1963 Rambler gets a new... Everything

In reply to NOHOME :

Good idea! I’ll call a shop next time I need more

Ive also learned a sledge hammer is an easy way to bust up aluminum parts

Be careful with modern pistons.  Many of them have insert molded steel pieces in the skirt around the wrist pin holes. I know the ones I just bought new for my Fiat X1/9 have them. You can sort of tell visually looking at the inside, but no steel shows to the surface. The old ones did show a little steel to the surface.

In reply to TurnerX19 :

I had no idea

Thanks for the good info!

I made my plan for how I want to distribute the aluminum to all parts of the mold. I'm going to locate my runners below the part. So the aluminum will be poured in at the top, like usual. Then it will flow through the runners below the part. It will enter the mold from the bottom. This is the best way I see to feed this large mold from several places. I want to hedge my bets and try to get aluminum to the entire mold without doing a bunch of experimenting like I did on the last part.

Here's the model of the part, in the boxes, with the runners underneath the part. There will still be one pouring point, but its feeding 8 runners. So the mold will feed from 5 points on the flange, and 3 points on the hollow section. 

I finally got the patterns to dimensions I like, so I smoothed them out, and painted them. 

I also got the boxes made, and most of my runners. 

All I've got left now is two risers on top to help with shrinkage. Then I'll be totally ready to try making a mold with these patterns. Next weekend I'll try making a mold.

If making the mold goes well, I'm going to try casting this baby!

I started my day today thinking I was totally ready to make my first mold and cast this plenum. I was wrong. 

I made my first mold, and discovered the area between the runners was not tapered properly on my patterns. You can see the sand that's supposed to be left between the runners broke away on almost every runner. 

So I added that sand to my giant pile in my driveway from failed attempts. I grabbed my die grinder to grind away all the areas that weren't tapered enough. I ran the die grinder and it slowly ran out of air, but the air compressor wouldn't kick on.... I'm not sure what's wrong, but the air compressor officially needs work now.

So I got out the hand files and filed away. I tapered the crap out of all the surfaces in between the runners to be totally sure the sand would release. All the white paint on the pattern is to help me remember where to put the risers when I'm packing the mold.

Those modifications paid off. The next mold I made released from the pattern nicely!

I packed the core pattern, and added support rods to the pattern to try to hold it up when it was inside the mold. When I laid the core into the mold this turned out to be too weak to support the core. Instead of this, I put a small piece of aluminum in the bottom of the mold for the core to sit on.

At this point I was feeling good, so I went ahead and packed the entire mold, all three layers. 

The bottom turned out well. This layer is just runners to feed the part from the bottom.

The top layer was the hardest. It has all the vents, which are tedious to pack in the mold.

I put the core in the bottom.

Then I put the top layer on and started the furnace. 

I was feeling really good at this point. All the molds were looking good. While the furnace was heating up, I got curious if the core was still sitting level in the mold. So I pulled the top layer off. As I was worried, the core was too heavy and the piece of support aluminum had gotten squished into the core. I pulled it out, and re-supported it using more than one piece of aluminum.

I weighed out all the aluminum I needed for this pour. I needed about 12 pounds, so I got about 15 pounds ready in case I poured poorly. Unfortunately, this is the point where I realized my math regarding how much aluminum this crucible will hold went very wrong somewhere. The crucible will only hold 12 pounds. And when it has that much in it, it's brimming. Unfortunately, with such a full crucible, I couldn't control the pour very well. As a result I ended up pouring probably 5 pounds of alumimum on the ground around my mold, rather than into it. 

When that happened, I knew this pour would be chalked up to a learning experiment. Since I only had 12 pounds in it there was no way I was going to have a full part when I opened it up. 

So after all that, here's my first attempt at casting the big plenum.

The surface finishes are pretty good. So that's encouraging. It looks like the core dropped in the mold again, since the top is so much thicker than the bottom. I'm going to have to modify how I support the core. 

