What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Beginner Riveting Question

SteveO

Member
I’m accumulating tools and doing some practice riveting before I dive into my first build, and have a lot of questions, this one about riveting. I drilled a #40 hole for a 3/32 AN426 rivet, then dimpled the hole. I noticed that after dimpling the rivet was somewhat loose in the hole before bucking. I decided to drill a 3/32 hole, dimple it, and see if I could fit a 3/32 rivet in the hole. It fit in very easily due to the hole increasing in size from dimpling. So the question is, if I’m dimpling and using an AN426 rivet is it ok to drill a 3/32 hole for a 3/32 rivet, or a 1/8 hole for a 1/8 rivet, etc?
 
No. I think you want to use a #40 drill for your 3/32 and a #30 for the 1/8 rivet holes. A couple of things to check are that your chuck runs true and that your bits are sharp and not bent. Some people use a #41 for the 3/32 rivets, but using a smaller hole, then relying on the dimple to open the hole may result in micro cracks around the hole. It has been discussed at length here before, just search for it. I have had a #41 drill make holes that would be #36 due to a bent or wobble in the chuck, so check that. It is acceptable for a certain amount of diameter increase after dimpling, someone here posted the milspec tolerances not too long ago that is allowed..

Great question though.. keep them coming! People here love to help!
 
Rivet expands

FAR from an expert but the rivet expands to fill the hole as a result of the setting process
 
I noticed that after dimpling the rivet was somewhat loose in the hole before bucking.

Part of the beauty of how a rivet works is that it will expand to fill that looseness. After you get to building, and have to drill out a few botched rivets, you'll see just how much a rivet can expand after driving them.
 
I prefer to use a reemer for the final hole size. It makes a perfect round hole and keeps it straight. I have a reemer for #40, #30, #6 and #8 screw plus a few other sizes for the bolts that I gathered along the way.

Jay
 
Reamers

2nd the reamers. The hole is still enlarged but the reamer leaves a cleaner hole before dimpling. Probably thousands of RVs flying were build without reamers so its6 a personal choice.
Standard sizes will suffice. 40,30,29,19,12, 3/16, 1/4
 
Not mentioned yet, is that the shear strength of a rivet is proportional to its cross sectional area. A (final size) rivet properly set in a #40 hole is about 8% larger in area than one in a 3/32” hole, and hence 8% stronger.
 
Back
Top