Author Topic: Distortion in a 3D print  (Read 1009 times)

Offline A7er

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Distortion in a 3D print
« on: May 01, 2023, 03:31:36 PM »
The picture shows two resin 3D printed interior panels for my one tenth scale model of my Austin 7. I am making four models, so I printed four pairs, four right and four left panels. They all came out of the printer with the distortion shown on the end of the left hand panel. The right hand panel is after treatment. I used a hair dryer set on low to warm the panel before clamping it to a flat board. I let the panel sit for half an hour before taking it off the flat board. So far they seem to be staying straight, but if there is still a bit of distortion after I take them off the board and I reheat the panel, the distortion returns and I have to do the treatment again. The kink in the far end is where the panel follows the shape of the body and is supposed to be there.
I forgot to include a coin for scale. The panels are 1mm thick by 37mm high. The panels are shown the right way up, but they were the other way up on the build plate with dozens of supports.


Offline Dave Otto

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Re: Distortion in a 3D print
« Reply #1 on: May 01, 2023, 04:47:46 PM »
It would have been interesting to see what it looked like before you removed it from the platform. I'm not clear how you built it or what the supports looked like.
What I do quite often at work is to build some support geometry to support the part during the build. I made a quick model to hopefully what I'm talking about. The gray part is the supporting structure and the blue is the part. The attachment points are very small and easily break away.

Just some food for thought.
Dave

Offline A7er

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Re: Distortion in a 3D print
« Reply #2 on: May 01, 2023, 05:13:22 PM »
I did wonder afterwards if I should have printed each pair about 5mm apart with supports between them, as you have done.

The bottom edge is 1mm wide by 130mm long. The panel has a kink towards the front. I set the support to 100% in Prusa and added as many again by hand.

Still learning!

Offline Dave Otto

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Re: Distortion in a 3D print
« Reply #3 on: May 01, 2023, 05:22:30 PM »
So the supports were only along the bottom edge!

Offline A7er

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Re: Distortion in a 3D print
« Reply #4 on: May 01, 2023, 05:32:31 PM »
Yes. The panels were printed vertically, on the bottom edge. There's not enough room on my build plate to lay them down, and I couldn't foresee any problems. I now wonder if the pressure on the panels as they dipped into the resin tank onto the fep caused the distortion? I might try printing a pair 5mm apart with supports between them to see if it improves things, especially if the existing panels prove to be unstable. I don't want them pinging off the model at a later date.

Offline cnr6400

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Re: Distortion in a 3D print
« Reply #5 on: May 01, 2023, 08:46:29 PM »
On tall thin prints in my FDM 3D printer (not a resin printer)  I add a couple of sacrificial ribs to make a T profile to keep the tall walls supported and more likely to be straight. If made thin, the sacrificial ribs can be easily cut off after printing. Just food for thought.
"I've cut that stock three times, and it's still too short!"

Offline A7er

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Re: Distortion in a 3D print
« Reply #6 on: May 01, 2023, 08:56:28 PM »
I did consider using my Ender3 instead of the resin printer, but the Ender print time was over 8 hours compared to the resin's just over 3. I even started to make them from thick cardboard. It didn't look right.

Offline cnr6400

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Re: Distortion in a 3D print
« Reply #7 on: May 01, 2023, 10:43:27 PM »
Tin plated steel or brass sheet from a hobby shop might be a good choice, rather than 3D printed plastic / resin. If thin, both are easy to cut with shears, and drill easily. Tin plated steel solders easily and paint adheres to it better than brass. (and the original car was steel sheet too!)  :cheers:
"I've cut that stock three times, and it's still too short!"

Offline A7er

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Re: Distortion in a 3D print
« Reply #8 on: May 01, 2023, 10:52:40 PM »
I have used the heat treatment on all the panels, and so far they have not sprung back. I would like to know what caused it though.

Offline BillTodd

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Re: Distortion in a 3D print
« Reply #9 on: May 02, 2023, 08:57:55 AM »
Interesting, I have tried to straighten parts and had really bad cracking and fracturing that made the part unusable.

The usual cause flat panel distortion is  lack of support . If you can't splatter the thing with support then try to print it vertical and hope it sticks to the bed (or design in a sacrificial foot)

If the cross section is asymmetric, adding a sacrificial the other side to compensate some of the shrinkage can help.

Offline A7er

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Re: Distortion in a 3D print
« Reply #10 on: May 02, 2023, 05:00:18 PM »
Because the panel is basically flat, apart from the kink, I did consider using an electric clothes iron on a low setting. The hair dryer was nearer. Some of the panels did crack and split. I super glued them back together which seems to have done the job. I wondered if a strong, clear packing tape applied to the back of the panel would keep them stable, but I am going to rely on glueing them to the inside of the body, which is 3D printed PLA. I will try JB weld when I do glue them.

Offline ddmckee54

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Re: Distortion in a 3D print
« Reply #11 on: May 02, 2023, 07:47:06 PM »
If the panels were going to be removeable, then the packing tape reinforcement would be a good idea.  Since you're going to glue the panels in place I'd skip that step. (Packing tape is often used as a release agent for parts you DON'T want to stick together in a glue-up.)

Any decent epoxy should work to glue the panels in place.  You might want to roughen the gluing surfaces with some sandpaper to give the epoxy a surface with a little more "tooth" to grab on to.

Offline A7er

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Re: Distortion in a 3D print
« Reply #12 on: May 02, 2023, 08:03:06 PM »
Good point about the tape. It would stop the panel from sticking to the body. I don't want to risk the panels becoming loose at a later date. Three of the model cars are going to my sisters, and they live 350 miles away. One might go to a nephew, he lives in Australia. I s'pose I could pop over and glue it back. :LittleAngel:

 

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