"One Perfect Part at a Time"

“Proofs” of Concept

I was doing some product research today. This is something I made in about five to six hours. I had been thinking of how I was going to make these all week. I just needed a good Saturday to give it a shot.

As the title indicates this is a proof of concept not a real project. I didn’t want to slow myself down doing all the pictures of the process. The process is still experimental so  full disclosure can wait until a better time. I have my camera at the ready.

Long time readers know I have experimented with pewter casting before. Here is the LINK.

The “thumbs up” graphic is a 3-D rendering received free with the Vectric Aspire software. I used it to create the medallion. The finished result is seen in the first picture above. The picture was created within the software. I combined the thumbs up with some freelance drawing to form the disk. Actually in my opinion the disk is much thicker than it should be.

The edges of the disk did not come out well in the tool pathing. I need to find a better way to create the disk in the software. As this was a trial, I didn’t want to spend all day on the drawing so I accepted some imperfection in the edge rendering and moved on.

Next I had Aspire produce a roughing toolpath for a 1/8 inch ball nose mill bit. Then I had Aspire produce a spiral finish pass with a 5/32 inch ball nose. The disk is 1-1/2 inches in diameter. The aluminum (both pieces) is 1/4 x 3 x3 inches. The back plate is not machined in this test trial.

The machining was done on the CNC Taig mill. A piece of cake for that machine. I used mist cooling. I wish I owned a truly quite air compressor that can make the amount of air I need for misting. That was the only annoying part of the machining. The compressors has reasonable cycles but is too close to the working area.

The gate or sprue hole was much too small so you will see in the picture I hogged it out a bit with a burr. Rather inglorious method but it got the job done. The vent lines were cut with a Dremel type rotary disk. The vents are necessary and effective.

The plates must be preheated before I got a good fill. It was the same with the rubber molds. The two halves were held together with heavy spring clamps as with the rubber molds. Once warmed up the pours went well. I am thinking in production a toaster oven could be a heat soaking pit for the molds. They don’t need to be super hot. A couple of hundred degrees at most.

The reason for the test is my long range plans. I am considering making the aluminum molds for sale to others. I have the shop and the CAM experience to make the aluminum molds of almost anything. If it can be drawn with no undercuts, I think I can make the mold. Perfect work for the small shop.

The aluminum molds will last almost indefinitely while there is a certain usable life to rubber molds. I am also considering offering various products that I will cast in my proprietary molds.

In an even longer vision I am thinking machinable wax and rubber molds for casting special or short run items. Starting to think like a jeweler I guess, but not quite. Here is the place to get rubber molding information.

This is a fun project.!


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