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Post by krazydiamond on Jan 28, 2008 20:18:55 GMT -5
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Post by docone31 on Jan 28, 2008 20:34:57 GMT -5
KD, Great photos! I sent them to her in a different format so she had to convert them. Essentially, I started with waxes, sprued them, invested them. I then vibrated to debubblize, then vaccum debubblized. I tried the new way and it looks like it works. I tried to show the entire casting process from premelt-to shocking the investment off. Later, I will cut the rings loose, size them, set the stone in the dolphin, and set the stones in the two engagement rings. All of them are due Friday! I vaccum cast. I prefer that method to Broken Arm Casting. I have one of those also. When it goes wrong vaccuming, it is an hot mess! With Broken Arm Casting, it spews silver or gold everywhere. At 1400* mind you. Vaccum casting is like steam casting, only it is a draw down rather than steam pressure. The rings are silver. Gold comes out of the caster black. They are now in the pickle, and tomorrow, cut loose, vibrate, and work on them. I use a single gas torch. I prefer simplicity. Oh yeah, I use ice water to shock the investment. There you see 1400*s in ice water. I like that part. Not enough noise or steam though. I had hoped for more. I cleaned up the kitchen after this, and made dinner. I am looking old though, I used to be 20. Photos do not lie, or do they? I love it when the metal flows like water.
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MidNight~Rocksi3
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Post by MidNight~Rocksi3 on Jan 28, 2008 21:58:54 GMT -5
What are you talking about Doc... you still look 20 silly! ;D
And yeah I think thats the sorta skills I wanna have .. (not to make wedding rings) But to make Bling Bling for sure!
Cool tutorial pics!
;D
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Post by docone31 on Jan 28, 2008 22:06:57 GMT -5
Boy, and I thought I needed glasses! When I look at my old albums in my rockin years, and see these.......and I still think I am at Woodstock. I originally started this way. users.frii.com/dnorris/onlineclasses.htmlActually not from Don, but from old books I found in a library. I used to sling to cast. That takes two people. I found out about steam casting by reading an article on potatoe casting! Potatoe casting is way cool. Does as well as vaccum. I do not really remember why I stopped doing it. It worked real well. I just ended up doing vaccum casting. I think I remember thinking vaccum casting was easier. Not so. But, for one offs, the process is worth it. And Roxy, I like your skull. I make one like it, except I set two rubies for eyes. A large, silver skull with rubies. I carved it myself.
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SteveHolmes
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Post by SteveHolmes on Jan 28, 2008 22:18:40 GMT -5
Pretty neat tutorial there Doc and KD! Is this how pewter castings are made?? and if so...do you do requests?? I need a couple of miner figures. Steve
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karenfh
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Post by karenfh on Jan 28, 2008 22:27:46 GMT -5
Great photos, glad it worked! Thanks, KD! Now.... What language are you speaking? ![???](//storage.proboards.com/forum/images/smiley/huh.png) I need Casting 101! I swear you made up some of those words... I think I need a very verrrry basic tutorial! Thanks for showing the whole (mystifying) process!
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Post by docone31 on Jan 28, 2008 22:29:41 GMT -5
I forgot to add, Mixing the investment is critical. I have had times, when I have taken the flask out of the kiln, set it on the vaccum, turned on the pump, and poof! A blow out. What that is, is when the vaccum pulls the investment out of the flask. Extremely hot ceramic slurry sitting on silicone rubber. Things catch on fire. The causes of blow out are several. Most I have had are caused by: Improper mixture. Should be 100%/40%, most times. Too much time at high temp. Should be cast at 900* for optimum casting, and detail. Hard water. The softener needs salt, and I do not know it. Usually when something blows out, I have one off custom rings on the sprue. Usually difficult and hard to replace. It takes sometimes all day to spru up the waxes for casting. Also, each time you melt sterling, it gives up some of its copper with the flux. I use a copper wire to stir the melt. Another failure is when a microscopic piece of investment is on the lip of the flask on top of the rubber. It prevents more than 15hg from being pulled. I machine every one of my flasks before using. I turn a 45* angle to both edges, sharp edge to the outside. That digs into the rubber for a better seal even if there is some contamination on the edge. Even when everything is perfect, all the ducks are in a row from the largest to smallest, Murphy the famous law maker and philosopher pays us a visit. Bad day! Nothing like a weeks work gone with the flick of a switch! Then there are mold warts, trapped wax, and other good stuff. So far, so good. Except for a few visits from Mr. Murphy once in a while.
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adrian65
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Post by adrian65 on Jan 28, 2008 22:41:47 GMT -5
You look like a wizzard to me, adding "star dust" to the molten silver. "Broken arm" casting? Wow, I was sure silversmithing involves some sacrifice, but not at THAT scale.
Adrian
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karenfh
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Post by karenfh on Jan 28, 2008 22:50:51 GMT -5
Uh huh, sounds like the latest Harry Potter book to me. (Mold warts, magic dust, spruing, debubbilizing, haha!) Amazing and wonderful! You need to give us (me) a verrry basic, in English, tutorial. I am fascinated! Some of your equipment looks like the things my brother uses for making his black powder bullets, and I get that. Thanks again!
