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yogi-bear

Home Made Vac Former - Forming RC bodies

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And today I managed to plaster cast the Truggy.

setup in a suitable tray in case the plaster leaks

Vac-Former-Ver-6-15.jpeg

 

I then made a wooden block to fill in some of that large space.

Vac-Former-Ver-6-16.jpeg

 

which is then encased in plasticine. This makes it much easier to remove afterwards

Vac-Former-Ver-6-17.jpeg

 

and setup, ready for casting.

Vac-Former-Ver-6-18.jpeg

 

I just used plaster of Paris for this. Its fairly cheap, will set hard and can be sanded and painted afterwards. I worked out I needed at least the whole bag and was lucky that I had extra on hand as I got the ratios the wrong way around :huh: adding in too much water initially. This time around I also left the plaster set a lot more before pouring into the mold. In previous attempts I would pour right after mixing, so its fairly runny, and if there are any leaks you can end up losing a fair bit of plaster. Waiting until it starts to set means you risk losing a lot less, but the trade off is you don't have very much time to pour it all in.

Vac-Former-Ver-6-19-scaled.jpeg

 

filled in, I ended up using about 4kg of plaster. I then let is sit for about 3 hours before I removed everything.

Vac-Former-Ver-6-22.jpeg

 

and the final result. I should have probably let it to cure a bit longer as some bits along the back broke off. I'll be able to fix that and the roughness, but will let the cast cure for a day or two first, and hoping to try vac forming a shell by the end of the week.

 

Vac-Former-Ver-6-23.jpeg

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ok, its been ages since I've updated this, or indeed done anything RC related except buy stuff I don't have time to work on!

So finally I have some updates. The last couple of years has been crazy busy for me, leaving me little 'play' time. I'd intended a number of upgrades to the vac former, mainly:

  • much better heating elements,
  • a better temperature controller, 
  • a better vacuum - this I did manage to do
  • and air assist, to help remove the mould afterwards, and also to help form tall items

well, pretty much none of that got done :blink: but there is good news, since business was going well, I was able to invest in a proper vac former. So in late November 2021, I put in an order for a Formech 686. It was meant to arrive around March, but I didn't get it until about late April. But that is ok, as there were some other things I had to sort out as well (plus by that time I'd injured my knee, so it was hard to do much anyway). I also need to sort out power, which meant a new power board in the work shop that included a 3-phase power point. Now I didn't buy this machine to do just car bodies, I actually want to make signs and other things with it, but most of my testing and setups will be on the few RC body projects I started at the beginning of this thread.

So finally this December I was able to start using the machine. Here it is installed, and yes it's still on the crate base in come shipped on. The thing weighs about 250 kg and it means I can move it if I need to with a fork lift.  

This machine has a maximum area of about 620 mm x 620 mm.  So you don't waste that much material on making smaller forms, smaller areas are achieved with a reducing plate. It came with one set as shown in the pic, and I need to make any others I want out of 1.6 mm steel. I'm currently in the process of making two other, they are pretty simple to make though.

vac-forming-0-4.jpeg

here you can see the reducing plate

vac-forming-0-3.jpeg

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That truggy I was working on, I still plan to make, but for that I'll need a reducing plate. So I plan on making one that will suit most car Bodie sizes. Also after reading the manual decided to seal the plaster casts I've been making. Apparently its not good for the vacuum pump in the machine.

So I've been using spray putty and then sand back. It also should up how rough this casting was

vac-forming-0-7.jpeg

I also briefly tried the other car body that this project belongs to, but this time in 1.5 and 1 mm polycarbonate.

The 1.5mm wasn't too successful, but I think thats more to do with me not getting the heat settings right. On this machine you don't set the temp, you install just adjust total power to the heats and there are also about 5 or 6 zones you can control.

the 1.5 mm sample, I didn't get very good detail

vac-forming-20.jpeg

 

but the 1mm I was able to form pretty well, except for the heat bubbles. But I can fix this by drying the sheets beforehand and I was probably overheating the plastic a bit too.

vac-forming-24.jpeg

 

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The last test I managed to do, was for the Nichimo Mid-ship body. This was draw in fusion 360 by @silvertriple and I 3D printed. I had a couple of goes before I got to this stage. Its printed in ABS, 1 mm layer height and  about 15 mm thickness.

vac-forming-1.jpeg

vac-forming-2.jpeg

I then drilled some air vent holes in the deep recesses. And you can see with 0.75 mm PETG if formed really well.

vac-forming-3.jpeg

 

PETG is great for detail, you can see all the 3D print marks etc, plus it can handle deep recesses really well. I will try and do the final version in 1 mm polycarbonate though.

vac-forming-9.jpeg

The next step is to compare against an actual body and then adjust. For the final version I'll also spray putty the body and sand back to get rid of the layer lines.

