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yogi-bear

Home Made Vac Former - Forming RC bodies

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For at least the last 15 years I have wanted a vac former. Years ago a friend had one, which he built himself and was pretty cool. It had the heating elements at the top, with a lever that would bring the plastic down onto the buck for forming. He use to vac form 2 mm PETG for me, and the suction was pretty industrial. Now I'm into RC cars and I want to finally have a go at making my own RC bodies. My first choice is the Volvo 850 Estate that I am working on (temporarily on hold until I build my new CNC machine). For this build log I will also be re-making some vintage car bodies that I need.

For my first version of a vac former I will be building something much simpler, and easy enough that anyone can make it. I will be honest and all my ideas came from searching the internet :) My goal for this is to be able to vac form the Volvo body I am making as well as re-making some vintage bodies that I need, but don't want to pay a small fortune obtaining. Plus is fun to make your own!

As I am going to make the Volvo body in two pieces, I don't need to make this vac former too wide. I also used as many scrap pieces as I could find and the total build cost was around $100 AUD, needing no electrical skills and only a modest amount of tools.

My first consideration was how to heat the plastic. Temperatures needed range from around 150C to 250C depending on the plastic you want to form. I intend on trying polycarbonate, styrene and maybe ABS and acrylic.

OK, here is the first warning, you see many people using their cooking oven to do this, but I wouldn't recommend doing that. The plastic sheets when heated will give of contaminates, polluting the oven. I also didn't want to wire up my own just yet as I am not an electrician. So to make it simple I bought new a small portable oven.

I settled on a new one from Kmart, costing me $69 AUD. You could save money by trying to get one second hand. The only drawback is this will give me a maximum length of around 350 mm and a maximum width of around 270 mm, which is not enough to do a full car body. The width can be increased slightly by placing the sheet inside the oven on an angle (something that I will try). You can also get wider ovens, but they are twice the price. The Volvo body is just over 400 mm long and it will be joined along the base of the windscreen, so this will be big enough for my needs. I need to do it this way as I want to have good detail on both ends with under hangs, meaning I can't vac form easily in one piece anyway.

Vac-Former-Ver-1_-0c.jpg

ok, my next post will be on making the frame to hold the plastic in the oven.

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A promising start.

Looking forward to see how you go about building it, for tips! :)

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The next step is the frame.

I ended using 12 x 12 mm aluminium angle I bought from a aluminium supplier. 6.4 metres cost me about $14 (I had them cut it up into 4 pieces to fit into my car :) ). Combine this with some right angle brackets (another $5) and some metal clips (I found these) and thats the frame. I also bought a box of screws and nuts (noticed the chamfer on the screws, very important!) from a nut and bolt supplier, which for about 60 units cost another $12 total. And that was all I bought apart from the material to vac form for this project, the rest I had laying around the workshop.

Vac-Former-Ver-1_-0a.jpg
I measured the oven and mitred the corners, using the right angle brackets to hold it together.
Vac-Former-Ver-1_-7.jpg
Make sure to chamfer in the holes so the screws sit flush, as this is the surface the plastic sheet goes onto. I used a mitre box to get the 45 degree angle cuts. Still they weren't very accurate. I also used a file to clean up the edges and help make the corners fit.
Vac-Former-Ver-1_-4.jpg
The final frame. You will need two of these, for a top and bottom. I did have to cut down the screws on the shorter sides to allow it to fit properly into the oven.
Vac-Former-Ver-1_-6.jpg
Here is the frame with some polycarb mounted inside the oven.

Vac-Former-Ver-1_-22.jpg

the next step is to make the vac former itself. That's even easier than the frame, but a lot more tedious. Be prepared for some very boring drilling :wacko:

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ok, the next part for this vac former is to make the base. While this is easy, its also the most tedious. Basically the base is just a box with holes. I opted to go for 1 mm holes, 10 mm apart, which meant drilling 775 holes :blink:

