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Non-dimpled nut plates on dimpled holes? Lower Firewall and Firewall Shelf

bsbarnes10

Active Member
We've just gotten the forward section of the fuselage and on page 22iS/U-03 (rev. 1) in steps 2 and 8 you are directed to rivet K1000-3 nut plates to the Lower Firewall (F-01201C-1) and the Firewall Shelf (F-01201B-1). In both steps the parts that the nut plates are being riveted to are dimpled for flush rivets but the nut plates are not dimpled, nor are you instructed to dimple them. Is this correct? If installed this way there will be a small gap between the nut plate the corresponding part.

Up to this point in the fuselage, the majority of nut plates have been pre-dimpled for flush rivets. I do seem to recall at least one location where a non-dimpled nut plate was installed on a dimpled component but I think this was specifically noted in the plans.

I searched the forums and couldn't find anyone else asking this question so perhaps this is a normal practice (non dimpled nut plates on dimpled components) but it's new to me so I just want to confirm with the experts out there....

Thanks,
Bruce
 
Like Ralph said, dimple them. You'll most likely need a ground down or reduced diameter female die though, and I suggest after dimpling that you carefully bend the tabs straight. They're much easier to rivet if they sit flush onto the surface and dimples.
 
Plate nuts

Many of us use “oops” rivets to fasten plate nuts . The head is so small you can machine countersink even in thinner material
 
I think it's an error in the manual and I stare at the results everyday as I'm now working on the engine ;-)

I didn't dimple the nut plate and it sits awkwardly on the back of that dimple. Now with more building experience I would have probably caught it but at the time I'm was thinking I assume there is a reason for not dimpling.

I would drill it out but it's those pesky stainless steel CCR rivets that love to spin in the hole. So I live with it.

Robert
 
Thanks guys, based on these responses we decided to dimple them and I think that was the right choice.

(I sure hope so, anyway, because you're right, drilling out those CR rivets is a pain in the butt!)

-Bruce
 
What I Did - "Dimple Shim"

These "shims" are available commercially, or so simple - just MYO.

Pretty self explanatory - a shim between the offending dimple and the nut plate.

HFS
 

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Van’s says dimple

I emailed Support to ask whether I should know by know to dimple the nutplates without being told, or whether I should know to trust Van’s instructions and not dimple them. They said the former, so I’m dimpling!

…Bryan
 
Many of us use “oops” rivets to fasten plate nuts . The head is so small you can machine countersink even in thinner material

Absolutely. Five turns with a deburring tool is just about right for the CS.

Using oops rivets for nut plates was probably one of the best 5 tips I got from another builder.
 
Same thing occurs on Section 23 page 7, and I wrote Van's support to ask:

"Step 6 and Figure 1 on this page call for dimpling to install nutplates around the triangular hole in the side skin, and riveting the nutplates with flush rivets. However, Figure 1 calls for K1000-08 rivets, which are flat rather than dimpled. Is this correct? Should these be K1000-08 rivets or -08D rivets?"

Sterling from Van's replied:
"The requirement to be flush is on the outside surface of the fuselage. The nut plates called out are fine to used on a dimple, they will stand off the surface of the sheet but this does not impact the way they will function. Dimpled nut plates are relatively new and look nice but are by no means necessary."

--CT Cole
 
Same thing occurs on Section 23 page 7, and I wrote Van's support to ask:

"Step 6 and Figure 1 on this page call for dimpling to install nutplates around the triangular hole in the side skin, and riveting the nutplates with flush rivets. However, Figure 1 calls for K1000-08 rivets, which are flat rather than dimpled. Is this correct? Should these be K1000-08 rivets or -08D rivets?"

Sterling from Van's replied:
"The requirement to be flush is on the outside surface of the fuselage. The nut plates called out are fine to used on a dimple, they will stand off the surface of the sheet but this does not impact the way they will function. Dimpled nut plates are relatively new and look nice but are by no means necessary."

--CT Cole

An 08 that you dimple yourself becomes an 08D. If the rivet holes that hold the nut plate are dimpled, dimple the nut plate or use one that is pre dimpled.

Pre dimpled nut plates is something newish from Vans. When I built my 7, I had to dimple them myself.

K1000-08 and K1000-08D is a nut plate part number not a rivet number.

To put a flat nut plate on top of dimpled holes is not the way things should be done. When the screw is torqued down, it will pull the nut plate up until that gap is gone. This will put unnecessary stress on the assembly and it will try to push the dimples flat and bend the nut plate ears.
 
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These "shims" are available commercially, or so simple - just MYO.

Pretty self explanatory - a shim between the offending dimple and the nut plate.

HFS

Extra weight. Not on my bird. ;)
 
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These "shims" are available commercially, or so simple - just MYO.

Pretty self explanatory - a shim between the offending dimple and the nut plate.

HFS

Are these intended for using a regular nutplate on a dimpled screw hole or a dimpled mounting ear hole?
 
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