Lownslow Posted January 7, 2012 Share Posted January 7, 2012 i have some nice 1 piece molds, but i want to make a nice tire for once and theres some bubble tires i want that wouldnt look good with one side flat so ill need to make a 2 piece mold do i do it the clay method some tires are too soft to mash into clay whats a good trick for doing so without the tire loosing shape. Quote Link to comment Share on other sites More sharing options...
crazyjim Posted January 7, 2012 Share Posted January 7, 2012 Buy them from Ma's Resin? Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 7, 2012 Author Share Posted January 7, 2012 Buy them from Ma's Resin? i need about 60 pieces Quote Link to comment Share on other sites More sharing options...
crazyjim Posted January 7, 2012 Share Posted January 7, 2012 Holy cow!! I bet Al would love an order like that. Don't send it yet though. Let me get the M/T Sportsman tires I ordered. More seriously, I wish I could help you but 2 piece molds are still kicking my butt. Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 7, 2012 Author Share Posted January 7, 2012 Holy cow!! I bet Al would love an order like that. Don't send it yet though. Let me get the M/T Sportsman tires I ordered. More seriously, I wish I could help you but 2 piece molds are still kicking my butt. i ran out of my fujimi tire stash i also need some super specific muscle car tires and a ton of low pro 20s and some 22.5 low pro dually tires. Quote Link to comment Share on other sites More sharing options...
my66s55 Posted January 7, 2012 Share Posted January 7, 2012 Try this website and see if it helps:http://smcbofphx.pro...ex.cgi?board=rs Quote Link to comment Share on other sites More sharing options...
Mike Kucaba Posted January 7, 2012 Share Posted January 7, 2012 A very good way to do a two piece mold for a tire was in a short lived magazine called IN SCALE. It was only out for two issues. (Very) simplistically you brush on some RTV on one side of the master and let cure,This way the RTV can gas out and let any bubbles pop. You then secure the master in to a vessel with this side down and pin it suspended in the vessel(a butter tub was shown in the article) you can then pour RTV into the tub and fill to the halfway point of the tire,let cure and then apply mold release to the cured rubber/master and finish the pour. Hope this is clear and I'll try and post this article if I can. Quote Link to comment Share on other sites More sharing options...
mikemodeler Posted January 8, 2012 Share Posted January 8, 2012 To follow up with Mike Kubaca's comments, I remember seeing something similar in an old issue of Scale Auto. IIRC the author of the article wanted to make copies of some old OOP VW tires/wheels and was faced with making a 2 piece mold like you described. I believe he used Legos to create a box and like Mike's description, the tire was suspended in the box and was poured in halves. I think straight pins were used to hold the tire in place. If I get a chance, I will dig through my old mags and see if I can find the article. Quote Link to comment Share on other sites More sharing options...
RyanSilva Posted January 8, 2012 Share Posted January 8, 2012 (edited) What you want to do are 1 piece glove molds, or some call slit molds. You do these by not using clay or doing 2 piece molds, but as a 1 piece..1 time casting. Start by glueing a piece of rod or the like to the tire ( i use hot glue) to act as the fill port, but what this does it suspends the tire in the mold box. glue the fill port to the base of your mold box, pour your silicone as you would. You pressure casts like me, correct frank? When your silicone is cured, you will use a xacto knife to slice part of the mold equally on both sides of the fill port to about halfway to either side of the tire, so only part of your mold pulls apart. You can cut the center of the wheel opening when you stretch the mold apart..or you can put a spacer in the tire before casting that shields both halves of the silicone. When your master is pulled from the mold and the 2 halves f the mold are together you are left with a pretty seamless mold aside from the fill port. Edited March 29, 2012 by RyanSilva Quote Link to comment Share on other sites More sharing options...
kitbash1 Posted January 8, 2012 Share Posted January 8, 2012 That's a mould type that I hadn't considered using for making tires. I was going to use a two part mould for the job. I'm going to give this a try. Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 8, 2012 Author Share Posted January 8, 2012 thanks that helps a lot. so when you pour the mold the fill port is upside down holding the tire up right, yes i plan on pressure casting my tires Quote Link to comment Share on other sites More sharing options...
