Strongest Bolt Anchors

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bachar

Trad climber
Mammoth Lakes, CA
Topic Author's Original Post - May 7, 2007 - 04:13pm PT
I just ordered a box of 50 MKT Taper Bolts (3/8" x 2 5/8") as I wanted to maybe put up some face routes soon. That afternoon I was at the bookstore and saw Long's new 'Anchors' book. I read through the section on bolts and saw something about how Taper Bolts were dangerous and only held 3,000 lbs. maximum on a pullout test ( and 700 lbs. if poorly placed). I was kind of bummed out to say the least.

I know I've read other articles in the climbing mags about how Taper Bolts were hard to place, but I still can't understand why. I've placed well over 150 Taper Bolts and have never had a single problem. By the way, in granite they hold over 5,000 lbs. in a pullout test (not 3,000). Per hole diameter, they are the strongest bolt on the market (correct me if I'm wrong please).

Here's a link to the strength test chart at MKT Fastening:
http://www.mktfastening.com/Products/Mechanical/Taperbolt/taper.htm

These bolts are routinely used by construction workers all over the world with incredibly safe results. Has anybody had any bad experiences with these things? Any failures? Difficulty placing them? Why the bad rap?

Just curious, JB
mojede

Trad climber
Butte, America
May 7, 2007 - 04:45pm PT
JB, I've never placed a taper bolt (tons of rawls and hiltis) and was curious as to how your first through tenth experience went with placing them. Maybe they are easier to place once the "learning curve" has been summounted. I trust YOUR placements, but wonder/ worry about those rookies that plunk down the cash for a bolt gun, then head out to the rock to "practice".
NoRushNoMore

climber
May 7, 2007 - 05:01pm PT
There is a small write up here on the taper bolts

http://www.safeclimbing.org/education/dangerbolts.htm
Russ Walling

Social climber
Out on the sand.... man.....
May 7, 2007 - 05:01pm PT
Duane Raleigh sez here: http://safeclimbing.org/education/dangerbolts.htm

Torque bolts
We didn't find any dependable torque bolts, although some climbers use and swear by the USE Diamond Taper Bolt, which can be strong but usually isn't. To place a torque bolt you tap the bolt into the hole and then torque it down, spreading an expansion cap at the back of the hole to create a friction hold. Sounds good enough, and USE Diamond touts this anchor as the strongest expansion bolt made, but the problem is these bolts don't have any leeway for user error. Torque the bolt too tight and you strip the expansion cap, ruining the placement. Get the bolt too loose and the cap will hold a pullout load about as well as bubble gum on the end of a nail.

We really gave Taper Bolts a chance, setting dozens of them in their optimum substrate, hard rock. We tried to set the bolts by "feel," just as you would when climbing. Half the time we got it right and the 3/8inch Taper Bolts held up to 3000 pounds in a straight pull out. But we blew it with the other half and the bolts slid out of the hole at only 700 pounds. Worse yet, we couldn't tell the good placements from the bad until we ripped them all out.


Russ sez: Seen good ones and seen bad ones. Operator error in all case I've seen. Stripped sleeve being the most common. Long term? Who knows...... Maybe Greg Barnes has some chopper insight to drop in here.
bachar

Trad climber
Mammoth Lakes, CA
Topic Author's Reply - May 7, 2007 - 06:48pm PT
mojede - We first started using 1/4" taper bolts in Tuolumne when we realized there's got to be something better than Rawl split shaft 1/4" bolts. The 1/4" Tapers were easy to over tighten. I quickly switched to 3/8" Taper bolts about the same time people switched to 3/8" Rawl 5-piece bolts. The 3/8" version is difficult to over tighten.

It is pretty hard to strip a 3/8" Taper bolt. When you look at how the bolt works, it's obvious that you need to place the bolt in its hole and leave the same amount of gap on the outside as there are exposed threads at the tip (a hair less than 1/4"). The bolt should be extremely tight after five full turns (you can actually turn it six times without stripping it). When I first started placing the 3/8" Tapers, I would put a little 1/4" ring of masking tape below the head so I knew exactly how far to push the bolt in before tightening it. After a while, I could tell how much gap was right and I didn't need the tape.

If placed properly, the Taper Bolt is indeed the strongest bolt on the market right now. Mark Blanchard, Bill Russell and I tested one in a granite river rock one day at his facility. It was only tightened three turns (less than the optimal five) and we broke the hanger at 5,300 lbs. in a straight pull out - the bolt was unfazed! We also tested a Rawl 5-piece - it failed at 2,200lbs.

Needless to say the shear strength of the Taper Bolt is also far greater than a 3/8" Rawl 5-piece - over 8,000 lbs. shear.

I guess I can see where some people might leave too much of a gap (more than 1/4") before tightening the 3/8" Taper Bolt and end up with a spinning hanger and I also suppose you could strip the sleeve if you really torqued on the wrench - the bolt gets really hard to turn after five turns however (hard to imagine someone wouldn't realize they are over-torquing the bolt at this point).

I've never encountered a poorly place Taper Bolt (3/8") so I can't say how bad they are. I have encountered poorly placed Rawl 3/8" bolts and pulled them out with my hands (with sling and biner). The point being, you can botch either type of bolt if you don't know what you're doing and once the bolt is in it's impossible to tell if it was placed correctly apart from jerking on it in a straight out manner to see if it flies out!

