What to Use for Making a "Buck" for Vacuum Forming?

[hooknladderno1]

Hi Gang,

I want to try my hand at replicating an accurate version of this lightbar by vacuum forming:

As the title states, what easily worked material would be best? Any suggestions are greatly appreciated. Thanks!

David

[Deathgoblin]

I see wood used a lot for vac forming. Some balsa or basswood would be easy to carve.

[Misha]

I've had success by making the initial mold out of Milliput, a British two part epoxy putty that is easily formed, smoothed with water and easily carved or sanded after hardening.

[Erik Smith]

You can try Renshape - it is a machinable material - you can sometimes find peices on eBay or go to THIS website and buy a sample kit for $25 (unless you want a 4 by 8 sheet )

The sample kit comes with a bunch of different materials you can try and are small, but large enough for hobby use - a salesman may call you later and see if you want to buy more, just tell him you're just a hobbyist.

[Ace-Garageguy]

You might also consider using wood or styrene as an undersized frame for the general shape, and then add 2-part automotive glazing putty (which is easily sanded to shape and plenty hard enough for a buck) to build up the surface to get the contours exactly right.

Vacuum forming will pick up small surface imperfections from your buck, so if your part going to be formed in a transparent material (red, I assume) you need to get the surface of the buck pretty slick and smooth. Also remember to make it undersized by the thickness of the material you'll be using for the final part.

Edited November 28, 2013 by Ace-Garageguy

[Tom Geiger]

I'm assuming that you want to be able to vacuform the five individual lights. There are three unique shapes, so you'd need to create those as masters. Since they can start with a square or rectangular shape, I'd see if Evergreen has a piece that large (I doubt it) or I'd find some pieces thick enough to laminate to get the height. Then file and sand it down to the shape you need. The corner one will need to be done as two pieces, then joined in the corner.

Otherwise go through your collection of kit lights and see if there are any the right size / shape that could be modified to work.

I have an old Mattel Vacuform machine, and there is a place, Callori Modelworks that makes the sheets, complete with the little holes around the perimeter. That's what I use to make clear windshields, should work for your lights as well.

[Kennyboy]

For two part epoxy putty, I use Apoxie Sculpt.......it is available at aves.com. Mold makers use it all the time.....I heard about it from a guy in a modeling club and also from Jimmy Flintstone (he uses it on his molds.) This stuff is amazing because you can shape it just like clay (with water.) 3 hours of working time then it hardens like a rock fully after 24 hours. The 1 lb kit (more than enough for over 10 models!) costs about $25.00. You can also get it on ebay.

[LDO]

If you want to try RenShape, let me know. I have some scraps. I could send you a little...but just a little. I'm stingy. :-)

Also- a way to avoid having to smooth out a somewhat porous material is to make your buck just a little bit more undersize, then vacuum some .010" or .015" over it, then polish up the plastic copy. A lot easier than getting a glass-smooth finish on putty or RenShape.

Edited December 2, 2013 by LDO

[Chariots of Fire]

If you want to try RenShape, let me know. I have some scraps. I could send you a little...but just a little. I'm stingy. :-)

 

Also- a way to avoid having to smooth out a somewhat porous material is to make your buck just a little bit more undersize, then vacuum some .010" or .015" over it, then polish up the plastic copy. A lot easier than getting a glass-smooth finish on putty or RenShape.

Lee:  Have you had experience with vacuum forming the 0.010 stock over the buck?  If you form plastic over it will the 0.010 stock bubble or buckle with the addition of the heated plastic over it?  I just bought a new VF machine and am experimenting with the best way to do this.

 

[LDO]

When I tried that, I was stretch-forming; just heating up the plastic, holding it with leather gloves, and stretching it over a canopy master. There were no problems, but I think it would be a good idea to use thicker plastic, like .020" or .030".

[LDO]

Something else I have heard of but have not tried: carving a master from Corian or similar solid-surface counterop material. I heard about a guy using a CNC mill to make a multi piece buck for a '50s Maserati race car, then vacuum forming over those bucks. You may not have a CNC, but good old power tools and files work just fine.

 You can find it on Craigslist. I have become somewhat of a Corian hoarder. I just can't get enough of it. I probably have 3 kitchens worth.