Small molds?

[eriksat1]

Is there a good way to make a 2 piece hard plastic mold. I want to make some micro plastics for ice fishing and spring crappie/bluegill. Not super small but like about 1" to 1-1/2" long baits. It seems the best way would be a injector and a 2 piece hard plastic mold. I'm thinking you could probably use the same hard plastic you use to make baits with??
I'm tired of paying about $2 a piece after shipping for the custom small plastics, I bet I go through 100 easy in the spring with my 2 kids.

[aka anglinarcher]

Are you saying you want to mold small baits from hard plastic, or do you want a hard plastic mold in which to mold soft plastics?

www.Makelure.com has a how to section that shows videos on how to make molds from silicone, both the RTV and the putty forms. Depending on what you are doing, I suggest the RTV2 and follow the directions for making a swimbait as shown in the video.

Once the mold is formed (make a multiple cavity like shown), you can either pour with soft plastic (Alumisol) or hard plastic (Alumilite White).

[Seachaser]

You can make about anything you want, BUT you will find that it is not cheap. You will invest upwards of 100-300 dollars in materials not counting hardware. Soft plastics are cheaper, in my opinion, than hard plastic. A gallon goes a loooong waaaays.

[Mike - Alumilite]

The Hard Bait kit comes with a 1 lb of High Strength 2, 28 oz of hard plastic, microballoons, and everything else you would need to make plenty tons of your 1-2" baits. You can still inject the molds with the resin using a plastic syringe or other tube even though the mold is rubber and not rigid. With a bait that small, you should be able to make at least 3-4 molds of your size bait with a lb of rubber.

Mike

[eriksat1]

I made a mold from Alumilite HS 2 and it is working ok on the small baits. My beginners mistake was making to many pieces in one mold. In about a 8"L X 3"W X 1"H mold box, I should have only made 3 pieces, or you burn your fingers spreading it open to pour. I used the same method as Larry making the Dragon fly larvae molds. I suspended my pieces with small wire in the mold box so my pieces come out round not flat on one side. My pieces are 1-1/2" long. My problem is when pouring I end up with more excess rubber than the actual piece. I see hard plastic 2 piece rubber worm molds so the worm is perfectly round, that you would use a injector to squeeze in the hot rubber (Alumisol) into the mold. Squeeze the hot rubber into a hole in one end until it comes out a hole on the other end of the mold. I just thought maybe it is possible to make a hard plastic mold the same way you make a silicone mold? But maybe it is not that easy? 2 problems I am having with making the small soft rubber baits.
1. Hard to pour without a lot of waste/excess plastic. (Yes I know you can re-melt it)
2. The hot rubber cools off too fast in the pouring cup and I need to re-heat in microwave after about every 6 pieces poured, is there a better way to keep the soft rubber hot? Without buying the expensive melting pots. Is there such a thing as a cast iron pouring cup? It would hold the heat a long time, you could pre-heat the cast iron cup in a oven @ 350°f then pour the heated alumisol in from a microwaved glass cup. Sorry for rambling on my brain is spinning to fast.

[Mike - Alumilite]

A small electric single stove burner for camping works well on low after you've already quickly melted it in the microwave to start. I typically mix up more than what I need and use a larger glass container that I store in the microwave when I'm done pouring which typially keeps it liquid a while longer. Then just zap it for 30 seconds or so inbetween each pour. The larger the volume the longer it takes to cool and the longer it will remain pourable for you.

If you are doing multiple colors, it gets tougher unless you use the bigger batch as a master nuetral color and then use smaller containers to mix your color and pour out of.

Yes, you can make a two piece hard mold but you need to make sure the Alumisol will continue to release from the mold. Silicone is so forgiving, most people just use that for their mold. If you need a harder two piece mold, I'd recommend the Quick Set which gives the release that you want but also gives you much better dimensional stability and smaller seam lines because its much stiffer and lines up better.

Mike
Alumilite

[eriksat1]

Thanks, I will keep playing around with it and post my results. It is nice to have this forum so we can all learn from each others mistakes, and what works and doesn't work. The silicone molds are working good, my daughter and I made about 20 pieces the other night and we are already catching bluegills and some big perch on them. The crappies have still not moved into the shallows yet. I know this is hunt for big fish, and I love musky fishing as much as anyone, but my goal for this spring is a 17" black crappie caught on my own homemade bait.

[aka anglinarcher]

A 17" black crappie IS A BIG FISH!

[aka anglinarcher]

With the idea of learning from past mistakes, I am an expert at making mistakes.

Alumilite does not sell them, and I have not had one in years, but you can buy injectors for hand molding. Mike talks about the plastic syringe, and it works very well. Still, the problem with both is that the plastic cools inside and cleaning them out can be a real pain. A disposable syringe works best in my opinion, but sometimes you need to nuke it as well to keep it flowing. If you find a commercial molding injector, make sure it is one you can take apart to clean or you will get plugs and color transfer.

I had the hard plastic molds that were pre-made. I tossed them away years ago. I just love the RTV molds; they are just so versatile.

Like Mike, I use a larger batch. I prefer Pyrex measuring cups because they have quite a bit of mass to help hold the heat in. If you heat the plastisol, or Alumisol, in a microwave, mixing frequently, you almost can't burn or scorch the material. Heating small amounts in a hot pan will often damage it - not cool. Never use cast iron; it will transfer rust and change the color. I copper bottom pan would heat more evenly than an aluminum pan (my old mistake).

Mike suggests a single burner camping stove. I think that a hot plate would work well and they can be found a second hand stores or at box stores. Use this only to keep it warm, watch the temperature. I would suggest a candy type thermometer in the plastic and keep the plastic below the danger point. I think the temperature needs to stay around 350 degrees, but I would need to double check on it. I just pop mine in the microwave for a few seconds when I need to add heat.

I don't know what you use for a pour cup, but if you use a one cup Pyrex cooking measuring cup it has a pour spout on it. You can do a really good job on small projects. If you have your molds too close together, pour every other one then come back and pour the skipped ones. Still, gloves are not a bad idea until you get the hang of it.

Buy the way; I caught a 17-7/8 inch black crappie last year. For Washington State, that is HUGE. I did not weight it, and I did not take the girth, but it might have almost been our States Record. Be smarter then I was and keep a camera with you.

Big fish is relative. I remember working a small spring creek for an 8" cutthroat trout many years ago. That water was super clear and that fish was super shy. It took hours to catch, and release, that little fish. For that stream, the 8" was a trophy. Like I said, in my humble opinion, ‘Big’ fish is indeed relative.

Ericksat1, and you thought you were rambling - what about me?