casting a car emblem. First try from a newby

I’ve started my first project. Since it's a custom part, I’m deviating from what I see most people do.

I want to make an emblem for my car that has a double racing flag with the Mercury Man head in between the two flags.

I found an emblem from a 65 Fairlane that has the double racing flags and a 289 engine designation. So, I cleaned that part up, made a mold from it using Alumilite’s High Strength 3 product. Next, I cast a part using Alumilite's RC3 product.

So, now I have a part made of plastic that I can cut up. I cut off the 289 section and trimmed down the center section. I also cast a copy of the Mercury man. I was able to modify the MM emblem so it fit the space in between the two racing flags.

Now that I had a working plastic part, I started making a mold using Smooth On Mold Max 60 so I could cast a part in pewter. Some of you might ask why pewter.

I chose pewter because it has a much lower melting temp and it can be chrome plated. I don’t have the space to store all of the equipment to pour aluminum or other metals that would probably be better suited for this project. I realize I might save money in the long run by buying the right equipment right off the bat than trying to make my own stuff.

I’m using my coleman camp stove to heat the pewter and a small toaster over to preheat the mold. The products I’m using don’t require vacuuming although I think the Mold Max 60 would benefit from it. I bought a cheap stainless steel camp cup to use in heating and pouring the pewter. I think I’m getting some contamination from the cup in the pewter as it gets a gold color on the pewter after being heated a few times.

I did try to convert my harbor freight automotive A/C compressor to use as a vacuum chamber pump but smoke comes out of the vent after just a couple of minutes of run time. I also made a top so I could use the body of a pressure cooker as a vacuum chamber. It doesn’t seal 100%. I’m not sure where it’s leaking from. I should try and correct that problem. I’m trying to be low budget.

To get this thread back on track…I tried to pour pewter today into an open mold. Since I can get by with a flat back on the part, I made an open mold. The pewter rose over the top of the mold as I poured it. I preheated the mold to 250 degrees and poured the metal at a little over 400 degrees. The part looked horrible.

I have work to do to correct these problems. I would appreciate any comments or advice on how to get a good part from this mold. I suspect I need to make a 2 part mold instead of using this one.

Would I be better off doing lost wax casting instead of what I’m doing now?

Thanks, Bill

 

Welcome Bill. I read your introductory post as well. That sounds like a nice project and although it's presenting a bit of a challenge for you I think it's very doable. Zamack is another option. I bought some from MasterYoda awhile back. He s a member here. I mention that because it's another fairly low temp metal and I think it can be plated as well. I know it's a common die casting metal so it may be a good fit for the vacuum option. It might be too much for your Coleman but it can be melted in a charcoal fire in a rusty steel can for a crucible. Others may have something to say about it.
I've cast pewter a couple of times. That goldish hue is normal I think. I was nodding along while reading David's post about the open mold. It really needs to be enclosed and definitely needs head pressure. A couple of possible ideas might be to clamp a flat board to your mold with a generous groove cut in it, say 1/4" deep and wide that leads down into the mold cavity. Stand the clamped assembly on end and pour from the top. Widen the groove to a large funnel shape at the top of the assembly so you have a large target and some head pressure. You may have to tinker with the groove size a bit, and make sure the wood is dry! The thin cross section of your part may still cause some fill problems which might be overcome by making the part thicker and then filing/milling/sanding it to the desired thickness afterward.

Pete

 

David, That just might work. It won't hurt to try it. I can always reuse the pewter. I appreciate the compliment on the master part. Thanks Bill

 

Pete, I like your suggestion too. I made a 2 part mold but it got burnt from having the liquid metal too hot. A friend of mine wants a couple of flat parts which is why I made this latest mold open at the top (saves mold making material). I noticed that when I poured the metal into the 2 part mold, the liquid flowed well due to the pressure created by gravity. Your comments are correct. Just need a couple of air vents and a pour spout and it should work. Thanks for the suggestions. Bill

 

Okay, I was able to run several tests this morning. I tried covering the top of the mold with a piece of 3/8 thick aluminum angle I had left over from a boat repower project. That definitely worked in getting the hot metal to flood all parts of the mold but I found it's hard to determine the right amount of metal to pour. On the first try, I put way too much in...the excess was everywhere. Second try, not enough...third try...still too much...Time to move to a 2 part mold.

My first mold was 2 part with a flat back. This mold got burnt from pouring the metal too hot but the back was okay. So, I cut off all the registration pins that were molded into it and used it for the back using the latest detailed mold I had made. (not burnt)

I preheated the part to 250 degrees and tried to pour the metal as close to 400 as possible. The part itself is much better but there are a lot of little blemishes that look to be air bubbles in it. (I had previously post cured the mold for 4 hours at 150 degrees as recommended by Smooth On)

Could these blemishes be coming out of the mold?

I'd appreciate any insight the group might have. Thanks Bill (the first photo shows an over pour of the open mold)

 

David, It's interesting you ask that question. The answer was no but I saw a you tube video where the guy put talcum powder on the mold. I tried this and the results were much better. I hope the chroming process will fix the small blemishes. Let me know what you think of this one. The weight is 62 grams. Kind of heavy.

I plan to make some extras and sell them. Can anyone give me an idea of what I should ask for them?

Thanks Bill

 

I'm glad to see the mold is filling well. It's a bit of a challenging mold because of the thin profile the metal has to move through after entering the head and then feeding the rest of the mold. I'd guess the preheating of the mold is helping but pewter freezes pretty quick. The short nubs in your vent holes are pretty good evidence of that.

Pete