DIY resin casting.

[Hamfist]

Anyone have any experience with resin casting/mold making?  I was thinking it could come in handy for making custom knobs.  Clear chicken heads... white MXR style etc...

I've looked at several tutorials around the web.  Just wondering if anyone has tried it and succeeded... or failed miserably. 

[R.G.]

Starting long ago, and many times. In fact, I've posted the advice for doing this several times here over the years.

There's an easier way, though. Go to a hobby store and get some Sculpy or Fimo brand polymer clays. These are hand-moldable clays that set up hard permanently when baked to 270F. They come in many colors and are used for craftsy stuff like plastic jewelry, toys, etc.

Plumber's epoxy putty and some stuff I think was called "Lab Metal" does much the same thing, I think.

If you must make stuff with casting resin, remember a few pointers:
- Polyester resin is the cheaper and more available.
- Epoxy resin is more costly and durable when cast.
- The stuff releases heat as it sets. The heat has to get out. If you pour too thickly, the inside will cure faster than the outside and the released heat will crack the casting. About 1/4" is good unless you're an expert.
- Use mold release...
- You can get casting colorants at marine stored for coloring fiberglass; likewise glass microbeads and silica for filling the resin into a putty. I think aluminum or bronze powder at paint supplies places.
- Polyester and to some extent epoxy will not set completely non-sticky in air; oxygen poisons the reaction and you have a permanently partially cured sticky surface. Get some Polyvinyl Alcohol to pour over the top of the mold as it sets to keep oxygen away. That gives you the hard surface upon cure. Saran wrap will do the same, but is harder to work with.

Micro Mark sells silicone rubber molding stuff suitable for making the molds.

Put a LOT of effort into getting the molds right.

[frank_p]

Check this company.  They make materials for different kinds of moldings.   In the past they used to make some technical booklets on the technique of molding in different sectors: arts, fast prototyping, foundry, etc...

http://www.polytek.com/

You will have to work with themosets polymers because other kind of polymers are very costly on the tooling necessities.

They have some documentation online.  Don't know if they still have their "how to" instructions...

Anyway, it is probably worth a look.

[SteveB]

I make lots of model car parts using silicon molds & polyurethane resin. A while back I thought about making knobs, but never followed through on it. The biggest problem I see with casting knobs is allowing for the set screw. I could have tried drilling & tapping the threads after the knob was cast, then I guess it would be okay, but a little too labor intensive for me.

I don't use mold release, & haven't had problems with any parts sticking to the molds. The smoother & cleaner the master is, the better the copies will be. You can also spray clear lacquer on the molds to act as a mold release.
This is where I get my supplies from.
http://www.polytek.com/

Steve

[R.G.]

I had problems with the shaft hole and set screw too. I found the simplest thing to do was to sacrifice an ugly knob that had a brass insert and setscrew, and to cast the knob around it. You can put a rod of wax or a toothpick or something similar to leave an indicator for where to drill the access hole for the setscrew and to keep the resin out of the setscrew.

[DougH]

Have you guys ever tried making your own box lid screws?

I think I've got it down but man, it was a PITA when I started...














Hahaha, just kidding...

[joegagan]

doug, you crack me up on a regular basis

but seriously, there was a guy at the telecaster disscusssion page reissue who was making a 50s tele replica from scratch, every single part. he owns a medical prototyping company , so has full use of very state of the art machinery/software. last i checked, it wasn't finished. 
the thread is amazing, the guy also takes killer photos and has posted every step.

i really would like to do some casting, gonna have to try it soon.

[R.G.]

Have you guys ever tried making your own box lid screws?

I think I've got it down but man, it was a PITA when I started...

um, actually, I recently bought a lathe and milling machine... 

Good point. There is a place where making a knife by refining your own iron ore gets to be a little much.

However, I get a charge out of collecting technologies. I will probably never cast replicas of chicken head knobs. But I ... might... make knobs shaped like feet or pigs' noses, or whatever. And while I will never make my own transistors, it pleases me to know that I could take high purity germanium and indium and do so.

What can I say? It's cheaper and less disruptive than heroin, although probably more addictive. 

[joegagan]

rg, you get extra points if your pigs feet knobs are made of the same material that the high end sex toys use.  i think a pig's foot knob with realistic feel would be the BOMB baby!

[joegagan]

oops i crossed up your items. pig nose too heh heh

[DougH]

I don't mean to be such a smart aleck, I just can't help it sometimes.

My only experience with resin was fixing some dings in my surfboard with fiberglass resin back when I was in high school. My buddy who was helping mix in the catalyst was kind of a doofus - "Dooood! It's not doing anything!" - and of course he added too much. Next thing we knew, the garage was filled with green smoke...

You could probably make some cool looking knobs with translucent resin like that, though. I don't see myself going to the trouble to make my own knobs, but if other people enjoy it, whatever flips your switch I always say.

[joegagan]

ok well clear would be damn cool too


especially if you lit the pedal with those new alpha mini mini 1/4" shaft pots with the led shining up through the shaft.

[frank_p]

YES.  MACHINING TOOLS ARE ADDICTIVE AND DISPENDIOUS AND CAN BE lead you to bankruptcy.
I know some folks (in the mold industry: casting and plastic) who were surprised that redemption was not possible with the rise of CNC technologies and China.
Very sad stories...

[Hamfist]

ok well clear would be damn cool too


especially if you lit the pedal with those new alpha mini mini 1/4" shaft pots with the led shining up through the shaft.

Bingo!  I was thinking the same thing, actually.

[joegagan]

Bingo!  I was thinking the same thing, actually.

that is what i love about this forum. lots of synergy.

[DougH]

Have you guys ever thought about using a 3-d printer for this?

[JDoyle]

um, actually, I recently bought a lathe and milling machine... 

R.G. - is it oil lubricated? I have access to an old one that I use from time to time and I can't imagine having to deal with the mess in my own house!

Don't forget to make a silencer!   

Kidding.

Jay Doyle

[DougH]

Have you guys ever thought about using a 3-d printer for this?

This is what I'm talking about: http://en.wikipedia.org/wiki/3D_printing

Typically these are used to make plastic or soft aluminum prototypes of stuff that will eventually be made out of metal. Since this is just a plastic knob, seems to me you could crank these out pretty easily. Use a CAD pkg to design whatever crazy-shaped knob you want, then send it to the printer. Not sure what the current prices of the printers are but I'm sure they are coming down as the technology gets more popular.

[AL]

Sculpy is great stuff and really convenient but you won't get the same thing every time.

Maybe someone else can chime in but I don't see why you couldn't make a mold of existing knob using something rigid - like Hydrocal or Ultra Cal 30 (mark this down - PLASTER IS TERRIBLE) and then pour in your resin etc. Just make sure you don't have undercuts. You'll probably have to drill the hole later unless you insert something to begin with.

Smooth on has some interesting products

http://www.smooth-on.com/

Also some great stuff here

http://www.monstermakers.com/

or here

http://www.burmanfoam.com/


AL

[joegagan]

wow i had never heard of 3d printers,that is fascinating.

i like the part where  it says there are projects underway to make the machine dupiclate itself.  the future is COOL