BassnRandy Posted January 2, 2009 Report Share Posted January 2, 2009 (edited) Made some twopiece molds for myself out of pop. they turned out nice except that most of the baits come out with a dent in them. i am giving them plenty of cooling time so i don't think early demolding is the problem. Any ideas. The mold is a 5'' fat senko style bait. Edited January 2, 2009 by BassnRandy spelling Quote Link to comment Share on other sites More sharing options...
JDBaits Posted January 2, 2009 Report Share Posted January 2, 2009 I pour a lot of these baits with dels Alum mold and have struggled with dimples like this one. im not sure if yours are the same but heres a few tips that helped me curb mine from happening as much 1. plastic too cold and drizzles out of pyrex cup instead of a nice stream, drizzling plastic stream hit sides of the mold. 2 too much salt 3 hot mold. hope this info helps Quote Link to comment Share on other sites More sharing options...
HJS Posted January 2, 2009 Report Share Posted January 2, 2009 (edited) I get them too. Maybe 10%-15% of my lures have some sort of noticeable dimple... and only one per lure... wierd!!! They don't affect performance but lures with dimples may not sell well. Either one of two things could be happening: - Maybe an air bubble got trapped during pouring (not likely since theres never more than one dimple per lure). - Or, most likely, air is gets sucked into the lure cavity thru the mold seam as the lure shrinks during cooling. As of yet I haven't found a solution. Been thinking of trying to find some sort of heat tolerate grease. I'm thinking a thin sheen of high temp grease on the flat surface of the mold may stop the cavities from sucking air. That would be just another step in pouring that I would like to avoid. So far I've decided to just tolerate the dimples... I think they look cute. Forgot to add that dimples generally appear in the same spot for a given lure cavity. Thats why I think its sucking air in thru the seam. Doesn't always do it. Maybe sometimes I put the clamps on at slightly different spots that will totally seal the seam to air passage. Edited January 2, 2009 by HJS Quote Link to comment Share on other sites More sharing options...
Bass-Boys Posted January 2, 2009 Report Share Posted January 2, 2009 are the dimples always in apx. the same area on the bait ? Quote Link to comment Share on other sites More sharing options...
nova Posted January 2, 2009 Report Share Posted January 2, 2009 (edited) I think that a lot of folks have this happen. I've played around with different solutions. The one I've found to be the best is right after you have topped off the sprue take a piece flat plastic(rigid) and lay it over the pouring holes, now put pressure with your hand and hold it there till the plastic completely sets up. It works but it is not condusive to production pouring(time consuming). I believe that the dimples are caused by "hot spots" in the mold. With POP it could be a bubble inside the plaster right next to the cavity. In the metal molds I'm not sure. It could have something to do with the "grain" of the metal. Maybe Delw can comment on that part. www.novalures.com Edited January 2, 2009 by nova Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted January 3, 2009 Report Share Posted January 3, 2009 This is a common problem and needs putting to bed. Nova's solution of applying pressure to the sprue struck me as a good solution. This was mentioned in another thread in the last two days. It is all about the plastic shrinking and as suggested by HJS, air being sucked in through the mold mating face, as the plastic solidifies at the sprue and is unable to draw more plastic into the mold. Another solution is to improve the mating face and prevent air leakage. I am currently enthused by the use of wax as a releasing agent. It is a lot stiffer than vaseline ( petroleum jelly) and may reduce the air leakage through the mating face. I don't think heating the mold or messing with the plastic temperature is going to solve this one. It is up to you guys, as plastics is not my game. Dave Quote Link to comment Share on other sites More sharing options...
mradamh Posted January 3, 2009 Report Share Posted January 3, 2009 I believe I read a post from Del awhile back saying it might be caused by pouring too fast. Not giving the air enough time to escape the mold during the pour. I've slowed down a bit and noticed that the dents have pretty much went away. I also tilt my two piece molds slightly. Haven't tried Nova's suggestion, but that sounds like it would work perfectly as well... Adam Quote Link to comment Share on other sites More sharing options...
