I want you guys to think about something.
When you torque a small bolt, you can get ALOT of Compression strength. Hundreds of pounds are possible from one small bolt.
Each bolt is additive.
When you have more bolts, you increase the chance of Bolt Crosstalk. Where by tightening one, you loosen another because you've reduced the stretch on that screw by compressing the plate nearby.
This means if you go too high you may be applying MORE than the needed in-lbs because the plate is already compressed.
You can test this by torquing all 6 screws to 10in lbs. Keep going until the torquing stops (Go over and over and over until you're not tightening anymore)
Now, remove one central screw from both sides, and try to remove the remaining 4 corner screws with the torque driver still at 10in lbs.... You can't move the bolts, you have to increase the torque higher to get the bolts to release... The torque you show now, is what those bolts are holding now. Even though you haven't tightened them any more, you'll see they are now like 16 in-lbs.....
Now think of something else......
A #6-40 bolt makes 371lbs of Tension with 10 inch lbs of torque. (
https://www.futek.com/bolttorque/american)
Now you have SIX per ring. . . . That's 2,226 LBS OF TENSION..... But over how much surface area?
A 1" LONG ring, 1.338" Diameter (34mm) has a surface area of:
Pi*d*l
3.14*1.338*1= 4.20 Square Inches.
2,226 lb / 4.2 si = 530 PSI.
WHY?
That's 10 INCH POUNDS.... and you guys are torquing to 20?
I asked my Civil Engineer Friend who designs structural bridges, how he would handle this, given that if you don't apply at least a minimum torque to a screw to induce stretching, then it really doesn't count for compression holding.
His answer: Reduce the number of bolts used.
I.E. Take out the center two. and if that's STILL too much, take out the 4 corners and ONLY use the center two.
I don't know if these Manufacturers even do these calculations.... Has anyone seen the "Data" ?
