Art & Inspiration Casting with resin questions

Ok, guys. I've done a search, but still have questions. I'm thinking of the built not bought approach with dash knobs. I have a few that I like the shape of, I just wanna make a mold of them and cast. If I'm using hobby shop clear resin, do I just add paint to color it? Or do I need to use dye? I also might dump in some glitter or metalflake or pearl powder to get the look I'm after. I just thought I'd ask what everyone here has done. Hope I'm not flogging a dead horse! Thanks!


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This would make a nice tech thread. Hope someone shares here.

 

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This is something I'd like to do also.

Looked on the 'net yesterday and found this company that seems to offer quite a few materials for casting.

Might be there, just didn't see the mixing ratios right off


http://www.eplastics.com/Resin

 

I've seen the dull black plastic casting kit that Eastwood sells, but I'm interested in how to get the clear glitter stuff to turn out good also.

 

I used to do some resin casting years ago for the model car crowd. You tint the resin with dye, not paint. A big part of it is how you make the mold so it will release the part without damaging the mold. The HO slot car crowd does a lot of resin casting as well.

One of the best, if not the best, suppliers is Alumilite, http://www.alumilite.com/ they have the silcone, resins, dyes etc...

Go for it and post pics!

 

these are the guys I use , http://alumilite.com/index.cfm

good stuff ( was Dow repack ) plus the staff is knowledgable . they have it all from the moulding material to the resins and dyes

 

Dude, JoAnn Fabrics and Michael's craft supplies sells everything you need. Not sure if you have these stores by you? They are just craft and fabric stores, like for old ladies to buy their scrap booking stuff. Art supply stores would also have the stuff needed.

And yes, you need to add dye. Oh, they also sell the release agent you'll need.
There are good how to videos on YouTube as well.

POST PICTS!!!!

 

we used to resin-cast plastic knick-knacks back in the 60's.

I never did a successful cast without ugly bubbles in it though.

I wanted to try it with a centrifuge or with vacuum de-gassing, but never did.

 

I use the pressure pot method and have had good results , you use a HF paint pressure pot ,

as for the Vac degasser , have to find a suitable cylinder to use , using a old fridge compressor as the vacuum source .

 

If you want to go old school... get some plexiglass sheet, some colored transparent some white, and laminate in layers. Use this material to make your knobs by turning it on a lathe, then polishing. Bob Hirohata made the dash knobs this way for his iconic Merc. He made sets for other Barris custom cars as well. This was in the early fifties.

http://www.jalopyjournal.com/?p=3904

 

I work with resin (epoxy and polyester) making surfboards and have done a little bit of casting too. Like Ulu says, the way to get zero bubbles is to use a vacuum pump and chamber to suck the bubbles out of your mixed resin before you pour it into the mold. Wood working supply places have them- used for laminating -"vacuum bagging" etc. They can also be rigged up from scrounged parts from old refrigerators. Boat builders are great info sources for that project. When it comes to the chamber though, be safe. Think IMPLOSION... use very stout materials.
But there are ways to minimize bubbles without a vacuum pump. The main thing is your technique in mixing the two parts together. For small batches use a narrow coffee stirrer stick. Don't go nuts whipping it around. Just go in nice, smooth circles, keeping the stick submerged the whole time. Switch directions a couple times.. It gets boring.
Now, wait for the bubbles to rise to the surface before pouring. You can help them to the edges with your little mixing stick. Some people might vibrate the cup with a DA sander or tap on the sides. The runnier the liquid, the faster the bubbles will rise. Warm it up. A "double boiler" really helps. Dip your cup of part A and part B in hot water before mixing. Higher temp=faster curing, so keep that in mind. Good luck, I've got a few other thoughts on this but need to get out to the shop and finish some surfboards! I will check in later.

 

Bitchin' info JJ. I own several vacuum-bagged skateboards, and it really works. I have a setup to vacuum A/C, which might work.

I just always thought a centrifuge would be easier to make and do the same thing: but I've never tried it.

 

I would stay away from any polyester or acrylic resins, they stink and turn cloudy over time.
I have used a 6" diameter (1/4 wall thickness) plexiglass tube about a foot long with a 1/4" thick plex sheet glued to one end for a vacuum chamber. I could pull 27 inches of vacuum without a problem, with a refrigerator compressor.
I have never tried casting glitter in clear/tinted resin, but my best guess is that you have to find a flake that weighs the same as the resin so the flake doesn't settle out or float to the top. Another way (more complicated) is a very quick setting 2 part resin that is mixed with a mixing nozzle like some of the fancier glues you can buy. The flake would have to be pre-mixed in one part of the resin.

 

I don't know if this would apply but the people that do epoxy resin tabletops use a heat gun and or a propane torch to get rid of bubbles.

https://www.youtube.com/watch?v=CsVLhk55pWM&feature=youtube_gdata_player

 

I already have some of those laminated striped ones like The Hirohata Merc has, I just want something different. Metalflake or pearl maybe? I know Ms. Metal used to make knobs but she's kinda disappeared! Yeah, I've got both a Michaels and Joann's close by. Used to work at both! I'll just have to give it a try and let y'all know what happens! Thanks!


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Can a Hurst shifter knob be recreated using this method? it has 2 colors.

This is what I'd like to make if possible.

 

If you have a master/original that you want to copy, RTV molds work great.
I fool around at home casting model parts in metal using two-part RTV molds. I get that kit from MicroMark. They'll last a while, though not as high quality as Alumilite.

Another thing to help with bubbles if you don't have a vacuum chamber, when you pour the resin, pour from up high in a very thin stream. This causes the bubbles in the stream to pop on their way down.

 

Make a silicone mold around the shape you like then tint up some resin. I do it when i make these types of lenses..

 

Those bumperette lights look great!

I did some molding with silicone molds back in the late 60's. Worked great and nice surface finish.

Still had lots of bubbles though.

Gee, now I wanna try the centrifuge thing.

 

Matt, I have admired your lenses for some time now - beautiful work by-the-way! Can you tell us how you deal with potential bubbles?

Thanks,
Dave

 

when i make them i try and form the molds so the air bubbles all float to the top or backside, it can be tricky... I also will pour the resin through a strainer and pour in a thin stream like was mentioned before on page 1.

 

Wouldn't a centrifuge cause all the bubbles to migrate to the rotational center of the mold? The resin, being heavier than the air bubbles, would be more subject to centrifugal forces and tend to push the bubbles to the center. Probably not a bad thing for knobs and such, but might really screw up an irregular shaped piece.
Stir a glass of water quickly and you'll get an idea of how the air is forced to the center.

 

I saw a guy mist acetone on his mold and that got rid of all the bubbles.

 

You set it up off-center, with a sprue, so the bubbles go up a sprue, then just nip it off.

 

Wow! That's cool. Was he casting epoxy, acrylic, polyester??

 

https://www.youtube.com/watch?v=-5uSTYNURJ0&feature=youtube_gdata_player

 

https://www.youtube.com/watch?v=2PKn-59pHNM&feature=youtube_gdata_player

 

I found this also:

"With unfilled epoxies, the centrifuge should be run from 1,000 to 3,000 RPM for 3 minutes. This will remove all minute bubbles suspended within the epoxy . . .Filled epoxies can also be degassed this way as well but special care needs to be taken to ensure that the filler does not separate out of the epoxy. Generally, the speed should be kept at a maximum of 1,000 RPM for 3 minutes. This will remove the bubbles but not drag the filler out of the resin."

 

You could make the Hurst shifter knob using the laminating method and acrylic sheet. Use the proper glue (it's runny as water), leave clamped overnight and finish as mentioned.