luvtwofish Posted January 26, 2011 Report Share Posted January 26, 2011 Hi, I'm using a 4 oz. hand injector and injecting into hand pour molds. The tip fits fine but after injecting the 1st cavity, it seems that pressure or air is making the previous filled cavity or cavities purge or push plastic out of the sprue. Do any of you have any advice on injecting hand pour molds? Thanks alot! Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted January 26, 2011 Report Share Posted January 26, 2011 Hi, I'm using a 4 oz. hand injector and injecting into hand pour molds. The tip fits fine but after injecting the 1st cavity, it seems that pressure or air is making the previous filled cavity or cavities purge or push plastic out of the sprue. Do any of you have any advice on injecting hand pour molds? Thanks alot! Can you post a pic of the mold. It sounds like your vents run from one cavity to the next instead of venting out to atmosphere. Dave Quote Link to comment Share on other sites More sharing options...
luvtwofish Posted January 26, 2011 Author Report Share Posted January 26, 2011 Thanks for your speedy response, Dave. I injected 2 different kinds of molds..Del's DES and Stik mold. They both only have vent holes on the bottom at the tails. Also closed up the two sides of the mold very tightly. Both gave me the same probs. I also tried different pressures on pushing down on the the injector..very slow, slow and med. Quote Link to comment Share on other sites More sharing options...
powerworm Posted January 26, 2011 Report Share Posted January 26, 2011 (edited) some molds werent made to inject without adequate venting. you actually might try tightening the molds up then loosen them a smidge to allow air to escape. but what you said about it pushing up in the previous cavity makes me think they are already loose maybe too loose. it could be a bubble from trying to inject it too fast??? Edited January 26, 2011 by powerworm Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted January 26, 2011 Report Share Posted January 26, 2011 some molds werent made to inject without adequate venting. you actually might try tightening the molds up then loosen them a smidge to allow air to escape. but what you said about it pushing up in the previous cavity makes me think they are already loose maybe too loose. it could be a bubble from trying to inject it too fast??? I think Powereorm nailed it. Dave Quote Link to comment Share on other sites More sharing options...
FuzzyGrub Posted January 26, 2011 Report Share Posted January 26, 2011 Thanks for your speedy response, Dave. I injected 2 different kinds of molds..Del's DES and Stik mold. They both only have vent holes on the bottom at the tails. Also closed up the two sides of the mold very tightly. Both gave me the same probs. I also tried different pressures on pushing down on the the injector..very slow, slow and med. I'm new at it, but have injected three of Del's pour style stick molds and have not seen what you describe. If it was plastic pushing the 1st cavity out, I would have thought that once you demold, the path would be obvious. Do you have pictures of the two baits? With the same clamping arrangement, do the molds hand pour fine? Is your plastic very thin and run out of the injector nozzle as you move from the 1st cavity to the 2nd? If so, you are pushing an air bubble into the mold. Last thought, what kind of work surface are you using? I have a wood bench, but was wondering if you might be using a very smooth and flat surface, such that when you push down with the injector, you are sealing off the bottom bleed holes. This is just a thought, and don't know if that is possible. Quote Link to comment Share on other sites More sharing options...
TheRegulator Posted January 26, 2011 Report Share Posted January 26, 2011 There was a mold maker on here (don't remember which one)who I remember posted that more of the mold was ground away on hand pour molds to help venting. So more of the surface where the molds meet is gone. When you look at the hand pour mold put together you can see a slight gap. I'm sure when you inject the the second cavity you are forcing gases in to first pushing plastic out. I would try shooting slower, or a few have been making adapters to place on the top and shoot the mold all cavities at once. I'm sure this would correct as the plastic is being pushed in all cavities together. Quote Link to comment Share on other sites More sharing options...
smallmouthaholic Posted January 26, 2011 Report Share Posted January 26, 2011 Hi, I'm using a 4 oz. hand injector and injecting into hand pour molds. The tip fits fine but after injecting the 1st cavity, it seems that pressure or air is making the previous filled cavity or cavities purge or push plastic out of the sprue. Do any of you have any advice on injecting hand pour molds? Thanks alot! Your pushing too hard on the injector-single cavity stick worms hold a small amount of plastic vs. A 4-5 cavity injection mold made specifically for injection. Quote Link to comment Share on other sites More sharing options...
