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Bears Tube Mold

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The injection tubes molds are tricky.The plastic can't be too hard or too soft and- if you continue re-heating old plastic w/out adding new material ,you'll end up w/ incomplete pours.I've shot hundreds of them in 3 different sizes including laminates.Push too hard on the injector and they flash-too light and the tails are incomplete.Each tail must be removed from the mold 1 @ a time or separated later.They are excellent when finished but take time to make and complete .You'll have flashing unless you have a precise method and pressure of injecting them.There are plenty of caveats associated w/ hand injecting so don't expect an early retirement w/ the $ you'll make from hand injection. :o Check the temperature of your plastic. I start w/ the temp. @ 360+ and shoot 24 molds in one round of injecting.

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I thought that would take care of it also but still no go.

Its the mold. There's too much clearance between the core pin and mold cavity. The core pin isn't quite large enough to stop the plastic from flowing between the grooves in the core pin. That style mold needs a precision slip fit of the core pin and mold cavity for it to work properly.

I would try a little hardener in the plastic and lighten up the injector pressure, if that doesn't help, then I would contact the manufacturer

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HOTTER PLASTIC AND DONT PUSH VERY HARD AT ALL TO GET A FEEL FOR IT I HAVE A DOZEN OF THESE MOLDS AND THEY WILL ALL FLASH PER SAY IF I PUSH TOO HARD. THEIR CLEARANCE IS LESS THAN .001 THATS THE SMALLEST SHIM MATERIAL I HAVE TOO CHECK IT WITH AND IT WONT FIT IN BETWEEN THE MANDREL AND SIDES OF THE MOLD SO ITS CLOSE ENOUGH TOLERANCE UNLESS YOU PUSH YOUR INJECTOR TOO HARD!!

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HOTTER PLASTIC AND DONT PUSH VERY HARD AT ALL TO GET A FEEL FOR IT I HAVE A DOZEN OF THESE MOLDS AND THEY WILL ALL FLASH PER SAY IF I PUSH TOO HARD. THEIR CLEARANCE IS LESS THAN .001 THATS THE SMALLEST SHIM MATERIAL I HAVE TOO CHECK IT WITH AND IT WONT FIT IN BETWEEN THE MANDREL AND SIDES OF THE MOLD SO ITS CLOSE ENOUGH TOLERANCE UNLESS YOU PUSH YOUR INJECTOR TOO HARD!!

Maybe the hinge is allowing the mold to open up when injector pressure is applied

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Plastisol will not flow into a gap less than .003" so there has to be more space between the core pin and cavity than that to allow for the flashing.

Try one pour with a 'G' clamp in front of the hinge. This would confirm.

Dave

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i still say its a pressure problem i went out and checked all of mine and the 1/1000th shim stock i have wont go in between the mandrel and the cavity of the mold but i can push on the injector hard enough to make the ends of the tail sections come out in 1 piece on the ends; but only if i push too hard they are alot easier to work with hotter plastic and just let the weight of your hand slide the plunger down!!

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i still say its a pressure problem i went out and checked all of mine and the 1/1000th shim stock i have wont go in between the mandrel and the cavity of the mold but i can push on the injector hard enough to make the ends of the tail sections come out in 1 piece on the ends; but only if i push too hard they are alot easier to work with hotter plastic and just let the weight of your hand slide the plunger down!!

I believe you, but the core pin and mold cavity are tapered, which puts the length of the pin and cavity into play. As the injection pressure is applied, it forces the core pin down, thus increasing the gap between the tapered pin and mold cavity. I've been in the Tool & Die trade for 30 years, (Good Lord I'm getting old) but to make the tapered design work properly, the machining tolerances of the mold cavity and core pin would have to be within +/-.0002"

It's simple trigonometry.

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I put a toothpick behind the mandrel to keep it from sliding back but it did'nt work, the best one tonight was the first one with a cold mold? It's like a slow day of fishing .... is it me or the fish? It's just hard to beleive the plastic would flow through such a small crack, I wonder if? If maybe the skirt went all the way to the end of the mandrel to releive the pressure, and then just trim the end? Or maybe just air flow grooves on each tentacle?

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Not amazing at all Considering it is Bear He customer service is second to NONE!!! Simply the BEST customer service in this business period..

There is NO ONE that could come close to bears Customer Service

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There is NO ONE that could come close to bears Customer Service

Yes I was amazed also I had a new mold in like three days. I dont know what was wrong with the first one , but the new one is perfect, it dont matter hard plastic or soft, and the temp either ....just not to cold! :D

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