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I've been testing different methods & materials for what will ultimately be my radial engine crankcase sealing decision. I'm not super happy with my test result implications thus far, so was wondering if anyone has experience using Teflon?
The pink line shows a path where oil could migrate externally between 2 mating parts. On the left side is the engine nose chamber which is partially filled with oil for bathing the gears & cam lobes. The designer calls for O-rings as seals between various components, 1mm section diameter. I'm finding that achieving the correct groove depth & nominal O ring diameter (made from cord line stock) is a bit fussy. Too shallow & the parts bind up. Too loose & I doesn't seal.
I think I can handle the radial O-rings ok, but the one on the CC face right by the pink line has me more concerned. I'll only have one shot to make that groove correctly & there will be a lot of machining operations on the CC before knowing for sure. Its also very close to the edge which I don't like.
My first idea was to cheat & bypass the CC face O-ring altogether. I bought Permatex RTV gasket caulking & tried on a test piece. It sealed perfect but unexpectedly stuck my test parts together like glue. Maybe FS auto parts have leverage to crack the seal but I'm concerned about my fickle little model components - there is nothing to grab onto for leverage. I tried some release agent which helps but this seems like a PITA if I have to re-assemble engine many times. I tried another silicone which was weaker but I don't think its intended for oil service like this.
Looks like the thinnest Teflon sheet comes in 0.002" thickness @ inexpensive 3$ for 12x12". Being that thin, it wont require altering dimensions of mating parts to compensate thickness. But I'm wondering if the Teflon itself might be 'hard' relative to softer gasket materials, ie. will it seal? The thinnest conventional (softer?) gasket sheet I can find is 1/64" (0.016"). Silicone sheet comes in 0.005" but its 31$ for 6x8".
Any thoughts or experience?
The pink line shows a path where oil could migrate externally between 2 mating parts. On the left side is the engine nose chamber which is partially filled with oil for bathing the gears & cam lobes. The designer calls for O-rings as seals between various components, 1mm section diameter. I'm finding that achieving the correct groove depth & nominal O ring diameter (made from cord line stock) is a bit fussy. Too shallow & the parts bind up. Too loose & I doesn't seal.
I think I can handle the radial O-rings ok, but the one on the CC face right by the pink line has me more concerned. I'll only have one shot to make that groove correctly & there will be a lot of machining operations on the CC before knowing for sure. Its also very close to the edge which I don't like.
My first idea was to cheat & bypass the CC face O-ring altogether. I bought Permatex RTV gasket caulking & tried on a test piece. It sealed perfect but unexpectedly stuck my test parts together like glue. Maybe FS auto parts have leverage to crack the seal but I'm concerned about my fickle little model components - there is nothing to grab onto for leverage. I tried some release agent which helps but this seems like a PITA if I have to re-assemble engine many times. I tried another silicone which was weaker but I don't think its intended for oil service like this.
Looks like the thinnest Teflon sheet comes in 0.002" thickness @ inexpensive 3$ for 12x12". Being that thin, it wont require altering dimensions of mating parts to compensate thickness. But I'm wondering if the Teflon itself might be 'hard' relative to softer gasket materials, ie. will it seal? The thinnest conventional (softer?) gasket sheet I can find is 1/64" (0.016"). Silicone sheet comes in 0.005" but its 31$ for 6x8".
Any thoughts or experience?