D printing for some of the more simple pieces.

Is there a reason you are using durable? You need a close analog to Polypropylene?

You could probably print the original model just fine in one of the more rigid resins- Tough- or even Rigid.

With the Durable I usually try to keep the part as LOW to the build plate as possible- To reduce the leverage on the print during peel. Or if printing a part that fills the volume, I try to make it as thin and well braced as possible.

Wall thickness is .410 in the model. Do you think more supports in the I.D. would help?
Also, what settings should I contact tech support about? Thank you for your help.

We need this masking to withstand shot peening. We originally tried the standard grey resin and it only lasted a handful of times. We then chose the durable resin because of its high impact strength, but getting it to print correctly is the issue.

That is a thick wall. I think that most models with that resin are much thinner so probably not many would run into the issue you are running into.

I would open up a ticket and show them the model and see if they can either fix the exposure OR have a setting you can load into Open FL and run the job from there.

Well- For a sacrificial part like that I would never waste the time and money on printing them.
I would either mill a pattern- or maybe print one pattern- and then make a quick mold to cast them at much lower per-unit cost. Urethane elastomers in a durometer of 80 or so can withstand peening pretty well. You would just have to scale up and print a model to mold that would compensate for the shrinkage of the mold and the urethane. Or even urethane resins can absorb a lot of impact and bounce right back.

Or even just buy polypro rod and drill the center out to the wall thickness you need.

Large masses like this can warp a lot just because of the cumulative shrinkage of each large profile layer.
the want to curl like a bimetal strip.

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Two things:

-Regarding the distortion - I never experienced something like this with Durable. I would contact tech support, maybe after one more try with a lot more supports, especially on the critical areas. Use 100µm resolution, you definitely don’t need 50µm for this shape.

-Regarding “we are trying to utilize 3-D printing for some of the more simple pieces”: I would do it the other way round, machining simple shapes and 3D-printing more complex ones that are difficult to machine. Printing these shapes in durable will never be cost-effective compared to simply turning them from a PE/PP/PA/POM rod, or molding them like @Sculptingman suggested.

Here is a picture of the orientation from our most recent print. I reduced the wall thickness to .150, flattened out the print orientation, made the point size a little but bigger on the supports, and added more I.D. supports. The print is so far successful. I just need to try to fit it onto a part. The second picture shows how well the material held up to shot peening at 15 P.S.I. We held it in one spot for 5 minutes and there seemed to be very little material removed. It holds up way better than the standard resin. @KenCitron

@Sculptingman I definitely agree that machining cylindrical masking is easier, but our tooling guy is getting backed up making fixturing for EDM, mill, jig grind, etc that we cannot print due to size constraints. We are just trying to explore other options that we can fall back on when needed. But the topic of my post is more for improving my durable resin prints. Thank you guys for the feedback.

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I see - then it makes sense of course. Great that you got better results, and thanks for keeping us posted :slight_smile:

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