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Post by docone31 on Jan 28, 2008 22:56:49 GMT -5
Steve, Pewter casting is different. First, the temps are way lower, second, the molds are either aluminum, or rubber. Rubber casting, they use a rubber disc that is two parts. An upper and lower. The molten pewter is poured into the mold while it is spinning. On one offs, they use a square mold and vaccum. Silicone rubber can take up to 1400* for a short time. Aluminum casting, the mold is heated and the pewter is poured. Rubber casting is faster and produces more detail. Usually without a parting line. The spru can be much smaller. Same with vaccum. Aluminum molds recquire heating the mold to operating temperature then casting. The temperature is a by gosh and by golly ball park. You start pouring and tossing the models back into the melt pot. As the mold heats, the models get better. Once you get the desired detail, you keep melting/molding. The timing between each model and the repour keeps the model and mold at optimum temperature for casting. You can melt pewter on the kitchen stove. I need acetylene for the silver melt. The discs for the centrifigal molding are about 14" in diameter with a 2" pour hole. They are poured with the mold cold.
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Post by docone31 on Jan 29, 2008 9:45:47 GMT -5
Hi, this is from Mrs. Doc, I will demystify if I can:
Casting vocabulary 101:
waxes- not as simple as it sounds. This is the model you use in lost wax casting. You either buy a wax, or do what we do, which is to carve it out of a lump of wax. If you carved a good one, you make a rubber mold (long story there, trust me) so you cam make many duplicates.
sprued them- this means that you stick something on the end of the model that you cast so that you have a channel for the molten metal to flow. In this case, a wax stick that was big enough to stick to the 'button', which looks like a funnel so you have a good target for the metal. A button and sprue attached to a model looks a lot like a funnel.
invested them- stuck the model in a flask and covered it up with a goopy stuff a lot like plaster of paris. Same nasty smell.
vibrated to debubblize- this means that you get rid of the bubbles in the investment so when you pour the metal in, it doesn't have bubbles to get into, so your cast piece doesn't look like it's got warts all over it.
Doc forgot to mention that you stick this in a kiln and cook it for about 12 hours at 1400 degrees so that the wax disappears and the mold is free of wax. This is called burn out.
The rest of this is straight forward, a broken arm caster (we have one in the shed) is a thing with an arm that rotates at high speed. You pour in the metal, and then it spins so that the metal uses centrifugal force to get into all the crannies in the wax. They do have occaisonal malfunctions which result in moten metal all over yourself and the wall. So we sprung for a vacumn caster, which uses a vacumn pump to yank the metal into the mold, it is more precise, and it has fewer moving parts to screw up and fling hot metal all over the place.
We actually have fun doing this. I think it is easier to learn to do when you are about 12, it's taught in a lot of high school vocational classes, people do it once or twice, and then join the real world.
I took the crummy picture, I hope you can see a little of what this is like.
Julie
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Post by docone31 on Jan 29, 2008 10:32:36 GMT -5
I just re-read this, I think I even made it more confusing. Sorry!
Now if I can just get Doc to clean up the kitchen sink, maybe I can make breakfast!
Julie
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rockdewd
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Post by rockdewd on Jan 29, 2008 16:04:23 GMT -5
Great pictures! I need to get into casting sometime. Every time I bring it up my wife points to the custom orders and repair bins and says, "You can't keep up with what you got and you want to add casting?"
It's worth mentioning that when mixing investment and quenching a flask you should be wearing a mask. Investment is made from super fine silicates and too much exposure could lead to silicosis. It's better to mix investment in a separate room that can be wiped down with a wet sponge before removing your mask and to quench outside. Quenchng releases silicates and other nasties.
And at the risk of being labeled a worry-wort the same applies for tumbling grit. Silicon Carbide is sharp and sticks in your lungs and you are unable to clear it out. Again, too much exposure and silicosis a possible result.
Rick
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Post by docone31 on Jan 29, 2008 16:15:50 GMT -5
I really haven't found that to be an issue. When I get the 100% mix for the powder, I fill the container in the bag. When I mix it, I pour the water on top of the investment rather than put the investment on top of the water. I use a plastic tupperware bowl, and flattened a spoon for mixing. When quenching, I find that any dust is absolutely contained within the quench. The steam produced seems to exit the flask in opposite directions and stay under water for almost all of the time. Here in Floriduh, dust shows immediately on everything. You would not think being in such an humid environment would have dust. It has more than I have ever experienced. Even more than in Los Angeles where it is real dry. Potatoe casting is like vaccum casting. Instead of a vaccum unit, cut a potatoe in half and press hard down on the flask. The resulting steam forces the melt into every available opening. I have even had dry flasks blow out under the steam pressure. It actually smells good also. To potatoe cast, all you need is a steel soup can, investment, and a tuna can and wood handle. Wet some paper towels, damp wet, and put them in the tuna can. Melt the metal in the opening to the sprue in the flask. When molten mash the potatoe or tuna can down on the melt. Hold it for a minute. Poof a casting! Works real well for one offs.
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rockdewd
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Post by rockdewd on Jan 29, 2008 16:29:02 GMT -5
Doc, Not to be argumentative but this subject has been brought up on Orchid a bunch of times. I cut and pasted paragraph from an article written by Charles Lewton-Brain an internationally recognized goldsmith, author, and teacher. >>There are dusts you can see in the air. It is, however, the smaller, completely invisible particles that are the most dangerous. These, especially fibrous or jagged ones like asbestos, cotton and silica, are stored between the air sacs of the lungs. That is, you breathe them in and they will never escape again. Once there, they cause scarring, thickening of tissues, eventually stressing the heart because it is more work to breathe. Cristobalite (a rather vicious form of silica) exposure is considered a real silicosis hazard. It is a major component of casting investment.<< The whole article can be found at: www.ganoksin.com/borisat/nenam/casting_safety.htmRick
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Post by creativeminded on Jan 30, 2008 8:17:46 GMT -5
I wish there was a silversmithing class where I live I have done a couple of castings and had alot of fun doing it. Tami
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Post by docone31 on Mar 18, 2008 9:53:09 GMT -5
I am bumping this one to the top also. Anyone want to put this one in Tips also?
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