8mm bolts?

Max Tepferwrote:

I took a 60 foot fall when an 8mm wedge bolt pulled out of good granite.  Pretty sure it was only 16 years old.  I'd complain.

Any photos?

What amp hour are the batteries you are using?  I have been drilling some really hard rock lately with my 18v Bosch and I get 18-20 holes 3/8x3".  I am also drilling on lead most of the time, I would maybe up the amp hour of your battery.  I'm using a 6aH at the moment.  

Trad Manwrote:

Any photos?

Not sure what I'd have photos of?  The fall happened in the dark and it was just me and my partner up there.  The bolt fell out of the hanger while I figured my way back up to the anchor where we then elected to spend the night.  The next day we were just stoked to make it up the pitch with the bolt MIA.  Stopping to take photos of a random hole in the rock seemed pretty low priority.  I still have the hanger though.  It's a nice memento of a wild experience.

timothy fisherwrote:

They (Raumer) do stipulate that they (8mm) are for caving and not climbing.

They don't meet the requirements of the European standard so it is illegal to sell them in the EU as anchors for climbing.

Kevin Mokracekwrote:

What amp hour are the batteries you are using?  I have been drilling some really hard rock lately with my 18v Bosch and I get 18-20 holes 3/8x3".  I am also drilling on lead most of the time, I would maybe up the amp hour of your battery.  I'm using a 6aH at the moment.  

Quartzite is like 3x more dense than granite. More than 2x more dense than basalt.

Trad Manwrote:

Quartzite is like 3x more dense than granite. More than 2x more dense than basalt.

It really sounds like you are either trolling or trying to justify being cheap. There are plenty of developers, some on this forum, who routinely develop on hard stone and have no trouble using 3/8” hardware. Personally, I’ve drilled on dolomite in MT and WY, and quartzite in ID with no problem getting 12 or more 3/8 x3” holes from a worn down 3.3ah Hilti battery. The biggest issue was the carbide tip tended to separate from the drill bit body if you didn’t stop to cool it down every 10 seconds. Bottom line, use the right equipment or leave the bolting to someone who can.

I don't think the bolts are any cheaper, my dude.

Max Tepferwrote:

Not sure what I'd have photos of?  The fall happened in the dark and it was just me and my partner up there.  The bolt fell out of the hanger while I figured my way back up to the anchor where we then elected to spend the night.  The next day we were just stoked to make it up the pitch with the bolt MIA.  Stopping to take photos of a random hole in the rock seemed pretty low priority.  I still have the hanger though.  It's a nice memento of a wild experience.

I'm curious to know how you know they were wedge bolts.

Trad Manwrote:

I'm curious to know how you know they were wedge bolts.

The threaded rod and nut on the outside end of the stud were the first clues.  The second was seeing the wedge on the other end of the bolt after it came out of the hole and was dangling in the hanger by my knot after the fall. 

Trad Manwrote:

Quartzite is like 3x more dense than granite. More than 2x more dense than basalt.

Rock densities (scroll down a bit): https://www.thoughtco.com/densities-of-common-rocks-and-minerals-1439119

There are factors other than density that affect ease of drilling. Maybe some materials scientists can pipe in here?

nbrownwrote:

Rock densities (scroll down a bit): https://www.thoughtco.com/densities-of-common-rocks-and-minerals-1439119

There are factors other than density that affect ease of drilling. Maybe some materials scientists can pipe in here?

Huh, I had been led to believe the specific gravity of quartzite was much higher. I can't find the source off hand, but I'm glad to be corrected.

Edit: could have been an article confusing Mohs Hardness Scale

Mikey Schaeferwrote:

Are you looking for the 8mm drop in style anchors that Petzl use to make?  It appears Kong still makes them.

Kong 8mm bolt

Not sure of your specifics but you can also just use a 1/4” split drive bolt.  They come in 1 1/4” lengths. I’ve placed hundreds of them on lead.  Easy to pull and replace after getting the rope up.

Steel drive bolts (scroll down a bit)

The self drive part you linked to by Kong (Raumer also makes them) is actually 12mm in diameter.  They require a very precise 32mm depth with a flat bottom or the cone wont seat correctly.  The part that threads in the self-drive sleeve is the 8mm bolt.  They are decently strong, but galvanized so only used in caving.  Exploration caving is wet but SRT doesnt have shock loads like in climbs and they arent used in tourist cave route development at all.

I'm curious about this super hard quartzite that goes through drill batteries so fast. The quartzite in my area ranges in hardness, and I average 4-5 holes per drill bit. Sometimes I get six, and sometimes I only get two. But even when I get two holes per bit I can get close to 20 holes with my run of the mill Dewalt hammer drill with a 5ah battery pack. 

Trad Manwrote:

Quartzite is like 3x more dense than granite. More than 2x more dense than basalt.

Citation?  Cause quartz is not actually any denser than most granites at ~2.6-2.7g/cm3.  

You're proposing to develop routes like they were in the 1990s with what is functionally a 1/4" x 2.5" bolt which are also specifically "Not Rated for Climbing".  Brand new and perfectly installed the 8mm Raumers are not even 20kn in shear or tension (18-17kn respectively).  Don't do that. You're leaving weak litter on the crags that someone else will just need to extract and rebolt properly.

Replace your battery with one that holds a charge, switch to 4 cutter SDS bits, change to a more efficient drill, or possibly even mentor with someone on better drilling technique.

Richard Jackwrote:

Citation?  Cause quartz is not actually any denser than most granites at ~2.6-2.7g/cm3.  

You're proposing to develop routes like they were in the 1990s with what is functionally a 1/4" x 2.5" bolt which are also specifically "Not Rated for Climbing".  Brand new and perfectly installed the 8mm Raumers are not even 20kn in shear or tension (18-17kn respectively).  Don't do that. You're leaving weak litter on the crags that someone else will just need to extract and rebolt properly.

Replace your battery with one that holds a charge, switch to 4 cutter SDS bits, change to a more efficient drill, or possibly even mentor with someone on better drilling technique.

4 cutters seem to do worse in quartzite for me, actually. Didn't make sense to me but I was talking to a machinist and he said that they will use more or less cutters on their tools for different materials and having less for harder material made sense to him. I don't know shit about shit but I've tried multiple different 4 cutter bits on my quartzite and I invariably pay more for less holes. 

Richard Jackwrote:

 Brand new and perfectly installed the 8mm Raumers are not even 20kn in shear or tension (18-17kn respectively).  

What is this 20kn standard coming from? Ever fall on a cam?

Trad Manwrote:

What is this 20kn standard coming from? Ever fall on a cam?

Would it be possible for you to make a list of all your climbs that you have established and their locations?

Kevin Mokracekwrote:

Would it be possible for you to make a list of all your climbs that you have established and their locations?

If you want, but I've never placed a permanent 8mm bolt. Instead I chase the holes with 3/8 just to make you happy.

I'd still like an answer to my non-rhetorical question.

When the standards were developed by the UIAA and CENORM they looked at both the theoretical loadings and more importantly the equipment that in practice had proved reliable/unreliable then worked backwards from this to a standard which could be consistently tested in a laboratory. The knew that 8mm bolts have failed in some rock and designed the standards value to make them fail the certification test. You can do what you like, the standard is the safety net for everyone.