psilvers Posted March 2, 2011 Report Share Posted March 2, 2011 I want to make a Bondo mold for some lead jigs so I can test a new design before I have a mold cut. Here are a couple of questions that I have: 1- Which Bondo do I use? I see there is auto body filler and body repair kit. 2- The directions call fo a "golf ball size" glob of filler (if that is the correct Bondo product) to be mixed with a certain amount of catalyst (or hardener - I forget which). How do I mix the two for a bigger mold? Any quick directions that someone can provide? Or do I have to just have to take 5 golf ball sized globs and mix it with 5 parts of the catalyst? Any quick ideas would help. BTW, I have searched for "Bondo" in the forums, and it appears that there are several discussions that have links to prior threads. However, the links to prior threads will not work for me Thanks, Pete Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted March 2, 2011 Report Share Posted March 2, 2011 (edited) Pete, I understand your problem. I did a quick google search and found nothing, other than advice to mix a small batch in the proportions you intend to use in the big batch. This is good advice, but you will need an accurate digital scale for the job. You may be better using polyester resin. This is basically bondo filler, but without the filler. It is also supplied by Bondo, which is only a trade name, not a product. The catalyst for the resin is MEKP, supplied in a small bottle from which you dispense drops. So many drops per ounce. I cannot remember the numbers, but there is a ton of information on the subject if you Google it. The actual number of drops is not critical, but just affects the setting time. Advice is given on various web sites about varying the mix according to how thick your part is. This because the chemical reaction is exothermic. If you mix too many drops, the part will overheat and crack. You can even mix the filler product with the liquid resin product. If you mix, use the MEKP drops as the sole catalyst. A word about safety. MEKP is an extremely nasty substance that needs treating with a lot of respect. Wear gloves and work in a well ventilated area. If you get any of these products on your skin, wash off immediately with soapy water. Dave Edited March 2, 2011 by Vodkaman Quote Link to comment Share on other sites More sharing options...
psilvers Posted March 2, 2011 Author Report Share Posted March 2, 2011 Thanks Dave. I have an accurate digital scale, so that is no problem. Do you use just the polyester resin without the filler, or should I also add the filler? I also assume that I should heat the lead so that it is only 650 - 700 degrees. When I think about it, I am surprised that the resins are that heat resistant. Thanks again. Pete Quote Link to comment Share on other sites More sharing options...
mkvnmtr Posted March 2, 2011 Report Share Posted March 2, 2011 I poured last night for the first time into some resin molds. The lead was hot enough to have turned a golden color. The molds stood the heat very well and the lead filled the molds way better than I thought it would. The resin does not suck the heat from the lead like a metal mold.I am not sure of the product because my friend made the molds. When I have all the information I believe I will post some pictures and a tutorial. These molds worked a lot better thanI expected and the cost was less than five dollars each. Quote Link to comment Share on other sites More sharing options...
Da big tuna Posted March 2, 2011 Report Share Posted March 2, 2011 (edited) I want to make a Bondo mold for some lead jigs so I can test a new design before I have a mold cut. Here are a couple of questions that I have: 1- Which Bondo do I use? I see there is auto body filler and body repair kit. 2- The directions call fo a "golf ball size" glob of filler (if that is the correct Bondo product) to be mixed with a certain amount of catalyst (or hardener - I forget which). How do I mix the two for a bigger mold? Any quick directions that someone can provide? Or do I have to just have to take 5 golf ball sized globs and mix it with 5 parts of the catalyst? Any quick ideas would help. BTW, I have searched for "Bondo" in the forums, and it appears that there are several discussions that have links to prior threads. However, the links to prior threads will not work for me Thanks, Pete Pete, Go to your local body shop and talk to a body man. Explain what your doing and I'm sure there a few out there that will give you all the info you need as far as working time,catalyst, and types that can be used. Probably even supply some for the cost of those kits . I do this a lot when im in search of new things and when I cant get a answer here. Good luck Edited March 2, 2011 by Da big tuna Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted March 2, 2011 Report Share Posted March 2, 2011 The only lead mold I have made was with a mix of the filler and the resin, so I cannot answer on the pure resin. Like MKV stated above, the mold will not suck up the heat as it is an insulating material, just like RTV. If you pour a lot of jigs in succession, the mold will get hot and take longer before you can de-mold. Also with the mix that I used, the mold starts to soften and becomes pliable. If you have even clamping, then this is not a big problem, but it is probably time to take a break and allow the mold to cool down. I am not sure if the pure resin mold will go soft, but I am sure someone will jump in with that information. Polyester resins and fillers make very good temporary molds for short runs, but if you want to make thousands, then either you gear up for making lots of molds or get an aluminium mold cut. You stated in your first post that this was a prototype exercise. Poly molds will serve you well for this purpose. Dave Quote Link to comment Share on other sites More sharing options...
psilvers Posted March 3, 2011 Author Report Share Posted March 3, 2011 Thanks for all the replies. I only need to pop out a few prototypes so that I can test them before I have a mold cut. Hopefully, the mixture of resin and filler will do the trick. I will keep you folks updated as to how it goes. Thanks again for all the help. Pete Quote Link to comment Share on other sites More sharing options...
