Aluminum Mold Alloys

[mark poulson]

I recently bought several of the Essential Do-It molds.

In the past, I've easily+- altered molds to accept different hooks, or to add details.

But these sand cast molds are much harder to machine for me.

Now that I think about it, they probably use different alloys for the machined molds, because they are softer.

My father was a machinist, so you'd think I would know about this stuff, but I'm a carpenter, so I know wood, not metal, and I give good house.

Edited December 10, 2015 by mark poulson

[Vodkaman]

The surface of a cast ingot has a very hard skin. When I worked in the aircraft design industry, I had to call up specs that defined how much of the surface had to be machined away, to leave behind a consistent material. It is this hard skin that you are experiencing, caused by the faster cooling at the mold surfaces.

 

Dave

[mark poulson]

Almost sounds like case hardening.

The sand cast molds are hard down a long way from the surface, so I think they may use a different/cheaper alloy to cast them, since they don't need to be machined.

[Vodkaman]

The sand cast molds that I have seen pictures of, are skimmed purely to achieve a good joint surface.

 

Dave

[mark poulson]

I tried a dremel with an abrasive grinding disc, like a cut off wheel, and it worked.

But I wasn't able to use my drill press like an end mill to remove material, like I could with the jig molds I altered.