Wedge anchors - Unable to reach the specified torque

Hi!

I'm starting to practice placing wedge anchors on the rock and I want to have all perfectly dialed in before bolting a route. I'm placing Fixe wedge anchors and I'm using a torque wrench. The problem I have is that while some bolts tighten just fine to 35 Nm exposing only a bit of the thread, others start to tighten but at some point they keep coming out of the hole exposing a good portion of the bolt without reaching the 35 Nm of torque. What's happening here? They are pretty tight but not to the manufacturer's specified torque. Maybe the rock is too soft? Will the bolts be reliable?

Thanks!

What type of rock? Are the holes clean? Is this occurring with a new bit?

did your shorts come into contact with the metal?  

I clean the holes with air and a brush, several times before placing the anchor. The drill bit is ok, the anchor goes in fine with a normal amount of hammer blows. The bolt does not spin in the hole, it's just that it tightens but it reaches a point where it won't tighten anymore, just continue to get out of the hole without increasing the force on the wrench.
I already bounce test them and it looks bomber but my supposition is that the rock is soft and would be fair to think that the anchor will not have full strength. The thing is that it depends, because some bolts reach the specified torque and a few of them doesn't.

The rock is schist. I tried wedge anchors because is what I saw people use here in Sierra Nevada area (Sierra Nevada of Spain) including the rescue team. Probably the hardness of this rock varies a lot.

Typical when the rock is too soft, they are pulling out. What force they will hold is easy to work out from the torque you can achieve but 35 Nm for a 10mm bolt is fine, less is not so good. Wether they are "safe" is something you should discuss with Fixe or the Spanish climbing community, not a load of unknown people on an American forum where the European standards have no relevance.

As well, your hole may not be as round as it could be.

Greg Germann recommends bits like this for wedge anchors to keep the hole more true:

It's most likely the rock type (most schist is soft and inconsistent by nature - it's low-grade metamorphic). If you're gonna use wedge bolts in this stuff I can say from a lot of experience (we have tons in NC) that long hilti bolts are pretty good but most other wedgies are junk in this rock.

I'ts all been said, but yes, most likely the rock is too soft and you are just dragging the clip through the rock without ever expanding it.  You need a different type of bolt.

Jim Titt wrote: Typical when the rock is too soft, they are pulling out. What force they will hold is easy to work out from the torque you can achieve but 35 Nm for a 10mm bolt is fine, less is not so good. Wether they are "safe" is something you should discuss with Fixe or the Spanish climbing community, not a load of unknown people on an American forum where the European standards have no relevance.

That's what I supposed. Maybe the bolts I'm placing achieve 25 o 30 Nm, next time I'll test it. About asking the people here: well, sadly I think that the majority of people who bolt routes in my area have even less idea than me. I haven't seen any stainless steel bolt here, and there are hundreds if not thousands of routes. I haven't seen a glue-in neither, or the use of a torque wrench. I just wanted opinion from different people to form my own ideas.

Using 3.5 inch by 3/8 SS wedge anchors, and the clip is not setting. 

I've had a similar problem on and off in a new area of granite I am developing. Some rock is hard and the holes take a good amount of time to drill with my Makita. Others go in faster, and sometimes I can insert the 3.5 inch bolt all the way with my fingers and pull it back out again with wiggling. Obviously they don't tighten up. 

I'm watching the drilling to not waggle the hole. It is just softer rock although I can't tell in advance. But the last one I did I forgot to blow it out (stressful lead bolting distraction). I don't think this has ever made a difference before, but I wonder what people here think. Could not blowing out the hole make it easier to pull the bolt out with my fingers/impossible to tighten? Sometimes they tighten with a lot of thread showing and not to the specified torque. It seems like it is more of an issue of the hole oversizing when the rock is on the softer side. Glad for any thoughts or advice.

Also, as background, I'm not new to bolting. Been doing it for thirty years in various rock types. This is a new area I am developing with my son and I am surprised at the unpredictable variation in this rock and trying to figure out how to make it work first time, every time. Its frustrating because now I have five holes I didn't use in different spots that I'll be going back to patch. Grr.

Already mentioned, new bits drill tighter holes. Perhaps the bit is too worn? Are you engaging the wedge then tightening?  If the rock is inconsistent perhaps choose a longer bolt with a sleeve anchor - like a Powers 5piece...   More contact area on the surface.   If you’re still seeing issues, larger diameter bolt? 

Thanks Pete. I’ll look at all these aspects.

If the wedge would engage I would not have a problem. But that gives me an idea to check the clips and see if they are free to engage.

As for “new bits drill tighter holes”...wouldn’t old bits drill tighter holes as the gauge of the carbides wears down? Your statement seems like the opposite of everything I have heard or observed.

Thanks again.

Yes old bits drill tighter holes, not the other way around.

As everyone has said, the rock is likely too soft for a wedge bolt, try a stainless 5-piece, or glue-in. If budget is a big issue, what I would do is get some stainless 5-piece and use those when you drill the holes really quickly, and use the wedge bolts for harder rock when drilling is slow/tough.

Greg,

Thanks. That's a really good suggestion. I'll add some 5-piece to my kit.