Rivet for pivoting frame
Rivet for pivoting frame
(OP)
I'm looking for fasteners for an aluminum flat bar frame that needs to be able to open and stay open. to visualize the situation, think scissor lift or convertible car roof structure. the fasteners must maintain a fairly constant clamping force, enough to support about 10 ft-lbs of torque, even after many openings and closings. low cost is important.
I've tried small bolts with lock washers and also lock nuts with nylon inserts, but after a few opening and closings, these all loosened up and the frame would not remain free standing. Pop rivets were slightly better but loosened after a few cycles. I've seen on ladders for example, the spreader bars that lock the ladder open have what appear to be semi-tubular rivets holding the joints together. these allow the bars to pivot open but seem to maintain a constant clamping force. I'm not sure rivets are the ideal fastener as they seem to be better for non-pivoting joints, or ones in which the joint moves freely.
maybe there are some other types that might work? also thinking of trying a conical spring washer (i.e. belleville spring) with a bolt and nut or rivot.
I've tried small bolts with lock washers and also lock nuts with nylon inserts, but after a few opening and closings, these all loosened up and the frame would not remain free standing. Pop rivets were slightly better but loosened after a few cycles. I've seen on ladders for example, the spreader bars that lock the ladder open have what appear to be semi-tubular rivets holding the joints together. these allow the bars to pivot open but seem to maintain a constant clamping force. I'm not sure rivets are the ideal fastener as they seem to be better for non-pivoting joints, or ones in which the joint moves freely.
maybe there are some other types that might work? also thinking of trying a conical spring washer (i.e. belleville spring) with a bolt and nut or rivot.





RE: Rivet for pivoting frame
Regards,
Cory
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RE: Rivet for pivoting frame
http://www.hansonrivet.com/w11.htm
Are you could check out something like this binder post.
http://www.hansonrivet.com/w74b.htm
You could use a tubular rivet with a washer.
Hanson has a lot of different close coupled fasteners, look around.
RE: Rivet for pivoting frame
i think what might be happening is that the clamping force needed to keep the assembly from colapsing back down due to gravity is so high that the aluminum is getting ground away and the joints are loosening, although the fasteners are not.
RE: Rivet for pivoting frame