robalo01 Posted April 19, 2013 Report Share Posted April 19, 2013 One thing I have struggled with for the last couple of years, since the whole hand injection craze started, is that I was moving to less and less bait designing and more simply replicating someone else's design in custom colors and textures. I have continued to hand pour about 60% of what I make, but my clients have more often than not opted to go for the hand injection model that I did not design -- no flat sides and versitilty of working in full 3-d is hard to compete with, especially in bass lures. I have experimented with diferent ways of creating my own hand injected designs: Had some custom aluminum molds made but the cost of experimenting is not practical Made some POP molds, but the ability to replicate the molds in a accurate and practical way is not ideal and time it takes to make a truly good mold is way too long for me. Used different epoxys for 2-part molds but most didn't last under the heat of multiple plastic pours. Attempted many, many ways of making resin molds but failed due to shrinkage until now. I have found a way to make hand injection molds out of resin that is fairly simple and I can replicate my molds to make as many as I want in about 30 min for each mold. Here is what I am doing: 1. I make my original out of any hard substance (wood, resin, ect). I suppose this process could be used to copy another soft plastice, but that just isn't what I am in to. The quality of the surface of the original is very important. The eventual product will only be as good as the model. The modle should be about 5-7% larger than you want the finished product to be. 2. Make a bondo (body filler) mold taking great car to make the exterior sides perfectly square to each other. (I suppose any medium which you could succesfully use to make an accurate 2-par mild would work as long as you can mill the exterior) I use a sander to make the exterior sides smooth and flat. I add just a shot of resin to the bondo to lower the vescocity. Took a long to time to learn how to make these without air pockets, mostly practice. It sometimes take 2-3 tries for me to make a "perfect" bondo mold, but I keep trying until I have something I want to replicate. From the outside it should look kind of like a single cavity alunimum mold. Each half should be no thinner that 3/4 inch, 1.5 inches overall. These dementions might go higher for large models. 3. Make an RTV "mold" of each side of the bondo mold. Make sure you do this on a level surface. so everything is square. 4. Mix enough resin for both sides of the mold and pour both at the same time. 5. Once the resin is solid but verytender (will be very hot), pull both sides out, quickly lubricate the ajoining faces with petrolium jelly, and clamp together. I use several clamps applying even but firm pressure. It is important that the sides are all square so the the mold doesn't deform. 6. Every three or four minutes (probably more often at first), re-adjust the pressure on the clamps. As the resin shrinks, the clamps will loosen. if you don't adjust the sides will not cure "together." Do this until the molds are completely cold. 7. Sometimes you have to "crack them open" once they are cold, but so far I haven't broken any molds. I have been able to use this process to perfectly replicate a hand-made injection mold up to 25 times without any failures. This means I can once again design my own creations and injucet them economically, working with 25 molds of the same model at a time, I can be more productive than hand pouring. I am too stingy to buy 25 aluminum injection molds of the same model. Making then perfectly square allows me to clamp sever molds together, the way you would do with alluminum molds. Each duplicate takes about 20-40 minutes to make. I do have some concerns about the durability of the molds. I am sure they won't last as long as their aluminum counter parts, but It is reallt cheap and easy to make a few more if I need them. I am still experimenting with making very small appendages and the larger the model, the more difficult this process becomes, but for me this is a game changer. I will likely be buying very few aluminum injection molds in the future. Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 I have been able to make a Resin injection mold of a 9" Fluke (about 1" in diameter at the thickest point.) I was concerned that I would have trouble making such a large size, but after a couple of adjustments to the resin formula, they are working out fine. We are introducing them at a local outdoors expo this weekend, people like them so far. We will see how they sell. I don't miss aluminum molds. The resin molds do just as well. I feel like I have been given back the freedom to experiment and compete with the big boys in terms of designing and prototyping. Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/IMG-20130612-00002_zpsc11a85b8.jpg http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/IMG-20130612-00001_zpsf10e0f4d.jpg http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/Santiago-20130608-00688_zpscc5db156.jpg Quote Link to comment Share on other sites More sharing options...
