DodgySam Posted January 8, 2013 Share Posted January 8, 2013 Fibreglassing parts is surprisingly easy. If you are trying to replicate a part then its particularly easy. This is a simple how to guide on how to take a mold off something and how to replicate that part. You will need a few things. 1: Fibreglass...(I prefer chopped mat as its cheap and easy to form and you can just rip it into the sized peice you want) 2: Resin. I use polyester resin as its not so harsh if you get it on your skin and its good for car parts...(so i was told by the guy selling it) 3: gelcoat. This goes onto the mold or part ur molding first to make a nice smooth surface. 4: Paint brushes 5: mixing pots 6: rubber gloves 7: rags 8: Mold release...(carnuba wax will work but a proper mold release works better) 9: a well ventilated area OK...First things first. Set urself up infront of the TV cos this first step takes a while. You will need the part ur going to replicate to be clean and dry and then you need to coat the surface ur molding with Mold release wax. Let this dry (only a few minutes). It will go cloudy when its dry so then take ur rag and polish this to a nice shine. Repeat this process about 10 times so there is a nice thick shiney coat of wax on it. (the shinier the surface the better really.) Then dry the surface...It may look dry once you have polished it but its not. If you were to put ur gelcoat down on this surface it would bead and give you a shit finish. So pop it out in the sun for a few hours or if you're less patient hit it with a hair dryer or heat gun on a low setting. Once its well and truely dry go out to ur well ventilated area like a garage with the door up and mix up some gelcoat. There is special gelcoats for making mold coatings but I find normal Gelcoat works as long as your not wanting to go into production making parts etc. Follow the instructions for mixing the gelcoat as some manufacturers are quite particular about their ratios. Then paint on a nice thick coat making sure all the areas you want molded are well covered. Then just leave it over night to dry. Next day tear up the fibreglass matte to the size you are wanting (make the size of the matte bigger than you need so you have plenty of overhang) and mix up some resin/hardner. (note: usually the hardner for the gelcoat is the same as for the resin so dont feel you NEED to buy 2 seperate lots...besides it comes with the gelcoat and resin) this isnt so critical so the old peach and pea measurements work just like they do with bog. then lay a coat of resin down ontop of the gelcoat you layed down last night...(no need to sand it first)...this will help the matting stick down and it wont slide around before you can get the resin on. Then slap down the matting and apply ur resin...dont skimp with the resin! This mold plug is going to take a beating...literally...so put down atleast 4 layers of matting and resin. When thats done smooth it all out with your hands and squeeze out any air bubbles...(you can thank me now for suggesting you get rubber gloves)...wet the matting with resin right out past the mold edges so its a big solid mass when its dry... this will make for easy cutting later. Once you are happy with the thickness of ur resin/matte and the air bubbles and folds are all smoothed out leave it to dry...a few hours to overnight is best. Once the resin is rock hard you will need to cut the matte back to be flush with the part you have molded. I sometimes trim it with scissors or a cutoff disc depending how much overhang is there. An angle grinder with a flap disc works well for this so go nuts with that. You will know its flush with the part when you can see the gelcoat layer hard up against the part surface. (sorry for the shit pic but macro on phones is REALLY shit) once thats all done whack the fibreglass HARD with a rubber mallet. This will break any bonds you may have between ur plug and part/break vacuum. Then slide a screw driver down between the pieces and gently pry them apart. They will make a satisfyling pop/crack when they seperate and you will be left with 2 perfect halves of the same thing. And this is what you will have...A nice negative of whatever you started with! for this part I have made a negative of both sides so i can get a particular thickness and finish. To make a part off this mold follow the exact same process. Clean Wax Buff Gelcoat Glass Grind. If you want to paint the part afterward just sand the gelcoat to key it up and paint away. I hope this helps and makes sense. If I have made no sense just ask away, Im happy to help. The key is the wax/mold release...if you think you have enough...put on another 2 coats. 1 Quote Link to comment Share on other sites More sharing options...
Bling Posted January 8, 2013 Share Posted January 8, 2013 Good write up! Where have you found to be the best(value) places to get materials? Quote Link to comment Share on other sites More sharing options...
