Updated Lost Foam Casting - Web Page

[FrankG]

Below is a link to the updated LFMC page that I periodically post...

Generally things are NOT turning out as I hoped...

http://www.theworkshop.ca/casting/Fo...ry5/Fndry5.htm

If you have any solutions to the problems outlined on that page Please, PLEASE... enlighten me!!!

[Pythagoras]

Thanks Frank for that link. That is a good web site.
It would have been better to give us the main link to your web site since it was a better read than the link you gave.

One day I will make a furnace just like yours.

[foamcutter]

Frank,
Checked out your link. I am also casting with lost foam. Not a lot of experience but some. Anything I tell you is only from my small experience and I am not an expert. Weigh this information in your own mind and never try any of it if it seems unsafe or unsound to you. Use common sense. Basically what I am saying is don't try anything I say if you are not willing to take full responsibility for your actions. Do not come back to me later and say I said to do it, now I owe you for burning down your house or injuring you or anything else. I am not responsible for your actions or what you do with this information. This also pertains to anyone else reading my post.
Now with that said here are some of my obsevations in casting with foam. I think you are on the right track to cast the plaques on edge. As your plaques get bigger they are not getting thicker, when I tried casting similiar pieces they would cast better on edge and not flat. I have yet to cast anything less than 1/4 inch thick that is very big. The alum just cools too fast. So as the area gets bigger I have had to go thicker also. Also the bigger it gets the more gas produced by the melting foam, it needs a place to go. Some of my castings I put an extra sprue up from the part not connected to the main one for the gas to escape, some pieces I actually had small short foam stems projecting out from the part into the sand to let the gas out. These were not plastered so that the gas can escape into the sand. They were also be in a place where the cast stem could be cut off later without ruining the part. Also the bigger the part got the faster I had to pour the aluminum into the mold so it didn't start to cool. Big sprues worked better for me than small ones. Also if the sprues connected to the part in several areas helped. I packed the sand firmly around the part, as firm as I could without distorting or breaking the mold part. I packed it by hand to make sure it smashed into any narrow spots.
Your test with petro bond may be the best bet. Larger pieces I tried, cast better without being coated in plaster, just packed firmly in a similier sand to petrobond. Then there isn't the problem of how to let the gas escape, it escapes all over the part out into the sand.
I made my own green sand type mix, WARNING I DO NOT RECOMMEND THIS METHOD I AM ABOUT TO DESCRIBE, I used motor oil and sand. WARNING I DO NOT RECOMMEND THIS because when I poured, the hot alum ignited the oil in the sand and I had an oil torch with a big flame and lots of smoke at the sprue where I was pouring, and when I removed the part from the sand I had lots of smoke, lots and lots of smoke. And smell, whew do it smell. I DO NOT RECOMMEND THIS or use this method at the house. Lesson learned!
The more sand and weight you have around the mold the better so the cast alum doesn't blow out.
I have not tried any of the other stuff you talk about on the link to make casting sand. I would not use antifreeze, I think it might produce some nasty or toxic fumes when burned. I don't know but that would concern me. I would not use anything I thought would produce nasty or toxic fumes when burned or heated.
Have you thought of just buying alum sheet material and milling it like you did the wood molds? Skip the casting?
I really don't know if this helps any but there are a few of my personal observations. Nothing works every time for me, I am still doing a lot of trial and lots of error. Read and use this information at your own risk. I am not responsible for your actions or the use of any of this information. Good luck and STAY SAFE.

[FrankG]

Holy Disclaimer, you must hang out w/lawyers...

Please review the link below...

http://www.theworkshop.ca/Disclaimer/Disclaim.htm

I'm quite happy with the success on the re-oriented molds and deeper boxes, though don't like where this is heading in terms of sheer weight, I'd bet that I'll be upto 150 to 200lbs of sand when I start into true 24" molds, and that's where I want to go...

I can't wait for the petro-bond to show up...

As to the Anti-Freeze, it too was one of the ingredients listed in the Kent-State PetroBond formula, but certainly appreciate the caution on toxicity etc...

Frank
www.theworkshop.ca

[foamcutter]

Frank,
Sorry about the disclaimer but I ain't interested in getting burned. I am sure however you are not that type of person, but you know what I mean. It's sad we have to put disclaimers on everything.
I think the petrobond will be a big help, may try it someday! Your 24 inch molds are going to create big heavy mold boxes to be built. Maybe get you a couple of those furniture moving dollies to put them on to move around. Sounds to me like your going to be firing a pretty big furnace pretty soon also. Are you going electric or gas?
I also discovered white foam melts out a lot easier than blue, but blue creates a better finish on the surface. I am getting ready to cast some bearing pillow blocks in the next couple weeks. I'll see if I can post a photo of them if I remember to take one when pouring. Keep me posted as to your progress. And as always you are responsible for your own actions in regards to any information I have written here. I am not responsible for what you or anyone else does with the information! Ya'll have fun now!Ron

[DragnsBane]

Here's a trick we used when I worked at a local foundry. Make your riser a little larger than normal and have a second person pour into the riser when it becomes about half to three-quarters full. it may be worth a shot.

All the usual disclaimers apply.

[FrankG]

Well that would be an issue... as I'm beyond legally blind, I simply can't work in the foundry with anybody else arround as I place my tools, molds, etc in a very specific way/orientation and even the slightest change in my work flow would lead to real problems...

Though I'm slowly gathering parts and working on the design of a tilting furnace with a liquid capacity of 1.5 Gallons or approx 12 X12" Cylinder size...

[GWheeler]

Speaking of disclaimers, don't use the yellow stuff, urethane foam or isocyanurate. Cyanide gas will be given off, nasty yellow smoke.

[FrankG]

... said "the yellow stuff, urethane foam or isocyanurate. Cyanide gas will be given off"

I think that would include the Spray foams that folks have posted (on other forums) for permenant mold fixtures...

Certainly a good caution.