Discussion Topic |
|
This thread has been locked |
mikeyschaefer
climber
Sport-o-land
|
|
|
Aug 24, 2018 - 11:15am PT
|
I've placed probably a couple hundred or so of the split shaft 1/4" drive bolts in mostly 1.25" length. For the most part they are pretty hard to screw up and have always felt plenty bomber to me. I've done the double washer trick like Minerals and just slip a medium size stopper wire between the washers. I do use the slightly longer 1.5" if I'm gonna be doing the washer trick as the the minimum embed depth is 1.125" and the two washers and space for stopper eat up some length.
|
|
klaus
Ice climber
6th and Mission
|
|
|
Aug 24, 2018 - 05:28pm PT
|
This seems to work for me just fine in granite for pro and belays. Rivets would be shorter.
|
|
Greg Barnes
climber
|
|
|
Aug 24, 2018 - 05:45pm PT
|
I've placed probably a couple hundred or so of the split shaft 1/4" drive bolts in mostly 1.25" length. For the most part they are pretty hard to screw up and have always felt plenty bomber to me. I've placed around the same number, but one failed at far less than body weight after 8 months (over the winter in Tuolumne) - and I had hung on it the previous season. It was 95% cracked/rusted, just a small sliver was freshly broken. And one of Mineral's bolts broke just under the weight of a quickdraw, again after a winter - one winter I think? I think both were in water streaks (mine was right in a water streak below the end of a ledge).
Also one of mine that I didn't get around to replacing for about 8 years snapped off with not too much effort, and it was cracked/rusted about 60% through. Not in a water streak, on a big slab at about 10,000' on the eastside.
The same mechanism is probably behind the 5/16" buttonhead failure at Owens, and a couple 3/8" split-shaft failures at Cochise. But that's just my guess.
Anyway...split-shafts can be suspect after a winter...
|
|
Steve Grossman
Trad climber
Seattle, WA
|
|
|
Aug 24, 2018 - 05:58pm PT
|
We've had reports on this forum of 1/4" split shaft bolts failing right after they were installed. Wrong design for the use we intend for them.
TORTURED METAL MAKES FOR POOR ANCHORS. Don't use them folks!
|
|
Ksolem
Trad climber
Monrovia, California
|
|
|
Aug 24, 2018 - 06:32pm PT
|
I seem to recall that when I did Mescalito in 2000 the steep headwalls featured these rivets (as we called them at the time) which were thin aluminum stock rolled into a peg. Some had wads of duct tape stuck on the end to hopefully keep your wire or hanger from slipping off. After each three or four of these there'd be a 1/4" buttonhead which was a great relief to clip.
|
|
deuce4
climber
Hobart, Australia
|
|
|
Aug 25, 2018 - 07:51pm PT
|
Minerals got me thinking. As I was never a fan of Zamacs (and I just learned the proper spelling), I never knew too much about them, except that I hated clipping them on walls.
They are indeed primarily Zinc, with aluminium as one of the alloying elements)
Here is some info:
Zamacs have always been known to be weak, but probably mostly because the material is weak and deforms in shear. Another problem is how they have been used on El Cap--On the first ascent of sheep ranch, the climbers drilled a deep hole, then mashed the zmac against a tie-off. On the third ascent only 3-4 years later, the tie-offs were rotten and stiff, and sometimes in the middle of a hard A4 section--making the route much harder for subsequent ascents than it was for the first (when the rivet and new sling had some chance of holding a short fall). Cutting away the sling took some craft and a lot of time, then there was only room for a #1 rivet hanger wire--bogus.
|
|
Minerals
Social climber
The Deli
|
|
|
Aug 25, 2018 - 09:24pm PT
|
^^Cool, you found more info on them. Who does like clipping them on walls??? Mad Bolter Richard may have expressed an affinity for these at some point in the past. They are, after all, a true rivet, in that they are pretty much a bodyweight placement, temporary as they may be.
Just took a look at Zamak on Wiki, which lists “Plumbing fittings” as a use of the alloy, which has me wondering if those old “plumber’s tape” rivet hangers, like what Harding used on the Porcelain Wall, are also made of a Zamak alloy. Hmmm... I think some of those tape hangers were used with Zamac rivets too. Ugg.
North, do I know you? Are you south?
