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#1
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Looking for: Small Metal Casting Foundry In Los Angeles
Hello to all in this group,
A) I am looking for a small foundry in the Los Angeles area ( I am based in Silverlake)able to do ultra accurate investment casting of aluminium from wax (this is a small pitch gear design). B) Please give me a good source for me to obtain wax for me to cast from a silicone mold. ( I have never molded wax before, so I am not sure wether it needs degassing before casting, in which case I may need to vacuum cast is this a factor in wax selection?) Perhaps you could give me a good source of info on the subject of molding wax (for casting or other objective) C) Eventually, I may need to create a permanent pattern to cast accurate aluminum gears I would appreciate sources of information on this. A1) It would be nice if the small foundry I find in Los Angeles can do both processes referenced in "B" and "C". Regards Steve |
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#2
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Scorsi wrote:
Hello to all in this group, A) I am looking for a small foundry in the Los Angeles area ( I am based in Silverlake)able to do ultra accurate investment casting of aluminium from wax (this is a small pitch gear design). B) Please give me a good source for me to obtain wax for me to cast from a silicone mold. ( I have never molded wax before, so I am not sure wether it needs degassing before casting, in which case I may need to vacuum cast is this a factor in wax selection?) Perhaps you could give me a good source of info on the subject of molding wax (for casting or other objective) C) Eventually, I may need to create a permanent pattern to cast accurate aluminum gears I would appreciate sources of information on this. A1) It would be nice if the small foundry I find in Los Angeles can do both processes referenced in "B" and "C". Regards Steve If You like to get informed about small casting supplies look here at my site: http://www.schmuckfabrik.de/englisch-index.htm -- Heinrich Butschal casting technologies http://butschal.de/werkstatt |
#3
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Ultra accurate investment casting might work for you , however you dont
define the actual accuracy you want. Without that your not going to get anywhere with casting. From what you seem to want to achieve , youll need to go the pressure die casting route. Try talking to that type of producer. , more of those in the Auto trade than any where else. Your cheapest bet is China .. Most of out small production Co's have moved their work to that country. |
#4
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"Scorsi" wrote in message ... Hello to all in this group, A) I am looking for a small foundry in the Los Angeles area ( I am based in Silverlake)able to do ultra accurate investment casting of aluminium from wax (this is a small pitch gear design). [What do you mean by "ultra accurate"? Casting, by its nature, is not going to reproduce an object exactly the same size as an original part. There will be shrinkage in the mold, shrinkage in the cast wax, and shrinkage in the metal. If you've figured out all these shrinkage factors and enlarged your wax gear appropriately, then it will come out the right size, but it's difficult to do this to very tight tolerances. Most parts like this are cast first and machined later - it sounds like you want to reverse the process.] B) Please give me a good source for me to obtain wax for me to cast from a silicone mold. ( I have never molded wax before, so I am not sure wether it needs degassing before casting, in which case I may need to vacuum cast is this a factor in wax selection?) Perhaps you could give me a good source of info on the subject of molding wax (for casting or other objective) [I've never heard of wax being vacuum cast, but that doesn't mean it's impossible, I suppose. Wax and other pattern-making supplies are available from Kindt-Collins: http://www.kindt-collins.com/index2.html There is some general information on waxworking, moldmaking, and casting in the Alt Sculpture FAQs: http://users.lmi.net/drewid/altsculpture_faqs.html ] C) Eventually, I may need to create a permanent pattern to cast accurate aluminum gears I would appreciate sources of information on this. [Permanent molds usually want draft to release from the mold, so I'm not sure this will work with your gear pattern. You'd want to show it to the die-casting house, if you decide to go this route, and ask them.] A1) It would be nice if the small foundry I find in Los Angeles can do both processes referenced in "B" and "C". Regards Steve [I think you'll want to figure out another way to make these, if you really must. But are you sure they can't just be purchased somewhere? Try WmBerg for a start: http://www.wmberg.com/prgears.html . Another thing I should mention: aluminum is not a great material for gears, since it is soft and wears easily. Of the various alloys of aluminum, the kind used for casting is one of the softest. Are you sure you can't use steel or bronze? You can get lengths of spur gear stock in these materials and turn your gears to the correct width on a lathe, then bore or ream them to your desired shaft size. This is a lot more accurate than casting, and also much cheaper and easier.] Andrew Werby www.unitedartworks.com |