JoKer Posted January 8, 2013 Share Posted January 8, 2013 *gloves* also highly recommended LOL Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 8, 2013 Author Share Posted January 8, 2013 I get most of my stuff from FGI (nuplex) in Henderson. Can get a couple of meters of offcut fibreglass for a few bux and their resins arent badly priced either. BUT their gelcoat has too much styrene in it so it tends to shrink and crack. I got my gelcoat thru a mate and its thicker and goopier and doesnt shrink or crack. So maybe try ringing a boat builder or bodykit maker and ask what gelcoat they recommend. Quote Link to comment Share on other sites More sharing options...
Truenotch Posted January 8, 2013 Share Posted January 8, 2013 And what were you making? Quote Link to comment Share on other sites More sharing options...
EURON8 Posted January 8, 2013 Share Posted January 8, 2013 Looks like a bash guard for a downhill mountain bike rear shock. Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 8, 2013 Author Share Posted January 8, 2013 Looks like a bash guard for a downhill mountain bike rear shock. Gee good spotting there chris...its almost like i told you what it was. Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted January 8, 2013 Share Posted January 8, 2013 awesome. spray on pva release film too if you really don't want to get things stuck. you can test the quality of your wax job with sticky tape. black gellcoat can be a prick ( I think it's the amount of pigment) use glass tissue if you get fibres showing through. use in a well ventilated area. don't take chances hope that helps someone Quote Link to comment Share on other sites More sharing options...
cletus Posted January 8, 2013 Share Posted January 8, 2013 why do you do a mold of both sides? is that so you can make a part that matches the original more closely? great write up Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 8, 2013 Author Share Posted January 8, 2013 its so i can use more layers of kevlar and then compress them with clamps to press out the resins and make it stronger and make it fit to a particular thickness. I got the idea from a company called Werner that made kayal paddles. They would lay a hundred layers of glass and then compress it down to 3mm thick. By doing so their blades were stronger and lighter than others and they just used fibreglass instead of carbon. Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 9, 2013 Author Share Posted January 9, 2013 This is the finished part that I was making yesterday. Started out 10mm thick until I clamped the shit out of the 2 halves of the mold and brought the thickness down to about 3mm. Nice and thin and strong. Its the first time I've tried clamping a part and tbh Im pretty stoked with the result. Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted January 9, 2013 Share Posted January 9, 2013 For clean up, handy andy and hot water works really well also, incase you want to reuse brushes or some shit. And another handy tip, if your making something from scratch, and you need to go from one shape to another, like say a square to a circle, set up a jig, and put a few layers of womans stockings over it, and then brush resin over the stocking (to use as a mold, or even a finished product) it will seamlessly blend from one shape to the other. I made a pod filter adaptor like this once. Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted January 9, 2013 Share Posted January 9, 2013 that looks great. even better results could be had if you had put the lot into a Mylar bag and sucked it with a fridge pump Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted January 9, 2013 Share Posted January 9, 2013 that looks great. even better results could be had if you had put the lot into a Mylar bag and sucked it with a fridge pump Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 9, 2013 Author Share Posted January 9, 2013 For clean up, handy andy and hot water works really well also, incase you want to reuse brushes or some shit. And another handy tip, if your making something from scratch, and you need to go from one shape to another, like say a square to a circle, set up a jig, and put a few layers of womans stockings over it, and then brush resin over the stocking (to use as a mold, or even a finished product) it will seamlessly blend from one shape to the other. I made a pod filter adaptor like this once. Lycra works too. Quote Link to comment Share on other sites More sharing options...
Vintage Grumble Posted January 9, 2013 Share Posted January 9, 2013 Another cheap way of doing things, is just get what evers the correct shape, cover it in brown packaging tape, and glass over it. The resin wont stick to the tape, meaning you can glass over things to get shapes (I borrowed some stainless tube reducers from work, used them, untaped/cleaned and returned them) and then glass the shapes together to get the final product. I made the below intake out of flat panels of glass, and glass taken off stainless reducers and exhaust steel. There is a bit of sanding involved in this process, but you dont have to make a mold, and can change shit as you go along easily. Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted January 9, 2013 Share Posted January 9, 2013 wow that looks great!! duct tape also works ( there is a release agent on the non glue side so it won't stick to itself when on the roll) Quote Link to comment Share on other sites More sharing options...
DodgySam Posted January 10, 2013 Author Share Posted January 10, 2013 Or use epoxy resin and just shape polystyrene. Epoxy/glass the polyetyrene. When you want to use the part just pour a bit of petrol or paint thinner onto the polystyrene and the polystyrene dissolves. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.