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McCoy

Injector build up

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I am having a lot of trouble out of both of my brand new 4 Oz do it injectors. They worked fine the first couple times I used them but then they started getting build up after every time I would shoot a mold. It’s just getting frustrating having to clean the injector after every time I shoot a mold. I use dead on plastix and have lubed the injector with worm oil and it still hasn’t helped. Im thinking my o-rings may need replaced but they are brand new. Anyone else have this issue?

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You never mentioned who’s injector it is. But if they are new sometimes they need a little time for the rings to set. But most of the time that comes from plastic to hot and to much pressure from your hand. Is your temp on your Plastic always about the same? Or does is fluctuate?  Don’t think new o rings will get you anywhere. 

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Thanks. These are both injectors from Do It mold company. The temp fluctuates but I shoot around 350-360 a lot of the time. I’m pretty new to making my own soft plastics and still learning. Do you think that I could have gotten the rings to hot and messed them up?

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Pam cooking spray last longer and does a better job vs worm oil. Shoot the plastic until it starts to stiffen up. Pull the injector handle(rod) all the way back,then shoot some PAM in the tube. Have a couple of paper towels handy when you push the plunger down. Wipe off the old plastic residue and you're ready to go.Some times,flat o ringers work better then oval rings.Never had a problem w/ Ultra-mold,hand  injectors in 8 years.

 

 

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Maybe I don't understand McCoy's problem, but it seems to me he is not injecting hot enough if it is cooling down enough to cause a build up. My guess is he is not injecting at 350 degrees or he is picking up some "still unmelted used plastic" from bottom of liquid container. Why is 350 to hot, that is where I inject all the time. Thanks for any info.

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I do get a plug at the end of the plunger and it gets plastisol past the O-ring also. I am using a infrared thermometer to get my temps. Dead on plastix says to get temp to at least 350 so that it cures correctly. It almost seems like the rubber isn’t out of the gooey stage. I wouldn’t see how though because I’ve shot baits at 380 degrees to see if that fixed the issue and still the same. 

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Lower the shooting temp down to 300-315. It will be thicker and won’t pass through so easy. Get the plastic to 350 and let it cool a bit. It is way to thin at 350. Especially if it’s a new injector. Takes time for the o ring to get settled in. As time goes on it will get better. But not if you keep changing the o rings. 

Edited by Frank
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Try using a digital thermometer that you put into the plastic.  Heat plastic, stir gently, take temp. Just don’t let the thermometer rest on the bottom of the cup. Hold the tip slightly off the bottom. Note the temp and then try your inferred thermometer and compare your readings. I’m curious if you’re getting false readings. 

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9 hours ago, Fishermanbt said:

Try using a digital thermometer that you put into the plastic.  Heat plastic, stir gently, take temp. Just don’t let the thermometer rest on the bottom of the cup. Hold the tip slightly off the bottom. Note the temp and then try your inferred thermometer and compare your readings. I’m curious if you’re getting false readings. 

With either temperature devise you need to be stirring while you take the temp. Some would think it will be different but at least with me it does not matter. I like stirring and taking the temp with an infrared which does not touch the hot plastic. With my probes the heat seems to migrate to the plastic tops and eventually cracks. 

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As far as the plug goes, Ultra molds makes a little gadget called an injector heater. Keeps your injector hot and eliminates the plug completely thus you don't have to takes it apart as often. Since I got mine last year I haven't had a plug ever.

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