For the base I used a piece of laminated chipboard I had, something reasonably thick and heavy. The sides were just pieces of pine, I had 10 mm wide pieces which where just high enough. Vacuum came from an old Dyson DC05, and I opted to use the thin nozzle that it come with, as this reduced the height of the bed. I worked on the theory that if there is less space, vacuum should be better.
Size wise I made it just a few mm smaller than the frames I had made, that way I can pull it over the base. Pieces where glued with wood glue and nailed together, so nothing special there. The hole for the nozzle I drilled along the edge with a 2 mm drill bit and knocked out the piece with a chisel, and then filed the edges smooth until the vacuum cleaner nozzle would fit. I did not get a perfect fit, but it was close enough.
Vac-Former-Ver-1_-12.jpg
For the lid you can use anything firm. Years ago a friend use to use plywood, MDF will also work. I ended up using aluminium composite panel as its lightweight and very stiff. I used that as I had some lying around and its very easy to cut. As you can see it was just stapled to the frame.
I drew up a grid and hand drilled them all!
Vac-Former-Ver-1_-15.jpg
Some time later! Holes drilled (I didn't try and do them too perfectly as in the end it doesn't matter :D ) and I used double sided tape all around the base to mount the frame to a base board.
Vac-Former-Ver-1_-18.jpg
A test fit with the frame over the top.
Vac-Former-Ver-1_-20.jpg
In the next post I will not only show how this pretty rough and simple vac former performs, but also talk about vac forming different materials, including PETG, Polycarbonate, acrylic and polystyrene as well as talking about the various properties of each. Of particular interest is the PETG bodies that Retro Racing made, as I want a poly carb version to bash around with, and it will be one of the items I demonstrate vac forming with.
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Looking forward to where this will be going.

Think the part of making the bucks is the main job.

About all those holes, shouldnt they be in the buck?

This is a nice readup on Polycarb. and one for wrinkles

How to cut, bend, heat etc.

Thanks for the links waterbok, they are very informative. The holes in the platform are needed to help suck down the air. Holes in the buck are only needed where detail is getting lost. I'll be able to show this on some examples I have done. That link on wrinkles will come in handy for one of the bodies I want to re-create.

And yes, the hard part is making the buck. I can think of 3 options,

1. home made buck out of wood, clay etc,

2. copying something in some form or

3. machining a buck from a 3D file.

I'll be mainly doing the last two. My Volvo build is an attempt to start machining bodies but requires some sort of cnc machine. I also want to copy some vintage bodies that I have, but can't easily get. I'll be remaking an Audi Quattro body that I ruined, plus some road wizard bodies. My first example will be re-making a Retro Racing Mk 1 Escort body in polycarbonate.

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So now I am ready to vac form something. I had originally bought some 1 mm polycarbonate as that was the easiest to get at the time. However that turned out to be too thick and I can't form it properly at the moment. Either I am not heating it enough, or I don't have enough sucking power. I'll be able get some 0.25 mm or 0.5 mm polycarb in the next week or two.

So in the mean time I will practice with 0.5 mm polystyrene. My first test was molding covers for NiCad batteries. I use to have a tamiya branded polycarbonate one in the 80s and it protected the battery quite well when exposed in my Fox.

So I heat the plastic in the oven at around 150C for 4 mins or so (until the plastic starts to sag). Turn on the vacuum cleaner and place the hot plastic over the buck. The suction part takes a matter of seconds (I'll do a video hopefully this weekend).

Vac-Former-Ver-1_-32.jpg

Ok, so that test worked, lets try something a bit better. Trini2DBone had sent me a Retro Racing Mk 1 Escort body set. When I started reading up on these, it turned out they were made from PETG. PETG is actually quite strong and is used in a lot of packaging because its cheap and it can form details very well. However, unlike polycarbonate, its not as elastic and so can shatter, and hence its not good for cars that get a lot of action. So time to re-make one in polycarbonate.

The first step is to make a plaster of paris copy. I rushed the pour on this and make the mistake of pouring it in layers. This means there are air bubbles and some of the plaster was a little weak. However I can still test it.

Ford-Escort-plaster-test-1.jpg

and now to vac form.

Vac-Former-Ver-1_-35.jpg

Vac-Former-Ver-1_-36.jpg

you can see some of the detail has been lost in the front area. Here I will drill some holes to the base to help with suction.

Also there are folds at the front base, which I will have to work out how to avoid. Waterbok's link has some good info that I will try.

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PETG is fine , BUT you can not use Tamiya PS paint on it , AS this is what make's it shatter . You have to use water base paint .

Big learning curve for alot of people , as we all didn't know @ the time ! :( ..... .

This is great stuff yogi-bear , Fantastic thread . Thanks .

Sorry , if i new you wanted a MK 1 Escort i have some . same as above , i also have MK1 cortina & MK2 Escort .

But only one of each ( cortina / escort mk2 ) .

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For this and all other forming from moulds plasticine is a godsend. It sticks enough to fill gaps and can be smoothed out to a near blemish free surface. I have used it to good effect building parts for boats.

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PETG is fine , BUT you can not use Tamiya PS paint on it , AS this is what make's it shatter . You have to use water base paint .

