Discussion Topic |
|
This thread has been locked |
mucci
Trad climber
The pitch of Bagalaar above you
|
|
|
Topic Author's Reply - Jun 5, 2010 - 03:01am PT
|
I don't think anyone made a direct comment as to the strength a placement needs to be on a rivet ladder on this thread.
But when I hear "Use 1/4" x 1" split shaft button heads as rivets, I think protection placements.
Edit : 5/16ths x 3/4 might be the ticket.
|
|
Erik Sloan
climber
|
|
Good discussion gang.
I don't agree with you Mucci about the machine heads. Having pulled hundreds of them I can assure you that most are not placed optimally, such is the variance of rock and the inconsistency with which anyone places them. Back in the 80s and early 90s the folks placing machine heads were doing a lot of FA's, and were more in tune with the inconsistencies in the rock and the necessity to vary the hole diameter, by drilling sloppy or tight holes depending on rock hardness in that position, than any climbers are today. Even those of us that learned in the 90s did a poor job of learning the trade--Chris Mac tells a great story of his route on the Northwest Buttress of Half Dome(Una Iglesia), where machine heads splintered the rock around the hole on one pitch and later one came out while he was standing on it due to the different nature of the rock.
No doubt, the scars that are created from removing an aging machine head eliminate the possibility of reusing the old bolt hole. That alone should be reason to consider the buttonhead as a better option for now for creating sustainable, upward-progress-oriented placements.
North American climbing history is replete with FAist using whatever bolting techniques were common at the time and later greatly regretting these actions. The choice is always there-follow the status quo or consider what might last longer and be more readily replaced in the same location. Dave Turner even told me he regretted using machine heads on Block Party and switched to more buttonheads on Atlantis.
Let's us this attention to visual the best possible rivet for bigwall climbs. We can create whatever we need.
cheers
e
|
|
ec
climber
ca
|
|
I didn't mention that we'd bathook 'bout a half-dozen moves, then a zmac, a half-dozen bathooks, then a 1/4" buttonhead...
that'll get some of yer panties in a bunch...
cheap? maybe...efficient? Hell Yes!
 ec
|
|
Greg Barnes
climber
|
|
Any strength issues, beyond what a rivet is intended for?
Strength ratings - ultimate load:
1/4" Zmac: 890 lbs tension, 880 lbs shear
1/4" buttonheads: 1,760 tension, 2,090 shear
from www.powers.com/mechanical.html
And while we're at it, take a look at the stats for 3/8" Lok-bolts, which you will see here and there - they snap easily (as Marty Lewis and Peter Croft found at Owens when doing a few routes with them):
3/8" Lok-bolts: 2700 tension, 2,440 shear
For comparison, short 3/8" 5-piece (Power-bolt): 5915 tension, 7440 shear
And for those stainless stud bolt lovers: short 3/8" : 3040 tension, 3760 shear. These stats used to be better (still not as good as the 5-piece), so it would be interesting to see why they are so low now...half the strength of a 5-piece.
The short of it is keep those Z-macs for sticking a sign on a concrete wall or TP in the bathroom...
|
|
|
SuperTopo on the Web
|
Let us know!