mainebassman Posted April 3, 2009 Report Share Posted April 3, 2009 Hi I am new at this. I have netcrafts plastic stik molds and injector and when i fill them to the top and let cool then take them out of the mold there are dents in the worms. What do i do to fix the problem? All info is appreciated. Thanks Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted April 3, 2009 Report Share Posted April 3, 2009 This link is to a thread that covered this subject comprehensively: http://www.tackleunderground.com/forum/soft-plastics/15558-dents.html You should find something in the reading to help you. Dave Quote Link to comment Share on other sites More sharing options...
carolinamike Posted April 3, 2009 Report Share Posted April 3, 2009 There's a couple of things that can cause this. Too soft plastic will do it. If the plastic is too soft some baits will naturally form a small dent when cooling, it's according to the size and shape of the bait. The way most large injectors get by this is by holding continual pressure on the bait until it's had enough time to set up. Next time maybe you can overfill your injector a little and when you make your shot, hold the pressure on it for a minute or so. That will probably take care of your problem. If this doesn't work, then I'd use just a little bit of hardener in the plastic and try holding continual pressure on the injector. If that doesn't work PM me or make another post maybe with some pictures. I'm sure there's enough of us on here that can put our heads together and come up with a solution. Quote Link to comment Share on other sites More sharing options...
mainebassman Posted April 3, 2009 Author Report Share Posted April 3, 2009 (edited) [i will try the suggestions you come up with to see if it makes a difference. I have been filling the mold so it just about overflows but it is hard to keep constant pressure on when cooling because it cools in the injection hole in the mold first cause that is the smallest part of the mold. I read alot of the post on dents but they seemed to refer to pouring instead of injecting. Where i am new at this i didn't know if there was a little different approach to fixing the problem Thanks for all the info. Jimmy Edited April 3, 2009 by mainebassman Quote Link to comment Share on other sites More sharing options...
Pitbull Baits Posted April 5, 2009 Report Share Posted April 5, 2009 Be careful with thoes injector's they will blow back on you. Quote Link to comment Share on other sites More sharing options...
james bradshaw Posted April 5, 2009 Report Share Posted April 5, 2009 Heat is also your enemy when it comes to dents in your baits, cut down your heat if possible. If you can hold the preasure longer and less heat, harder plastic. All of these things change the outcome! I have shot a bunch of baits both in a large production injection machine and shot hundreds of baits in prototype molds with a syringe, and those are the first things that I look at when dents show up. Maniac Custom Lures Quote Link to comment Share on other sites More sharing options...
wildtail97 Posted May 5, 2009 Report Share Posted May 5, 2009 Anyone figure out what else to do about dents in lures? I am injecting aluminum molds. I have checked all the threads and still dont have a "clear" answer. Any help would be great! Quote Link to comment Share on other sites More sharing options...
gone2long Posted May 5, 2009 Report Share Posted May 5, 2009 Are you de-molding too soon? That's the only time I have had a dent. Quote Link to comment Share on other sites More sharing options...
Delw Posted May 5, 2009 Report Share Posted May 5, 2009 Anyone figure out what else to do about dents in lures? I am injecting aluminum molds. I have checked all the threads and still dont have a "clear" answer. Any help would be great! you wont get a clear answer unless your more specifc as its anyones guess and nothing more. would help with a picture of the dent, type of injector ( hand or machine) psi , type of mold plastic with or with our salt etc etc. the dent phrase is used too much and its meaning is different depending on who is useing it. Dents and voids get easly confused so with out a picture and specifics your not going to get a close answer to your problem. A dent is usually cause by the plastic hitting the side of the mold then sucking back into the center of the mold, it will give you a imression of the ribs or what ever is on the side of the mold but its dented. this is usually cause by plastic hitting the side cooling and be sucked in during the cureing process as plastic shrinks. what enhances the shrinking is air bubbles in the places salt or glitter NOT completely mixed, and on very rare occourances( which I just figured out a few weeks ago is someing oily on the aluminum in that one area) yeah blew my mind too. the plastic will lightly stick to a machined aluminum mold but if somethign on it is very slick only in one part then everything will stick during cooling except for that one part. to fix that use accetone and clean the mold or a brake carb cleaner then blow it off with air. the other thing that will cause it is if you have a very smooth fininsh in one part of the mold that will also likely be dented. Like I said there are many things but with out specifics and details you will never get the correct answer and know it. Delw Quote Link to comment Share on other sites More sharing options...
wildtail97 Posted May 6, 2009 Report Share Posted May 6, 2009 We hand inject and get dents/voids. We also have a small injection machine that we have ran lower pressures from 5 psi - 25 psi. I am unable to show images of our lures due to patent info that has not been published yet. We get the dents/voids any way that we try to shoot the molds. It always seems to be the same size dent/void, its about a half inch long and varys 1/8 inch deep. We do NOT use salt or glitter and we are using Calhoon medium adding hardener. Hope this helps! Thanks Quote Link to comment Share on other sites More sharing options...
Tubeman Posted May 6, 2009 Report Share Posted May 6, 2009 My experiance is the thicker the bait, the more likely your going to get dents. Plastisol shrinks slighlty when it cools. This is why you get a slight depression on open face hand pour molds if you don't fill them up enough. I've found that I get better results if the molds are fairly hot and demolding takes place as soon as possible. I leave the bait in the one half of the mold and let it cool. This way as shrinking does take place, it's more evenly distributed. Like Del mentioned, if you have any air bubbles at all you will get dents. The key is to slowly inject with as low a temp as possible into a warm mold. Quote Link to comment Share on other sites More sharing options...
wildtail97 Posted May 6, 2009 Report Share Posted May 6, 2009 Whats the lowest temp I could run this at? We are running it at about 315. Quote Link to comment Share on other sites More sharing options...