Bottom line - a correctly placed 3/8" Taper Bolt is stronger than a correctly placed 3/8" Rawl (or any other bolt that I know of). The huge bummer of this whole thing is that once any bolt is placed, the climber will never be able to tell if it's been done properly!

peace, jb
Dragon with Matches

climber
Bamboo Grove
May 7, 2007 - 06:58pm PT
Karma dictates the integrity of the bolts is dependent on whether the installer approached from below or above.
WBraun

climber
May 7, 2007 - 07:11pm PT
They may or may not be any good depending on the guy who places them.

All I know is if John places the bolt I'm not going to worry about it because John knows how to place bolts properly.

I have seen ......
G_Gnome

Trad climber
Knob Central
May 7, 2007 - 07:19pm PT
All I know is if John places the bolt I'm not going to worry about it because John knows how to place bolts properly.

I have fallen on them ......
KP Ariza

climber
SCC
May 8, 2007 - 02:09am PT
John places solid anchors, that we've established (not that he needs em'). I agree w/ Werner that a good anchor has as much to do with the person placing it as it does with the actual hardware itself. For overhanging face routes titanium eye bolts set with Hilti's industrial epoxy can be bomb proof. They are relatively easy to place (though a bit messy)and, as stated above, are regularly tested and utilized in the construction industry. Many routes along the Bay Area coastline are equipped w/ these anchors and after over a decade of use, in the harshest salt water exposd environment, they show zero signs of deterioration.
BadInfluence

Mountain climber
Dak side
May 8, 2007 - 08:35am PT
JB i thought you chopped bolts
Steve Grossman

Trad climber
Seattle, WA
May 8, 2007 - 10:39am PT
Hey John,

Take those Taperbolts back to the store if you can. The main problem with their design is that all of the straight out holding power comes from the soft metal split end piece and the tapered threads. The design can't withstand any movement in the hole or repeated long axis loading without weakening. If you place these things on overhanging routes, they are doomed to fail eventually. Let me know off thread the kinds of routes that you are setting up and I may be able to hand you a much better bolting system to check out. I've been prototyping several combinations. I have been using stainless Powers (Rawl)1/2" 5 piece bolts but they have become far too expensive once my stash runs out.

Contact me JB.

PS EVERYBODY STOP WASTING TIME AND EFFORT PLACING MILD STEEL BOLTS! Stainless Steel is the only responsible option if you want to do lasting, quality bolt work. Cheapness is no real excuse here, think about it.
bachar

Trad climber
Mammoth Lakes, CA
Topic Author's Reply - May 8, 2007 - 11:32am PT
Badinfluence - rumors, ha! No, seriously, I stopped chopping a long time ago. Anyway, you can unscrew bolts nowadays - no need to chop anymore (if you're into that sort of thing).

Steve, I really can't see how these Taper bolts can move at all once they're tightened - maybe in some softer rock??? They are stainless steel by the way. All the engineering reports give them extremely high marks and they are used in 5,000 psi concrete for some very serious construction situations where failure is not an option. I like them cuz I can place them one handed on the lead with no hammer (just a drill and a wrench).

I'm always on the look out for something better however and I totally agree with you that we should try and place the best quality bolts possible.

Thanx, JB
WBraun

climber
May 8, 2007 - 12:33pm PT
Place Bachar approved taper bolt into rock.

Next, long slack piece of static rope clipped to bolt and other end to car bumper.

Now gas it outa there.

If bumper rips off car, bolt is strong .....
dryfly

Trad climber
utah
May 8, 2007 - 01:09pm PT
If bolt not strong..Climber driving car eat bolt/hanger to back of head through window...If climber survive, climber is stronger than bolt.
DrCrankenstein

Social climber
too many places, actually
May 8, 2007 - 01:46pm PT
Enough with all this nonsense...

JB, I'll clip a bolt you placed anytime! When do we get to hear about the new area???? I'm intrigued!!! We talkin' like Dexter Canyon style? Cause yer box o'fifty will go far like that.
KP Ariza

climber
SCC
May 8, 2007 - 02:01pm PT
Glue in's or stainless wedge anchors-
Howie

Trad climber
Calgary, Alberta
May 8, 2007 - 02:15pm PT
All this talk of weak bolts makes me shiver. Never placed one in my life but do use them.
Sounds like we are heading to small metal plates on each bolt detailing date, time and person placing them!
Seriously how do we really know the interity of any bolt?
Nothing like a whacking big piece of aluminium jammed in crack for me. I know, not always possible.
Howie.
Pistol Pete

Trad climber
Pasadena, CA
May 8, 2007 - 03:27pm PT
Why don't you just use a torque wrench and tighten to the right specs. Worked for me with FIXE wedge bolts. (Had to e-mail Spain to get the right specs)
Howie

Trad climber
Calgary, Alberta
May 8, 2007 - 04:21pm PT
Hmmm power drills, torque wrenches, what next - pull test equipment?
Surely bolts should be placed with some degree on confidence without resorting to a torque wrench. I realise a wrench is neeed to tighten them in the first place.
Howie
Darryl Cramer

Social climber
May 8, 2007 - 06:45pm PT
As a practical matter I placed 3 Taper bolts (1/4" on lead) in the 80's and messed the third up. I decided to stop using them. Hilti has a similar design (http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-12371); that a friend swears by. Although he is using them pretty much exclusively on slabs. The coil is much beefier than the Taper bolt design.

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