Lonnie-S wrote:
So, Rob, you're having a good experience with the rivnuts from McMaster-Carr? Because of what's been written in several other threads, I've got the impression rivnuts are all bad, bad, bad. They seem like a very handy solution for sheet metal. It would be good to know that the ones you've used have held up well.
Hey Lonnie, Like I'd mentioned, you've got to do your hole prep correctly - which basically means don't poke a bigger hole than the rivnut requires, and make sure you're using a rivnut that's the correct grip range for the panel thickness you're putting it in. I've had a few spinners, but those were directly attributable to me botching the installation - that is, I drilled the hole too big. I've also over-collapsed a few which makes the threads bind. Again attributable to user error, tightening the installation tool a turn or two beyond the full collapse.
10-24/32 and bigger sizes are easy to feel when the shank collapses and tightens against the panel (that includes similar metric sizes, 5mm-.80 ans up), 8-32 and smaller takes a bit more practice and finesse, its harder to "feel" the collapse with the threaded twist tool. I actually broke the mandrel on my 8-32 tool over-tightening it. oops!
you don't want to mix stainless with stainless of course, that will invite galling and seizure. But, I've got stainless screws into Cad-plated inserts in several places besides the new battery holder, and they're fine. you DO have to make sure there arent' any side loads on the screws that will cause undue friction and binding on the stainless because, galling!
if you're going to use them, practice on some scraps first, run some screws in and out.
I've gotten decent results with the smooth-side aluminum inserts, but I really prefer the Cad-plated steel with the external knurling. I practiced on some scraps before committing to the B-3 installs, and I really did learn a lot about making them work correctly during my tenure as a MFG support engineer 2011-2013 at my day gig. there, I saw radar shelters coming back for refurbishment from the field from long deployments - some measured in decades - and properly installed rivet nuts working just fine, the screws threaded right out no problem.
on the new battery holder, I ran the screws in and out at least a half dozen times doing fit checks and massaging the shape. no problems.
so, good hole prep, correct grip length, use a GOOD installation tool, make sure the shank collapses all the way (but isn't over-collapsed), and you'll get good results.
they are also good for composite panels, but the install is a bit trickier.
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The B-3 build log:
http://www.locostusa.com/forums/viewtopic.php?f=36&t=13941 unfortunately, all the pictures were lost in the massive server crash
The beginnings of the Jag Special,
https://www.locostusa.com/forums/viewtopic.php?f=36&t=19012Again, all pictures were lost.
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