robbor

Silicone Mold Frame

9 posts in this topic

I just finished two aluminum mold frames to try and vulcanize silicone in an oven. One is 2.5 x 3.5 and the other is 3 x 5. I even found sprue formers in sizes 3/8 to 9/16. My last step is to drill holes for the sprue formers. I milled out the frames on an x/y table on a drill press. They turned out ok.

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Hey Rob, how about some photos as you progress through your project. Your description may leave some wondering what you are doing while a picture is still worth a thousand words. I am interested in following along with your progress.

Thanks

George Reeves

H&P Tackle

Welch, OK

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I will post some pics in a week or so. Right not I dont have a program installed to resize the pic so they will post.

My frame is 1 1/4" in thich and about 7 x 8 outside. Inside it is milled to 3 x 5 and has 8 hols drilled all the way through for studs. Each side of the mold takes a 1/2 aluminum plate which bolts on. The sprue formers are sall cones on 1/8 in rods. If you look at a jewelry mold frame they are almost the same, mine is just beefier and with studs. The thickness in 1 1/4 so i can put in a 1/4 spacer plate to compess and not hove excess sticking out the top when I add the cover plate.

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Yay!!! I got the pic posted!

So the frame is way over built yes! The top and bottem are removable plates(1/2") and ther are holes on all four sides. So far each end has one hole and one side has 8 holes spaced out 1/2" apart and the other has 5 holes spaced out 3/4" apart. The holes are 1/8" for sprue formers used in jewelry making. Now I have not made anything in the mold yet so, Im not shure about plugging the holes yet. I dont know if the sprue rods will just stay in place under the pressure or if I will have to either tap each 1/8" hole or tap a hole on either side of each series to screw a block over each series to hold all the rods in under the pressure. The scrap of aluminum I bought was the smallest they had in 1 1/4 thick and was actually big enough to make 2 frames out of, I cut it in half and it was still bigger than needed so rather than cut it I just chose to leave the sides thick, I think one side is 1.5" and the other is about 2". The block was milled out with a crappY extruded aluminum x/y table and an old 4 flute mill that some gave to me. I first cut out the hole in the center and then milled it roughly square. Its rougher than it looks but turned out well I thought. I determined the size by drawing 1/4 of a 12" circle(silicone 12" unvulcanized disc) then figure out how large I could make it and what shape I wanted. So It is made to mold 2 rows of small jigs heads at the same time with a row of 8 small heads(aprox 1/100th ice jigs) on one side and a row of 5 larger(aprox up to about 1/8 oz). But can obviously mold a single row or larger lures from the ends. I made a large and a smaller mold frame and should be able to get roughly 4 large and 4 small molds out of one disc but the small mold will probably have corner spilices to have the silicone fill the inside but is supposed to bond and be one piece. I also left room for small lock nuts in the corners to allign the molds.

It took alot longer than I thought to to mill out and layout and drill all the holes. Not knowing anything about milling a 2 flute bit didnt work worth anything at 1000 rpm but the 4 flute did fine. I used automatic trans fluid to lube and keep the chips clear.

This was a project to be able to make masters and play with designs with out using a whole spincasting silicone disk up. I will have more pics tward the end of the year with 12" mold frame and homemade spincaster.

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well I tapped all the holes from the outside so I can set the depth of the sprue rods and i also drilled thr rods and beveled the ends so i can glue un a small piece of .050" wire. I am planning that they will only extend about 1/16" or less. Here you will see a 1/2" x about 4 1/2" plate installed inder the sprue formers to form a trough connecting all the sprues(recomended by Rich). (Rich)I shure this is not exactly what you meant but i put the sprue formers on top. I can always make a thicker bar and just have the 1/8" rods come through and connect to the lures. I also picked up the silicone so this week I will make a mold.

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I have no idea whay they are greyed out, i tried to resize again and repost but still came out grey. If you click on them they come up in color.

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Well I finally got around to trying to vulcanize the first mold. It was a trial and error effort. It turned out ok but I had made a few sprue forming rods that tapered down to about a .025 piece of needle for a small ice jig but it wanted to go under the silicone instead of being in the seem. So on the real small stuff I will have to just cut the gates. I was not shure about using mold release or how much. So I grabbed my mica used in reloading and a solvent brush and wiped down the 1/2 mold with the master in it then i wiped the other half and put them todather. I was tough to get apart but turned out well for the first try. PS the small hooks are size #20

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Well I finally got around to trying to vulcanize the first mold. It was a trial and error effort. It turned out ok but I had made a few sprue forming rods that tapered down to about a .025 piece of needle for a small ice jig but it wanted to go under the silicone instead of being in the seem. So on the real small stuff I will have to just cut the gates. I was not shure about using mold release or how much. So I grabbed my mica used in reloading and a solvent brush and wiped down the 1/2 mold with the master in it then i wiped the other half and put them todather. I was tough to get apart but turned out well for the first try. PS the small hooks are size #20

robbor i went to a scrap yard and picked some pices of square alum. pipe also i dont use a sprue i cut them with a razor blade it is easier cutting the pipe than milling all that out some of my forms are6inches use powder for the seperator for the silicone

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