#5
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"ted.frater" wrote in message
. .. Ultra accurate investment casting might work for you , however you dont define the actual accuracy you want. Without that your not going to get anywhere with casting. Sorry, for my nebulous use of "ultra accurate". You are right about shrinkage of course, howwever I am not too worried about shrinkage as all critical parts will be cast using the same process. Any constraints can be taken care of on my lathe. This does not mean that I will not take account of shrinkage though. My use of the accuracy phrase was meant to convey that I want nice clean parts. Its no point doing this if they will not mesh properly. There is a lot of time invested in designing these. From what you seem to want to achieve , youll need to go the pressure die casting route. Try talking to that type of producer. , more of those in the Auto trade than any where else. Your cheapest bet is China . Most of out small production Co's have moved their work to that country. I was at a Westec convention talking to some Chinese companies that did this. The process is just priced out of my league right now. But, if I had the budget, I would much prefer to do it this way. I may enquire further. Steve |
#6
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"Andrew Werby" wrote in message
. .. "Scorsi" wrote in message ... Hello to all in this group, A) I am looking for a small foundry in the Los Angeles area ( I am based in Silverlake)able to do ultra accurate investment casting of aluminium from wax (this is a small pitch gear design). [What do you mean by "ultra accurate"? Casting, by its nature, is not going to reproduce an object exactly the same size as an original part. There will be shrinkage in the mold, shrinkage in the cast wax, and shrinkage in the metal. If you've figured out all these shrinkage factors and enlarged your wax gear appropriately, then it will come out the right size, but it's difficult to do this to very tight tolerances. Most parts like this are cast first and machined later - it sounds like you want to reverse the process.] Please see my reply to Ted's previous post. I was very unclear I admit-I simply wanted to imply to any small Los Angeles foundrys that I wanted nice clean parts, ie not a sloppy job. B) Please give me a good source for me to obtain wax for me to cast from a silicone mold. ( I have never molded wax before, so I am not sure wether it needs degassing before casting, in which case I may need to vacuum cast is this a factor in wax selection?) Perhaps you could give me a good source of info on the subject of molding wax (for casting or other objective) [I've never heard of wax being vacuum cast, but that doesn't mean it's impossible, I suppose. Wax and other pattern-making supplies are available from Kindt-Collins: http://www.kindt-collins.com/index2.html There is some general information on waxworking, moldmaking, and casting in the Alt Sculpture FAQs: http://users.lmi.net/drewid/altsculpture_faqs.html ] Thankyou for this source of wax casting supply I will check this out fully. Well, I am not sure if air bubbles are a problem in wax casting as air can be with RTV silicone, urethane and resins. If air bubbles in the wax can mess up the surface of a metal casting then I assume you have to degass the wax. I AM guessing though, I am not an expert in this-yet. C) Eventually, I may need to create a permanent pattern to cast accurate aluminum gears I would appreciate sources of information on this. [Permanent molds usually want draft to release from the mold, so I'm not sure this will work with your gear pattern. You'd want to show it to the die-casting house, if you decide to go this route, and ask them.] I will probably have to modify some aspects, but it shouldn't be too difficult A1) It would be nice if the small foundry I find in Los Angeles can do both processes referenced in "B" and "C". Regards Steve [I think you'll want to figure out another way to make these, if you really must. But are you sure they can't just be purchased somewhere? Try WmBerg for a start: http://www.wmberg.com/prgears.html . These are hypoid type gears computer calculated, designed and simulated. I am going to produce them using SLS then silicone mold then wax cast. Wax cast sent to foundry. Another thing I should mention: aluminum is not a great material for gears, since it is soft and wears easily. Of the various alloys of aluminum, the kind used for casting is one of the softest. Are you sure you can't use steel or bronze? Well, I am still in the prototype stage on this project. Wear may be useful to me to aid meshing if my "real world" design is just a little off . I intend to send the final parts for hardening. However, I would certainly not rule out casting in bronze or steel if feasable. Also, these are for low rpm, low load function. You can get lengths of spur gear stock in these materials and turn your gears to the correct width on a lathe, then bore or ream them to your desired shaft size. This is a lot more accurate than casting, and also much cheaper and easier.] I will be using a lathe to get the shaft size perfect etc when I get the metal parts back. Steve |