Greg Wann Posted January 8, 2012 Share Posted January 8, 2012 (edited) Here is a tire mold I made a few years back. These are the rear drag slicks from an original Tom Daniels Groovy Grader kit. You have to imagine that the part just left of the tires is the blue clay and the master tires are just barely setting on the little stands of clay. The mold part to the left of that is the silicone that is poured over the tires and clay. Once the silicone is cured. It is unboxed and flipped over and the clay is removed. there is no reason to remove the tires. A good coat of Price Driscoll mold release is sprayed over the exposed surface so the next pour of silicone will not stick to the other part. And then you pour the silicone in and cure. The tires are really hard to remove, but they are better than nothing. The bottom pic shows how wide these babies are! I think it is a 1:24 scale kit. Here is yet another tire mold I made. It is more recent. I think it is from a diecast. Notice that the inside opening is formed nicely. It is to be stretched over the two piece diecast wheels. One has some black resin residue stuck to it. I bought some resin that does the black tires from Aero Marine and it set around for sometime before I tried it. I pretty much ruined this mold from trying to remove the uncured resin from it. This type of mold goes through a lot of stretching to remove a tire from it. I made some from Task 8 resin just for showing you. I don't have the master tire anymore. Edited January 8, 2012 by Greg Wann Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 8, 2012 Author Share Posted January 8, 2012 all or nothing Quote Link to comment Share on other sites More sharing options...
RyanSilva Posted January 8, 2012 Share Posted January 8, 2012 Frank I would leave a bit more room around the tire, unless you are using this as a test. One more thing about when its time to slice the mold, make nice clean cuts, if you do short jagged strokes, you can make a rough parting line and that will reflect on the tread line. I found using a stiffer silicone helps with the block molds and making clean parting lines. @ Dave, Thanks! Its been working for me for a few years now, with both rubber tires and resin, I aim to produce only clean high quality castings of everything I do. 2 more things about this. The length of your fill port/support reflects in the mold, so when casting you want it to be at least a 1/4 inch long. Dont try to skimp and make a smaller one to save on silicone, what happens here is that half of the mold will be left with less support when its all cured, and can give you oblong tires. The width of your port matters however small parts can have smaller ones, just flap part of the mold open and pour, then close it, with wider tires sometimes you will get bubbles that rise up and hide under hard edges like around the fill port, sometimes they cant sneak around that edge and up the port to gas out, so to combat this you make a wider fill port with some styrene, the width of the master tire (say a pro street) if using resin you can get away with a thin wide fill port, if using rubbers I suggest using a 1/4 inch bub in center and the .60 styrene on either side of it. I will have more pics tomorrow. Quote Link to comment Share on other sites More sharing options...
Greg Wann Posted January 8, 2012 Share Posted January 8, 2012 (edited) Ryan, that is some SUPER nice work there and a very helpful post Greg? sorry, but that is some rough looking stuff there Yes, the bottom tire is pretty rough as I beat the mold up trying to get the black uncured resin out of it. Your focus is supposed to be on the mold design. Did you even notice that my mold re creates that groove that is supposed to be in the tire? I had made some perfectly good tires from this mold before. I'm still on a learning curve for making tires. http://smcbofphx.pro...play&thread=661 Here is a link to a post on my forum from when the mold made perfectly good tires and I made the other wheel parts. Edited January 8, 2012 by Greg Wann Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 8, 2012 Author Share Posted January 8, 2012 Frank I would leave a bit more room around the tire, unless you are using this as a test. One more thing about when its time to slice the mold, make nice clean cuts, if you do short jagged strokes, you can make a rough parting line and that will reflect on the tread line. I found using a stiffer silicone helps with the block molds and making clean parting lines. @ Dave, Thanks! Its been working for me for a few years now, with both rubber tires and resin, I aim to produce only clean high quality castings of everything I do. 2 more things about this. The length of your fill port/support reflects in the mold, so when casting you want it to be at least a 1/4 inch long. Dont try to skimp and make a smaller one to save on silicone, what happens here is that half of the mold will be left with less support when its all cured, and can give you oblong tires. The width of your port matters however small parts can have smaller ones, just flap part of the mold open and pour, then close it, with wider tires sometimes you will get bubbles that rise up and hide under hard edges like around the fill port, sometimes they cant sneak around that edge and up the port to gas out, so to combat this you make a wider fill port with some styrene, the width of the master tire (say a pro street) if using resin you can get away with a thin wide fill port, if using rubbers I suggest using a 1/4 inch bub in center and the .60 styrene on either side of it. I will have more pics tomorrow. its a test but the rubber compound i use is a solid as a brick too Quote Link to comment Share on other sites More sharing options...
crazyjim Posted January 8, 2012 Share Posted January 8, 2012 For this procedure do you have to use a pressure pot? Quote Link to comment Share on other sites More sharing options...
RyanSilva Posted January 8, 2012 Share Posted January 8, 2012 No you dont need one, but I highly suggest a pot if you sell any resin at all, the quality is night and day and worth the 80 dollar investment. Quote Link to comment Share on other sites More sharing options...
Lownslow Posted January 8, 2012 Author Share Posted January 8, 2012 For this procedure do you have to use a pressure pot? it came out fine i used talcum powder on mine i wont use the pot till after i get the stuff i order from Ma's hopefully this week or the next i hate being broke Quote Link to comment Share on other sites More sharing options...
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