 

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Oh boy this is exciting mate, cant wait to see progress

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3 minutes ago, mtbkym01 said:

Oh boy this is exciting mate, cant wait to see progress

cheers, I have some new ideas on casting the bodies too. Maybe not for all of them, but it will allow for some overhangs, and more detail around the lower half of the body. It's a two step process using a silicon shell and a harder internal support. I'll be more expensive but worth doing to get better formed bodies. 

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This entire thread is mental! 

In a good way of course.

Hats off to you.

 

Used to do a little bit of vac forming way, way back at school (boat hulls i remember) so this is all quite nostalgic too.

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4 hours ago, yogi-bear said:

cheers, I have some new ideas on casting the bodies too. Maybe not for all of them, but it will allow for some overhangs, and more detail around the lower half of the body. It's a two step process using a silicon shell and a harder internal support. I'll be more expensive but worth doing to get better formed bodies.

This popped up on my YouTube feed last night - Video about vacuum forming using silicone molds - and thought of sharing it with you. Though it sounds like you may have already seen it, or something like it. Anyway, with the method shown, you can get very detailed and scale-looking overhangs with a one-piece mold. 

 

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8 hours ago, yogi-bear said:

The last test I managed to do, was for the Nichimo Mid-ship body. This was draw in fusion 360 by @silvertriple and I 3D printed. I had a couple of goes before I got to this stage. Its printed in ABS, 1 mm layer height and  about 15 mm thickness.

vac-forming-1.jpeg

vac-forming-2.jpeg

I then drilled some air vent holes in the deep recesses. And you can see with 0.75 mm PETG if formed really well.

vac-forming-3.jpeg

 

PETG is great for detail, you can see all the 3D print marks etc, plus it can handle deep recesses really well. I will try and do the final version in 1 mm polycarbonate though.

vac-forming-9.jpeg

The next step is to compare against an actual body and then adjust. For the final version I'll also spray putty the body and sand back to get rid of the layer lines.

 

I am very curious that the ABS print was not melting trough the heat of the vacuum-former?

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8 hours ago, Elbowloh said:

This entire thread is mental! 

In a good way of course.

Hats off to you.

Used to do a little bit of vac forming way, way back at school (boat hulls i remember) so this is all quite nostalgic too.

cheers, its been a bit of a mission, but something I've wanted to do for quite a while

4 hours ago, rich_f said:

This popped up on my YouTube feed last night - Video about vacuum forming using silicone molds - and thought of sharing it with you. Though it sounds like you may have already seen it, or something like it. Anyway, with the method shown, you can get very detailed and scale-looking overhangs with a one-piece mold. 

cheers, thats the video I saw too, its a great idea, and also means you don't have to do multi-part moulds, which also have seam lines.

43 minutes ago, Collin said:

I am very curious that the ABS print was not melting trough the heat of the vacuum-former?

PETG softens at a lower temp than ABS - 85C compared to about 105C, so the mould should stand up to PETG for quite awhile. Polycarbonate softens higher at 140C, so the ABS mould won't last doing polycarbonate, but I think I could get 5 or so good bodies before it starts to deform. The wall is reasonably thick and the heat isn't in contact for too long, but the surface will start to lose detail I think. I did try a PLA mould for a small light covering, and after 3 goes the mould badly warped, but I only need two. PLA softens around 60C though, which is too low really.

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I saw you mention not wanting to do multi part molds but if cost in an issue (mold making silicone was quite expensive when i did some tabletop miniature casting a decade or so ago) i think you could print a negative, either in a flexible filament, or in multiple keyed  parts that can be clamped or bolted together and plaster cast bucks out of those.

