Love Machine
NES Member
Comrades,
I'm doing some engineering math.
The solid rivets we use in the AK builds are 5/32" in diameter, made of 18-8 stainless steel. The 18-8 stainless will shear at 45000psi, so using the cross-section calculation, r^2*pi*Ss where Ss is shear strength, we get (0.078)(3.14)(45000)=862lbs of force needed to shear the rivet. With a safety factor of 0.4 we get 345lbs.
A grade 5 bolt in 10-32 would be calculated as follows: minor diameter of 10-32 is. 0.15 and the shear strength is 90000psi. 0.075*0.075*3.14*90000=1590lbs. With a safety factor of 0.4 we get 636 lbs allowable shear force.
A grade 3 bolt in 10-32 would be calculated as follows: minor diameter of 10-32 is. 0.15 and the shear strength is 57000psi. 0.075*0.075*3.14*57000=1006lbs. With a safety factor of 0.4 we get 403 lbs allowable shear force.
A 5/32 stainless steel blind rivet from McMaster lists a shear strength of 650 lbs. With a safety factor of 0.4 that comes to 260lbs allowable shear.
A 3/16 stainless steel high strength blind rivet from McMaster lists a shear strength of 1650lbs, 660 with safety. Similar zinc plated high strength blind rivet is 1050lbs absolute and 420lbs safe.
Now the twist here is that Grade 5 bolts are listed to have Rockwell C hardness of 25 to 34, higher than 1080 steel. Unless you are hardening the entire receiver, the bolts will "eat" through the sheet metal once they vibrate loose and the load is place directly on the threads. Grade 3 bolts are much lower, they may actually be ok given the shear rating.
Another conclusion is that if you pick the right high strength blind rivet and set it correctly, it will match the performance of the solid rivet.
I'm doing some engineering math.
The solid rivets we use in the AK builds are 5/32" in diameter, made of 18-8 stainless steel. The 18-8 stainless will shear at 45000psi, so using the cross-section calculation, r^2*pi*Ss where Ss is shear strength, we get (0.078)(3.14)(45000)=862lbs of force needed to shear the rivet. With a safety factor of 0.4 we get 345lbs.
A grade 5 bolt in 10-32 would be calculated as follows: minor diameter of 10-32 is. 0.15 and the shear strength is 90000psi. 0.075*0.075*3.14*90000=1590lbs. With a safety factor of 0.4 we get 636 lbs allowable shear force.
A grade 3 bolt in 10-32 would be calculated as follows: minor diameter of 10-32 is. 0.15 and the shear strength is 57000psi. 0.075*0.075*3.14*57000=1006lbs. With a safety factor of 0.4 we get 403 lbs allowable shear force.
A 5/32 stainless steel blind rivet from McMaster lists a shear strength of 650 lbs. With a safety factor of 0.4 that comes to 260lbs allowable shear.
A 3/16 stainless steel high strength blind rivet from McMaster lists a shear strength of 1650lbs, 660 with safety. Similar zinc plated high strength blind rivet is 1050lbs absolute and 420lbs safe.
Now the twist here is that Grade 5 bolts are listed to have Rockwell C hardness of 25 to 34, higher than 1080 steel. Unless you are hardening the entire receiver, the bolts will "eat" through the sheet metal once they vibrate loose and the load is place directly on the threads. Grade 3 bolts are much lower, they may actually be ok given the shear rating.
Another conclusion is that if you pick the right high strength blind rivet and set it correctly, it will match the performance of the solid rivet.