First 2 piece mold

I finally was able to some machining done on my first 2 piece mold design for my "brush hog" replica. I decided to try and use black delrin to machine the cavity into this time, just because I could decrease the machining time by half compared to aluminum. I include a short "runner" at the top of the mold to fill the cavity. Overall I am very happy with the way the cavity and runner turned out.

The recipe:

100ml plastisol
10 drops motoroil
3 drops green
Gold flake
Red flake

Pretty disappointed with the results of the performance of the mold. I just could not get it to fill. I tried to pour slow, I tried to pour fast, neither method was successful a filling the entire cavity. Each attempt only filled the the main body, the "arms", the "legs" and a very small portion of the tail of the hog. I also found that the worm would not release from the mold as easily as it would from the aluminum molds previously used. My fix for the sticky problem, that's right, cooking oil spray. This actually worked well, but did not aid in the filling of the cavity. Next I tried to open the runner diameter from 1/4 inch to 3/8 inch, no change. I tried to drill a 1/4 inch hole on the back of the mold through to the cavity body, and tried to fill the cavity with the mold laying horizontal instead of vertically, no changes.

Now, I am little frustrated at this point, I think mostly because I had very high hopes for this process, and for it to fail so miserably, is very disappointing. I remind myself that this is how R&D works and to not give up, and learn from mistakes, analyze the situation and come up with some improved processes and develop better ideas. I think that I am trying to be too precise with my designs, too much detail. Or maybe the size of the extremities on the worm are just too small to fill properly, I designed the worm with an overall length of about 4 inches, I think I need to go bigger, bigger legs, arms tail, everything. The other thing I think I need to change is the delivery of the plastic to the cavity. I need some sort of injector, I think. Something that will inject plastic quickly, and with some pressure.

I continued to pour the reaming plastic in the 1 piece aluminum molds that I had previously made, so that I could get a good look at the color scheme and the flake distribution in the plastic. This I am very pleased with! The color is awesome, and I do not think the photos give it justice. Out of direct sunlight the worm appears to be a dark, mossy, green color with dark red flakes. But in direct sunlight, the craw is a medium brown and transparent gold, with bright reflective gold and red flake. This is definitely a keeper recipe.

My first 2 piece mold, made from Delrin.

First pours from new 2 piece mold (FAIL).