Quorn castings.

Aluminum castings

Here are some pictures of the castings I made. If you have comments on them, I will look forward to having them. Even those I'm satisfied with may not have been done the right way, and I want to learn. This machine still has some 8-10 different castings I haven't even made patterns for yet.

All of these castings use split patterns. This is because I tried excavating down to a parting line and then ramming the cope. That did not turn out very good. Now I only need to scrap the mold half that doesn't come out well. It's easy: I just make the pattern, drill two indexing holes, then cut it in two with the bandsaw. After this, I plug the index holes where they come through on the outside and glue on a thin plywood sheet to make up for the width of the bandsaw blade.

Fig. 1 First attempt at the macine end base.
This was my first attempt at the base casting. Actually I'm fairly pleased with the result. But there is some shrinkage inside the red ellipse I made on this picture. On the left inside the ellipse you can see where the riser was. It was cylindric with the same diameter all the way up.
You can see the marks from the ingates on the feet of the casting. It was done very similar to the later casting on the picture below.

Fig. 2 Second attempt
And this is the second casting made. This one I'm very pleased with. The only things I can find wrong with this is some broken off edge of sand from the draw. The sand broken off was of course blown out of the mold before pouring. But I thought it better to file off the bumps afterwards than try to repair it, and have that fall of and embed in the casting. You cannot see this on the picture.
But what I tried to show on the picture is the placement of sprue, ingates and riser.
The "mushroom" and the "dick" in two of the holes are from the vent holes in the cores, that filled up with aluminum this time also. The mushrooming got that way because the core was not quite long enough.

Fig. 3.
This is another view of the same casting that shows better how the gating was done. Does it look right or wrong?

Fig. 4. The tilting bracket, three attempts.
Now this is a nasty little bugger! I thought this small one would be easy. Well it turned out not to be. The first is the one in the middle. The nipple is a vent opening. Problem is it is almost hollow. There is a hole where the arrow points, with a big cave inside. It seems some sand must have broken loose when I put together the two halves of the mold, as I poured sand out of this cave.

The next attempt is on the right. It has sunk in quite considerably inside the circle. It had a riser at the place where the first just had a vent hole.
It also looks like it has a crack in the largest cylinder just where the arm joins it. Probably the sand did not yield when the casting shrunk?
Maybe drilling a hole in the sand between the "toe" of the leg and this cylinder would be a good idea?

The last one is on the left. I gave it a really large reservoir for a riser, and tried to bring it close to the casting to have the heat from it. It could have been even closer, but I was afraid to break through while excavating it. This time the casting was fine. The sprue is on the other side, with the feedgate going round and into the top of the big cylindrical portion in an axial direction.

This bracket will have a pointer too that I did not dare make part of the casting. I will make it from 5mm aluminum plate and fix it to the "wart" facing up on the two at the right, down on the one at the left. (I turned it around when casting the last one.)

Fig. 5. Base for the tilting bracket.
This is another casting showing the sprue, gate and riser. In this case the riser also will function as a convenient piece to grip in the 4-jaw for the first machining operations. That will be boring a hole in the part that the riser is an extension of, and cleaning up the D-shaped part, and engraving degree marks on it's face.

Fig. 6.This is the rotating head. It will go on top of the tilting bracket, with the "arm" of that bracket reaching around to the periphery of this part. Obviously I had a lot of aluminum left in the pot, and this was the last part I cast from that pot. So the sprue and riser became one. But that may have been a good thing, as it came out good. But the riser was full before they overflowed into each other. So the narrow gate must have been wide enough. I was not sure it would be. It happened to me before that the gate froze before the casting was filled.

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Feedback to: Einar Sjaavik.

Last change: Nov. 15 1998, moved to NMDF site Dec. 18, 2000

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