Help/Tips on making molds of open style rims

[LouO]

Just started playing around with making molds/resin parts and having success so far with solid style rims (i.e. centerlines) and now experimenting with open style rims (i.e. cragar SS's) but running into issues with getting the areas between the spokes to stay open. Any tips, tricks or suggestions are welcomed.

[Art Anderson]

Just started playing around with making molds/resin parts and having success so far with solid style rims (i.e. centerlines) and now experimenting with open style rims (i.e. cragar SS's) but running into issues with getting the areas between the spokes to stay open. Any tips, tricks or suggestions are welcomed.

To cast wheels (or any other parts) which need to have clean, open holes or slots really takes a two piece mold.

Art

[Erik Smith]

Post a photo of actual wheel - you might be able to still use a one piece mold if the openings are flush with the back of the wheel. Otherwise, as Art says, you will need a two part mold. Even with a two part, resin will flow into the gap but, with a good mold, will be thin and easy to clean up.

[Art Anderson]

Post a photo of actual wheel - you might be able to still use a one piece mold if the openings are flush with the back of the wheel. Otherwise, as Art says, you will need a two part mold. Even with a two part, resin will flow into the gap but, with a good mold, will be thin and easy to clean up.

Even if the wheel is flat on the back side, making a separate, flat mold (easy enough to do, just make a mold box with some Evergreen sheet and 1/8X1/4 inch Evergreen strip stock--that makes a smooth, perfectly flat block of rubber!) which can be pressed down on top of the female mold used to make the wheel--that will guarrantee very thin flash in any openings in the wheel castings, as well as giving a wheel that is as precise as the one used for the master(s). Something from years of experience resin-casting (and several thousand resin wheels)

Art

[Erik Smith]

That's what I was thinking Art - I guess technically that's two part mold, but a simple one that you can pour at the same time and doesn't involve claying up, etc.

[Art Anderson]

That's what I was thinking Art - I guess technically that's two part mold, but a simple one that you can pour at the same time and doesn't involve claying up, etc.

Yup Erik,

For wheel halves that had nice flat back sides, the smooth block for the second mold half worked like a charm--especially as at times, I was literally mass-casting wheels. However, for a wheel needing a 2-piece mold, but that is not flat on the back side, then it takes some clay work.

Art