Then again, since you picked up a really nice machine for this sorta stuff, there might not be much of a money issue :P

One thing ive had on my mind relating to this topic that you might be able to answer, does anyone do vac pulls into negatives? Would that make for sharper details as there isnt the thickness of the material to smooth things out on the finished product?
(i guess a stipulation would that there has to be good places in the negative/on the model for the air escape holes but other than that i dont see issues)

This is real interesting stuff, thank you for sharing!

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1 minute ago, Ziddan said:

I saw you mention not wanting to do multi part molds but if cost in an issue (mold making silicone was quite expensive when i did some tabletop miniature casting a decade or so ago) i think you could print a negative, either in a flexible filament, or in multiple keyed  parts that can be clamped or bolted together and plaster cast bucks out of those.

Then again, since you picked up a really nice machine for this sorta stuff, there might not be much of a money issue :P

thats a good idea. I definitely don't have an endless budget! and I think for shorter runs, this might be a good approach, or just doing multipart moulds. For longer runs where I might be able to sell the shells, thats probably where I'd target the silicone ones.

1 minute ago, Ziddan said:

One thing ive had on my mind relating to this topic that you might be able to answer, does anyone do vac pulls into negatives? Would that make for sharper details as there isnt the thickness of the material to smooth things out on the finished product?

This is real interesting stuff, thank you for sharing!

I have thought about this, and even tried do a copy of the cockpit that way. It's definitely a thing though. As long as you don't have any deep recesses, which I did on the cockpit (the seats). I was wondering if the Retro Racing RC bodies were done this way.  This was one of the first tests I did lots of years ago, but too many recesses to get a good pull.

Vac-Former-Ver-2_-17.jpg

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20 minutes ago, yogi-bear said:

multipart

I think thats one of the strengths of 3d printed multipart for the application, being able to do good keying and bolt holes for easy alignment.

24 minutes ago, yogi-bear said:

too many recesses

Hmm, i guess having the sheet spreading over something might let it have an easier job of conforming to the shape than if its trying to fill something in.

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On 5 January 2023 at 3:50 AM, yogi-bear said:

cheers, its been a bit of a mission, but something I've wanted to do for quite a while

cheers, thats the video I saw too, its a great idea, and also means you don't have to do multi-part moulds, which also have seam lines.

PETG softens at a lower temp than ABS - 85C compared to about 105C, so the mould should stand up to PETG for quite awhile. Polycarbonate softens higher at 140C, so the ABS mould won't last doing polycarbonate, but I think I could get 5 or so good bodies before it starts to deform. The wall is reasonably thick and the heat isn't in contact for too long, but the surface will start to lose detail I think. I did try a PLA mould for a small light covering, and after 3 goes the mould badly warped, but I only need two. PLA softens around 60C though, which is too low really.

Wow , isn't funny . 3D petg temp 220- 260  degs .

looking great @yogi-bear . So ya still 3D printing much . .  

Not been on tc much  , much like u , gee last update April 24 2021 . You have been busy .

hi all 

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ok, small update. So I have serveral Marui Hunters that need bodies. I have a used body and only need about 3. So for this I am trying a variation of the plaster casting. The body fits into an Ikea plastic tub. I use cheap insulating foam from the hardware store to support the sides and parts of the underneath.

Vac-Forming-Ver-7-1.jpeg

I then add in plasticine to make it watertight. As well as an inner piece so I don't use a lot of plaster. It also makes it easer to drill in vent holes if needed.

Vac-Forming-Ver-7-2.jpeg

all in place awaiting the plaster.

Vac-Forming-Ver-7-3.jpeg

For this I am using standard plaster of Paris, mixed at 100:70 for hardest set. I did rush this a bit and didn't take shake out the bubbles. I think this is part of the reason is crumbled a little when I vac formed it.

Vac-Forming-Ver-7-4.jpeg

 

Vac-Forming-Ver-7-5.jpeg

 

I then let is set and after about 5 hours, pulled out the pieces.

Vac-Forming-Ver-7-6.jpeg

Vac-Forming-Ver-7-7.jpeg

Vac-Forming-Ver-7-8.jpeg

my final step once is had dried a bit was to give it a coat of spray putty. I do this to protect the plaster a little and also it means I can sand it down a little if I need to.

