More Foundry Fun!
Boy it sure takes long before I can make something! I'm trying a different approach here. Instead of sand casting, I'm gonna try to do some lost foam casting. Here I'm making a 'head pressure' device to pour my aluminum into. This will go on top of the sand, just above the sprue of the foam mold. First I cut this four inch pipe with my chop saw.
Then I used the chop saw again to cut it lengthwise. This is about four inches long.
I found this hinge and I'm bending it to fit the pipe.
A perfect fit!
Holding this hinge in place is a clamping nightmare. I finally figured out how to hold everything in place while I weld.
Here's another view of my clamps to hold the hinge in place.
All welded up. I was hoping that I could use this spring hinge to hold the device closed but when I welded it on, the spring heated up and got real loose. The spring is basically useless now. I probably should have spot welded the ends of the hinge instead of such an aggressive weld.
Here's another clamping nightmare, holding the handles on while I weld them.
This is just after the last weld, the metal is still glowing red hot!
I found I have another problem, the handles weigh too much and it pulls the whole thing over to the side. No problem, back to the chop saw.
Nice and short now, much better.
Here's a view of it open.
Since the spring doesn't work, I'm going to have to use some bailing wire to hold it closed while I pour the aluminum.
I was tired of sweating in the sun and put up my 10 x 10 foot canopy.
OK, switching gears, I've thought long and hard about this and threw it together....
I cold forged some rebar and used some duct tape to hold my dremmel on my drill press.
I'm using a 1/4 inch steel plate for a flat surface. I bet you are in suspense as to what I'm doing here....
When doing lost foam, you need foam! Forget the hot wire, it cuts real good and fast and smooth with the table saw and a plywood blade.
Here are the sprues, looking good.
Here I'm testing out my dremel / table saw / router setup. Works great! If you notice in the photo when I cut there is a rough side and a smooth side to the cut. I found that if you keep the direction of cut on a certain side of the bit in relation to the direction of the cut, it always cuts real smooth.
I'm glad I did this test because there are flaws from cutting. I tried several speeds, too slow drags and tears, too fast will burn. A mid speed about 3/4 to full is just about right. Plus if you take off small 'rows' about 1/2 the width of the bit and work in half circles you eliminate the flaws.
OK, now I'm trying a layout that I printed from the computer. I'm sticking with a single word to keep the cutting easy for now. I think if this turns out, I'll put this plaque on my drums at church!
I cut out the letters.
And then did some fine cutting.
I placed the letters on the foam and traced them with a sharpie. It seems that the sharpie doesn't affect the foam. I was going to use a spray glue but I thought that it might melt the foam.
I used a couple pieces of angle iron here to hold the foam but it seemed to scratch the surface. I did have one instance where the foam came up and the bit cut too deep in the foam. Some kind of weight on the foam would be a good idea in the future.
Finished! I did find that the steel table that I'm using gets my foam and hands real dirty. I should have cleaned it up better, maybe sanded it a little to take off the rust and oxidation. I hit it with a wire brush on my angle grinder before I started but that didn't seem to be enough.
I used a hot glue gun to attach the sprues.
Here's another shot of the back with the sprues glued on.
I mixed up some wall texture and put a coating on. I forgot that before I can cast this I'm going to have to let this dry and set up. This puts me at a dead end for the day.
I put a fan on this to speed the drying. Stay tuned for page five - LOST FOAM CASTING OF THE JESUS PLAQUE!
Of course this will be the first thing I've ever made since I started, except my pigs of course. I think this project may take just about all the pigs I have. Maybe while this dries I can melt down some pistons or something and have more pigs ready for this project.
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Site posted on August 27, 2005