The muller is back but I'm unsure whether it's fixed because I haven't used it much. There's still a small puddle of oil. Residual? Yesterday I made some pouring cups. They will all work as pouring cups but is the dark one more ideal for inside a mold, all surrounded by molten aluminum and all?
Today, I used one of the pouring cups to make a six inch diameter disk with a recess of one inch deep x 3-1/4" dia. The sprue was 0.4" dia. The circumference runout is 0.068 and the face runout is 0.040". The baked, molasses core sat around for a half year and was heated to 250F a couple of weeks ago. I vented only the core and not the rest of the mold. I'm happy this new year.
With the previous casting, I made the following pattern. Drag side... Cope side. This resulted in... The round stock next to the finished casting was yesterday's casting adventure. The six inch diameter casting pattern will be used to produce several parts in upcoming projects.
After tiring myself out from patting myself on the back, I realized the basic problem hadn't been solved. I need to be able to chuck these castings in the lathe. My pattern diameter is too small. I also need to get rid of the hub. Looks like more work on the lathe
I did manage to separate the hub from the ring. There was a problem with the lathe. It's fixed. A grub/set screw came loose. Pressing on.
I made a few alterations to my 8 inch square flask. I've eliminated those annoying alignment pins that keep dropping into the sand heap. I found a way to clamp the cope to the drag preventing cope float. The new design worked okay.
I'm tired of thinking about bifilm theory. Let's see if I can implement some of it. I also want to try out the renovated flask. The cope and drag match plates. The pouring area is ready Hmmm, the pattern is a little too rough. I added scoth tape to create fillets. That fixed the tear out problem for the most part. Bottom of pouring basin. Drag ready to go. Mold ready for hot metal. The flask is working out pretty well.
The foil thermo valve worked well. The pour was steady and it was easy to keep the basin 2/3 full. I just stopped when I saw the vent fill and it filled real fast. The 1/4" sections are flat and the 1" section is very close to it. If I moved the riser to the center there may have been no shrink. I see no flaws in the surface finish though it's tough to tell with this rough pattern. Least ways I don't see any flow patterns.
Nice! You kept the top of the sprue full? I've pretty much been unable to do that. From my recent experience, a lot larger riser would have helped, and would have held a lot more overflow.
I cut off the gate at the part, the bottom of the sprue, and bottom of the riser. I detect no holes. My file kept clogging up when trying to file a clean surface on the gate. This is not good. Would this be an indication of oxides in the mix?
I milled the top section where the shrink was to just below the bottom of the pit. Picture shows a climb-cut surface (conventional cut looks the same). Under a loop there are a dozen or two dots per sq.in. homogeneously distributed. It's not shiny like you get with 6061.
The casting looks good, but how are you going to get those wood screws out of there? (just kidding, but they did copy rather accurately). The 356 I have cast tends to gum up the tool bits. Heat treating/tempering improves the hardness quite a bit, but there is still some clogging of the tool bits (more than I care for). I think some cutting oil helps. That is one of the reasons I went to gray iron. It is not gummy, although it can have chills if not done carefully. .
I'm a novice at maching as well as casting. What I've found so far is to use carbide tips on the lathe and hone them frequently with a diamond honing stone. For the mill I use an aggressive looking mill to get near 0.01" then use a nicer looking 4-flute to finish. I put WD-40 only on the tool bit occasionally or after honing. Putting WD-40 on the part seems to keep the tool bit from digging into the aluminium.
That looks great! I use kerosene in a squirt bottle with a small hole drilled in the cap. Adds just enough. I'm sure WD-40 does the same.