Daytonarc
70cc twin V2
Mcmaster actualy has that same bolt in the high strength nylon, that is what I use with a bonded washerActually the picture that comes up from the link I posted isn't what they actually look like. That part number is for a 1/4-20 Thumbscrew with a raised, knurled head that is about 5/8" in diameter and there is no screw driver slot. Not sure why I couldn't get the link to the proper part.
They actually look like this:
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