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Banquo
climber
Amerricka
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Topic Author's Original Post - Apr 1, 2013 - 08:31pm PT
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Received two Star Dryvins from supertopo member rick d. He sent a 3/8x2 and a 3/8x1-1/2. I wanted to test one in shear and in pullout. I decided to test the 2" in pullout since I figured the pullout result wouldn't be very different for the two lengths. I tested the 1.5" in shear since I figured it would be weaker and since you can't tell how long they are when installed perhaps you should assume shorter. As always, I am testing in very good granite and results will be different in softer rock. (I'm not much on geology so it may not be granite for all I know. Granodiorite? Diorite?)
For you youngsters, Star Dryvins were once pretty common but have mostly been replaced. I used to see quite a few of them at Pinnacles. They consist of a steel nail which fits into a split steel sleeve. The steel sleeve has a bit of lead wrapped around the end. When the nail is driven into the sleeve, the lead is pressed into the rock and forms the mechanical connection to the rock.
Peak load in tension was 1870 pounds
Peak load in shear was 2670 pounds
For comparison, 1/4" by 1-1/2" split buttonhead 1860 pounds tension and 3340 shear.
The 3/8 Dryvin would probably outperform the 1/4 buttonheads in softer rock like that found at Pinnacles.
[Click to View YouTube Video]
[Click to View YouTube Video]
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Salamanizer
Trad climber
The land of Fruits & Nuts!
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Bomber!
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Fritz
Trad climber
Choss Creek, ID
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Fascinating! Thank you for the testing.
I've always clipped them---if there was no other choice.
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Batrock
Trad climber
Burbank
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Keep em coming, first few routes I ever established were with Star Drives, until I found split shafts lol. This is great stuff, thank you for your effort.
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rick d
climber
ol pueblo, az
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the short was 1 1/2".
I would bet the 2" would have done better in shear.
the 3 1/2" would be great in shear.
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bhilden
Trad climber
Mountain View, CA
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I am not surprised that the shear strength of a 3/8" Star Dryvin in solid rock, like granite, is the same as a 1/4" Rawl split shaft. The nail of the Star Dryvin is 1/4" in diameter.
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Jerry Dodrill
climber
Sebastopol
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Nice, but where's the Leeper hangers ? ;-)
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Banquo
climber
Amerricka
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Topic Author's Reply - Apr 2, 2013 - 10:50am PT
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The shear test left all of the lead in the hole. The pullout test left most of the lead in the hole.
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Roots
Mountain climber
SoCal
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Great! I was always hesitant to think they were trustworthy.
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Elcapinyoazz
Social climber
Joshua Tree
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Thanks, good stuff.
Nice to see they are stronger than appearances. I guess the downside is, I've almost never seen these placed in granite, I've mostly only seen them on desert sandstone, which would surely have lower results.
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Dingus McGee
Social climber
Laramie
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Elcapinyoazz,
which would surely have lower results
real scientific? OR just your dumb ass authority??
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Salamanizer
Trad climber
The land of Fruits & Nuts!
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Theres always tons of different factors to consider, and it's best to assume that all star drives are just total crap. Especially considering the adverage age of most of these things.
That being said, I've replaced several dozen of them in both granite and soft (makes the fishers look solid) sandstone with varying results, but in general, they tend to be way harder to pull than split drive and even wedge anchors in sandstone. In granite, they par well with the split drives.
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Clint Cummins
Trad climber
SF Bay area, CA
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Nice work, Dan.
When age (rust) is a factor, I think the 3/8" Star Dryvins would do better than the 1/4" split shaft (Rawldrive), because the 1/4" nail in the Star Dryvin is full diameter, while the 1/4" Rawl is split and subject to cracking after it gets rusty.
There were some 3/8" Star Dryvins on the Arches Terrace traverse, and I believe they were quite good when Roger replaced them.
Sometimes the hangers are pretty bogus, though, and you can't just easily replace the hangers.
One other issue is that sometimes people install the hanger on the Star Dryin incorrectly. They only put the nail through the hanger, instead of the sleeve through the hanger before inserting the nail. Something to look out for.... I recall Bruce has found several this way when replacing.
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mucci
Trad climber
The pitch of Bagalaar above you
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Every star drive I have replaced, in granite or choss has been truck worthy.
If placed correctly as Clint just mentioned.
The others, which had the lead below the hanger, were still very tough to pull.
Cool Test DAN! Dig that drill too, just not as much as that short A-Taper unit :)
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Banquo
climber
Amerricka
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Topic Author's Reply - Apr 4, 2013 - 09:14pm PT
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Since the Dryvin requires a 3/8" hole, I thought I'd test some 3/8" wedge bolts for comparison.
The tension test didn't quite go according to plan. I used a coupler nut to pull on it. I think the coupler was a cheap Chinese one from Home Depot or someplace and the threads were a bit loose. The threads stripped at 6310 pounds. I a bit more thread had pulled into view and I took out the washers which left some good threads in view. I ran it again but the Made in China eye bolt failed at 6800 pounds.
I then did one in shear. The hanger failed at 4180 pounds leaving the bolt looking pretty good. I didn't have anything heftier to test load it with so left it at that.
I'm thinking that in solid granite even a 2-1/4 wedge bolt may be longer than needed. I might cut some down and see how they work.
Josh- The A-Taper drill seems to drill faster than the SDS drill. Perhaps because the bit is rigidly attached to the holder and the holder is lighter resulting in the hammer blow being transmitted directly to the tip of the bit. Bob used it one day with Clint and liked it but said the bits I have blew out after a couple holes. They were cheap bits and perhaps I need to buy better ones although the tips don't seem to blow out when I use it. The A-Taper holder is a bit fussier to change bits in stance but I find that if I insert the wedge and pound on the rock with it I can get the bit out fairly easily. Bob tried to pound in the wedge with the hammer and had trouble supporting the holder to do so. Today I beat on it as hard as I could while drilling and the bit didn't shatter and I could still get the bit out without the hammer. I even used a 32 oz Omega Pacific hammer rather than the 25 oz BD hammer.
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Clint Cummins
Trad climber
SF Bay area, CA
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Yeah, for sure if I drill a 3/8" hole in granite on one of my routes,
I won't be putting a Star Dryvin into it (will use SS wedge instead).
Of course there are valid reasons for using a SS Powerbolt (5 piece / sleeve) instead of a wedge bolt.
There is also the choice of 304 vs. 316 stainless wedge bolts (Bob uses 316).
The idea of going shorter than 2.25" is interesting....
Bob breaks a lot of bits (and hammer tangs) - he just hits so hard....
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DanaB
climber
CT
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** Apr 2, 2013 - 09:06am PT
Elcapinyoazz,
which would surely have lower results
real scientific? OR just your dumb ass authority??**
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kennyt
climber
Woodfords,California
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I'm thinking that in solid granite even a 2-1/4 wedge bolt may be longer than needed.
ya think?
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