Rivet nuts in tubes?

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piepermd

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So does anyone think using structural acrylic or epoxy adhesives to bond nut plates to the fiberglass as attachment points for skins, switch boxes, and controls is NOT a good idea? I’m trying to turn #1 into #2.

1F32D781-68CC-4875-944D-9EB22094496B.jpeg9D44396C-595C-4F20-9ACD-CFAE1186D52A.png
 

TFF

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As long as you put a base on the nutplare you can bond it. There are inserts for composites that would be better.
 

D Hillberg

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So does anyone think using structural acrylic or epoxy adhesives to bond nut plates to the fiberglass as attachment points for skins, switch boxes, and controls is NOT a good idea? I’m trying to turn #1 into #2.

View attachment 99605View attachment 99606
Aircraft Spruce Catalog , Look up VaryEasy Nut strips/plates for 'hard point' for mounting screws
They are bonded in place
 

piepermd

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Cli
As long as you put a base on the nutplare you can bond it. There are inserts for composites that would be better.
Click Bond has nut plates and studs with composite base plates for just such applications.
 

piepermd

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Actually the studs have composite base plates available but the nut plates do not. I would hate to disseminate misinformation!
 

rv7charlie

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Peruse the post copied below, from Bob Nuckolls over on the Aeroelectric Connection email list/forum (you really need to be subscribed there, before starting your electrical work). E6000 (from any hardware store) is monstrously tenacious stuff. My neighbor bonded his air/oil separator to his firewall, and it was just about unremovable. You can make 'hat sections' ( a wide U with wings), mount your nutplate in the middle, and bond the wings to the....well, anything. Height of the U to match whatever standoff height you need at any location. If you use 3/32" pop rivets to mount the nutplates, you'll always be able to easily swap the fastener in the unlikely event that you trash it at some point down the road.

Charlie

At 08:03 AM 11/15/2017
I've been using a dab of "shoe glue" right on the anchors without removing their adhesive. Seems to work. Shoe glue is tough stuff but can be removed if needed unlike JB Weld.
Sho Goo, like its industrial cousin E6000 was
the adhesive of choice for crafting and installing
bond studs to surfaces without drilling holes.

http://tinyurl.com/ydasnwk9

http://tinyurl.com/j2gxbqy

Early studies for suitable adhesives included
JB weld but while it does get a good grip
on things, it's not as compliant nor
does it adhere to slick and/or plastic
surfaces as the E6000. My adhesive of
choice would be the E6000.

3M does produce VHB (very high bond) mounting
tapes that are quite strong

http://tinyurl.com/ydfql26k

Run some tests with any alternative adhesive.
Bond the part down. Wait 24 hours and then
pull it off. What breaks first and how
hard was it to get it off.

Generally speaking, bonded on fasteners
should be used only for non-structural,
low risk security on wire bundles, coax
feeders, perhaps NylaFlo pitot or static
pressure lines.


Bob . . .
 

wsimpso1

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Quick question- Would there be any significant reduction in the structural strength of a 1” diameter steel tube longeron if a series of small holes were to be drilled, say 6 or 8 mm holes along a line at 12-18 inch intervals? This is for placement of rivet nuts for attachment of cockpit skins, etc. Thanks!
Given the sum of your restrictions and the fact that these are non-structural panels, I would sure give Click-Bond studs, bosses, anchor nuts, stand-off anchor nuts, etc a really good look.

Billski
 

BBerson

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Hmm...I don’t think I understand. How does a clamp help me if it attached to the fiberglass and not clamped around a steel tube?
It is clamped around the tube. Just like a conduit tube is clamped to the wall board.
A throttle quadrant could be clamped to the inside of the tube also with a block made from Micarta or plastic. 1" bolts through from the outside skin on both sides of the tube.
 

piepermd

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It is clamped around the tube. Just like a conduit tube is clamped to the wall board.
A throttle quadrant could be clamped to the inside of the tube also with a block made from Micarta or plastic. 1" bolts through from the outside skin on both sides of the tube.
I can’t clamp anything around the tube because it is already encased in fiberglass.
 

piepermd

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A grinder can fix that.
That’s what I was hoping to avoid, but I will still consider it if you think it is far preferable to using structural adhesive to attach hard points to the fiberglass. By the way, I really appreciate you taking the time to provide advice and share your expertise!
 

TFF

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If you are going to tug on it, it needs to be anchored. Switches and small things can just be in the panel. I recommend you go for the feel of the cockpit and not go crazy with a lot of details that don’t do anything. A throttle quadrant needs to be very secure. Covers for switches can be inserts.
 

piepermd

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Messages
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If you are going to tug on it, it needs to be anchored. Switches and small things can just be in the panel. I recommend you go for the feel of the cockpit and not go crazy with a lot of details that don’t do anything. A throttle quadrant needs to be very secure. Covers for switches can be inserts.
Thanks for your reply! How would you recommend anchoring? Welding a tab to the tubes? Some other method?
 

TFF

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If you can figure a way without welding, that’s what I would do. I would prefer to weld, but it would destroy a bunch of the present work. Not just a little bit. People have been known to yank stuff out in emergencies that were not in strong.
 
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