Miniature Tools

[Art Rafael]

Master mold lubricated and ready for injection.





Injection





3 copies form a casting tree.  It is often more efficient and cost effective to cast multiple pieces in one mold, but the possible hazards are multiplied when a heavier pour is conducted.  This cast will call for 3.0 ounces - about the maximum that I dare.





The tree is mounted in a flask.  I do have fancy professional flasks but sometimes resort to an old tried and true 12 0z soup can.





The plaster is mixed in proper proportion, and air is vacuumed and vibrated out on a  shake table under a bell jar hooked up to a vacuum pump.





In the burn- out oven  8 hours with heat stepped up incrementally to about 900 degrees F,





Next comes the exciting part - centrifugal casting machine and molten metal.  I'll try to do a video of this process so that it can be fully appreciated





A perfect shot as demonstrated by the "cast button".  This is desirable so that as metal in the mold cools and shrinks it can draw from this.





The mold is broken to reveal a successful cast.  Now I can breathe again.








The pieces are cut from the cast tree





And now the finish work begins.





The most precise operation may be drilling and tapping these tiny parts.






** see page 18 for details

[OilyRascal]

5th picture down speaks volumes to your creativity in engineering.  I could stare at it all day (learning).

[rusty]

> creativity in engineering

Ditto...you are going to put that back in the fridge after, right? The beer is getting warm....

Are you casting in brass or bronze?

[Art Rafael]

Thanks guys.  Necessity really does create invention.  When I started this venture some 30 years ago, I was exploring the process and could not begin to afford the equipment that would yield good results.  Commercial vacuum pumps still command over $1000, and vibrating tables as much.  Casting machines now go for 8k (I picked up my antique for nothing from an old dentist).  I still can't afford that equipment.  So I rigged up stuff and made it work.  And it works well.  I'm getting good results -- usually.  I've learned the process well.  But it is so complex and intensive that it is hardly worth doing, except if one were building a crown for the Queen or another nice little tool for my collection.   : )   So to make it all worth doing I mostly cast silver and used to cast gold when It was affordable.  But now I have to buy a new fridge for mama and to keep my beer cold.   Ralph

[Chillylulu]

Casting services are reasonably priced. 

They will work to any level you want.  You can send in the model and they will take to fully finished, or any stages in between.  Centrifugal casters are still common on the shelves of jewelry suppliers.

I have my own equipment similar to yours, except I gave away a vibrator I had (I wish I hadn't now.)  The previous owner made teeth for dentists.  I'll put a cast iron tool on the whats it tomorrow or wednesday for everyone's guess.

[Branson]

In the days before vibrators, I was taught to make a thin solution of plaster and paint the wax with a very soft bristled brush (like camel hair) before creating the mold.  It did eliminate air bubbles from forming where they hurt the casting.

[Art Rafael]

Hi Chillylulu.  I should explore casting services if I ever seriously want to mass produce and sell my models, but, for now, It's just a hobby, and I usually need only one (or very few) copies of any model.  I am usually more eager to go on to the next model than to get stuck creating multiples.  That may be the difference between a hobby and business (job) work.  And casting is where the fun and excitement really is.  I'd really rather do that part myself.  I have seen centrifugal casting machines on Ebay, but they still aren't giving them away.  Have you seen those "new automatic vacuum casting machines" they advertise at jewelry supply stores?  Before I could afford one of those, I'd find a casting service or a new hobby.  Sometimes I wish that I could cast iron, but I think that is a whole new world for my next life.

Right Branson.  I still paint a thin coat of "debubbled" plaster on the wax patterns - then fill the flask and vacuum again.  I've tried every trick I can to yield a piece that requires less finishing.  I even have "painted" the wax models with "debubbleizer" (a mixture of alcohol and liquid soap) that tends to disallow bubbles to stick to the model.

Ralph

[Art Rafael]

The mold produced three good casts.  I often cast multiple pieces in one mold ( especially so when it is a commissioned piece) just in case one piece is ruined along the way.  And sometimes both pieces turn out ok, and I get to keep a copy.  In this case three pieces were cast, and already I've had to cannibalize one to complete the two promised pieces.  Here are pics of the first one in sterling silver with a brass adjusting nut and tight grained Bocote handle grips.  Ralph

[Papaw]

Just beautiful!

[OilyRascal]

I'm astounded you continue to pull "it" off in whatever form you choose.  <hat off>.  Thank you again for sharing with us your methods and art.  Appreciate you being part of the forum.

[Chillylulu]

I have a vacuum pump off of a core drill machine.  I have been thinking that it could be rigged up to both de-bubble the investment, and then hook up to apply vacuum when casting.  Those vacuum flasks are full of holes, I haven't thought how they get the investment to stay in. 

Do you tumble finish,  or is it all hand work? 

Beautiful tools, btw.

Chilly

[Art Rafael]

Thanks again gents.  I do tend to pursue the project that I have envisioned with intense concentration and vigor till I figure out how to do it and ultimately have one in hand.  This often calls for design of new instruments to facilitate the process. 

[Art Rafael]

I have tried several vacuum devices - rotary vane, piston compressors, etc and found that an old refrig compressor draws best.  But I am always looking to improve.  And I just don't understand how those vacuum flasks work - must be new technologies.  I do all my work as simplistically as possible and hand finish everything with small files and ever decreasing grit sand parer, but I do buff & polish with a commercial wheel.   Ralph

[Art Rafael]

Thought I'd post a few pictures of related interest.  I think that, ultimately, the casting trees are interesting works of art in their own right.   Ralph





a little closer up





Somehow, this casting tree resembled something unintended -  a "hammer flower"?, and I didn't have the heart to separate them.  I may just build handles for them and display them as they are.


 
This also happened with a set of playing jacks, but I had to separate them because it was a commissioned piece -- a gift for a lady (Jacqulin Jackson) that has everything.  A set of solid 14k gold jacks. (for those who can afford it - wish I could have kept more than the pictures).   Ralph

[Papaw]

I am grateful that Ralph sent me one of the miniature monkey wrenches!
http://www.papawswrench.com/vboard/index.php?topic=10124.msg64767#msg64767