Mechanical Fastener Strength Comparison

During nearly one year (and 520 hours) of building on our standard -9A project, our riveting technique has improved significantly. But there are those times when forward progress stops and we need to drill out a rivet.

With a drawer full of "opps" rivets, this is less of an issue than with the 3/32" rivets particularly if we end up enlarging the original hole. This is more of a problem when we end up enlarging an 1/8" hole (this occurs most often when we are working with the angle drill in tight quarters). Our first inclination is always to "fatten" another 1/8" rivet and set it straight. Or there is always the option of moving up to a -5 rivet. But difficult access tempts us use an 1/8" pop rivet (blind rivet) in place of a driven rivet. We have not faced this yet, but I can see that if the hole is terribly ragged we might consider even moving up to a 1/4" bolt. That leave us with the following questions.

1) How does the strength of an 1/8" driven rivet compare with the strength of an 1/8" pop rivet (blind rivet) both in shear and overall strength?

2) How does the strenth of a 1/8" driven rivet compare with the strength of a 1/4" bolt both in shear and overall strength?

pop rivets

i dont know actual comparison numbers for your querry but i will say the cherry lock, and cherry max have equal strentgh as a solid rivet provided they are installed correctly. as far as pop rivets most of them are not as strong as solid but how much strentgh does the joint require? map box or wing spar kind of thing. the bolts are certainly stronger but will they provide a interference fit (tight shear joint)or are you depending on the clamping action to hold the parts together?

I also have a question with cherrymax or other blind rivet being compatible. On my 9A QB, I'm getting ready to rivet the junction(don't have my plans with me so I can't give part #'s) of the middle bulkhead, where the seat backs rest, to the side skin, longeron, and slider brace. The problem is with the rivets that insert from the top and go into the longeron. You know, the tight ones where people have to find creative ways to set them. The problem is the when the folks in the Phillipines drilled these holes, they drilled them at an angle. About 5 degrees off. I'm afraid if I attempt to drive these, they'll bend over. Any suggestions or appropriate substitutions?

Certain Cherry rivets are structural and compare favorably to a solid rivet of the same nominal dimension. http://tinyurl.com/trgsx
A word on typical blind fasteners as supplied by Van. Generally speaking, a blind fastener is not as strong as a solid rivet. In addition, over time many types of blind rivets can work loose. For that reason, you need to pay particular attention to hole quality and this is where I sometimes cringe when people routinely use a #30 drill bit for those holes filled with blind rivets. A #30 hole translates to .1285. That hole size for a -4 blind rivet is too big! If you mic the kit supplied blind rivets, you will find most of them range from .1230 to .1250. This means a 1/8 drill bit which is .125 should be used for hole preparation, NOT a #30 drill bit. The photo demonstrates what I am talking about. MSP-42 blind rivets are used to assemble the push/pull control tubes. Rightly or wrongly, I personally tend to consider this installation a particularly critical application. As the micrometer shows, the diameter of an MSP-42 blind rivet is approximately .123 ballpark. Where I came from, the acceptable tolerance for blind fastener installation INCLUDING CHERRY RIVETS was 2 thousandths over. Anything more than that and the hole had to be brought up oversize.

Oversize CherryMax

jlfernan said:

I also have a question with cherrymax or other blind rivet being compatible. On my 9A QB, I'm getting ready to rivet the junction(don't have my plans with me so I can't give part #'s) of the middle bulkhead, where the seat backs rest, to the side skin, longeron, and slider brace. The problem is with the rivets that insert from the top and go into the longeron. You know, the tight ones where people have to find creative ways to set them. The problem is the when the folks in the Phillipines drilled these holes, they drilled them at an angle. About 5 degrees off. I'm afraid if I attempt to drive these, they'll bend over. Any suggestions or appropriate substitutions?

Click to expand...

Yes... re-drill the holes straight for oversize CherryMax rivets...

The oversize ones are 0.157 diameter.... which should clean up your angled hole...

http://www.aircraftspruce.com/catalog/hapages/cherrymax.php

gil in Tucson

how much angle

jlfernan said:

I also have a question with cherrymax or other blind rivet being compatible. On my 9A QB, I'm getting ready to rivet the junction(don't have my plans with me so I can't give part #'s) of the middle bulkhead, where the seat backs rest, to the side skin, longeron, and slider brace. The problem is with the rivets that insert from the top and go into the longeron. You know, the tight ones where people have to find creative ways to set them. The problem is the when the folks in the Phillipines drilled these holes, they drilled them at an angle. About 5 degrees off. I'm afraid if I attempt to drive these, they'll bend over. Any suggestions or appropriate substitutions?

Click to expand...

1. how much angle before you go oversizing?
2. can the rivet be driven?
3. watch the edge distance esp. on the longeron.


i am dreading this juncture myself cause the 705 g bracket looks to be in the way. have been saving it for all of hunting season and now it's due.

This poses another problem. These are 3- rivets, I really don't want to drill out to a 4- for a Cherrymax. I know they have a new rivet, the Cherry SPR? 3/32" Self-Plugging Rivet. It comes in the correct size but I don't know if this would be acceptable. Oh well, might as well call the source, Vans, tommorrow.

Only 1/64 larger...

jlfernan said:

This poses another problem. These are 3- rivets, I really don't want to drill out to a 4- for a Cherrymax. I know they have a new rivet, the Cherry SPR? 3/32" Self-Plugging Rivet. It comes in the correct size but I don't know if this would be acceptable. Oh well, might as well call the source, Vans, tommorrow.

Click to expand...

CherryMax oversize are only 1/64 larger than the standard...
They are made for slightly enlarged holes, not "drilled out to the next size" holes.
Check the link in my previous post....

gil in Tucson

Gil I understand that, but the rivets I have a problem with are 3/32" drilled with a #40 bit. The Cherrymax from A.S. need a #30 hole and I don't feel right going that large in this spot.

jlfernan said:

Gil I understand that, but the rivets I have a problem with are 3/32" drilled with a #40 bit. The Cherrymax from A.S. need a #30 hole and I don't feel right going that large in this spot.

Click to expand...

Sorry... mis-read the -3....

gil