I put a lot of work into this plenum mold, and I was feeling very good about it when I started the furnace. As a result, I was pretty bummed when I realized my crucible would barely hold all the aluminum. I was even more bummed when I couldn't control the pour well enough to make it work. But after writing this up and looking at the pictures, I'm feeling better about it. It went pretty good for the first attempt at a really complicated part. 

After this attempt, I'm totally certain I can do it though. That's pretty cool!

I think you will have better success with a thicker wall on the intake.  The aluminum shouldn't cool down as quickly as it tries to get through the mold.

I've done lots of casting at work (high school metal teacher), but never anything that big.

Then again, thicker wall means you need to melt more aluminum, which means bigger crucible/furnace.

I think this is freaking awesome, nevertheless!

In reply to SkinnyG :

I’m going to have to get a bigger crucible for sure. 

The thin areas on this attempt were caused by the core falling inside the mold. If the core stays in place, the walls will be at least 1/4” all over the part. 

On my next attempt in going to change the way I’m supporting the core, and we’ll see if 1/4” is enough

You'll likely find you need more/bigger risers to feed a part like this. A complex part with relatively thin walls is going to be prone to shrinkage defects and cold shuts. Two or three big risers will provide a nice pressure head of material during pouring and cooling. Open top risers are a good visual indicator for filling as well. You can make up for a lot of inadequacy in gating design by adding adequate to excessive riser volume.

And better core support usually requires holes that you later plug with "core plugs" (frost plugs). (grin)

In reply to newrider3 :

I had two open top risers coming off the top of the flange. I forgot to pack them into this mold, but in this case it wouldn’t have helped since I didn’t have enough aluminum to fill the part. I think you’re right, once I get a good pour they will be key. It’s amaxing how much material gets sucked out of the risers during cooling.

In reply to SkinnyG :

That’s exactly what I’m planning on doing. I’m going to modify my core mold so I have a sand core support. I’m going to put it in the place where I think I’m going to attach the 2nd piece of this intake, that way the hole will get cut away. If it happens to be in an area that doesn’t get cut away, then I can just plug it, or weld a patch over it.

I’ve had all kinds of commitments and work keep me away from this project the last few weeks. Today I finally ordered a larger crucible. Hopefully it arrives this week so I can make another attempt at casting the manifold next weekend. 

Curious.

For such a large piece, would there be any benefit to having a helper to pour into the mold in a second location to help get the material in faster?

Cheers,

Fox

In reply to Foxworx :

I have no idea. I’m learning as I go.

I hope that’s not necessary, but it’s always possible I think 

The ladle showed up today... and it wasn’t what I ordered!!!

im going to return it and get the right one. This one is too small :(

Okay, this is cool. 

My new crucible showed up this week, and got me super excited. It's huge. It could probably hold 20-25 lbs of aluminum. Theres no risk of running out now! 

I got it hot....

Made a pour... and success!!!!!!

Damn, congratulations!  Those look like great successes for such big parts. Will they be usable, or will you need to cast again? You really should crank out a few extra...I bet you could get a few bucks for your trouble. 

In reply to Mezzanine :

They’re both usable, but not perfect. 

I might cast a few more to sell to guys on the Facebook page I’m a part of. I probably won’t do many though. It takes a long time to cast, and after I defeat a project, I like to move on

How do you handle such a big crucible? Even empty and cold it looks formidable.

In reply to TurnerX19 :

I’ll poat pics of the tools I made

I used the same tools for both, although the larger crucible was a real handfull

I might modify my tools for future attempts, cause I didn’t have the most warm fuzzy feeling pulling it out of the furnace today

Friggen amazing. I know forging stuff has been done for a long time but it still strikes me as a crazy project to tackle on your own.

aselmike said:

In reply to Mezzanine :

They’re both usable, but not perfect. 

I might cast a few more to sell to guys on the Facebook page I’m a part of. I probably won’t do many though. It takes a long time to cast, and after I defeat a project, I like to move on

What group is that? After this and the Studebaker Lark i'm real interested in the 4200.

In reply to GIRTHQUAKE :

Vortex 4200 Engine Swap and Performance

In reply to 1SlowVW :

The crazy projects are are the ones that are the most satisfying to finish!