Re progressive solidification: I was thinking that could be taken care of with all the connections and thick sprues?
Each unit would be slightly different but not different enough to justify a separate mold.
hi
…it looks like each element will have between 2-6 sprue attachment points, which will need to be cut off/ sanded/ blended.
…it might be easier to access/ finish edges if pieces were not all attached…and less sprue contact points…
…have you looked into mass finishing…?
julie
hi
here is s link yo Judy Hoch’s book on mass finishing
julie
Mass finishing sounds like a big improvement over traditional finishing. Judy Hoch’s book isn’t available until her new edition comes out. The info at Rio is interesting but not as detailed as I’d like.
We have had a fairly good discussion of mass finishing in a recent conversation. There is a lot more to be found in the archives and learning center. Judy’s book is a good comprehensive source of information too. Following is a link…Rob
Thank you! The more knowledge, the better!
My plan is to polish the wax master model and then repolish the metal model before it’s rubber-molded so that finishing the final pieces would only need rouge (except for the sprue bumps). Is that a realistic plan or just wishful thinking?
hi,
so…in the sketch, there appears to be 16 pieces, approximately 1/2” to 3/4” in length…?
and…they will have a broad, non-uniform, softly contoured surface detail…
and you want to limit hand finishing…
…mass finishing might be your best friend here.
julie
Hi Julie, you have a total grasp of what I have in mind…Rio has a tumbler kit for about C$250. Would that be good enough for one or two dozen pieces at a time? Going through the sequence of cutting/filing/etc. the sprue bumps, at what point does it go into the tumbler?
hi,
hopefully others with more mass finishing experience than i, will jump in here…
also, try searching the forum…many different steps, times, etc
julie
I have to be careful how the money gets spent. C$250 would buy about 6 oz of silver. If I buy all the tools I want I’ll be making jewellery out of empty bean cans.
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hi
i understand
consider what your selling price will be
sales channels, etc
is this a hobby or a business
business capitol expense budget
etc
etc
etc
challenging
you dont neccessarily need a mass finishing setup
you could do it by hand
you dont need alot of tools to start
prioritize the needs versus the wants
i need to finish the item
i want it to be easier
i need it to be within budget
etc
fun fun fun
julie
Consignment.
Business.
Budget: mostly spent.
Being shipped:
Flexshaft for carving/grinding/polishing.
Bench to contain everything.
Mini dust collector. Some wax, some burs.
Maybe easier gets thrown overboard…
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hi
saw frame, wax blade
large flat file from hardware store
make a pointed scribe to draw on wax
julie
hi
oh! i just remembered…also, consider shrinkage…
i
perhaps search the forum…
this may not be a big concern as fit/ size is not critical, such as for a ring…but good to know about…
julie
Regarding minimizing hand finishing, no matter how polished your original is the cast pieces come out with a surface texture imparted by the investment and the nature of cooling metal. How one treats this “casting skin,” as it is often called, depends on the finish you desire.
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Hi Eliot,
thank you for the clarity of your response.
I’d greatly appreciate your opinion on whether or not a rubber mold could successfully be made using a model that looks like the rough drawing I posted previously.
Thanks!
Hi Elliot…sorry about the misspelling.
Certainly a rubber mold can be made around such a model. But I’m not sanguine that you’d be able to pull waxes successfully from it. That’s an awful lot of narrow passages the hot wax would have to follow before it hardens. Back when I still made and cut my own molds I never needed to make one of such size and complexity.
The other thing to consider is how such a model will work with your casting practice. Flat models such as this are used in sand casting or any technique that uses split molds. But waxes for lost wax casting are invested in cylindrical molds, and a layout like that wastes a lot of space. Since you ask about rubber molds I assume you intend lost wax casting.
Casting houses figure the per piece casting labor based on how much space the wax takes up in the flask. Fifteen pieces like the ones in your image would probably cost less to cast if the casting house could sprue them on a traditional tree. Spruing up the tree is figured into the casting labor, so shooting the pieces as separate waxes and letting the casting house do the sprueing would be the most economical approach, once the cost of the rubber molds is amortized.