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Building Tips and technical articles. => 1/2 A building. => Topic started by: Phillip Kenney on June 21, 2012, 03:08:46 PM
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Finishing up a Dick Sarpolus Mustang and had a question about the mounting of the engine. While the mounting holes will fit a 4-40 screw would a 2-56 be a better choice to go into the 1/4 square motor mount?
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Hello Phillip, I use 2-56 for installation myself. The Norvel mount came with screws that were metric and are slightly larger than the 2-56 diameter. The 2-56 screws are completely safe and will suffice. Ken
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IMO a 2-56 is perfectly adequate for 1/2A engines. If the holes in the engine are too large a washer may be needed to keep the screw from pulling through. I bliessed with a lathe, so in extreme cases I make a stepped washer. 3/16 OD, with 1/32 thick flange, boss diameter to match the hole in the engine with length just less than the mount lug thickness, then a through #44 (.081) for the mounting screw.
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oops the magic fingers messed up I meant. "I'm blessed ...."
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Philip, glad your getting along with the Mustang,the metric engine to tank mount screws were very similar to 3-48 in size. I generally use 4-40, 2-56 might be the better choice for the 1/4 inch mounting wood, i have used 2-56 quite often i just like to check the tightness a little more often with that size just for peace of mind! Hope it turns out great for you!
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I have to agree with Ray as I usually use 3-48. They are not a difficult size to obtain and you can get them in many sizes also washers,lock washers,nuts and locknuts. I usually go to Micro fasteners but any supply house can fix you up. They are the correct size for a baby bee ,T,D and others I suppose.
Dennis
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I've used both 3-48 and 2-56, prefer the smaller as its blind nuts fit a 1/4" wide mounting beam better. Smaller hole surely makes for a stronger beam too. In my experience 2-56 is plenty beefy enough for 1/2 As.