Author Topic: First pour questions.  (Read 1700 times)

Offline Nails

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First pour questions.
« on: 01/08/18 23:23 UTC »
Finally got my shop ready to go and made my first pour last night. Baits actually turned out pretty good except for how fast my plastic cooled. I wasn't able to pour my 3 cavity Ripper and then move to my chub grub/split tail grub before the plastic cooled and plugged up my injector. Made sure the plastic was 350+. Next pour I'm gonna try warming the injector, also gonna buy a new microwave. The one I'm using I pulled off a shelf in the basement, it has no turntable(used the motor for my lure turner to turn cranks after painting) and is about 25-30 years old. Does plastic normally cool as fast as I experienced or are there steps that I can take to extend my pouring time? Maybe with that old microwave I didn't get a good even heat, even though my digital thermometer showed 350?

Offline Apdriver

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Re: First pour questions.
« Reply #1 on: 01/08/18 23:56 UTC »
What you experienced is quite normal. You didn’t mention which injector you were using, but if it’s thick walled, you should preheat it. I keep a propane torch with a piezo igniter on the bench just for that purpose. Others use a griddle, toaster oven, what have you. Torch works for me. Pops the heck out of bubbles too. ;D

Online Lines

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Re: First pour questions.
« Reply #2 on: 01/09/18 06:30 UTC »
Preheating the injector helps a bunch. Not actually "heating" but more "warming". I modified an electric skillet to warm my injectors. Simply cut 2 slots (I have 2 injectors) for the injector handles, so they lay flat on the skillet bottom. I normally set the temp to warm, or maybe 250°. One is always warming while the other is in use. I'll try to post a picture soon.

Offline Nails

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Re: First pour questions.
« Reply #3 on: 01/09/18 07:15 UTC »
Thanks guys, keep the tips coming. I have a toaster oven that I use to cure jigs after painting, I should be able to use that. If not, a trip to ST. Vinny's for an electric griddle/fry pan. I'm also gonna upgrade the microwave, no turntable and very old.

Offline bassinfool

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Re: First pour questions.
« Reply #4 on: 01/09/18 07:49 UTC »
Thanks guys, keep the tips coming. I have a toaster oven that I use to cure jigs after painting, I should be able to use that. If not, a trip to ST. Vinny's for an electric griddle/fry pan. I'm also gonna upgrade the microwave, no turntable and very old.
Check out craigslist or second hand stores and you may be able to find a good deal for one.

Online andrewlamberson

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Re: First pour questions.
« Reply #5 on: 01/09/18 07:58 UTC »
When you buy that new microwave get a less expensive low wattage unit. It is my observation that high  wattage microwaves cook the plastic too fast leading to yellowing...and dare I say it...micro bubbles.

I have noticed a difference in the amount of micro bubbles when I heat slowly in 30 sec vs a quick 2 minutes straight. I think a  carefull stir between heats helps to keep from jacking the chemistry of the liquid.

More experimentation is needed.
" You can't buy happiness...But you can buy fishing gear...and that's kind of the same thing"

Offline Fishermanbt

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Re: First pour questions.
« Reply #6 on: 01/09/18 15:53 UTC »
I too have an ancient microwave w/ no turn table. I believe Columbus brought it over on the Mayflower. But it was free. I run an electric heater in the garage while pouring and I’m able to set my injector on the safety bar on the front of it. When it’s not in use I go to the toaster oven used to bake jigs. Both work great for my set up.

Offline slowguy

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Re: First pour questions.
« Reply #7 on: 01/09/18 19:15 UTC »
I agree with Andrew, you can pick up a small microwave at discount stores.  The one I use came from Walmart for just $35 dollars.  Big enough to melt my plastic, yet small enough to fit on a shelf by my work table.

Offline Nails

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Re: First pour questions.
« Reply #8 on: 01/12/18 06:59 UTC »
UPDATE: I got the clogging issue in the injector fixed, preheating the injector and pouring plastic into instead of drawing plastic in helped. Now I have to figure out how to get rid of the large air bubbles I'm getting. I have an ES Ripper Mold and a 3'' Chub Grub Combo. I'm getting a large air bubble in the top of the body of the bait. On the Ripper it happens occasionally on the single cavity. On the double cavity part of the mold, never on the bottom cavity but always on the top cavity. On the Chub Grub, never on the bottom and always on the top. Seems air is getting trapped there and not escaping the mold through (vents ?) Now, if I really push down on the injector then tip it a bit then push down hard again my success rate goes up. Am I doing something wrong. The baits that are turning out are really nice but production is slow because of all the bad baits. Can't wait to get this figured out to I can start playing with some different colors. Thanks guys.

Offline Nails

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Re: First pour questions.
« Reply #9 on: 01/12/18 07:03 UTC »
Oh and by the way. I picked up a new microwave at home depot and that helped a ton with heating the plastic. The old one was heating so unevenly that I had to stir a lot which caused tiny air bubbles and also would burn the plastic causing a small marble sized black glob right in the middle of the cup. All that is gone now with the new oven.

Online andrewlamberson

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Re: First pour questions.
« Reply #10 on: 01/12/18 08:29 UTC »
Are you purging the remaining air out your injector before you inject? Inject a little bit of plastic back into your cup so when you inject into the cup you are starting with plastic not air.

It sounds like you may be running out of plastic and youb are injecting some air into the mold. Make sure your injector is completely full.

The last possibility given your description of how you avoid it is that the o-rings on the nozzle are worn.

Andy
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Online ctom

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Re: First pour questions.
« Reply #11 on: 01/12/18 08:56 UTC »
I always pull plastic into the injector from the cup with the nozzle down into the mass about 1/2", let it rest a second while still in the cup then shoot a tiny amount back in the cup then inject holding the injector straight up and down, not tilting it to one side while plastic is in it and I never have issues with air. I've gotten more pour-burns filling an injector than any other way so I simply quit doing it that way. Lots of air goes in with the plastic too.

Secondarily to filling by pulling plastic from the cup into the injector is that the nozzle is left with a ring of plastic around it that acts as a positive seal at the injection port of the mold in the off chance that the port has is not a perfect match to the nozzle's shape. Way less spilled plastic at the injection site. 

There's no right way or wrong way to fill the injector but its been my experience that bubbles in baits are almost always associated with air in the injection system from pour-filling. Bad rings don't happen often with regular injector cleaning and care so air from that aspect is not often an issue. Micro bubbles are a plastic issue and are addressed in an entirely different way.

Offline bigmitch

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Re: First pour questions.
« Reply #12 on: 01/13/18 13:06 UTC »
Could he possibly be talking about "Denting" and not a large air bubble?  Are you holding pressure for a few seconds with your injector at the end of your shot?

Offline Nails

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Re: First pour questions.
« Reply #13 on: 01/14/18 10:24 UTC »
Yep, large air bubbles. Have gotten a bunch of good tips and have gone back through the archives reading old posts and watching videos. It seems I must be letting air get into the injector. I'm sure there is a simple fix, I just need to get it figured out. Heading down to the shop now to pour a few baits. Gonna puts these tips to use and will post results after pour.

Online Lines

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Re: First pour questions.
« Reply #14 on: 01/14/18 14:18 UTC »
I have a couple molds that, if shot too fast, will get air bubbles. If I shoot slowly I don't get that.
« Last Edit: 01/14/18 17:30 UTC by Lines »