Big learning curve for alot of people , as we all didn't know @ the time ! :( ..... .

This is great stuff yogi-bear , Fantastic thread . Thanks .

Sorry , if i new you wanted a MK 1 Escort i have some . same as above , i also have MK1 cortina & MK2 Escort .

But only one of each ( cortina / escort mk2 ) .

Yeah, the paints are an issue, something I want to talk about later on. Its unfortunate there was not enough info at the time Retro Racing brought out their car bodies, as I think apart from the choice of material, they did a fantastic job.

Hmm, you have a Cortina, and I see you are in Perth, I will PM you, maybe we can work something out.

For this and all other forming from moulds plasticine is a godsend. It sticks enough to fill gaps and can be smoothed out to a near blemish free surface. I have used it to good effect building parts for boats.

go to know!

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Ford-Escort-plaster-test-1.jpg

That's come out really well.

What have you used as a release agent?

I tried vasiline and various oils,olive,rapeseed,semi synthetic!

Got the best results with vegetable.(cheapest too :) )

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That's come out really well.

What have you used as a release agent?

I tried vasiline and various oils,olive,rapeseed,semi synthetic!

Got the best results with vegetable.(cheapest too :) )

doh, I forgot to mention the release agents. For the plaster casting, I just used talc powder, just a very light sprinkle and brushed off the excess.

For vac forming I found I didn't need to use anything.

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I thought talc would just all fall to the bottom.

I'll give it a try! :)

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Very impressive results.

At school (20+years ago) we had a small vac forming machine for making project boxes etc. Made a few scratch build RC bodies out of clay and vac formed them with good results for various cars.

Also made a few spare shells by filling old shells with plaster of Paris and casting them.

It was great fun and normally used coloured sheet to save time painting them.

Great project write up, looking forward to seeing how the 850 shell comes out.

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Very impressive results.

At school (20+years ago) we had a small vac forming machine for making project boxes etc. Made a few scratch build RC bodies out of clay and vac formed them with good results for various cars.

Also made a few spare shells by filling old shells with plaster of Paris and casting them.

It was great fun and normally used coloured sheet to save time painting them.

Great project write up, looking forward to seeing how the 850 shell comes out.

cheers mrmoots,

I like the idea of different colour plastic for forming.

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the Escort front end I plaster cast has two problems. Basically I mixed the plaster too fast, and didn't make enough, and ended up pouring it in layers. Layers is fine when done properly, but not done properly it can weaken the plaster. Also mixing too quickly and not taking care will introduce bubbles, of which I had a lot of!

So I decided to practice on something smaller to see if I could improve my plaster making skills. The other thing I needed to try is giving the body more support, so there is no movement and distortion. I had tried to plaster cast a damaged Audi Quattro body earlier and found that the shell moved quite a lot with the weight of the plaster. Looking into options I ended up making a basic version of greensand. Using bentonite clay (ground up kitty litter clay), river sand and water, you can make a semi-sticky sand for metal casting.

Here is the setup, using a rally cockpit

Vac-Former-Ver-1_-44.jpg

formed, dried (the seat tops gave me lots of issues and broke off). I got a lot less bubble this time and the consistency of the pour was a lot better.

Vac-Former-Ver-1_-37.jpg

This was going to be interesting to vac form with all those deep areas. I didn't expect it to be perfect!

Vac-Former-Ver-1_-38.jpg

and a side by side comparison. Left is the original, middle it the plaster cast and right is my vac form attempt. There is a fair bit of detail loss. So I might re-do this, casting it in reverse, drilling holes in the deeper recesses. However for a basher it'll be fine.

Vac-Former-Ver-1_-40.jpg

I'm also doing tests to remove the wrinkles with vac forming the front. I'm almost there and will post once I've sorted that out. One thing I have learned is that I can't adequately can form 1 mm polycarbonate, I just don't have enough sucking power. However 1 mm is overkill for an RC body.

Polycarb also has a narrow temperature range between is Glass Transition temp and its melting temp, about 9C difference. To form properly, the plastic has to be above its glass transition temp, for polycarb that is 145C, but it melts at 155C :unsure: So another problem I have is that I might be over heating the polycarb I am testing on as its forming bubbles on the surface. Pic below is the best I've been about to do with 1 mm polycarb. Tomorrow the plastic supplier I use should have re-opened (here in Australia pretty much all suppliers shut for at least two weeks over christmas), then I can order some 0.5 mm sheets.

Vac-Former-Ver-1_-48.jpg

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Excellent!

Being to think my,all in one,vac former plans are a bit overkill lol.

