HugoW

I do that to dry the Lexan. I have no good storage, so when I use the Lexan little bubbles appear after the pull. Gas bubbles, steam inside the plate. When I keep the plates for a certain time I presume just above boiling point, the water exits the Lexan. I might try to dewater and let it cool down first, before I do the next attempt. I now go from de-vapour temperature straight to forming temperature.

Hmmm, although that seems logical, I don’t like it. I made my own design F1 body and would like to produce a series of 10 or 20. If they all need heat gun work after cutting them out, it is not workable. I am considering to place the product in an oven for a certain amount of time just below forming temperature, to release the stress from the material. Just like it is done with cast steel and alloys.

Thanks. It is actually a lot of scrap wood, the inside of the heater box is covered with aluminium tape. It has two table-top grill heating elements parallel. I bought a 3,8kW controller for US$ 7 from e-bay, and a voltage / amp gauge from that source. I am still looking for an el-cheapo temp gauge that will go up to 250 degree C. I am working on a new vacuum table, this one is a box with large volume which takes more effort to suck empty. The new table will have a lot less own volume, and I need a better vacuum source.

Also I am looking for a resin type casting mould material. I now use plaster, which is very brittle and the gets chipped easily. I also tried a 2K variant called Acrylic One, it seems a bit better but not yet what I would like.

I’ve never done wings, I’m pretty new to this game. I’m bit far away from you to give you a hand… I copied a few Tamiya bodies to start learning the casting and vacuum pulling process. The F1 is my own design based on a Sauber F1 of 1993, and it fits my F103 with a shorty LiPo. Here’s a few pics and a link to my F103 project bucket if you want more:

the incubus

iTrader: (17)

That's pretty nice. Sauber is my little darling F1 team.

BTW, I had that same rug, actually 3 of them when my kids were small and when they outgrew playing on them I lined my garage floor with them. Versatility from RC guys… who'd've thought?!?!?!? LOL


As for my wing, they're pretty easy to copy and with my design being so simplistic it would be easily copied by someone and I'd rather not post. However, a couple years ago when I was running the a B4.2, I was frustrated that the only nice bodies you could get for it were cab forward and while I didn't want to go back to rear cab bodies, I knew there was a happy medium. So, I designed my own body that I never got into production because my buddy who is a 3D animator and modeler slacked on me and never made it a point to sit with me to bang it out.

Anyhow here is the lid.

First up is the initial design phase for the profile of the lid itself. Starting from top to bottom, each one features slight changes from the one above, making it's way down to the last and final one.


Here is the final profile enlarged


And here is the front view with the sides



This took me several hours to create manually in Illustrator. There is a bit of trial and error with shapes and profiles and mating them together in a way that flows properly. Had my buddy created the rendering I'd have sent it out for a 3D print to test fit to the car and if all was perfect I'd have opted for a machined master cut from a hard delrin I used to make paintball bolts out of.

Lunchie

once you have done the initial pull and it's still on the mold use a heat gun to go around the sides to get rid of any stress in the lexan

Lunchie

from watching your video i think the main problem is that you are heating from the top only. the underside wont be hot enough compared to the top. the top side ends up being the outside surface so contracts more because it was hotter. redesign your rig so it heats from the underside of the lexan.

HugoW

Thanks. I had a heater that heats from below, but the sagging plastic reaches the heating element with undesired effects. Do you mean heat from below as well as from the top? Do you have any design suggestions?

I will definately try to stress relieve the next pull with a heat gun, thanks.

Hugo

Lunchie

Im certainly no expert but Comparing your video to others it seems like you are getting enough (too much??) Sag. Many of the vids I've seen the lexan was either in an oven or heated from underneath with foil on top to trap the heat above for more even heat absorbtion.

HugoW

I think I will experiment with a heating-from-below rig. Now the plastic moves away from the heat when is sags, heating from below will get it closer to the heat source, that might be better.

I found this clip:

+ YouTube Video

Seems a pretty good way of doing it.

Hugo

snoopyrc

iTrader: (2)

I think heating from below will make no difference. If you have even heat and good vacuum it should be fine. I would look at a tank and vacuum pump set up for the bottom of your rig. Reduce the amount of sag before you pull. I might shave that base down a little so the draw depth is not so far.

Honestly I think your shell looks pretty good.

HugoW

Thanks for your reply. I will try heating from below to see if it makes a difference. I think in the current set-up the lexan moves away from the heat, heating from below will reverse that.

My new vacuumtable will have hardly any internal volume, and I have my eye on an old vacuum cleaner which I can take apart. I want to fit the pump directly to the table, again reducing volume and resistance. I hope to get it working without tanks and plumbing.

I am also experimenting with making moulds directly from MDF. My current models are made from balsa, contra mould from silicone, and final mould cast from resin or plaster. Here's my first attempt under way, a simple F1:



So far it goed fairly quick and well, but detailing seems more difficult.

Hugo

firefoxussr

iTrader: (5)

I'm going to try this for a couple of out-of-production Tamiya shells I have. Tried to make a buck of my last 911 GT1 shell but had a horrible time getting the old shell to release (it has many under cuts / details on front and back). Clearly two piece buck is the way to go.

snoopyrc

iTrader: (2)

This video above is the only thing I have ever seen posted where someone at home is using a two piece plug. I think reproducing the plug is probably a challenge. The shell he makes looks great in the pictures. I wonder how it looks up close.

hyper-driver

iTrader: (4)

any one still doing this? if so, anyone want to pull me a few? i have a plug that ive been working on and was hoping someone would pull it for me. it a body for 1:8 hyper 9e. the bodies they made for that car are hard to come by, and they never really fit well. i was hoping some one would pull some bodies and chassis trays for me. ill just ship you the plugs i have made and pay you.

Lunchie

What's the best way to repair small imperfections in plaster of paris molds? I made some copies of bodies but there's just a couple of places that need a touch up.

firefoxussr

iTrader: (5)

I'm going to find out!

Here's the mold making video:
https://www.youtube.com/watch?v=AXaafKOQ7Uw

Lunchie

What temperatures are you guys using?
Specifically the pre drying temp and time.