Ramblin' Dan's Workshop Blog
Welcome! Blog pages are intended for two way dialog with the author of the posts presented. Readers are encouraged to participate in this expression of thoughts and ideas. Guest comments are welcome. Personal emails are never published. You don't need to register to post a comment although you can join to subscribe to the blog and receive email notifications of new posts. Registering does not enable personal posting of new topics.
This blog replaces the original function and intention of the Shop Notes Menu tab. Shop notes will remain available and may be used occasionally for high priority topics. The blog format is friendlier and encourages reader feedback if desired. This is the place where new projects and updates will first appear.
Ramblin' Dan's Workshop Blog
Making a Medallion
I spent a full day this weekend working on a casting project for a 50 year reunion medallion. I have been working on this project for at least six months trying to create a mold for casting for what will be hundreds of medals.
I have the design but I have been experimenting with how it should exactly look. I have drawn it both in Vectric Aspire and Rhino. Aspire has been the easiest. The big problem is making a mold that can withstand all the casting. I want to cast them in pewter.
I can make perfect versions in blue wax using 3D CNC. The run time is between 3 to 4 hours. There is usually 250,000 lines of code. I haven't been so good at machining aluminum. It's probably because I am using the wrong alloy for making the fine detail I want. Eventually I'll get the aluminum mold figured out as that is my preferred method
I have some pictures and video of the processes I have been trying. I don't want to publish until I have something that works perfectly. I first tried some high temp RTV (red) casting rubber but I think I got the mix wrong. The rubber didn't cure quite right and seemed to out-gas when I poured hot pewter into the mold. I switched to making aluminum molds which works, but like I said above, I am having problems with the detail machining.
I am making another rubber mold from the wax master I made this weekend. The cure looks good this morning.
Comments 1
I think I am on to the problem. I am trying to figure how to test my theory. I don't completely know metal flow but I just realized what I have been looking at. The pro's use spin casting for pewter items. Especially small items. It is because flow casting isn't fast enough or heavy enough to drive all the air out and force the pewter into all the fine detail of the mold. The pewter starts to solidify.
I have to use spin casting or perhaps a large tall sprue to get enough weight behind the pour. I'll bet the only real cure will be a spin casting system. I don't know if I want to get into the cost unless this is going to be a full time process for me.
By accepting you will be accessing a service provided by a third-party external to https://workshop.ramblindan.org/jla/