Basseducer Posted January 3, 2009 Report Share Posted January 3, 2009 (edited) bassnrandy, You can also try lowering the temp of your plastic. With a stick bait it is not necessary to have ultra hot plastic. Avoid getting it too cool as you will start getting tiny voids in the ribbs of the bait. Your salt and glitter will suspend better as well. Edited January 3, 2009 by Basseducer spelling Quote Link to comment Share on other sites More sharing options...
outdooradvantage Posted January 3, 2009 Report Share Posted January 3, 2009 I have also experienced this problem, and I believe it is from a hot mold. When my mold gets too hot, I wrap it in a towel a put it in the freezer for a minute. It seems to work for me, I hope it may help you. Quote Link to comment Share on other sites More sharing options...
Bass-Boys Posted January 3, 2009 Report Share Posted January 3, 2009 slowing your pour is a good idea. also try to pour the cavities 1/2 -3/4 full then go back and top off. make sure the plastic is not to cool or you will get a seam between the 2 pours. Quote Link to comment Share on other sites More sharing options...
BassnRandy Posted January 3, 2009 Author Report Share Posted January 3, 2009 Thanks for the input guys. I will try all of these suggestions as I made several cavities and would hate to scrap the molds. Ecspecially when they actually turned out lokingOK for once for me. I know a hot mold is not the problem as this happens on the first pour. and it always happens in the uper one third of the bait. My guess from what has been said is that the sprue hole is getting hard quick while the inside is not. Pop holds heat alot better than Aluminum and the sprue is out in the air in my rather chilly pouring room. Today i will try to pour a little over half the bait first give it a minute and pour the remainder of the bait and also try the plastic on top that Nova suggested. Thanks again everyone! Randy Quote Link to comment Share on other sites More sharing options...
Bountiful Waters Posted January 3, 2009 Report Share Posted January 3, 2009 I have come to the conclusion none of us may have the right answer on this one. I thought the mold was too hot. Then I thought the plastic was too hot. I have settled on having about 85% of the pours being ok. I cannot figure those dents out and it seems we all have different ideas on reasoning. They will happen with or without salt. Quote Link to comment Share on other sites More sharing options...
nova Posted January 3, 2009 Report Share Posted January 3, 2009 I also believe that what we have here is a basic physics problem. For the most part materials expand in volumn when heated; some more than others. So; as the plastic is heated it increases in volumn and then as it cools it returns to it's origional size; and there's your problem. I feel that this is what causing the "dimples". The pressure tactic I suggested simply forces the expansion back down the sprue and fills in the dimples. The real trick will be to solve this problem in a way that doesn't effect production time too much. www.novalures.com Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted January 3, 2009 Report Share Posted January 3, 2009 (edited) I agree with Nova, it is a laws of physics problem. There are two more solutions that can be tried. First a is a wider sprue. This was mentioned by BassnRandy in post No11, it has also been mentioned in the wire baits forum when pouring lead, in the last day or so. Normally, the sprue is widened to aid pouring without touching the sides. But widening the pour hole will slow down the cooling of the sprue and the consequent plugging effect. Also, shortening the pour hole to an absolute minimum and increase the pour reservoir above the hole. This will slow down the plug forming even more by having molten plastic above and below the narrow section. Dave Edited January 3, 2009 by Vodkaman Quote Link to comment Share on other sites More sharing options...
jigman2 Posted January 3, 2009 Report Share Posted January 3, 2009 This is all very intresting, I just finished pouring a gallon of 5 1/4" stick baits and discovered DENTS on about 6 or 7 of them, upon further investigation I also found that the same dented baits were a bit longer than the rest. My conclusion was that those 6 or 7 had been taken out of the mold too soon and were streched and dented by the removing of the baits from the mold too soon. I'm not saying that is what caused your DENTS but I beleve that is what caused mine as I am using a 7 cavity mold. jigman2 Quote Link to comment Share on other sites More sharing options...
pastorshane Posted January 4, 2009 Report Share Posted January 4, 2009 For what ever it's worth I had the same problem with a differant type bait this time last year. I tried EVERYTHING from letting the mold set over night before opening to drilling holes in the molds to tilting the molds, you name it:drool:. To no avail we {those of us on here} never figured it out. The only thing that makes since to me is the vescosity of the individual plastic.{chemical thickness} Every mold had at least one if not 3 dented. I just gave up and went to a one piece mold. Man I hope someone wiser than me can chime in. Quote Link to comment Share on other sites More sharing options...
