Preventing galling with Stainless insert nuts

[Quickstep192]

I was assembling something yesterday using a 5/8” 316 bolt and nylon insert nut.

Damn if that thing didn’t gall right before the final tightening turn.

I was tightening with hand tools.
Is there any way to prevent galling when using insert nuts?

 

[Feisty!]

I dip all nuts and machine screws in Maclube Sailkote ...

 

[LewSipfher]

I’d suggest antiseize, but I’m damned if I understand how this even happened unless the bolt or nut was flawed in some way

 

[El Borracho]

Not surprising at all. Spinning a bolt with fingers can start the galling. It is like a bunch of tiny wedges. Once they get a grip it is Game Over. Mass produced nuts can have nasty rough unseen threads. Anti-seize can help. Might not. Angle grinder?

 

[LewSipfher]

Mass produced nuts can have nasty rough unseen threads. Anti-seize can help. Might not. Angle grinder?

And did my above post not say, “unless the bolt or nut was flawed in some way”?

 

[Marty Gingras]

And did my above post not say, “unless the bolt or nut was flawed in some way”?

 

[El Borracho]

And did my above post not say, “unless the bolt or nut was flawed in some way”?

Yeah, you won the thread. Take your victory lap. Sorry. 😜

 

[SloopJonB]

Tef-Gel

I've used it lots and never had a problem.

 

[mckenzie.keith]

Would it help to chase the threads with a tap first?

 

[SASSAFRASS]

SS is very soft, when using nylocks you load the threads, pretty much always should use a antizeize compound on the threads. The food grade ones are the cleanest if you are worried about stains etc, otherwise any copper or nickel one is fine. Tefgel as above probably also fine but I would probably not use on big stuff like 5/8. Tefgel and antizeize compounds have much better resistance to being washed out and are preferred over regular greases and oils. Molycote also makes specific products that are good. As El B said when loaded and not lubricated small amounts of metal are pealed up reducing the gap and eventually closing between external and internal threads, it ends up being a friction weld in the end. I had some acme thread winch brake assemblies at work recently that had poor machining tolerances, it was pretty amazing, even fully lubed up a single turn by hand completely welded together, needed a 5' wrench to break apart. SS on SS can suck. Chasing threads on something galled is not a good idea, more often you will make it worse.

One last note, only lubricant the sides of the male threads just up from the end when using blind holes, not the female blind threads. You can hydraulically lock the fastener from going all the way in.

 

[DrewR]

Bolt Depot - About Thread Galling

www.boltdepot.com

 

[WhoaTed]

Tef-Gel

I've used it lots and never had a problem.

^^^^^^This right here.

TEF-GEL - Ultra safety systems - Home page

 

[SloopJonB]

Would it help to chase the threads with a tap first?

Always. Use a good tap though - cheapies can oversize the threads enough to make them sloppy.

 

[mckenzie.keith]

Chasing threads on something galled is not a good idea, more often you will make it worse.

I meant routinely chasing threads before inserting the bolt. Not after the galling happens.

 

[SASSAFRASS]

I'm relatively sure, but not 100% most bulk fasteners you get are rolled threads, also not a machinist but when cutting threads you usually have three taps from start to finish, chasing with a single tap the odds are more than likely you will end up disturbing the threads and causing more damage on off the shelf nuts and bolts. Machined parts etc are a different story, IE chasing a blind hole in a piece of equipment you suspect there might be a bur in is probably a good idea, at least with starting and finishing blind tap.

 

[SloopJonB]

Chasing the threads on a nut or bolt is only for emergencies - fasteners are too cheap to fuck around with otherwise.

I'm on my second fiberglass boat that I can claim is "completely re-fastened" like people say about wood boats.

 

[El Borracho]

I'm relatively sure, but not 100% most bulk fasteners you get are rolled threads, also not a machinist but when cutting threads you usually have three taps from start to finish, chasing with a single tap the odds are more than likely you will end up disturbing the threads and causing more damage on off the shelf nuts and bolts. Machined parts etc are a different story, IE chasing a blind hole in a piece of equipment you suspect there might be a bur in is probably a good idea, at least with starting and finishing blind tap.

I like getting my nuts rolled. Not tapped. But that is just me.

 

[DDW]

I have had 316 locknuts gall just turning them down by hand, well before they clamp anything. In fact I have given up supplying 316 fasteners with the product I sell, because the galling potential is too great. 304 is more forgiving, but then you have 304. Another solution is to use nuts with a different and harder material, like Nitronic. I had huge problems with galling on my K500 keel bolts, completely solved by using Nitronic 60 nuts. Not going to find them at the local ACE hardware store though.

All that said, Tef Gel seems to eliminate this possibility. I have not had a 316 fastener gall if coated first with Tef Gel, thousands of fasteners at this point.

 

[Quickstep192]

On the 5/8 bolt I just installed, it seems like I could feel it starting to gall right as the bolt engaged the nylon insert.

I’m not looking forward to cutting that bolt apart.

 

[SASSAFRASS]

Yep, as soon as the nylon engages it can go south without some sort of never seize. We use and renew thousands and thousands of 316 SS fasteners all with nylocks nuts in our production plants and rarely have issues, a lot of the time they even use impact guns. A plain old hacksaw with a good starette blade and a vise grip can make quick work of a SS bolt to get apart. Having a good hacksaw frame like a Lenox etc is key. Very little mess.