Distortion in a resin 3D print

[lee webster]

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.

 

[ddmckee54]

I wonder if when you are heating it with the heat gun you are getting the part soft enough to move, but not holding it at that temperature long enough for the internal stresses to normalize?

It's probably more work than you really want to go through, but... I'm wondering if you could "heat treat" the part that you straightened using the heat gun with the part clamped into a form/mold of the correct shape? If you brought the part up to it's slump temperature with it clamped in the correct position and held it there long enough, then the stresses should normalize in that position. Keep the part clamped and let it cool slowly, and I'd think that every thing should now be happy in that position. (Kind of like trying to weld/braze cast iron?)

 

[lee webster]

It wouldn't be hard to make form like that from two sheets of thin aluminium. If they do start to buckle again I will try that, thanks.

 

[kf2qd]

You are working with a very thin, high aspect profile (meaning it is very large for its thickness) you may also be seeing some effect of degrading the resin near where it has been cured during printing. You might try some low agitation of the resin to keep a better quality of resin at the point of printing. Not sure the thermal properties of the cured resin, but seeing how it is a laser or UV cured resin, heat is probably not going to be all that effective.

 

[Zeb]

I'll get warping if the room temperature is too low. Could be the case if too high as well. Having the temp set to the "can" and adding supports usually solved my thin-walled prints.

 

[lee webster]

At the moment the warping is very little. If it stays like this, then I will rely on strong advesive to hold the panels in place. I must admit that the temp in the insulated box the printer is housed in may not have been as high as it could have been. I use a 40 watt filament bulb for the heat source. The bulb had broken, they don't like being moved, so I fitted the only other small filament bulb I had. A 15 watt. This brought the temp up to 65f, I normally wait for the temp to reach 80f before printing. The 15 watt would have needed another half an hour to get the temp up. My fault for not waiting. Still, we learn from our mistakes! I now know for future prints, get the temp up, and if the part is thin, add extra supports.

I would like to have printed the panels on my Ender3, but the panels have vertical grooves to replicate pleated upholstery. They are half a mm deep (in a 1mm thick panel) by 1mm wide. I don't think the Ender could have printed something like that

 

[terryd]

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.

View attachment 146849

Hi Lee,
In my experience I would print the panels in two parts and join them with a suitable solvent cement or cyano acrylate (superglue), araldite or whatever adhesive you are best with, it's the bed temperature and hot end that are critical. I can't say that I've had warping that bad in th past, just luck I suppose. but my printer is a scratch built one in the early days of RepRap. Frame and brackets etc from plywood with added electronics, motors and 8mm ms steel runners. Still works well though but I also use a commercial one which is less sturdy and have just bought a resin printer to try... By the way the latest Prusa 2.6 slicer enables 'tree end branch' organic supports which use a lot less filament and is easier to remove than' scaffolding' with less scarring.

Here's a picture of my home bodged Printer, it gives surprisingly good reults though.

the brackets an carriers wewe designed in a simple 2d cad package with tabs and slots, printed to size then stukh on to 6mm plywood and cut out on a bandsaw before assembly. pVA was used as the adhesive and it's held up well in the 12 years or so since I built it. It has since been fitted with an automatic bed levelling system to get past what I thought a rather frustrating manual system with sheets of paper and adjuatable scress and springs. I sourced the electronics and motors from a variety of sources (motors were 2nd hand from th eStates in excellent condition for a fraction of new ones.

Regards
TerryD

 

[lee webster]

If the panels don't stay flat after the heat treatment to remove the distortion, I will print them on my Ender3. It's not as good as your 3D printer, but it gets the job done. It will take nearly 9 hours though.