Hello everyone
I am looking for some recipes for the ceramic slery and a recipes for some sand for sand casting ??
I seen someware on guy have one part plaster and 2 part silaca sand ??
i wounder if i could use plaster of paris ??
Thanks
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Hello everyone
I am looking for some recipes for the ceramic slery and a recipes for some sand for sand casting ??
I seen someware on guy have one part plaster and 2 part silaca sand ??
i wounder if i could use plaster of paris ??
Thanks
I've used 50/50 Plaster of Paris and Silica flour. I've had mixed results so far.
http://i183.photobucket.com/albums/x...5/IMG_0701.jpg
[There's ceramic shell casting, which uses alternating layers of slurry and stucco to build up a durable shell around a wax part. There's sand casting, which uses a permanent pattern (traditionally made out of wood) pressed between boxes of sand and then removed. And there's investment casting, which uses a mixture of plaster and aggregate (like silica sand) to surround a wax pattern, which is then baked in a kiln to remove the wax.Quote:
Originally Posted by Biggermens
Each of these processes are different; you can't just "mix and match" and expect things to work. It can also be quite dangerous to experiment by pouring molten metals on various things. Tell us what you're trying to do, and I'm sure someone will try to help. What metal did you want to cast? Are you making art or car parts? Is this a one-shot project, or did you want to make multiple parts all the same? Have you got any of the equipment required, or are you trying to do this in your kitchen?]
Andrew Werby
www.computersculpture.com
Hello
I understand the dangers and how it works it just I want to do lost wax castings with a wax model of my part and sand castings for more simple parts.
all i am using is aluminium
All I wanted to know is what a good recipe the slurry. If I can use plaster of paris ??
I will start with that I will leave the sand casting for later.
Thanks
Paprjam good job on the rose it looks good .
Thanks, that the mixed results. There are supposed to be 3 of them, the other 2 didn't fill.
PreHeating Molds will help them fill and also make sure there is not any water or moisture in the mold.
I had a Cast Iron mold I was pouring white hot cast iron in. It had a few drops of moisture in it. It exploded like a burst of fireworks with the dozens of flying sparks bursting again after 10 feet. It is no fun being in the middle of a burst of molten metal.
A large weed burner type propane torch heating the mold till it is well above the boiling point of water and it is no longer giving off steam might be a safer ideal and the heat will help the mold fill better.
Somthing like a tiger torch would work good for that ?????
To pre heat the mold
I heated the mold with the weed burner. Those things put out some heat.
I was doing an experiment with the wax, different sized spues. The 2 smaller ones didn't fill. The roses were little candles from the craft store. I think the brass cooled some while I was removeing the dross. I didn't check the temp.
http://i183.photobucket.com/albums/x...5/IMG_0668.jpg
As I recall the lost wax process you need to do more then heat the mold with a torch. The wax needs to be burned out after dewaxing at low temperature. A small bit of wax can cause porosity. More will cause the pour to resemble a volcano. We used a pottery kiln over hours to get the hot enough to pour bronze. The pour temperature of the mold varies with metal too. Did not do alu.
I have the recipe for DIY lost wax investment someplace.
[QUOTE=Biggermens;744495]Hello
I understand the dangers and how it works it just I want to do lost wax castings with a wax model of my part and sand castings for more simple parts.
all i am using is aluminium
[Have you already succeeded in melting aluminum?]
All I wanted to know is what a good recipe the slurry. If I can use plaster of paris ??
[Slurry and investment are different. Slurry is a permanently liquid material used for ceramic shell casting; investment is poured into a flask around the wax pattern and then it sets. You can't dip your parts in investment, and you can't invest with slurry.
Plaster of Paris is the material that holds the aggregate together. It's like the cement in concrete; too much binder and not enough aggregate will lead to weak investment that cracks up. A common mixture is by volume: 2 parts sand to 1 part plaster. The amount of water is a critical factor, though. Too much water will leave the mixture weak, with lots of "water trails" that destroy your detail. Also the sand will settle out. Too little water, and the mixture's too thick, plus it sets too fast. But it's not really possible to give you exact figures for the amount of water to use without knowing the moisture content of your aggregate. Also, the hardware-store Plaster of Paris that comes in little boxes is usually old and somewhat hydrated; you should get this in 100 or 50 lb sacks from a masonry supply house.]
