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Hard Plastic Crankbait Material....
16 replies to this topic
Posted 12 February 2012 - 07:01 PM
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?
Posted 12 February 2012 - 07:42 PM
Or has anyone ever used to the material from smooth-on? is this stuff durable enough to make a crankbait?
Posted 12 February 2012 - 08:13 PM
look up alumalite on u tube or larry dalburge that might work for you
Posted 13 February 2012 - 01:05 AM
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.
Posted 13 February 2012 - 08:32 AM
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...
Posted 13 February 2012 - 08:43 AM
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.
I know this from experience with both foam and resin in aluminum mold.
Posted 13 February 2012 - 08:56 AM
A while back a TU member named Hillbilly posted how he made two part plastic cranks.
Try the search tab with his handle.
Posted 13 February 2012 - 10:10 AM
That is an amazing video Hillbilly made.......I would love to see how he made the molds!
Posted 13 February 2012 - 02:56 PM
Yeah I saw that video! What material is he using does anyone know?
Also does anyone know what type of plastic is normally used for crankbaits?
Posted 13 February 2012 - 07:34 PM
I thought he said two part epoxy, but I don't know which kind. His blanks looked grey to me, if that helps.
Posted 14 February 2012 - 04:35 AM
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.
Posted 15 February 2012 - 01:35 PM
I'll second that Skeeter..Coley definatley knows his stuff when it comes to molds and pouring baits!!.. Nathan
Posted 15 February 2012 - 06:07 PM
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, 15 February 2012 - 06:08 PM.
Posted 16 February 2012 - 01:45 PM
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