Nutplates...do you re-tap them?

[flion]

I tap nutplates for interior panels. In the 10 years my RV-6A has been flying, the seat pans and even the baggage bulkhead have never fallen out. I also replaced screws with allen head screws. You can get allen pan head screws for areas under the carpet and seats.

For the exterior screws (tank attachment especially) I don't use a tap but I will run a stainless steel, allen head screw through the nutplate before I run a regular screw in there, to allow for the over-crimped plates because I have ruined too many screws. I also keep a healthy oversupply of screws because even now every once in a while, one will strip the head.

[SHIPCHIEF]

I'm with Patrick. I use Allen head cap-screws when I can, they are usually black phosphate coated, which is a lubricant in itself.
I like to use a dab anti-seize compound on the tip of the threads of the first screw into a new nut-plate. It's a little messier than Boelube or wax, but I think it does better job.

[dwranda]

In my 9A instructions it says you can tap them so if Vans says it's ok.........

[CubedRoot]

I think you guys have convinced me that I need to just bit the bullet and buy some allen head or torx screws for my wings.

Is there a good part number cross reference out there somewhere that will let me find the right screws (hardness, size, flush head degrees, etc)? It'd be nice to be able to swap out all of them with either torx or allen head, even the countersunk ones.

I'm guessing McMaster Carr is probably the cheapest place to buy them? Any other good recommendations?

[Bdalporto]

I use a roll tap or forge tap to loosen up nut plates also good to fix nut plates. A roll tap doesn't have cutting flutes so it doesn't remove any material. Kind of pricey but never wears out.

https://www.mcmaster.com/#standard-taps/=190mq3c

Brian

[BillL]

Originally Posted by CubedRoot

I think you guys have convinced me that I need to just bit the bullet and buy some allen head or torx screws for my wings.

Is there a good part number cross reference out there somewhere that will let me find the right screws (hardness, size, flush head degrees, etc)? It'd be nice to be able to swap out all of them with either torx or allen head, even the countersunk ones.

I'm guessing McMaster Carr is probably the cheapest place to buy them? Any other good recommendations?

Deja vu all over again. Every few years this topic comes up, it starts with nut plates, breaking screws, then stripping, then using stainless (worse BTW) then using allen or torx heads, then some esoteric company that will sell a 100 deg head.

Well - I got pulled into this same discussion early in my build and kept it in mind for many years. Here is what I accidentally discovered -driver bits - if you use these with a phillips screw (carbon steel/cad screws) it is very strong, less likely to slip and you can take a little longer screw (or a hand full of them) and use with an electric nut nut driver to rapidly spin the screw in and out of a green nut plate. Antiseize selection is your choice, use what works, but you can get really happy with phillips screws. And if you need another hundred, they are very easy to source from Spruce or other suppliers. Like anything, a good brand is important, but you can pitch a lot of $0.40 Wiha #2 phillips bit for the price one $8 Wiha screw driver.

Don't knock the phillips for slipping until you try some good driver bits, even ACR bits. I found they are 10x better than a typical screwdriver. Cheap and easily replaced, work very well. Better, faster, AND cheaper. Almost like a miracle.

OK - so they are not good for tight spaces, but a Wiha, SnapOn or other pricey hand tool will work in those rare places. But for glass tips, floor panels and the like, the driver bits (maybe a good ACR) should be on your list to try. The cheap, poorly made, evil screw drivers (Craftsman) have ruined the good rep of phillips head screws.

Stainless screws do look good, so I used them after the panels, tips etc have been on and off a dozen times and ready for final assembly. Then replace them all with new stainless after everything is broken in and using new driver bits.

Just something to try.

[RV6_flyer]

Originally Posted by BillL

Deja vu all over again. Every few years this topic comes up, it starts with nut plates, breaking screws, then stripping, then using stainless (worse BTW) then using allen or torx heads, then some esoteric company that will sell a 100 deg head.

Well - I got pulled into this same discussion early in my build and kept it in mind for many years. Here is what I accidentally discovered -driver bits - if you use these with a phillips screw (carbon steel/cad screws) it is very strong, less likely to slip and you can take a little longer screw (or a hand full of them) and use with an electric nut nut driver to rapidly spin the screw in and out of a green nut plate. Antiseize selection is your choice, use what works, but you can get really happy with phillips screws. And if you need another hundred, they are very easy to source from Spruce or other suppliers. Like anything, a good brand is important, but you can pitch a lot of $0.40 Wiha #2 phillips bit for the price one $8 Wiha screw driver.

Don't knock the phillips for slipping until you try some good driver bits, even ACR bits. I found they are 10x better than a typical screwdriver. Cheap and easily replaced, work very well. Better, faster, AND cheaper. Almost like a miracle.

OK - so they are not good for tight spaces, but a Wiha, SnapOn or other pricey hand tool will work in those rare places. But for glass tips, floor panels and the like, the driver bits (maybe a good ACR) should be on your list to try. The cheap, poorly made, evil screw drivers (Craftsman) have ruined the good rep of phillips head screws.

Stainless screws do look good, so I used them after the panels, tips etc have been on and off a dozen times and ready for final assembly. Then replace them all with new stainless after everything is broken in and using new driver bits.

Just something to try.

I need to quit assuming. I thought everyone used ACR screw driver bits. The lube helps but you must have the correct tool to do the job.

[AlexPeterson]

If the screws are snapping when using boelube or equivalent, the drivers don't matter. In this case, Torx head will not help, and will be weaker in torsion.

I had a batch of -8 nutplates from Van's a couple decades ago that were the same way. I fixed them by using a vise-grip on the body, in the opposite direction as the factory crimp. It took some trial and error to get the vise grip set, to be sure that a fair bit of residual factory crimp was present. Easier than tapping post install, but obviously needs to be done prior to install.

[rvanstory]

I had same experience until I started using Johnson's paste wax to lube threads prior to install. Made them MUCH easier to install. No problems since.

I would assume Boelube would do the same, but haven't personally used any, so not sure if paste wax is better or not.

[Rupester]

Early in my engineering career I was told by a wisened old dude that Phillips screws were explicitly designed to "torque out", i.e. have a slipping point to limit the amount of torque that could be applied . They were a solution to overtorquing and stripping problems that were rampant in assembly plants factories in that day. We neophyte engineers were told, "if you want something that gobs of torque can be applied to, don't use Phillips!" Ever since, I don't hesitate to replace Phillips with allen head, torqx, or square drive whenever applied torque - or access - are a problem.
..... so the next time your muttering about a stupid, slipping Phillips head screw, recall that it's just performing as designed.