Delw Posted May 6, 2009 Report Share Posted May 6, 2009 Are those Jason's Molds? if they are have HIM call me I know them very well. that big of a dent is due to blow back I am pretty sure Quote Link to comment Share on other sites More sharing options...
wildtail97 Posted May 6, 2009 Report Share Posted May 6, 2009 No, we design and cut our own molds. Quote Link to comment Share on other sites More sharing options...
Delw Posted May 6, 2009 Report Share Posted May 6, 2009 the size of the dent you mentioned got me to thinking, it could very well be the direction you are shooting it. I have never seen a dent that big even in injected swimbaits. some how your getting a big air pocket in there . could be the turbulance from the direction of the plastic coming in. Quote Link to comment Share on other sites More sharing options...
Tubeman Posted May 8, 2009 Report Share Posted May 8, 2009 Whats the lowest temp I could run this at? We are running it at about 315. I'm about the same, maybe as low as 300 with Calhoun...any lower and I get incomplete lures. Maybe I need bigger pipes to hold that pressure until the plastic cools Quote Link to comment Share on other sites More sharing options...
Tubeman Posted May 11, 2009 Report Share Posted May 11, 2009 Just shot some baits last night and I have some new advice. I remembered Shawn Collins telling me it was continuous pressure that used in large scale injection machines to stop any denting (others have probably mentioned it as well) So after each mold had filled I pushed down on the plunger for another 20-30 seconds so the bait had a chance to set under pressure....presto 95 percent of the denting was gone !! I don't know how the plastic syringes will hold up to this so be careful. I use a custom machined metal hand injector that will not burst under pressure. Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted May 11, 2009 Report Share Posted May 11, 2009 polishing the entrance to the mold could possibly make a difference. Less grip for the plastic plug, allowing it to be drawn into the mold as the plastic shrinks. Possibly combine the idea with a suitable lubricant. Sorry I cannot test this out for you, just an idea. Dave Quote Link to comment Share on other sites More sharing options...
MTfishingrods Posted May 12, 2009 Report Share Posted May 12, 2009 (edited) You will find that the plastic ones will not hold up very well whether your putting pressure on them or not. I have 2 of them and they both have the spiderweb cracks all through them and i have yet to get a good shoot with either of them. My next one will be a bears baits injector. Everyone i know of that has one loves them. They are aluminum and will last. And they are a whole lot safer in my opinion. They are available at Bears Baits There may be others out there as well, but this is my choice. Heres a link to the tutorial on this site using one. http://www.tackleunderground.com/forum/soft-plastics-how/16920-using-hand-injector.html I know this dont help the ones with injection machines though. Edited May 12, 2009 by MTfishingrods Quote Link to comment Share on other sites More sharing options...
pigdestroyer Posted May 12, 2009 Report Share Posted May 12, 2009 Great... Dents!?! I just bought Bears hand injector. I haven't recieved it yet, so I can't give any feedback on it. I've avoided injectors until I saw this one. For some reason I thought the injector was going to solve all of my problems. Now I hear about DENTS! hahaha. Well hopefully with all of the info in this thread I will be able to avoid them. Quote Link to comment Share on other sites More sharing options...
wildtail97 Posted May 12, 2009 Report Share Posted May 12, 2009 We are going to do some reworking on our molds and then I think we will have it. We will try polishing the port , that might help. Quote Link to comment Share on other sites More sharing options...
bear21211 Posted May 12, 2009 Report Share Posted May 12, 2009 Pigdestroyer I can honestly say with the molds we have on the market we have not had 1 single dent issue. We have a 5 cavity Trick worm mold in 6" and 7 1/2 " that is an injected mold and the 7 1/2' will give you dents in the mold shooting them from the top of the mold. Now yesterday I tried an experiment with turning the mold upside down when I Injected it and then just flipping it back up right to cure. NO dents . I shot the mold 15 times and never got 1 single dent. With it shooting from the top you will get one or 2 worms that have dents every time. So do not let it scare you. it does not happen on very many molds.By The Way the 6" or 7 1/2" Trick worm molds are not on the market yet in case you think I contradicted myself. Once we get them right they will be released. Quote Link to comment Share on other sites More sharing options...
outdooradvantage Posted May 13, 2009 Report Share Posted May 13, 2009 I have a injector from Bear that I use on a 5in Grub mold from LC and havent had any denting issues. Works a lot better than having to pour the tail first. Quote Link to comment Share on other sites More sharing options...
Bountiful Waters Posted May 13, 2009 Report Share Posted May 13, 2009 I just finished a large order of the 6" T-Sticks which are normally very bad about denting on one color pours. I poured from a Presto Pot, temp set at 320 and a small stream. I had 3 dents on average for every 50 baits. Key was lower temp and allowing time for the gas to escape by pouring a small stream. Quote Link to comment Share on other sites More sharing options...
carolinamike Posted May 14, 2009 Report Share Posted May 14, 2009 Bear, Is the hole on the bottom smaller than the one on top? If so, then it's definitely a shrinkage problem. What happened by flipping it over, if the hole is bigger, when the plastic cools it's pulling back the other way, if that makes sense to you. In other words, the bigger hole was allowing it more room to shrink. By going from the other end, it cooled faster at the big hole end, not allowing the shrinkage. I kind of felt sure it was a shrinkage problem and if it works better from a small hole instead of a large hole, then that kind of summed it up. Hope that helps you understand a little more of what was going on. Quote Link to comment Share on other sites More sharing options...
