dr.olds Posted August 25, 2015 Report Share Posted August 25, 2015 Can anyone tell me at what thickness plastisol will flash at. I am cutting some molds and want to vent them for a more complete fill.also does plastisol shrink much or at all when it cures . Thanks in advance Noel Quote Link to comment Share on other sites More sharing options...
Stock's Lures Posted August 26, 2015 Report Share Posted August 26, 2015 Plastisol does shrink when It cools. A way to resolve that is to have a big sprue hole so the plastic will have more to suck in when it cools. Hope that made sense. 1 Quote Link to comment Share on other sites More sharing options...
dr.olds Posted August 26, 2015 Author Report Share Posted August 26, 2015 Makes perfect sense. If I am pouring through a nice big sprue do I need to vent the cavities.? Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted August 26, 2015 Report Share Posted August 26, 2015 Depending on the bait design, you may well need vents, to allow trapped pockets of air to escape. If you are making your own molds out of plaster or RTV, you could cut these as required, after a few test pours, to determine where the problems are. Dave 1 Quote Link to comment Share on other sites More sharing options...
mark poulson Posted August 26, 2015 Report Share Posted August 26, 2015 I was very worried about venting when I made my first plaster of paris molds, so I erred on the side of too big. I've since learned that smaller works, just as long as it's at the furthest point the plastic needs to get to. 1 Quote Link to comment Share on other sites More sharing options...
dr.olds Posted August 26, 2015 Author Report Share Posted August 26, 2015 (edited) The molds are all being done on a cnc mill. I am lucky enough to program and run a high end cnc mill. I have drawn up a 4 and 5 " senko to try. Noel Edited August 26, 2015 by dr.olds Quote Link to comment Share on other sites More sharing options...
MonteSS Posted August 26, 2015 Report Share Posted August 26, 2015 (edited) Make sure the gates (sprue to bait) are large enough. You dont wants them closing up and not allowing more plastic to be drawn in. Especially on large baits like a stick Edited August 26, 2015 by MonteSS Quote Link to comment Share on other sites More sharing options...
dr.olds Posted August 26, 2015 Author Report Share Posted August 26, 2015 How long before you can de-mould a hand poured bait safely. I cut a test cavity and melted some old senkos down for a test. . i sprayed both halves with mould release. I see what you mean about sucking material down from the spru as it cools. I am jonesing to open it ,but will remain patient. Quote Link to comment Share on other sites More sharing options...
Apdriver Posted August 26, 2015 Report Share Posted August 26, 2015 2 minutes is what I use before de molding. Quote Link to comment Share on other sites More sharing options...
dr.olds Posted August 27, 2015 Author Report Share Posted August 27, 2015 Thanks for the replies. It looks like I am addicted now. Its a long winter so now i have something to keep me busy in the off season. Like I said I am fortunate to be a mould maker so a lot of the same principles and materials apply. Next step is to build a few injectors and a multi cavity mould. I'm sure there will be many more questions to follow. Thanks Noel Quote Link to comment Share on other sites More sharing options...
