Raumer wedge anchors

Does anyone have experience with these wedge anchors: https://www.raumerclimbing.com/en/products/classic/stainless-steel-hang-fix-bolts/hang-fix-inox-m10al-d-10x86mm-a316l/

Do not use on soft rocks (such as sandstone) or too hard (such as quartzite, granite).

I've never seen a warning against using wedge bolts in very hard rock. I wonder what the problem is.

Good catch, I'll ask the manufacturer about that.

That is the first time that I have seen a warning from any manufacturer, distributor, or climber about wedge anchors used in hard rock (quartzite, granite). 

I suspect that the person writing the catalog text was in error or mixed up the wording. I wonder if the Raumer online catalog may have even mixed up my words, as I specifically mentioned granite and quartzite as appropriate hard rock for wedge anchors in a 2009 e-mail.

There was an issue in 2009 with Raumer's wedge anchors. They were incorrectly listed as being acceptable for "less than hard" rock. After a fatal accident in Australia with 8mm Raumer sedge anchors, I identified that error and notified Raumer.  Cesare Raumer got back to me and immediately amended the product description.

My notes as "Juan Maderita" on SuperTopo:

http://www.supertopo.com/climbing/thread.php?topic_id=772824 

As to quality, the 10mm Raumer seem fine and are now made with 316 ("marine grade") SS. They also produce a very nicely finished bolt hanger. From the catalog photo, it appears that the threads may be cut vs. rolled. But it is difficult to be sure from the photo. Rolled threads are generally regarded as stronger to my knowledge. The deciding factor, if in the USA, may be the price and that a metric SDS bit is required. Metric SDS bits are not so difficult to source now on the internet, but you can't just pick one up at the local hardware store.

The other interesting bit is that they are recommending “Multi-Monti” screw anchors for soft rock. AKA Titen Screw Anchors… 

YGD

A rare goldilocks bolt, rock can't be too soft or too hard, gotta be just right.  How do you know what is just right?

Austin Donisan wrote:

I've never seen a warning against using wedge bolts in very hard rock. I wonder what the problem is.

It's that the two small bent out corners that provide the initial engagement get blunted by hard rock and the bolt doesn't hook up, soft rock they can just slide through. I've used Italian made bolts with this clip design over 20 years ago and gave up with them.

Rolled or machined threads should be a deal breaker, around ten years ago I had an offer for wedge bolts made fairly locally to to me in Germany by a company who machines parts for the aerospace industry and used spare capacity to make them. All the certification was was great and so I bought 5,000 of them but when I tested them for certification to EN 959 (the climbing gear standard) they failed miserably at around 8.7kN compared with the normal 38kN one expected. 

The company were very good, accepted the return and were curious why they broke so I went there and we played with different ways of testing them then we went to the German lab for testing and certifying construction materials and discovered their fixtures for testing are rigid (like 12mm steel plate) so an axial pull is exactly that, the bolt is tested perfectly in tension. Using a bolt hanger the force comes on the bolt effectively diagonally and they rip across starting at the bottom of the thread. We all learnt something about what the numbers on the packet mean!

Jim Titt wrote:

It's that the two small bent out corners that provide the initial engagement get blunted by hard rock and the bolt doesn't hook up, soft rock they can just slide through. I've used Italian made bolts with this clip design over 20 years ago and gave up with them.

Thanks, great info, just the kind of thing I was looking for.

Austin Donisan wrote:

I've never seen a warning against using wedge bolts in very hard rock. I wonder what the problem is.

fwiw, Raumer replied to my question with this:

because sometimes when the rock is too hard, the sectors do not expand and therefore the hang fix comes out of the rock. 

This seems to correspond to Jim's comment about the pointed corners getting too blunted and not catching.

Derek Woods wrote:

fwiw, Raumer replied to my question with this:

because sometimes when the rock is too hard, the sectors do not expand and therefore the hang fix comes out of the rock. 

This seems to correspond to Jim's comment about the pointed corners getting too blunted and not catching.

Anyone know what the point of this design is then? Because Raumer also makes a "standard" design wedge bolt, with a more normal clip, that works fine in hard rock. If I had to guess I'd say because of this bolt's smaller size?