casting techniques

[Guest 1930]

I am wondering if anyone out there has had any experience casting small parts, I have been lucky enough to have another member here let me borrow a switch escutchion from his DA so that I may replicate it, it seems that no matter how I experiment with the sand casting I cannot get the detail of the original, I have posted here what I have been able to do along with the original, the first is the original the second is one after polishing the third is unpolished and of course the fourth is just out of the sand, the finer it is polished of course the more detail lost, also the back of the item is supposed to be cut out so that the switch fits into it and with the part being so small the sandcasting just wony do it, I am considering ordering a delftclay kit from overseas, it seems it is the only place to get it, has anyone had any experince with this technique and what were your results, any help at all would be appresiated as my plans are to be able to help other old car owners with things that they may need that dont require alot of machining ....thanks

[bobs1916]

Hi

Ask your dentist if he can help. An accurate impression can be made of the plate.Next a wax pattern is made by melting wax into the imprint of the plate. The wax pattern is then sent to a dental lab for centrifical casting.... Good luck...I've never done it but always theorized that It could be done

bob

[Guest 1930]

What is centrifical casting and how would that help me to reproduce the item on brass or aluminum, also I can make a very accurate impression it seems by placing the part in a container and sprinkling talcum powder ( release agent ) and then pouring liquified plaster paris. Trouble is the plaster mold will not withstand the heat, even if I bake it at 300 degrees it will only take about 400 degrees but yes a very good impression. I also dabbled with pottery clay, I found there that the impression while crystal crisp shrinks to much as it dries leaving an innacurate mold. I need the mold to withstand around 1200 degrees, just out of curiousity does anyone know what technique Glen uses in Aust. He works with alot of stainless steel if I remember right and that temp is way up there, how does he do it??

[keiser31]

That original piece looks stamped. Is it a cast piece? You can try to call a foundry like Silverton Foundry in Silverton, Oregon or a local place. They might give you tips on how to do it or take it in and they may do it themselves without too much expense. If it is a stamped brass piece, it should be easily reproduced using a die setup. Plaster with an epoxy sealer may withstand enough pressure to stamp out if thin brass. It looks like the same pattern and style as my 1931 DB DH6 interior escutcheons.

[Guest 1930]

Yes the part is a stamped piece, I have contacted a few different people across the country on this without to much luck, it seems unless I want a thousand of them or am willing to pay ten thousand to have one made they cannot help, or they can help but cannot guarantee that all of the details that are admittedely so faint already on the original will be there, that is why I am interested in learning myself how to do these sorts of things, I would be appreciative if you would tell me for sure if it is the same as used on your car, I always find it interesting to see what other year cars interchanged, I assume that if yours is the same that your interior handle esutchions would have the same design? I know that I can find someone eventually that can make the piece to my standards but I really enjoy learning myself. I have researched lost wax process, I believe that a friend of mine a few years ago told me that is how these parts or some of them were originally cast, I see alot of info on you-tube ( which is something I only recently discovered ) but it is spuratic, difficult for me to understand the steps, if anyone is as interested in this sort of thing as I am than I would reccomend going to you tube, typing in delftclay ( make sure you make that all one word or it wont get you where you want to be ) and then viewing the 6 part series by Hans Kerreman the english version, it is very informative and really breaks down the steps in easy to understand format. I found the info given much easier to understand than any info I got on sandcasting from there. Anyway also if anyone can tell me the lost wax process in simple ( kindergarten ) terms that would be great also. Thanks for the pict. by the way look forward to seeing more if ever you have the time, looked like quite a project but again a great job

[keiser31]

The interior escutcheon plates, window cranks and door handles have the same design for 1930 and 1931 6 cylinder Dodges, I believe. They match your switch plate.

[Guest 1930]

Yes they do good to know, thanks

[nearchoclatetown]

1200 degrees sounds like you might be useing aluminum? If you have to cast the part why not try zinc that melts at around 420? For the switch plate soft solder would probaly even work. Then you might be able to use the plaster mold you spoke of.

[Guest 1930]

Yes I have been using aluminum, someone else suggested to me soft solder, I could not figure out what they were talking about but assumed they meant actual solder that is used for say a/c repair, is this what you mean? if so then yes I used that with the plaster paris but the mold will only last about 4 casts before deteriating, I went to my local gas/welding shop and suggested the soft solder that I think you mean and for a small role it is so expensive, it took 3 rolls to produce this one part if I remember right maybe 20 dollars a role, the cost does not bother me except that as mentioned I would like to get into reproducing other parts, anyway is this the solder you are referring to and where would I get zinc, had not thought of that but it is something to think about. Here is another stupid question but are there any problems with plating zinc? and I also wonder if there would be any problem plating the solder, I am thinking I like the aluminum and brass but I sure appreciate any other ideas

[keiser31]

A friend of mine used to cast up toys and things. He sent the carving/molded piece to a place in Chicago that made what they call a "serro-copy". It was hard aluminum/zinc compound, I believe. He used that for the mold. The place is called "Accurate Casting" and is in Addison (west of Chicago, I believe). They can provide a serro-copy or match plates to cast your goodies with. Here is one of his toys. John

[bobs1916]

Hi

to withstand the heat you need to get INVESTMENT PLASTER. That is what is used for centriphical casting. That by the way is a technique that is used in jewelry and dental manufacturing when molten metal is propelled into a negative mold formed of investment plaster. But if all you need is a heat resistant plater for your project investment plaster is for you and forget about a centrifuge. It is available through dentist and jewelry suppliers whose clients need excellent detail and high heat resistance for the products they cast.

bob

[nearchoclatetown]

Zinc is also called potmetal. It can be plated, and is available in bar form from McMaster-Carr. Soft solder is plumber's solder, haven't bought any for years. I'm not sure of the cost. Babbit is available too, melts pretty low.