Injector Problem

[patrick reif]

First of all, I'm not slamming Bears company in any way with this thread.

I think he makes a top notch mold, has excellent customer service, and is a respectable business man with genuinely innovative ideas.

 

However, I recently bought one of his injectors and have had nothing but troubles with it.  

It won't pull the plastic up, and because of the lack of a locking pin, I've shot the nozzle in hot plastic several times.  

 

I've finally resolved myself to just removing the nozzle and hand pouring the plastisol into the injector, inserting the nozzle, and shooting my mold. 

This is more trouble than it's worth, but for larger multi-cavity molds, it's a means to an end.

 

Has anyone else had a similar issue and how did you resolve it?

 

Please, let's not turn this into a bashing fest.  Bear deserves better than that.

[mark poulson]

Have you contacted him for his advice?  

[CNC Molds N Stuff]

I make my own injectors, and I have made a few that did not work.  Its always an air leak.  If it does not draw plastic I would be a little nervous about pouring plastic in it given that the leak is probably around the piston.  It does not happen often, but if the o-ring groove is machined a smidgeon too deep it will not draw plastic. 

 

Its also possible that the piston and nozzle are exactly the same as previous parts they make but the tube has a slightly larger ID than previous batches of tube, and they are not aware of it yet.  This sort of thing happens in the metal industry.  Sizes are not highly precise in stock.  They have a degree of tolerance that can vary fairly dramatically.  Even the same vendor may have gotten their tube from a different mill, or the same mill have had to replace a drawing die for extruding the tube. 

 

That being said I suspect an email or a call to Bears will get it fixed or replaced or taken back at zero cost to you.  That is the way they have treated me when I had a problem.  Anything they can do to help, and then your money back if they can not.  You might have to ship back the injector, but with priority mail that does not cost all that much.  It might even fit in a padded flat rate envelope if you take it apart. 

 

Also, do not worry about the call Bears first responses.  Most of us are highly loyal to our suppliers in this group, and its tempting to take a question about a problem as a negative criticism.  Yeah, I agree you need to ask Bears as they are the most familiar with their product, but I also know its a holiday weekend and the odds of getting a fast response are slim, so asking here too makes perfect sense. 

 

If the problem is a slightly too loose o-ring fit in the cylinder you might try "long shot here" seeing if anybody is open that has an open bin selection of O-rings.  One with a larger cross section might be too tight.  One with a larger cross section and a smaller diameter stretched to fit might be a good compromise as the cross section will decrease slightly when the ring is stretched. 

 

Given that you think the nozzle falls out to easily perhaps you have an air leak there.  It could also cause the injector to draw air instead of plastic.  The same thing might help... and it might not. 

 

Another options other than looking for a tighter o-ring fit combination if you decide the problem is a loose fit might be to make a wrap or two of Teflon tape in the groove.  The o-ring will have to hold the Teflon tape in place as its not a sticky tape, but it is something that can act as a "shim" in the groove that should be able to take the relatively low (as industrial process go) heat of molten plastisol.  Teflon tape should be available at any hardware store that might be open. 

Edited December 23, 2012 by Bob La Londe

[Painter1]

I, too, struggled with getting my injectors to draw plastic, as I saw done in Frank's videos.  I think mine are from BT (They are the ones you can combine into "Twinjector").  I saw a Caney Creek video where Jason poured the plastic into the injector and just adopted that as my SOP.  (even though he warns not to do that)

 

Pouring the plastic into the cylinder can be dangerous, however.  It is almost impossible to see the rising volume inside the cylinder while actively pouring because of the steam/smoke.  Temperature is a consideration so I never wanted to dally.  Most times I was able to get the level right, insert and twist on the injector tip, and adjust level with the plunger.  One day I poured too much and I burned my thumb with the overflow when putting the nozzle on.  I was careless and was not wearing a glove on that hand (dexterity issues).  

 

The other problem I had with hand pouring into the injector was heat sink.  I had to "waste" one cylinders worth of plastic by letting it heat the aluminum from inside.  It did seem to hold the heat well after that.  

 

I vowed to stop pouring into the injector and ended up buying the Shooting Star system.   Someday soon, however, I will need to address the issue properly.

[carolinamike]

Patrick, Definatly contact Bear. He is aware of the problem with a few of the injectors, I talked to him last week and he had told me about a couple that he had replaced due to the specs being off a little, so just let him know whats going on and i'm sure he will get you a replacement out asap.

[Bass-Boys]

I have 2 keep the ones i have clean inside to get good plastic draw. when clean they work great.

[Jig Man]

I have Bear's injectors with two sizes of nozzles.  I have been using them for about 3 years and don't have any problem with them drawing.  I work in an unheated garage so before I use them I place them on a griddle to get them warm. 

 

Then I dip the plunger head into cooking oil to get the O ring lubed.  I pull the plunger a couple of times to lube the inside of the tube.  Then I put the nozzle on and draw up the plasitsol.

 

When I evacuate the injector I have learned to hold the nozzle with my off hand to keep it in the injector.  Those good to 500° gloves that I got from Bear are invaluable for this operation.

 

Let me know if I can offer any more assistance.

[mark poulson]

I use spray PAM to lube my plunger before I load it each time.

[carolinamike]

Mark, Pam also makes a great mold release when needed.

[mark poulson]

Mike,

I took your PAM advice and sprayed the allen wrench I used for dipping a tube.  It came out okay, and slid right off when I was done dipping.

Thanks.

[gcl58]

spray the cylinder with pam oil to help give it a seal?

 

untill you get yours fixed, go down to a major sporting good store and purchase the stainless steel turkey basser, break the needle and drill out the injection port, been using three of them for about six years, i can shoot two 8-inch of shore baites, 4.5 ounces per cavity, the only failure, plunger rod broke, replaced it with s.s all thread

 

good luck