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MK321-BS Source?

blaplante

Well Known Member
I'm looking for the longer version of the MK319-BS blind rivets. I can't seem to find anyone that has them in stock. Suggestions?

Alternatively... I'm trying to install piano hinge for the cowling on the fuselage sides. But the prior owner already installed the engine mount and engine, so my squeezer and bucking bars don't fit! The squeezer hits the engine mount tube.
 
I'd check with Vans before I wholesale replaced a line of driven rivets with a line of pull rivets. One or two, sure, but not a whole row.

If you have a hand squeezer, a no hole yoke with the tip ground down to give it more of a duck bill profile will probably fit.
 
I made a custom bucking bar out of a piece of steel bar stock to get the rivets around the engine mount on my -8. Practice with it first. It rattles around more than a heavy bucking bar

There is a cherry pull rivet, CCC-32 that is a flush 3/32” diameter that I have used for nut plates. ACS has them. Not sure how critical those rivets are. They are ugly and everybody will see them.

There is also the Cherry Max 3214-4 rivets that are structural that look good but are harder to source. You have to specify the grip length. Available from
https://www.gen-aircraft-hardware.com/
 
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I'd check with Vans before I wholesale replaced a line of driven rivets with a line of pull rivets. One or two, sure, but not a whole row.

If you have a hand squeezer, a no hole yoke with the tip ground down to give it more of a duck bill profile will probably fit.

The no hole is a no go as I need to clear the ears (eyes?) of the piano hinge
 
I made a custom bucking bar out of a piece of steel bar stock to get the rivets around the engine mount on my -8. Practice with it first. It rattles around more than a heavy bucking bar

There is a cherry pull rivet, CCC-32 that is a flush 3/32” diameter that I have used for nut plates. ACS has them. Not sure how critical those rivets are. They are ugly and everybody will see them.

There is also the Cherry Max 3214-4 rivets that are structural that look good but are harder to source. You have to specify the grip length. Available from
https://www.gen-aircraft-hardware.com/

I have some CCC-32 ... I'd never use them in this structure. Just don't seem very strong.
 
I'd check with Vans before I wholesale replaced a line of driven rivets with a line of pull rivets. One or two, sure, but not a whole row.

I agree a confirmation w/Vans is always a good idea. I do like to avoid asking stupid questions... so the homework:

These (MK319 / MK321) are Monel metal rivets, shear strength = 258 lbs, tensile strength = 298 lbs.
Some quick calc on the AN426 rivets (2117 aluminum - assuming T4, which is 28,000 psi shear strength) gives 193 lbs to shear the rivet called out in the plans.
 
Is the engine just installed on the mount with no other work done, or is all the engine plumbing and wiring hooked up too? If the former, it wouldn't be a bad job to suspend the engine from a crane and unbolt the engine mount for an hour while you squeeze the firewall rivets. If the latter, it still might not be too bad of a job, just more tedious.
 
Like Matt said, removing the engine mount from the fuselage is pretty easy, especially if the top skin is not yet closed out. Much easier than removing the engine from the mount.
 
Is the engine just installed on the mount with no other work done, or is all the engine plumbing and wiring hooked up too? If the former, it wouldn't be a bad job to suspend the engine from a crane and unbolt the engine mount for an hour while you squeeze the firewall rivets. If the latter, it still might not be too bad of a job, just more tedious.
+1

Like Matt said, removing the engine mount from the fuselage is pretty easy, especially if the top skin is not yet closed out. Much easier than removing the engine from the mount.

+1 again. I did the above. Solo.
 
this is a 6... so main wheels are on the mount. And no wings installed. So it involves supporting both the fuselage and the engine. Fabbing a custom bucking bar might be easier.
 
Another option: switch to screws, camlocs, or whatever else you like that isn't a piano hinge. Then you'll just be riveting flat pieces of aluminum, and will be able to use your no-hole yoke for most of the rivets.
 
I agree a confirmation w/Vans is always a good idea. I do like to avoid asking stupid questions... so the homework:

These (MK319 / MK321) are Monel metal rivets, shear strength = 258 lbs, tensile strength = 298 lbs.
Some quick calc on the AN426 rivets (2117 aluminum - assuming T4, which is 28,000 psi shear strength) gives 193 lbs to shear the rivet called out in the plans.

Are those calculated shear values on the Monel rivets based on just the material, or is it from test data on the rivets themselves? Calculated values tend to be a bit optimistic (i.e. unconservative).
 
Anyone have any MK321-BS?

I need 1 and trying not to buy 250 to meet the $50 minimum at the one supplier I found that carries them.

Thanks!
 
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