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Top skin blind rivets

cdeerinck

cdeerinck

Well Known Member
Two questions here:

1) Does anyone know why the plans call for two different rivets as indicated below by the purple arrows? This is for the RV-8 top skin over the avionics and luggage areas. The row that attaches the skin to the firewall calls for 3-5 rivets, but those two call for 3-4 rivets. The material is the same thickness throughout. I can't for the life of me figure out why.

2) I need to get some Cherrymax rivets for some of the AN426AD3-6 and AN426AD3-8 rivets on the sides, given that I don't have fairy hands. It seems there are three product lines that might do the job: CR1122's (Self-Plugging Rivets), CR9116's (MS Rivets), or CR264CS's (Pull thru nut plate rivets). I am not sure which makes the most sense, and I can't seem to find suppliers for the -3-06 and -3-08 sizes. Can anyone help me out?

I am just about done with the avionics, so my next job is to pull them all out, rivet this skin, then put them all back in. Yay!

33fdtu8.jpg
 
Don't give up now, you are almost finished. Someone in your EAA chapter must have small hands and riveting experience.
 
If you have to work alone, ask Vans if it is OK to upsize the rivets you can't buck along the longeron to 1/8 (#30 holes)?

If it's OK then CherryMax rivets would work well.
 
If you have access to the back side, you can use a rope to tie a heavy steel back rivet plate to the top, and back rivet. Very slow but it can be done.
 
Call-outs.

cdeerinck said:
Two questions here:

1) Does anyone know why the plans call for two different rivets as indicated below by the purple arrows? This is for the RV-8 top skin over the avionics and luggage areas. The row that attaches the skin to the firewall calls for 3-5 rivets, but those two call for 3-4 rivets. The material is the same thickness throughout. I can't for the life of me figure out why.

2) I need to get some Cherrymax rivets for some of the AN426AD3-6 and AN426AD3-8 rivets on the sides, given that I don't have fairy hands. It seems there are three product lines that might do the job: CR1122's (Self-Plugging Rivets), CR9116's (MS Rivets), or CR264CS's (Pull thru nut plate rivets). I am not sure which makes the most sense, and I can't seem to find suppliers for the -3-06 and -3-08 sizes. Can anyone help me out?

I am just about done with the avionics, so my next job is to pull them all out, rivet this skin, then put them all back in. Yay!

33fdtu8.jpg
Click to expand...

It has been a long time now that we did this area, and I do not remember this being called out. However it is an area that is not under heavy stress. The rule in sheet metal work is general in cases like this. You gage the length of rivet needed and that is what you drive. There were and have been places during construction that had a factory "call out" that when gaged needed a shorter or longer rivet to make that stack-up have a good shop head once driven. So that is what is done, trim some off the shank, use a longer rivet or oversize it when you have a bad hole. I think the best I can recall is this spot is where the two hinge pins come together when installed from the inside to mate the upper cowl to the fire wall. This may be a spot set aside for a mount to lock those ends in place there. This would be an option you may wish to consider. Hope this helps, Yours, R.E.A. III #80888
 
Getting Old

Man, I must be getting old. I read that whole thread about Cherry rivets about 2-3 weeks ago and completely forgot about it.

I still don't understand how people are using 4-4 rivets when the plans call for 3-6 and 3-8 rivets. I understand widening the hole, but how would that change the grip length?

Just to be sure, I ordered a Cherry Grip Cage, and will do a survey and inventory of what I need. I am concerned that even Genuine Aircraft Hardware only goes up to a -4-06, and I think I need a few -4-08's.

I guess I will know for sure when I get the Cage. Thank you everyone for setting me straight.
 
cdeerinck said:
Man, I must be getting old. I read that whole thread about Cherry rivets about 2-3 weeks ago and completely forgot about it.

I still don't understand how people are using 4-4 rivets when the plans call for 3-6 and 3-8 rivets. I understand widening the hole, but how would that change the grip length?

Just to be sure, I ordered a Cherry Grip Cage, and will do a survey and inventory of what I need. I am concerned that even Genuine Aircraft Hardware only goes up to a -4-06, and I think I need a few -4-08's.

I guess I will know for sure when I get the Cage. Thank you everyone for setting me straight.
Click to expand...

You can't directly link the dash numbers of CherryMax and solid rivets.

CherryMax dash numbers are for the total grip required while the solid rivets add approx. 1.5 D to this grip (material stack up thickness) to give the extra rivet sticking out that you hammer down to 0.5 D thick.

The CherryMax grip gauge you ordered works well, however you can calculate it easily if you know the material thicknesses involved. If you primered, don't forget to add 1 to 2 thousands for each primed surface involved since this can easily move you to the next grip length.
 
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Two different size fw rivets

Regarding (1), I think you will find if using the hinge method for attaching the cowl, there's a small break in the hinge right where you highlighted.
 
Different Rivets

cdeerinck said:
Two questions here:

1) Does anyone know why the plans call for two different rivets as indicated below by the purple arrows? This is for the RV-8 top skin over the avionics and luggage areas. The row that attaches the skin to the firewall calls for 3-5 rivets, but those two call for 3-4 rivets. The material is the same thickness throughout. I can't for the life of me figure out why.

As I remember; This is the area where there is a space where there is no hinge. It is where you will reach in through the oil check door and insert or remove the hinge pins that hold the upper edge of the upper cowl. No hinge...less thick.
Click to expand...
 
8 Builder said:
cdeerinck said:
Two questions here:

1) Does anyone know why the plans call for two different rivets as indicated below by the purple arrows? This is for the RV-8 top skin over the avionics and luggage areas. The row that attaches the skin to the firewall calls for 3-5 rivets, but those two call for 3-4 rivets. The material is the same thickness throughout. I can't for the life of me figure out why.

As I remember; This is the area where there is a space where there is no hinge. It is where you will reach in through the oil check door and insert or remove the hinge pins that hold the upper edge of the upper cowl. No hinge...less thick.
Click to expand...

Yep exactly, I just looked and verified. No hinge at that point where those two rivets are, for the insertion of the pins that join the halves together to attach the top cowl half.
Click to expand...
 
Hinges

I used a dremel tool to remove a couple of the hinge eyelets on both hinges so no need to actually install two separate pieces...worked great. Then there is no need to use the Cherry Max here.
 
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