Custom Baits - Forum
General => General Discussion => Topic started by: Mic on 01/27/13 11:45 UTC
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Guys,
I need some help here. I have 4 new ringed swim bait molds and have not shot one bait that is clean. I thought that the bait was bad, so I hand poured each side to check the rings...good to go. I knew the voids are coming from bubbles after that experiment. I then poured the plastic in the injector and burped the bubbles...no good still had voids. I have tried a larger mix...4 cups, 1 cup all white with pearl powder..and no go...all are bad. The bait looks great in the water but I can't get the bubbles out. I use pyrex cups, a microwave, and stir between shoots just like ever other run. I have always had a few bubbles but nothing like this. I am using the same plastic...I am not doing anything different than any other mold. ANY IDEAS.
Mick
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Are they BT molds?
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yes
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is there a problems with BT molds
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No, BT molds are fine. I have the six inch ring worm, and also had some trouble getting the air out. All those ribs act as a heat sink and cool your plastic quickly. I had to pre heat the mold, actually had to get it pretty hot to solve the issue. The problem I had then was waiting a lot longer to de mold. I ended up taking a small triangle file and making a very small vent at the tail of each one and that took care of it for me. You could try it on one bait to see if it helps, but it's not easy to undo a mod on a mold.
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How about if you try injecting slower and holding the pressure. This gives the rings more time to fill in completely and holding the pressure should help with the voids too.
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X2 on the slower injecting. I have caused the exact same issue by injecting fast thnking i had to to gett all the little appendages to fill in.. Also is the plastic in the cup bubble free? If no I will heat the plastic to about 360(add stablizer) and that will usually cook out the micro bubbles but i then let it sit and cool down to 330-340 and then inject..
I dont know if any of this will help you out.. Good luck
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Thanks guys, I will try one more time. been at it for 2 weeks
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Sounds like Voids and not Bubbles. Two totally different things.
As said make sure mold is hot, inject slower, and hold pressure at least 15 secs
....Bill
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the rings have voids that look like I have bubbles in my plastic. I have injected slow, real slow...slow enough for the plastic to set up for a partial shot on the 2nd mold. I have tried heating the mold up ... still no good.
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Just curious what formula plastic are you shooting, soft, medium or hard maybe try some softener?
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If you are grasping at straws. Here is something you might consider.
Try 350 degree plastic that has been reheated a couple of times to clear all existing microbubbles; purge the injector well; Inject a small bait mold just before you inject the ring worm. Then inject the ring worm mold slowly and hold light pressure for longer than normal. That might determine if it is voids vs bubbles. If there are no bubbles in the small bait mold there should be no bubbles in the ringworm mold.
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Had the same problem. I found I was tightening the screws in the BT mold too tight...I now only tighten until the wing nut stops. I was tightening so much the air couldn't vent out the small vents.
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I have the same mold and have shot 2000 of them with about 5 bad baits. In your initial post you mentioned pouring plastic into your injector. That shouldn't be done. bring the plastic up to temp and with a closed injector, suck of plastic and shoot...you can top it off as well.
Tim
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heat the mold to to about 150 to 200 the temp makes big differice
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I have tried the molds with the wing nuts tighter and looser, and with Irwin clamps, heating the mold, cold mold, holding pressure for 5,10, 15 and 20 counts, opened as soon as possible, with another plastic per bt and still no good. I am sending them back. been in contact with bt and they are good to work with.
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X2 with TTDuckman. Don't pour plastic into Your injector. Suck/draw the plastic into Your injector...with the injector. Put the tip of the injector in the plastic and draw with the plunger handle...shoot the mold...hold pressure for 10+ seconds, then top off the sprue with a little shot of plastic...and yes, shoot slow.
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mic,
Are you pouring the plastic into the injector? Please don't this as an arguement, I am only trying to help. If your plastic is getting to a proper temperature and you are sucking up the plastic and shooting it into the mold. It should work.
I know people have different ideas on this, but here is my take on any injection mold (except tube molds) I have ever used. The only thing that should ever be heated is the injector and that is merely for the first injection in your run (to make sure that the plastic doesn't cool prematurely in the injector). After the first injection, the injector is plenty warm. I live in northern IL and my molds are always cold in the winter on the first shot (20-50), sometimes colder. Injection molds in my mind don't need to be heated. In production, the biggest problem with productivity is mold heat. The cooler I can keep molds the better.
Tim
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In my experience working in my basement a cold mold no matter what the plastic temp with baits that use a lot of plastic or have a lot of appendages will create a shock when the hot plastic hits it. This makes the plastic cure way faster then it should. This does two things one it stops the plastic in the topped off sprue from being sucked down long enough and in turn creates the plastic voids you speak of. Now to clarify what I see as heating a mold. I don't go as far as to put them on the griddle. I don't think they need to be that hot in most circumstance they just can't be ice cubes. I actually have one of those oil filed radiator space heaters that I use to warm my shop a little and I just set the molds I plan to use on top of that for a little to take the chill off and it seems to work well for me. I found this process to be extremely helpful in the 4.5" swim shads and regular diameter carrots which both have a tendency to dent. I have a feeling it will help with your mold as well. Good luck and I hope this helps.
Don