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self leveling or spherical washer use acceptable practice?

G

Gonzo24

Well Known Member
has anyone used self leveling or spherical washers on bolt applications that are not perpendicular on your RV? If so, do you have a good source for these? google brings up several options but I would like to know fellow builders experiences here with use and reliable sources.

My particular issue is a HS RR spar -3 bolt that is about 4 degrees off. I'm guessing that I could sand a washer to angle on one side for the bolt head and nut side but how do you get it the same angle?

if I use a spherical washer set, it will add .5 inches to the overall bolt length to maintain the grip range throught the washers and structure. The -7 bolt grows to a -12 for grip and minimal threads sticking out of the nut after torquing. Is this acceptable?
 
If you can find them...
For a bolt/nut you would need one on both sides.

43-13, Chapt 7

7-88. BALL SOCKET AND SEAT
WASHERS (AN950 AND AN955). Ball
socket and seat washers are used in special applications
where the bolt is installed at an angle
to the surface or when perfect alignment
with the surface is required. These washers
are used together as a pair.
 
Last edited:
So you have a ~.025" gap under one side of the head when the other is touching?

Gonzo24 said:
has anyone used self leveling or spherical washers on bolt applications that are not perpendicular on your RV? If so, do you have a good source for these? google brings up several options but I would like to know fellow builders experiences here with use and reliable sources.

My particular issue is a HS RR spar -3 bolt that is about 4 degrees off. I'm guessing that I could sand a washer to angle on one side for the bolt head and nut side but how do you get it the same angle?

if I use a spherical washer set, it will add .5 inches to the overall bolt length to maintain the grip range throught the washers and structure. The -7 bolt grows to a -12 for grip and minimal threads sticking out of the nut after torquing. Is this acceptable?
Click to expand...
 
Walt - thanks for the reference. did not know that they were called ball socket and seat washers also. I read the Chap 7 section and it makes sense. good to see it is a "sanctioned" fix.

gtmule - yes, there is a gap under one side when the head is seated. havent measured the exact gap but a protractor ref showed between 3-4 degrees with a longer bolt for checking.

Andrew - thanks for the reference. Thats looks like a good source.
 
spherical washers

I used them on the aft spar (both sides, bolt head and nut) to ensure no contact point stress riser.
 
I had the same problem when I built my RV4, but on the gascolator mounting, so I made aluminium tapered washers to suit. My T.C. was happy with that and so far no problems.
 
Here's what I did

Here is what I did.

...well that's not totally true. Although the fix would have been fine from a structural standpoint, I wasn't happy with the job, so I removed and replaced the affected parts.

FYI, a while back I did some research into the effect a non-perpendicular hole had on bolted joint strength. IIRC, a .5 degree angle reduced strength by about 10% and a 2 degree angle reduced strength by about 80%. :eek:

I'll see if I can dig up the reference tomorrow.
 
Pic of the fix

Stainless spherical washers from McMaster Carr installed. Easy fix. Thanks for the tip on where to find them. Had to go from a -7 bolt up to -11 for grip and thread margin in the nut.

291nv6b.jpg
 
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