#7
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If You like to get informed about small casting supplies look here at my site: http://www.schmuckfabrik.de/englisch-index.htm Thankyou Heinrich, I will check out this site fully. Steve |
#8
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On Sat, 28 Feb 2004 21:51:47 -0800, in rec.crafts.jewelry
(Scorsi) wrote: Please see my reply to Ted's previous post. I was very unclear I admit-I simply wanted to imply to any small Los Angeles foundrys that I wanted nice clean parts, ie not a sloppy job. There are any number of jewelry casters specializing in small custom cast parts, and normally, they expect to produce nice clean castings. You're problem may be finding one of these firms that knows beans about casting aluminum. Higher melting metals are much more their specialty. Aluminum requires somewhat different handling, and needs, for good castings, the selection of the right alloys as well. I don't know any castings in the L.A. area, but if you can deal with mail order, there are a number of firms I can suggest that you could try. Don't know if they'll do it, but it's worth the phone call, and getting casting done via mail can end up cheaper than running around town getting it done locally, at least if traffic problems and parking fees in L.A. are anything like they are around here, where getting a box to UPS or fedex, and shipped, is easier and cheaper than finding some downtown firm, wading through traffic, paying a parking garage, etc... Let me know if you need those names. B) Please give me a good source for me to obtain wax for me to cast from a silicone mold. ( I have never molded wax before, so I am not sure wether it needs degassing before casting, in which case I may need to vacuum cast is this a factor in wax selection?) Perhaps you could give me a good source of info on the subject of molding wax (for casting or other objective) Thankyou for this source of wax casting supply I will check this out fully. Well, I am not sure if air bubbles are a problem in wax casting as air can be with RTV silicone, urethane and resins. If air bubbles in the wax can mess up the surface of a metal casting then I assume you have to degass the wax. I AM guessing though, I am not an expert in this-yet. Normally, in jewelry type casting at least, the molds are made so as to be fully closed, rather than open faced. A small funnel shaped opening is provided to a channel into the part cavity, and of course the mold is cut apart so that it can be dissembled, usually into two halves, and reassembled with proper registration of the halves. Silicone RTV molds have less or no shrinkage in the mold process, but the molds aren't as strong as a vulcanized mold. For your purpose, though, they should be fine. The wax is generally injected into the mold with an air pressure driven wax injector which keeps the wax at a closely controlled melt temperature, and uses fairly low air pressure (a few psi) to drive the wax into the mold. The cuts that allow the mold to be seperated, as well as, if needed, additional vent cuts in the mold, allow air in the mold to escape, but are too thin to allow wax to leak, beyond, perhaps, faint mold lines. The placement of the cuts when the mold is first made is hopefully such that any such faint lines are either of no consequence, or easily cleaned off of either the wax model, or the casting. Injection waxes are made with a number of variant properties, including controlling of shrinkage in the cooling wax, flexibility, durability, memory, and resistance to getting shrinkage "dips", where the wax model ends up with a concave surface on flat areas, even though the mold did not have such. The size, detail, and weight of your models will dictate what waxes to choose from, and they are available from most jewelry tools supplier, including www.Gesswein.com, www.contenti.com, www.riogrande.com (in no particular order, and these are just three major dealers who's URLs I happen to remember). Contenti in particular is well priced, and has extensive casting supplies, including RTV rubbers and waxes. So does Rio Grande, though their catalog is not on the web. Shrinkage of the wax model as it cools in the mold will likely be your biggest problem for shrinkage, as it both shrinks, and can cause some distortion of the model. Air bubbles are not usually a factor. Their is not generally air included in the wax, if it's melted properly, and any bubbles that are in the wax end up usually imbedded in the wax. They don't stick to the mold surfaces, so they don't usually break the surface of the wax model, and as such, have little impact on the casting. If they are very close to the surface, then subsequent vacuum investing procedures can burst them, but this is, frankly, more rare than some wax workers believe. There are, for molds of exceptional complexity, or high production needs, wax injectors that pull a vacuum on the mold before switching to the wax injection mode, so that the wax is injected (still by air pressure) into a mold that's free of air, and therefor free of back pressure that might cause incomplete fills of the mold. These machines are VERY expensive, and many smaller casters don't bother using them. Most of