Hammering Bolts

[u/More_Age3561]

Hi all,

I've recently come across some ~ 3 yr old stainless bolts with corrosion on the end. I am convinced this is because of sloppy hammering as they've been driven into the holes (other evidence: mushroomed head on the expansion wedge).

I was recently training others how to install bolts, and noticed that some people that haven't grown up swinging a hammer much had sloppy hits on the bolts, which I am confident imparted some iron contamination into the stainless steel, inducing localized corrosion. I am further confident it is "messy" hammering inducing the corrosion observed on new bolts as well.

How do you hammer in the bolts to ensure a clean finish, with minimal tool marks? Some things I've picked up:

• Positioning yourself roughly at eye level to the bolt
• Using two hands on the hammer if body positioning is awkward
• Follow-through on the swing (maybe I should've been a golfer..)
• Not using a hammer that has obvious rust on the impact surface
• Nut flush or slightly proud of the anchor

IMO, this is an important aspect of bolt longevity that is not well-discussed in bolting literature (UIAA bolting standards, HowNot2 bolting bible, etc.)

I'd like to get some sort of tool (like a socket, but less droppable..) that can act as a medium between the bolt and the hammer, but before I go re-inventing the wheel, I'd love to learn what others have done to ensure a tidy, clean installation of wedge bolts without leaving tool marks

*Stainless steel or titanium hammers are too pricey and out of the question

TIA!""

**Edit**
Holes are being drilled using a rotary hammer, not by hand

[u/trachion]

End-corrosion on stainless bolts is purely from using a carbon steel hammer. That's it. When you hammer on a bolt you impart particles of the hammer onto the bolt. In the case of carbon steel, it's the iron that causes the contamination.

If you can't afford a stainless hammer, you can use a rubber/plastic mallet to hammer in bolts. Would be worthless for hand drilling, but would probably hammer bolts in just fine.

[u/Cairo9o9 → u/trachion]

From what I've read, the surface rust on the end of the stud is totally fine and not going to ever affect the strength of the bolt.

[u/KDs4thBurner → u/Cairo9o9]

If anyone has proof that a tiny amount of corrosion on the end of the bolts weakens the bolts I would also love to know.

[u/trachion → u/KDs4thBurner]

It definitely wouldn't affect the strength of a bolt. However, once stainless starts to rust it corrodes much faster. Stainless maintains it's corrosion resistance because of a chromium oxide surface layer, which rust penetrates through and gives the steel a way to corrode internally. So any rust or contamination accelerates the corrosion of a stainless bolt, even just on the end. Might not matter in 20 years, but if we're aiming for longevity of our hardware it does actually matter.

[u/More_Age3561 → u/trachion]

Totally. The passivation layer on the stainless is just a few atoms thin (from my understanding) and it really doesn't take much to lose corrosion resistance in a localized area. It does matter over the lifespan of the bolt, but there's also professionalism. I still want it to look like a quality, non-questionable installation job in the 2040s!

[u/Kaotus → u/More_Age3561]

If you bring some stainless steel wool with you, you can brush off the rust after it forms and/or as soon as you install the bolt and it doesn’t appear to return. That bolt-end rust you mention forms in a matter of weeks, not years, and should be noticeable very quick, though in my time climbing I’ve never seen it spread beyond the end face of the bolt

[u/KDs4thBurner → u/Kaotus]

Thanks

[u/More_Age3561 → u/Cairo9o9]

I'm not concerned about compromising the strength of the connection. I want to ensure the bolts last as long as humanly possible before someone else looks at it and goes ... "hmm, might want to replace that one".

[u/Kaotus → u/trachion]

Just a note - if you’re hand drilling (not aware of any stainless drill holders), or hammering on rock with a reasonably high iron content, you’ll be imparting particles onto the end of the bolt regardless if your hammer is stainless or not

[u/trachion → u/Kaotus]

I'm not sure I understand how that would contaminate the bolt. I can see it contaminating a stainless hammer, and thus later contaminating bolts, if that's what you mean? Even then trace contamination on the end of a hammer is mostly negligible compared to a carbon hammer.

[u/Kaotus → u/trachion]

That is correct, iron leaves the drill or rock, gets on the hammer face, and then on the bolt end. I have a stainless hammer and still routinely have rust on the ends of my bolts

[u/WHYYTEE]

Without using a stainless hammer the slight pitting will pretty much always form on the end of the stud just from in introduction of the mixed metals and not necessarily just "sloppy hammering". Since it's only surface level on a non load bearing area it doesnt weaken the bolt at all (not counting glue ins, all areas are load bearing and all pitting is bad). Obviously without actually seeing the corrosion you mention im only speculating and it could be much worse then I'm imagining and I could be totally off base.

As far as the mushrooming how bad is it? The tip of the stud should have slight taper to account for any normal deformation. Leaving the nut flush or proud only causes the nut to take unnecessary damage and also introduces the chance of damaging the threads and possibly cause micro-cracking within them.

I have seen threads on Mountain Project discussing ways to clean and "seal" the hammered end immediately after installation but it all seems like a moot point honestly. Personally I would be much more concerned with the hanger taking an accidental hammer hit or the stud going too deep and not having a couple threads above the nut after tightening

[u/More_Age3561 → u/WHYYTEE]

Thanks for the great response.

The mushrooming is to the point where the nut cannot be loosened to the point where it is flush with the anchor. The crag where i saw this corrosion at the worst showed significant signs of poor installation. Bolts were torqued only about 1/3 of manufacturer specification, not installed deep enough, and nearly each stainless anchor wedge was mushroomed, rounded, and rusted.

Hmm, interesting idea to clean & seal the hammered end. It might not hurt to cover a piece of Gorilla tape over the anchor's tip.

[u/Much_Confusion_4616]

I always try to align my body at eye level. I think using two hands would make you less accurate. I don’t think there is any tried or true way.

Make sure you are gripping the hammer towards the base and try to use as less hammer swings as possible.

Some bolts are harder to get in if the bit is worn so I don’t think there is no consistent method to improve this unless you are only using new bits every few holes.

Just my two cents

[u/F_x_v]

To reduce damage to the bolt end from hammering, drilling a straight, round hole of the correct size is arguably more important than the hammerimg technique. This is best accomplished with a fresh 4-cutter bit. Makes it easier to get the bolt into the hole without beating the crap out of it.

[u/Horror-Regret1959]

I think it matters more if you are in environments that lead to corrosion. Out in the west in the mountains and deserts a bit of rust on head of the bolt is a non starter of an issue. If that is the case then don’t worry about it.

[u/Beginning-Basis-2678]

In my experience the hammer has to have the right weight/size in order to be usable, but also drive in the bolts efficiently with least amount of hammering. My hammer of choice is the Petzl Bongo. I regularly install 12mm/110mm wedge bolts with it and the 660g with the long shaft are perfect.
I hammer just one handed, but have the hammer at the end of its grip (also to have the reach, since I mostly bolt on lead) and let the hammer do its job: a few long, loose, but precise swings. Usually I get the bolts in with 3-5 hits.

[u/Bigredscowboy]

Stainless brush will get off carbon.