bflp Posted June 30, 2013 Report Share Posted June 30, 2013 Thanks for the write up! I may have missed I, but what kind of resin are you using? Also, do you have any pictures you could post to help show what you are doing? Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted June 30, 2013 Report Share Posted June 30, 2013 This is very good. Had to read it twice, but a genius method. It is all about the clamping together while soft and then the mating surfaces are forced to match - love it Dave Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 That is exactly it. You can replicate the mold as many times as you want. Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 This is the "template" for the mold: http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/IMG-20130630-00028_zpsb997ada5.jpg A couple of pics of the finished molds: http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/IMG-20130630-00029_zps2cf379dc.jpg http://i1294.photobucket.com/albums/b602/Stephen_Ashcraft/IMG-20130630-00030_zps78f66798.jpg I like to add little bit of color to the resin to helkp distinguish them. Keeps me from mixing them up. I am using a casting resin and adding about 30% (volume) industrial Talk. I have also used POP as a filler with similar success. The talk is cheaper. The filler makes the resin shrink less and makes the mold a lot stronge. They flex better when clamping the sides together. Quote Link to comment Share on other sites More sharing options...
bflp Posted June 30, 2013 Report Share Posted June 30, 2013 Very cool idea. I have Alumilite casting resin, will that work or is there a better option? Does the resin hold up to the heat well? Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 I don't see why the Aluminite wouldn't work. Keep adding filler until it is as thick as you can manage. So far the resin I use has helkp up to hundreds of casts. The more molds you make the less they are individually exposed to the heat. Quote Link to comment Share on other sites More sharing options...
bflp Posted June 30, 2013 Report Share Posted June 30, 2013 I'm not really familiar with Resins. What brand/type do you use for yours? Quote Link to comment Share on other sites More sharing options...
robalo01 Posted June 30, 2013 Author Report Share Posted June 30, 2013 Sorry, I get mine locally (Mexico) wouldn't be much help to you. But, it is a polyester casting resin used by hobbiests. It is basically like The stuff used for fibeglass but has less cobalt promotor. I would guess you could get Fiberglass resin to work. Whatever you might use for the singles sided mold will work. Quote Link to comment Share on other sites More sharing options...
daveh Posted July 1, 2013 Report Share Posted July 1, 2013 Nice work Quote Link to comment Share on other sites More sharing options...
blanx Posted July 4, 2013 Report Share Posted July 4, 2013 I say its youtube video time Quote Link to comment Share on other sites More sharing options...
joelhains Posted July 5, 2013 Report Share Posted July 5, 2013 This sounds great! +1 on the YouTube video. I would love to see exactly how you are doing these molds. my molds never seem to work out right. I think I am just too impatient with them! LOL! Quote Link to comment Share on other sites More sharing options...
Arkansaskiller247 Posted July 5, 2013 Report Share Posted July 5, 2013 +2 on the YouTube video it would really help me out with a few projects!!! Quote Link to comment Share on other sites More sharing options...
robalo01 Posted July 5, 2013 Author Report Share Posted July 5, 2013 Guys, I am reluctant to go so far as a Youtube video with local competitors chomping at the bit. Those of you who are familiar with making 2-part molds and working with Resins will be able to follow the steps in the original post. If you have any specific questions, I would be happy to answer private messages to the best of my ability. One big key to this is the filler for the Resin. You have to play with your formula to get is as thick as you can without getting air pockets. The filler makes it easier to work with and muck stronger once cured. I am flattered you would ask. Quote Link to comment Share on other sites More sharing options...
Arkansaskiller247 Posted July 5, 2013 Report Share Posted July 5, 2013 Worth a try. But i completely understand! Quote Link to comment Share on other sites More sharing options...