I've always had trouble with the initial molds,bits snapping off etc,and air bubbles.

How do you get rid of them?,or is the key to not have any in the first place?!?

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Excellent!

Being to think my,all in one,vac former plans are a bit overkill lol.

I've always had trouble with the initial molds,bits snapping off etc,and air bubbles.

How do you get rid of them?,or is the key to not have any in the first place?!?

Plaster should be workable, but I am finding that difficult, so ideally you form it without bubbles in the first place, so this is what I am aiming towards - molds that require little work once formed. There are lots of techniques for getting a good mold though, from how you stir the plaster mix, pouring techniques and even using a vacuum to draw out bubbles.

I myself do like the all in one vac formers, but they take longer to build. At some stage I intend on making a version that is bigger, with the heating element at the top and a sliding mechanism to bring down the plastic sheet onto the vac former. This is what a friend of my use to have, but the build is a lot more complicated.

I'm really happy with what I have made, as its simple to use, and cheap to make. However alignment of the frame onto the buck is a little hit and miss, and more sucking power would be good for thicker plastics.

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Plaster should be workable, but I am finding that difficult, so ideally you form it without bubbles in the first place, so this is what I am aiming towards - molds that require little work once formed. There are lots of techniques for getting a good mold though, from how you stir the plaster mix, pouring techniques and even using a vacuum to draw out bubbles.

Last time I made molds it was more a guesstimate as to the mix,next time around I need to take notes.Saying that I still have some,and they've move house with me 3 times and still intact!

I myself do like the all in one vac formers, but they take longer to build. At some stage I intend on making a version that is bigger, with the heating element at the top and a sliding mechanism to bring down the plastic sheet onto the vac former. This is what a friend of my use to have, but the build is a lot more complicated.

My plan was to have the heater on casters,the plastic sheet clamped and the mold raised from underneath with pneumatic cylinders.

Also thought to have micro switches trigger the vacuum pump as the cylinders reached a certain point,and to have everything triggered of one button,but, that really does start to overcomplicate things! lol

I'm really happy with what I have made

You should be!

You're getting good results and actually doing it!

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cheers Wooders, I've been keeping a record of how I mix things so I can repeat easily and a journal of things of what I want to try out.

I had to work out how to avoid wrinkles on the parts of the body I need to keep and finally today I worked that out. Just careful placement of some objects to help draw the plastic away from the right areas.
Vac-Former-Ver-1_-49.jpg
Vac-Former-Ver-1_-50.jpg
Vac-Former-Ver-1_-51.jpg
and these are all the test samples I made.
Vac-Former-Ver-1_-52.jpg
next step is to get some 0.5 mm polycarbonate and to make a new plaster casts of the Escort and I should be ready to make a copy for a runner. I've got a TA02 chassis to mount it to, just have to choose a paint scheme.
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only a minor update. My quest for some 0.5 mm polycarb has been fruitless. The one supplier that stocks it isn't fully open after the christmas shutdown yet, so I am hoping next week will be better. Still I did manage to get some black 1 mm ABS plastic to try, which gave average results. It shrinks a fair bit when heated (although seems to shrink back a little after awhile), so I needed to add more clamps to the frame. Still this would be good to make parts like the bonnet if I want to have an opening version. I'm thinking also if I made a mold of a chassis or floor plan that the ABS would work very well.

Vac-Former-Ver-1_-53.jpg

Still, I couldn't get the front to vac form very well.

Vac-Former-Ver-1_-54.jpg

If I want to vac form thicker materials I am definitely going to have to improve on the design. Obviously more vacuum power is needed, but I think I will also need to warm the buck to stop the plastic cooling too quickly.

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Really interesting progress, especially the placing of objects to stop the wrinkles. Keep the updates coming!

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If you find the plastic/poly hardening too quickly, get a heat gun and reheat areas during the vacuum stage. You may find you need to manually press/shape areas during the vf process as well to get the full detail/reduce creasing.

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Really interesting progress, especially the placing of objects to stop the wrinkles. Keep the updates coming!

cheers, will try to update as much as I can!

If you find the plastic/poly hardening too quickly, get a heat gun and reheat areas during the vacuum stage. You may find you need to manually press/shape areas during the vf process as well to get the full detail/reduce creasing.

cheers, that is a good idea and I did try it once. I didn't find it useful, but that might be because my heat gun wasn't very good and I think I need more vacuum power for some of the plastics I want to try. I a thinking a cheap one from eBay, which should give me at least 4 times more sucking power. I also want to try heating the buck first, which should keep the plastic softer for longer. Using a heat gun should also be for effective too.

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