Cmiller23

Hard Plastic Crankbait Material....

17 posts in this topic

Some of you may remember I am doing a research study at school about crankbaits. I have an opportunity to create an aluminum mold and was wondering if anyone knew exactly what material is normally used for plastic crankbaits. Im assuming its injected ABS plastic, if so is there a way to buy this material and an injector?

Thanks,

Cory

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The molded crankbaits made by hobbiests or small scale builders are solid body cast versions made from urethane or urethane foam. If there is anyone who is molding holllow plastic bodies such as you would see in a commercial bait, they haven't shared it on TU.

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I will admit that I know next to nothing on composite materials. Thanks for your responses. Has anyone had much experience the urethane castings? Are they durable enough to made as a hollow cast mold? I.E. make left side, right side epoxy them together...

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A major problem you will have with urethane resin

is getting it out of an Aluminum mold, even with mold release.

The resin gets very hard and needs to be poured in a flexible

mold such as silicone rubber.

Coley

I know this from experience with both foam and resin in aluminum mold.

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Plastic injection is not easy to do. Plastic pellets are heated up and melted in an injection machine and it is shot into the mold at very high pressure. A true mold is judged by how many pounds of pressure it will take while it is being injected. The more pressure it can take the more the mold costs. Crankbait lip molds can cost anywhere from $2500.00 to $5,000.00. So foam injection is the way to go. The best mold person on this site in my opinion is Coley. The man has done it all. In my opinion he is the best there is.

Skeeter

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I'll second that Skeeter..Coley definatley knows his stuff when it comes to molds and pouring baits!!.. Nathan

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Thanks for the info guys.

At my college here we have a CNC machine that will cut out the aluminum mold for me. It does not cost me anything, besides outrageous tuition :)

I was thinking of making a right side / left side molds with that CNC machine with 4 points to bolt it together on each corner. Do you think that the mold would withstand the amount of pressure for an injection mold. Im a mechanical engineering major, but over in the chemical engineering department they already have a small injection molding machine that I may be able to get access to as well. Im not exactly sure of the tolerances of the CNC machine but im hoping I an make a good mold. (I get to keep the mold after my research study is over) So basically I can design my own crankbait! Probably a 2" - 2 1/8" flat sider much like the spro little john with a few modifications of my own.

Edited by Cmiller23

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If they have a molding machine your plan may work. The machine will have platens to clamp your mold too; those platens are what will withstand the injection pressure. You’ll need a lip or some slots on your mold for these clamps to hold them onto the platens with. You should have an ejection system (some pins to push your part out when done), but if you’re just going to make a few you might be able to pry them out. Put in some water lines to cool your mold. Use lots of release spray. I use ABS plastic on my baits; there are a lot of plastics that will work. Polystyrene is a cheap one that a lot use. Stay away from polypropylene or polyethylene. You’ll have a hard time getting paint to stick to those.

You have some more studying to do

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