Printing a non manifold rc car body

[schafe 3]

I want to print an RC car body I designed in Blender - see pic.  What I want is to print 2 halves of the shell with whatever support Cura calculates is needed.  Is there a way to do this?

[GregValiant 1,355]

Thin walled models present unique problems.  Not being watertight on such thin walls...I don't know.  You can try uploading to service.netfabb.com.  It's free and pretty good.  Making it watertight gets rid of one issue.

If you were to remove the side mirrors (make them glue-ons - you're going to knock them off all the time anyway) you can eliminate one problem area.  If you can alter one half of the body so it has a centerline flange that fits under the other half, it will make assembly much easier.  Even with tabs glued here and there, it won't fit well unless it has the support of the other half.

As far as print supports go, you'll need to play around.  It's so thin that the roof is going to be a problem.  Remember that the supports will need to come out.  If you sweep a shape across the top of the front window to the top of the rear window it would add layers to the roof.  I think that would print better and hold up better during support removal as well.  I would suggest a dense support interface of 50 to 60%.  I've had better luck removing supports with dense interfaces without hurting the print.  When you slice it, make sure to look very closely at the preview so you can pick out problem areas before you print.  You'll have a lot of time invested in this.

[tinkergnome 927]

On 2/19/2021 at 5:17 AM, schafe said:

I want to print an RC car body I designed in Blender - see pic.

 

It looks like this are only (infinite thin) faces, so... that's an object that can't exist in the physical world.

First step: be sure that you have a clean mesh topology (remove duplicate vertices with "Merge by distance").

Take sure that all Normals are facing outwards and try (at least) the "Solidify" modifier in Blender to give the walls some "thickness".

With other words... make it manifold! 🙂 That should do it.

 

[Pizzastreichler 1]

Suggestion 1:  Besides above named things, you might want to cut and slice the body lateraly, so the angles are steeper and you might not need so much supports. Probably printing the front and rear as a short segment would make things even easier and some well attached supports could be left in place.

 

Suggestion 2: Did you also concider the rigidity of the material and the final print? I would have some doubts about using this on a RC car. I'd rather print a quite solid positive model and vacuum form the body with a more stressable material.

that way it's also not such a big deal when you flip the thing over  😉

[geert_2 558]

On 2/20/2021 at 11:47 PM, Pizzastreichler said:

Suggestion 1:  Besides above named things, you might want to cut and slice the body lateraly, so the angles are steeper and you might not need so much supports. Probably printing the front and rear as a short segment would make things even easier and some well attached supports could be left in place.

 

Suggestion 2: Did you also concider the rigidity of the material and the final print? I would have some doubts about using this on a RC car. I'd rather print a quite solid positive model and vacuum form the body with a more stressable material.

that way it's also not such a big deal when you flip the thing over  😉

 

Yes, vacuum thermoforming might be a good idea. I think most commercial RC car kits are also vacuum formed?

 

But I am not sure if you can vacuum thermoform around a PLA model, without it being deformed due to heat? Also, it might not pull vacuum very well, since the air can not escape from deeper areas. However, you can definitely vacuum thermoform around plaster. That is how some dental applyance are (were) made. Plaster is porous and lets enough air pass through. So you could 3D-print a mould in PLA in multiple parts (to be able to release the cast), and then pour plaster in it. Then remove the plaster cast, and carefully sand it and correct minor defects like bubbles. And use that plaster cast as mould to vacuum thermoform your car, using a somewhat flexible plastic sheet. In this way, you can always re-use the mould to quickly produce new body shells, for painting in different color schemes, or when one gets damaged in a crash.

 

You can buy a commercial vacuum thermoforming kit, or make one yourself. Take a hard wooden plate, MDF or multiplex or so, for a base plate. Drill a hole in it and attach a powerfull vacuum cleaner to it. Then make a double frame out of wood, of the same size as the base plate. You need to clamp both frames on top of each other, so you can clamp a sheet of plastic between those frames. Once clamped in the frame, heat that plastic sheet with a heat gun untill it really sags. If you poke into the sagged plastic with a tool, the dent should almost immediately straighten out again. (If it doesn't, it is not warm enough yet.) While heating, switch on the vacuum cleaner. And then when hot enough, pull that frame with sagging sheet over the plaster model, so it gets pulled vacuum around the plaster. Let cool, and remove. I had a small professional unit for dental models some years ago, but the principle is the same, and I have seen home-built models. Maybe you can find Youtube videos?