Injector Plug At End Of Stroke

[FuzzyGrub]

I am new to injection and still new to soft plastic making. When using my Bass Tackle Injector, I notice it always plugs near the end of the stroke. The tip allows easy removal of the plug. At first I thought I was doing something wrong, but a search shows that this is common across most/all? injectors.

From reading, many people seem to indicate they think it has to do with the tip cooling. As a newbie, I came to a different theory.

My thought is, it is caused by the cooling of the piston. As the injector is pushed forward, cold air is drawn into the back. This cools the back side of the piston. Also, the piston shaft acts as a long heat sink.

I haven't tested my "newbie" theory yet, but will. It should be an easy test. Add a layer of rubber gasket material to the back side of the piston, and a phenolic washer between the piston shaft and piston.

It probaly won't eliminate the plug, but maybe it will reduce it significantly. Thoughts?

Anybody already try this?

As a newbie, am I doing something dangerous or stupid?

[Vodkaman]

My thought is, it is caused by the cooling of the piston. As the injector is pushed forward, cold air is drawn into the back. This cools the back side of the piston. Also, the piston shaft acts as a long heat sink.

I haven't tested my "newbie" theory yet, but will. It should be an easy test. Add a layer of rubber gasket material to the back side of the piston, and a phenolic washer between the piston shaft and piston.

You could be right, what you have written makes sense. If you ARE right and the solution is that simple, then their are going to be a lot of engineers kicking themselves for not thinking the problem through properly. I include myself too, even though I don't pour plastics or own an injector, I have read all the problem posts and feel that if a problem exists, I want to solve it.

Good luck with the testing. Be thorough and certain before publishing.

Dave

[powerworm]

they dont clog if we are doing our part and getting the plastic out of the injector in a timely manner!! just dont dilly dally and it wont clog up!!

[Frank]

The whole thing is a heat sink. If you seal off the shaft end it will be hard to fill it. The plug at the end is just a thing that we all have to deal with unless you want to inject with an injector that is 350 deg. The thicker the aluminium the more heat it will hold but then most of us dont keep the plastic in the injector that long. Would love to see someone come up with a solution that does not require a hot injector. Frank

[t-billy]

Had the same problem at first. Now I have the top half of my caney creek injector wrapped with an old sock to help hold heat. I brought an old steel bushing from the eye of a hydraulic cylinder home from work and now stand my injector inside of it. I use the sock to keep the tip suspended slightly above the hotplate burner. Problem solved. I can handle the injector bare handed and the tip never plugs. I'm going to make my own injector using a brass pipe nipple and a couple caps soon. Should be a major improvement.

[Delw]

your always going to have some kind of plastic that cools off in the injector, even if its a small amount it will need to be cleaned out, I would think it would be impossible to make it otherwise.

one reason to have more than 1 injector and alwyas leaves the ones your NOT using in a batch of hot plastic.

I'd be curious about getting one ceramic coated on the outside to see how that worked, I dont shoot hours on end I shoot a few baits at a time so I dont have to wrap the injector, but the napa 1 pint one made of steel I do have to wrap with a towel and duct tape to use it when testing the bigger molds.

I liek the sock Idea, if I would have thought of that I would have used it.

Would love to see someone come up with a solution that does not require a hot injector. Frank

Frank its been out for years and years, its called a injection machine LOL,dont have to do anything but let it run

[t-billy]

Frank is right about sealing the rod bushing.It won't work if you do. You must have air flow behind the piston. Hand injectors are very basic hydraulic cylinders. If you seal the rod bushing you'll have a very basic shock absorber.

[FuzzyGrub]

Thx for comments. One thing I'd like to clear up, is the thin insolator pad would go directly on the back of the piston. It will not cover the hole on the end of the injector that lets air in. The phenelic washer would attach at the back of the piston, as well.

I'm sure by next season, I will have two injectors. For now, just the one and if I can get a little more plastic out of it, the better.

It will be a few days before I will be able to test. Finishing up some molds and other things.

Additional comments welcome.

[Frank]

your always going to have some kind of plastic that cools off in the injector, even if its a small amount it will need to be cleaned out, I would think it would be impossible to make it otherwise.

one reason to have more than 1 injector and alwyas leaves the ones your NOT using in a batch of hot plastic.

I'd be curious about getting one ceramic coated on the outside to see how that worked, I dont shoot hours on end I shoot a few baits at a time so I dont have to wrap the injector, but the napa 1 pint one made of steel I do have to wrap with a towel and duct tape to use it when testing the bigger molds.

I liek the sock Idea, if I would have thought of that I would have used it.

Frank its been out for years and years, its called a injection machine LOL,dont have to do anything but let it run

Yes Del you are right it is out there but not in my Shop. I do shoot alot but dont want it to be like a JOB. Frank

[t-billy]

Oops. Sorry bout the misunderstanding Fuzzygrub. The washer/insulator shouldn't cause any problems. The only issue I have with the sock/bushing setup is plastic dripping on the burner and scorching. Hmmm. Sounds like a good lunchtime project. My injector has thin walls. It kept clogging the first time I used it. But once I wrapped the sock on it and hung it inside the steel bushing,problem solved. I shot 3 dozen frogs. Not one clog.

[mark poulson]

Oops. Sorry bout the misunderstanding Fuzzygrub. The washer/insulator shouldn't cause any problems. The only issue I have with the sock/bushing setup is plastic dripping on the burner and scorching. Hmmm. Sounds like a good lunchtime project. My injector has thin walls. It kept clogging the first time I used it. But once I wrapped the sock on it and hung it inside the steel bushing,problem solved. I shot 3 dozen frogs. Not one clog.

Like the old lymric goes:

"In days of old, when knights were bold, and condums weren't invented,

they stuck a sock upon their ____, and babies were prevented".

Old socks do come in handy.

[t-billy]

Like the old lymric goes:

"In days of old, when knights were bold, and condums weren't invented,

they stuck a sock upon their ____, and babies were prevented".

Old socks do come in handy.

LOL!!! That's funny. Depending on what your using it for,you might want to make sure it has no holes in it.

[FuzzyGrub]

FWIW: I made a washer out of phenelic circuit board to go on the back of the piston, and had a pvc pipe that fit tightly over the barrel. Only did one little quick pour. At this point, all I can say is, it didn't make it worse. I will repost when I have some more "run" time.