the time, with a bit of care, you get just as consistant and good results with standard wax pots. If your models are very large (by jewelry scales) and thick, then you may indeed have trouble getting standard jewelry casting equipment like this to fill a larger mold, since then the shrinkage of the wax as it cools does indeed become an increasingly problematic concern. In a few cases, larger molds like this do better as open faced molds that are not injected, but just poured by hand. But usually this is stuff who's size is more in like with small sculpture, than it is with jewelry sized work. C) Eventually, I may need to create a permanent pattern to cast accurate aluminum gears I would appreciate sources of information on this. Your RTV mold can be fair permanent. If you are careful with it, you can make hundreds or thousands of wax models with such a mold. Vulcanized rubber molds can be good for several decades of frequent high production work, but to make those, you do need to start with a metal model, rather than your SLS one. These are hypoid type gears computer calculated, designed and simulated. I am going to produce them using SLS then silicone mold then wax cast. Wax cast sent to foundry. Depending on the size of the part, and the degree of surface finish you wish, consider using a model made on a Solidscape machine. Last I heard, these can be produced with surface finishes that are about an order of magnitude better than most other RP processes, including SLS. it's enough better to make a substantial difference in how clean and smooth your finished castings will be, if you wish to not have to remachine the cast surfaces. I suspect the model will cost you more, but you really only need one to make the RTV mold. If you wish a metal mold, have the Solidscape model burned out and cast just as one would do with wax. it casts very well (this is it's main use. These models are too fragile for much else, unlike the SLS models) Well, I am still in the prototype stage on this project. Wear may be useful to me to aid meshing if my "real world" design is just a little off . I intend to send the final parts for hardening. However, I would certainly not rule out casting in bronze or steel if feasable. Also, these are for low rpm, low load function. You might also check out some of the zinc based alloys. They can cast very smooth, generally have less shrinkage than aluminum, some of them are surprisingly hard, some are self lubricating, and the stuff is cheap by comparison. It's actually quite commonly used in the type of lower load, lower rpm, less costly gears that you're trying to make. Aluminum generally is hardened only by a hard anodizing process, and since this is a surface film on the metal, rather than any deep process or intrinsic property of the metal, once it wears down, you then have a higher friction and higher wear rate again. One advantage of the zinc based alloys is that they melt low enough that it's possible to cast them directly into some of the silicone rubbers, meaing you can make a mold directly from your model, into which you then cast the metal directly, eliminating the whole wax model part of the process. its capable of considerable economy and accuracy. The best of these rubbers need to be vulcanized, and do have a little shrinkage, so you'd go about it by making your RP model (preferably Solidscape type), directly casting the model, doing any fitting/cleanup on that model as needed, and making your vulcanized mold, or several of them if you like, from that casting. You'd then cast your multiple end parts directly in those molds. Depending on your mold type and end metal and process, etc, this could be centrifugal casting in a standard jewelry type casting machine or the faster, higher production "spin casting' machines which are often used for high production casting of low melting white metals of this type (much costume jewelry is made this way from these alloys), or for smaller runs, it's even possible to cast some of these alloys just with hand pouring directly into the rubber molds. However, to the best of my knowledge, aluminum alloys melt a bit too high for this type of direct casting into a rubber mold, and it needs to be lost wax cast in investment molds. That, of course, is a good deal more costly than the direct casting into the rubber molds that you can do with the low melting white metals. The folks at Contenti have extensive sections of their supplies for this type of white metal casting. So does Gesswein, and you might also look up Romanoff co. Hope this is of use. Peter Rowe |
#9
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Scorsi wrote:
If You like to get informed about small casting supplies look here at my site: http://www.schmuckfabrik.de/englisch-index.htm Thankyou Heinrich, I will check out this site fully. Especially here is a presentation of possibilities to cast structures smaller than 1/1000 part of a mm in highly developed casting process: http://www.schmuckfabrik.de/Mikroguss_Butschal.htm I´m sorry it´s only in german, however the pictures are impressive. -- Heinrich Butschal casting technologies http://butschal.de/werkstatt |
#10
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Making a stirling engine??
Les |
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