If you are going up Tribal, then I think some sort of a backup kit would be a good idea. When Kirk and I did it in ’99, there were a couple of small ‘issues’ on one of the rivet pitches (either pitch 3 or 4). While Kirk was cleaning, two of the rivets popped out of the rock as he lifted the keyhole hanger off of them, and the rivets went to the deck. The original rivets on these pitches are stainless machine bolts. Not sure why there was an issue with these two, but I’d be suspect of any of them that still remain.
The bolt that Greg mentioned above was on Cheetos and Everclear, on Dozier Dome, in Tuolumne. Jeff was leading on the second ascent, which I think was just a day or two after we finished the pitch (definitely less than a week; no winter involved), and suddenly there was a metal-on-rock jingling sound, which was a bolt hanger and his quickdraw sliding down the lead line, as he was already a few moves above where the draw ‘used to be’ clipped. I remember him saying… “This route just got a lot harder...” : ) I was sitting at the base, off to the side, thinking WTF...? Turns out the bolt had broken midway along the shaft sometime after we finished the pitch and when he climbed it, and the movement of the rope and draw simply pulled the outer half of the bolt out. This is the only time that I have seen something like this happen.
I agree that there should be a better option for the 1/4” buttonhead, but so far I have not found one, and so will continue to use them. I don’t keep them around for too long, though. As does Greg, I pull them later and replace them with a stainless 3/8” 5-piece, preferably that same season.
Steve, I agree too that a stainless 5/16” machine bolt may be a better rivet option in the long run, compared to the carbon-steel grade 5 version. However, I am not familiar with the difference in properties between the two metals, i.e. hardness, malleability, and strength, and how they relate to rivet placement and strength. The grade 5 versions can certainly be way bomber when they are new. Deuce, any comments on this from an engineering perspective?
Nice stuff, Dammerr. Interesting idea with the RE magnets.
|
|
Minerals
Social climber
The Deli
|
|
|
Aug 25, 2018 - 09:50pm PT
|
|
|
deuce4
climber
Hobart, Australia
|
|
|
Aug 26, 2018 - 11:49am PT
|
^ that is nuts, Russ. Back to the concept of intentionally making drilled placements dicey...
... making subsequent ascents harder than the first.
|
|
deuce4
climber
Hobart, Australia
|
|
|
Aug 26, 2018 - 12:06pm PT
|
Minerals, regarding your comment about stainless machine bolts—I am not really sure, haven’t ever really seen any coarse thread stainless machine bolts.
I did test some Grade 8 machine bolts back in the day, and they did not perform as well, my hypothesis is that you want the softness of the grade 5 coarse threads to meld into the hole giving it some outward holding strength.
One thing I discovered in all those tests is that bolt failure is really about pullout strength; in tests, even with a shearing force, the rock would crumble slightly at the edge of the hole, and the bolt would bend, so the way it eventually failed was it was getting pulled out, even in shear. (Not sure if that is clear).
Anyway, the only way to really find out is to set up a hydraulic puller with a pressure gauge (about a $200 rig) in the field and test a bunch of them!
|
|
deuce4
climber
Hobart, Australia
|
|
|
Aug 26, 2018 - 12:15pm PT
|
For reference, this is the additional collet one would need to get to use 17/64” cobalt or HSS hardware store drills—the recommended drill hole size for 1/4” buttonheads.
( in Minerals photo above, his 1/4” drill setup has one of these collets).
The whole concept behind this drill holder is you don’t need any custom made drills like we did in the old days when the only game in town was the RAWL holder which often got jammed and was hard to replace broken bits en route.
With the Hurricane, you can use any size drill, not just SDS, with the appropriate collet. Thus more versatile. Of course it works with SDS as well.
|
|
DanMerrick
Social climber
FKA Banquo from Mo' Hill, CA
|
|
|
Aug 26, 2018 - 03:00pm PT
|
I've tested a lot of 1/4" anchors. Most really aren't too bad. I can't find the results right now but I have also tested Zamacs and they are worthless.
Some numbers for shear tests with stoppers for comparison. Tests in good granite:
Pounds
3500 tested Powers 1/4" Drive (split shank)
3100 tested Powers Spike 1/4"
2500 tested Simpson Strong Bolt 1/4" 316 SS
2250 rated #6 stopper
2160 tested wej-it 1/4" 304 Stainless Sleeve Anchor
1350 rated #5 stopper
If anybody needs some anchors, contact me.
|
|
|
SuperTopo on the Web
|
Let us know!