Bass-Boys Posted January 4, 2009 Report Share Posted January 4, 2009 Randy, fill the mold past 1/2 way. fill it to the point the dents are then wait, but not a minute I do not think ? maybe 30 seconds and if using a micro reheat the plastic for 15 sec. then finish the pours. just mite work . Quote Link to comment Share on other sites More sharing options...
GB GONE Posted January 7, 2009 Report Share Posted January 7, 2009 My acrylic molds from Janns may help some on this issue as I can watch the process of the cooling plastic as it happens. First a word on the fluke molds from Janns. Janns claims the mold can be hand poured but I am very skeptical as I tried very hard with maybe 1 out of 8 baits coming out correctly. The sprue holes are very tiny and the clamps are worthless at best. But, I digress..... I was able to learn something with these molds. The baits do get a dimple in them at various points in each bait. The dimple was definitely related to where the clamps were placed on the molds. The areas were there was not a clamp and air could be pulled in dimpled. I modified a couple molds opening the sprue to allow for a successful pour and found the dimples to persist in the areas that a clamp was not located. I then added some parafilm wax to all the sides of the mold and poured a bait. No dimples found. I will have to believe that air being pulled into the mold as the bait cools causes the dimpling effect. I have yet to experiment on some aluminum molds however I am re-stocking my parafilm supplies at work today. Jim Quote Link to comment Share on other sites More sharing options...
Richard Prager Posted January 7, 2009 Report Share Posted January 7, 2009 Now, that makes some sense Jim! Thanks. What exactly is parafilm? Quote Link to comment Share on other sites More sharing options...
GB GONE Posted January 7, 2009 Report Share Posted January 7, 2009 Parafilm is like a thin, stretchy sheet of wax! You can use it to seal almost any small area. In the hospital, we use it to re-seal a test tube or small opening to prevent liquid from evaporating. It comes on a roll and you can cut or tear off what you need. Jim Quote Link to comment Share on other sites More sharing options...
JSC Posted January 8, 2009 Report Share Posted January 8, 2009 I belive Jim nailed it .. this has been my thought on it but had not proven it any way ... at least he could see it happen and I belive that is what happens with an Alum mold. How do you stop it with an Alum mold ???? More questions JSC Quote Link to comment Share on other sites More sharing options...
Richard Prager Posted January 8, 2009 Report Share Posted January 8, 2009 Maybe a spring clamp near the area that dents??? Quote Link to comment Share on other sites More sharing options...
braveviper Posted January 8, 2009 Report Share Posted January 8, 2009 Maybe a spring clamp near the area that dents??? Gently hold mold in a clamp while pouring? Quote Link to comment Share on other sites More sharing options...
GB GONE Posted January 8, 2009 Report Share Posted January 8, 2009 My thoughts were just built on Dave and others comments. I am not sure there will be a practical solution on our aluminum molds as adding and removing something on every mold for every pour would be tedious and tiresome. I wonder if the mold was built with some sort of seal built in. I have ideas of a seal like that of one on a door or window. I believe I can replicate the seal on a pop mold but adding one on an aluminum mold would probably be to cumbersome for the mold designers and builders. It might not even work when completed as physics can be tricky with all these variables. I will work on a pop version to further the testing on this theory. Jim Quote Link to comment Share on other sites More sharing options...
Richard Prager Posted January 8, 2009 Report Share Posted January 8, 2009 If it is the seal that is causing dents, then why don't we see dents in molds other than worms. I only get an occasional dent in one cavity of one mold. This is with the 10 1/2" trick. I also do not pour with any salt whatsoever. Quote Link to comment Share on other sites More sharing options...