I will start with that I will leave the sand casting for later.
[Good plan. Make sure you've got a kiln that can handle the moisture and fumes, that you can easily get your mold in and out of, and that won't choke everybody in your house when it gets going. Remember every speck of carbon residue should be consumed in the burnout, which should get up to at least 1000F; if there's anything left to burn down in the mold, it will spray molten aluminum all over the place as it erupts back out the pour-cup.]
Andrew Werby
www.unitedartworks.com
Your rose looks similar to some rings I made a while ago in pewter. That was a good idea to get them from the craft store. http://metalshop.homestead.com/DSCN0421.JPG
Here is my web page with more pictures
I like the ring. Looks about the same size, I was just looking for something with some detail to try out lost wax. I wanted to try it out a couple times before I tried a larger project.
I did a full burnout as well as I could. Put it in the oven (when the wife was gone for the day:)) melted out most of the wax. Then I piled up some fire brick to make an oven and put the torch in a hole in the side. I had to keep moving stuff around to try to get even heat. I kept it hot with the torch until I was ready to pour. The wax spot in the center of the pattern is where I pulled the wick out.
Hi Folks
With small parts like these rings / roses suggest you use a simple spring driven centrifuge. These used to be available from jewlery factors but are easy to make as they only need to do three or four revs. The mould is first warmed not heated and spun with the spues outer most this removes most of the wax and it culd be reused if you like! Then heat the mould slowly to drive out any water and then heat full blast to burn off any remaining wax. The mould is then reveresed on the swing arm - molten metal poured into the mould - the pin holding back the previously wound spring arm released to spin the molten metal hard into the cavity of the mould.
As far as I can rember the plaster was a special grade that was called 'investment casting plaster'. It was mixed with water to a thin cream consistency and painted over the wax form, sprues and filling chamber with a small artists paint brush.
After coating the form was then set into a suitable form to make a solid 'plaster block' that fits on to the arm of the centrifuge. A vaccum degassing outfit can help here - even a simple bicycle pump with the washer reversed helps avoid air bubbles and hence weaknesses in the mould by degassing the plaster mix. I used a screw to jam jar to good effect as the vaccum chamber but only with the bike pump with it's reversed washer! The 'plaster' mix being thick cream consistency. All plaster based mixes set very quickly and overworking causes cracks to form and the surface to be less than perfect. As far as I can rember liquid soap was added to the thin coating 'plaster' to aid wetting of the surface detail.
For safety reasons the centrifuge arm rotated inside a deep metal screen so that molten metal was not flung arround in the event of the accident.
The wax used was some stuff called glitter wax that was available in several colours as well as various melting points from just above hand heat to less than too hot to touch. The wax was and I believe still is available and is used by florists - jewlers - as well as for making small sculptures / parts for casting.
The secret was to drive out both the wax residues as well as any water and to soak the mould at near the melt temperatue for several hours befor spining in the molten metal which should obviously be free from scum.
This process is much used for making gold and silver items.
Hope these memories from a mow long distant youth help. Regards Pat
Hi all,
I used to be in the Jewelry manufacturing business and have done thousands of lost wax castings. It is very important to use investment casting plaster its not very expensive and easily obtained through jewelry supply companies. Its also important like mentioned before that the after the investment dries to remove all wax and moister. After it dried over night we would use a kiln over the coarse of a day to bring the casting up to the melting temp of the metal we were going to cast.
I was always doing gold so we would bring up to 2000f or so. As soon as it was up to temp we use a centrifugal casting machine with the metal already melted and ready to spin. Once it had stopped spinning I would drop in to a bucket of water and after the explosion! the casting would be exposed. The investment would just crumble away. If any one wants more detail I can answer any questions just send me a note.
Here is a pic of the casting machine.
http://www.enasco.com/prod/images/pr.../VC100910l.jpg