Air bubbles help

[gulfhobieman]

I'm new to injecting my own baits, and I've got a problem. After a couple of injections I start to get large air bubbles in my baits. I suck up the plastic and it's at least 320 degrees every time after the first time. I've tried tightening and loosing my clamp and heating my mold and injector. The bubbles remain. I'm thinking I might be sucking up air in my later rounds when I have less plastic in the cup. Any ideas?


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[Apdriver]

Be sure and check your injector. Hold your finger over the end where plastic would be drawn and pull the plunger and let go. The plunger should snap back to the bottom of the injector. If it doesn't, you're probably drawing some air. Replace o rings and/or add Teflon tape behind them to get a good seal. Also purge first draw or two to evacuate any air. Hope this helps. Good luck.

[Justin9j]

And make sure your injector has enough plastic to fill the mold.

[pjmcla]

Also be sure to purge ( or burp ) the injector.  After sucking up your plastic, hold the injector, nozzle up, for several seconds.  Then slowly push the plunger in while still holding the nozzle almost vertical over your pyrex / plastic vessel.   Air will come out first and then the hot plastic <- Do this SLOWLY.  This process really helps purge air from the injector.  Be Careful. 

[efishnc]

I had/have the same problem with O-rings, but my cure was/is to put the cup right next o the mold, then draw plastic into the injector, and leave it stationary (vertical) in the cup for a second or two (which allows the air bubbles to float to the plunger)... then without purging, I hop the injector from the cup to the mold and inject.  I get good quality plastics this way.

Hey APD- I'm going to give your Teflon tape idea a try... I think it definitely has merit, and I hope it can speed things up for me... have you done this to your injector?

[gulfhobieman]

If I wait several seconds to purge it will I not run the risk of it cooling in the tip as I inject?


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[efishnc]

I don't purge my injector, I simply allow any air bubbles to float up and away from the plastic that will be getting get pushed into the mold.  If your plastic is warm enough, you shouldn't have problems either method.

[Justin9j]

I use the Teflon tape on both my injectors. 

[Apdriver]

I had/have the same problem with O-rings, but my cure was/is to put the cup right next o the mold, then draw plastic into the injector, and leave it stationary (vertical) in the cup for a second or two (which allows the air bubbles to float to the plunger)... then without purging, I hop the injector from the cup to the mold and inject.  I get good quality plastics this way.

Hey APD- I'm going to give your Teflon tape idea a try... I think it definitely has merit, and I hope it can speed things up for me... have you done this to your injector?

Yes sir, definitely use the Teflon Tape myself too. I also cut a slot in the end of a piece of dowel rod just like a shotgun cleaning patch holder. I use this with a good size piece of terry cloth with worm oil to clean and lube the injector when I need to. Also speeds up this part of the puzzle.

[pjmcla]

You will not have nozzle problems.  I clear the solidified plastic from the nozzle just before I purge.  Usually a straw of plastic comes from inside the nozzle.  Then when you purge to liquid plastic; this reheats the nozzle.

[efishnc]

I use the Teflon tape on both my injectors. 

For as much of a tinkerer as I am, I can't believe I didn't think of the Teflon tape on my own... I'm looking forward to trying it later this week.

Thanks for posting the tip, ADP.

[BigFoot_158]

I like to heat my injector almost to the same temp as the plastic. The molds I warm them up too, if they feel cold they are.