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xavirojas wrote:

Thanks For sharing your progress Yogi! Impresive results

thanks! I'm still trying to improve it too. At the moment I an experimenting with making resin casts instead of plaster. Plus I and thinking of replacing the solenoids I have with pneumatic ones.

I'm trying myself to vac my own bodies and not close to your level of detail yet... Not to mention that my "gear" is very domestic... but still, having fun trying to achieve an acceptable result from my 3D printed mold.

cool, you can still achieve very good results with very domestic gear. You only really need two things, the right temp and good suction that gets sealed around the edge. A good vacuum cleaner will get you there for PETG, HIPS and maybe even ABS. ABS is a good choice as it quite durable, but you'll need a decent control of your temp and you can't get it in clear. So no windows or you cut them out. ABS can also be worked a bit afterwards. So you can sand, drill etc afterwards.

These days is hard to source plastic sheets due to Covid, so I'm testing with any sheet I can find. So far, my tests failed with 1mm lexan and succeded with 0.5 PETG and 0.7 PVC.

yeah, lexan is the tricky one, there is only about a 5 degree temperature window for it to soften, so you need very good temp control. Plus its prone to forming bubbles if its heated too quickly.

Reading from your experience, the problem with lexan is it gets cold so fast, so I don't even get to pull the sheet all the way down over the body... at half way it just won't deform more so I can't really vac. Want to try with 0.5 or 0.75 lexan but haven't sourced any sheet yet.
PETG is way easier to deform and with 0.5 the level of detail is great. But too thick, so want to try with 0.75 and 1mm PETG.
At last, I found a sheet of 0.7 PVC that is giving me good results. Ever tried that? I really don't know the specs of this plastic, so I don't know how bad it can be for a RC body (breakable? no UV?). But it's way cheaper that lexan!

I quite like PETG, its very easy to form and has some durability to it. HIPS is good too, but not very structural (it will shatter), but for things like interior cockpits its a good choice. I'm really only sticking to ABS, PETG and HIPS, I'm not too keen on PVC, and didn't have a lot of luck with it. My temp was off, which didn't help, but I don't think its a very durable plastic for RC use. You only really see it used on the cheapest RC bodies. I don't think there is any UV stabilisers in the sheets you can get, so any I have seen many go brittle after a few years (well that is at least my experience). Lexan is the best of course, as its the toughest, but it needs very precise temp control and suction. I think it would be difficult to get good consistent results on a home setup. I've also found it quite difficult to get hold of. I can get 0.375 mm and a 1.5 mm roofing grade, but nothing in-between in Australia. Whereabouts are you?

I'll try to post my results later

please do!

gee, its been quite a while since I have updated this thread, so here are some updates.

First, work has been super busy, one of the reasons I don't post much, but that has enabled me to purchase a better vac former, namely this:


and some testing, this is PETG

Superb thread!
Thanks Johann!

I also took some plaster casts from a Mariu Hunter body


this time I tried using ABS, this one is called "hair cell" as it has a pattern on one side and gloss on the other




and I'd also done some testing with 3D printed bodies, this one was the test for Silvertriple, using a 0.75 mm I think PETG. 3D printing molds is something I'd eventually like to do more of.

Fantastic Johann

Thats great to see. I  have 1 question regarding your printed mold parts. How thick are your walls on the printed parts. What kind of infill do you use. What material? so many questions....
I want to convert my 3d models to moldable parts too.
Thank you in advance, Lem

Thick enough, and full : You need to print it in a material that is the higher temp possible, but not the same material as you plan to vacform...

My current idea is 1cm thick walls and filling the inside with expandable foam to save material and printing time.
 

Hi Lemsko,
depending on how many you want to make, and what material you want to form at, you can get away with a low temp plastic like PLA, but you'll only get one to two got before it starts to warp. But it is a cheap way to test what you are forming. Ideally you'll want the melting temp on what you are printing to be higher than what you are vac forming with.

For the Nichimo body I used ABS, it'll last a fair while, and I vac formed with PETG, polycarbonate would be a bit harder.
The walls I made about 10 mm thick. You don't need to go crazy with the infill, something like about 50% should be plenty, but instead up the number of shells though, you'll want that outer shell at least a couple of mm thick to handle the sudden input of heat.
You'll also want to smooth the surface, as you get all the line details of the 3D print in the vac form. Spray putty is good there as it also helps seal surface. The other option is to resin print with a high temp resin, I've tried this a couple of times and you get can surfaces that need a lot less prep.

And you'll want to add vent holes for any deep recess or corners to help pull in the shape.

Thank you for the detailed answer. My Hotend only goes to 250°. My plan was to use HIPS, which is my favourite material so far. Sealing it with high temp resin is a great idea i hadnt in mind.
How does paint stick on PETG?