Making clear knobs with molds

[Lezam]

Working with the excellent tutorial on making your own knobs here:

http://personales.ya.com/micabina737...es/moldesi.htm

Does anyone know of an easy alternative to their mold that will make clear knobs, which will then be coated with paint? Something like simknobs did?

[Mike.Powell]

The book The Prop Builder's Molding & Casting Handbook by Thurston James covers several approaches to molding and casting. The silicon rubber mold is one of the best because of its accuracy and because it can be reused. There are less expensive approaches, but I don't think they would be any easier.

[Lezam]

I'm just looking for a material to substitute his "Cronodur A + B" that will produce clear knobs to be used with backlighting.

[Mike.Powell]

Tap Plastics carries various materials. http://www.tapplastics.com/shop/category.php?bid=33&

Also check Ebay using "casting resins" as search terms.

[Lezam]

Thanks Mike! Just what I needed

[phil744]

I use a 2 pak product called DR006 made by Atlas polymers here in the UK with stunning results. even down to having metal inserts encapsulated !!

But its never simple, I have to spin each knob in a lathe to get the bottom flat and have to apply 4 different layers of paint to get them right.

When producing a mould from RTV silicone remember to read the datasheet carefully, the stuff i use needs 7 days to cure, if you cast before the silicone has cured you get a nasty reaction between the two, also keep in mind the shrink ratio of whatever resin you use.

But here are some ive done before

[Mike.Powell]

Very nice work!

[Matt Olieman]

Excellent job Phil. I've made clear knobs but, NEVER, got results like yours. Fantastic!!!!

[Lezam]

Thats amazing work Phil! I have a couple of questions for you:

Where do you get your original knobs, they look extremely realistic.
What kind of paint do you recommend for the knobs, so they get a textured feel?

[phil744]

OK,

Basically all Knobs I produce have been master casted from an original part, with the exception of the boeing IRS knob that i have turned down with a lathe, I have spent many months aquiring them.

I use 4 layers of 2pak acrylic, first coat is white with 30% 2K clear coat mix (this produces a bright wight that light will shine through) then a standard matt black (to avoid light bleed through) then a coat of 2K beige (actually a Lada colour, perfect match!!) finished with a satin lacquer (not really needed but gives a dull finish that wont wear for quite some time). the paint itself is the same stuff you use on your car