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And now the vac forming attempts. I first tried PETG, about 1 mm I think. Its a little hydroscopic and I think I also heated it too much, so got a bad form and lots of bubbles in the plastic.

Vac-Forming-Ver-7-11.jpeg

next to try was hair cell ABS, it forms really nicely and only takes about 30 seconds to heat up and soften. Hair cell ABS is smooth on one side and has a pattern on the other.

hair cell pattern on the top

Vac-Forming-Ver-7-12.jpeg

and smooth side on the top. Unfortunately the smooth side is perfectly smooth, but it can be sanded.

Vac-Forming-Ver-7-9.jpeg

 

all 3 attempts.

Vac-Forming-Ver-7-16.jpeg

 

and now the downside to using plaster. Maybe the edges are too thin or it hasn't dried properly, but even so, plaster will eventually chip and this did pretty quickly. I think in my case I should have been more careful with the bubbles, I was rushing too much. You can see some in the chip in the wing part.

Vac-Forming-Ver-7-14.jpeg

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I'll remake this mold, but will do it another way. I'll use air drying clay instead. In the meantime I need to sort out a drying cabinet for the polycarbonate and PETG sheets. Luckily I have a paper drying, it's a small heating plate to keep the humidity out of paper. Important for thin paper used in production digital printers.

Vac-Forming-Ver-7-17.jpeg

turn it on and it gets pretty warm.

and I'll put it in this. A mobile cabinet I made ages ago, just need to block out 3 sides and put doors on the other side. I'll leave a small air gap at the top for venting.

Vac-Forming-Ver-7-18.jpeg

The last thing I did today was apply some filler to the truck body mold.

https://vintagerc.com.au/wp-content/uploads/2023/02/Vac-Forming-Ver-7-19.jpeg

 

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Good work mate. I like what you are doing and can certainly appreciate it as I've been vacuum forming styrene for the first time over the last six months or so.

All if that hard work creating moulds for the fraction of a second it takes to suck the plastic down over it :D:lol:...we must be mad. Sooo satisfying when it works though and quite addictive I must say.

Keep up the good work!

Kurt

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ok, some more minor updates. @silvertriple has been 3D modelling the Hunter Prototype body and kindly sent me a file 3D for printing. The body has under hangs on each side, so in order to vac form properly one option is to have the mold in a couple of pieces for easy removable. So this is a test of that. Silvertriple set it up so it's in 5 pieces. Two side pods, a front and back and a connector underneath. As it's only a test, I printing this at a smaller scale to save on filament and in PLA+. I'll only really get one or two goes, but it should show if the concept of the mold pieces works.

 

 

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50 minutes ago, yogi-bear said:

ok, some more minor updates. @silvertriple has been 3D modelling the Hunter Prototype body and kindly sent me a file 3D for printing. The body has under hangs on each side, so in order to vac form properly one option is to have the mold in a couple of pieces for easy removable. So this is a test of that. Silvertriple set it up so it's in 5 pieces. Two side pods, a front and back and a connector underneath. As it's only a test, I printing this at a smaller scale to save on filament and in PLA+. I'll only really get one or two goes, but it should show if the concept of the mold pieces works.

 

 

This looks like a success :-)

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ok, managed to do a second test, this time full scale and printed in eSun ABS+

a couple of errors, but overall not too bad.

Hunter-prototype-vac-form-test-4-1.jpeg

Hunter-prototype-vac-form-test-4-2.jpeg

Hunter-prototype-vac-form-test-4-3.jpeg

Hunter-prototype-vac-form-test-4-5.jpeg

 

I had planned to clean it up a little, but ran out of time and thought just do it! So I ran 5 forms using 1.5 mm hair cell ABS, a little bit of trouble getting the mold out, I need better grip on the underneath, but otherwise no real dramas and the all formed really well.

Hunter-prototype-vac-form-test-3-2.jpeg

 

The 3D printed mold is starting to smooth a little, but otherwise I think I could have kept going for 20 or more forms with out too much trouble.

Hunter-prototype-vac-form-test-3-1.jpeg

 

 

Hunter-prototype-vac-form-test-3-3.jpeg

 

I'll start cutting them out over the weekend and take some better pics.

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