small crappie bluegill mold

[robbor]

I just made my first mold today in a cnc class i have been taking.

So the pic is for 1/2 of a small injection mold and 48 cavaties, i did not want to push 50 as it was getting tight. It turned out pretty good so far. The lure is just under 1" and have a pertty small tapering tail, i also mill'd it almost exactly 10% larger than the size i wanted for shrinkage. I cant wait to until i can get some plastic and try some. Today was our last day of work so Ill have to wait for next semester for the other mold programs I wrote.

[Vodkaman]

The mold looks very good. I think you are going to make a lot of friends.

I have not done any injection molds, so if my concerns are unfounded, then at least I learn more. My concern is the lack of vents, especially for the tails. With no vent, there is going to be nowhere for the air to go in the short time of the injection process. This back pressure is going to prevent the plastic flowing into the tails.

Dave

[robbor]

The other mold I had made years ago had very slight vents put in by what looked like a engraver. Anyways I left the vents out figuring i could easily put them in by hand with a razor blade and ruler and then a swipe or 2 with some sand paper and its good to go. I also made 2 jighead molds that i just totally finished last week but they were made on a manual mill. Here is my other mold and if you look on the half with the most detail you will see the small vents. Good call though. both mold are the same size

Edited December 14, 2008 by robbor

[Vodkaman]

That is good that you have already considered the problem. I tend to analyze things to death and then prepare plan 'B's for the possible issues, because I hate surprises.

Your solution is what I had in mind, scratching a vent to the side, venting to atmosphere. This is only required on one half, a fact I am sure that you are aware of.

Dave