Originally Posted by InsideOut
Another vote for "no washers". The will deteriorate over time and then rivets will be loose and leak. Dip each rivet in Vulkem instead...that's what we've done
Part of the purpose of using Olympic rivets with washers, is to compensate for sloppy drilling as well as using the wrong drill bit size.
Olympics have been around for a long time.
Caravanner Insurance Company, gave strick instructions to shops doing sheet metal work, to NEVER
evr use olympics with washers.
THey were told to add some Vulkem sealer to the back side of the rivet head, then insert the rivet in the hole.
Contrary to many, the absolute correct size drill bit to use for the Olympic rivets that should be used, is a # 21 drill bit.
Dimensions for what is in question are:
# 21 drill = .159 inches
# 20 drill = .161 inches
Olympic rivet = .15625 inches.
# 20 drill hole is .00475 over size
# 21 drill hole is .00275 over size
Obviously, a tighter fit takes place when using the # 21 drill bit, but a tighter fit is always superior to a loose fit.