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Jaybro
Social climber
Wolf City, Wyoming
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Apr 20, 2017 - 07:11am PT
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More to follow,I have things to do right now...
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edavidso
Trad climber
Oakland, CA
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Apr 20, 2017 - 07:50am PT
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Thanks for the interest and emails. And thanks, Nutstory, for cleaning up that sheetrock wall!
Just to answer the question on the long, skinny stem. I actually addressed this earlier in the thread but to make it clear: the stem is a solid 5/32" 17-4 SST rod. I cold head one end to taper it out to about 1/4" and then heat treat to the H925 condition. At that point it has a tensile strength of nearly 1400 MPa and is one of the strongest stainless steels available. Also not a cheap part! To assemble, it is pressed into the stem end (also 17-4), which has a mating taper, with 2 tons. The other end gets silver soldered to the 304 SST handle. Since the stem is solid, it does not flop around at all, and because it is so strong it can be bent up to about 2.5" in any direction before yielding (not returning to centered). If it does get torqued off center in a fall, you can just hold the cam lobes and bend it back to centered. Due to its strength and toughness, it also has amazing fatigue properties and you can bend it like this hundreds of times.
I also experimented with making the cam with a 3/16" wire rope stem with 1x7 construction for stiffness. Due to the single stem design, this was still a little floppier than I wanted it to be. It also ends up being heavier since wire rope is not as strong as 17-4. You also add one silver solder joint, which is undesirable for a few reasons.
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nutstory
climber
Ajaccio, Corsica, France
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Apr 20, 2017 - 08:04am PT
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Great Jaybro, thank you again!
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ionlyski
Trad climber
Kalispell, Montana
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Apr 20, 2017 - 08:13am PT
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OK then!
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Matt's
climber
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Apr 20, 2017 - 08:13am PT
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edavidso-- looks great! email sent.
best,
matt
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Moof
Big Wall climber
Orygun
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Apr 20, 2017 - 11:09am PT
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Email sent.
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Clint Cummins
Trad climber
SF Bay area, CA
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Apr 20, 2017 - 01:15pm PT
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Wow, Erick - thanks for explaining your stem design!
Your creativity (multiple innovations) and engineering skill are at a level well above other cams!
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Alexey
climber
San Jose, CA
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Apr 20, 2017 - 02:22pm PT
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Email sent
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Gnome Ofthe Diabase
climber
Out Of Bed
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Apr 20, 2017 - 03:00pm PT
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The Anniversary of the start of My 20th year of bliss, just passed. Idid everything I could think of, trying to convince the good wife that I needed a massive cam.
She said to me:
"the only hard wide you'll be climbing - is Me!" this old lady! Has my number and knows to feed me beer & pizza once a month @least.
The Merlin's look amazing!
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matty
Trad climber
under the sea
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Apr 20, 2017 - 04:59pm PT
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Email sent =)
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Idahoan
Trad climber
Idaho
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Apr 20, 2017 - 06:32pm PT
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Email sent here as well. Damn I'm low on that list
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BLUEBLOCR
Social climber
joshua tree
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Apr 20, 2017 - 06:50pm PT
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Bowwww! I'm gettin my pyche on for the WHYYYYED! 😳
PM sent.
But if there's a better way to connect, I didn't see a link?
Edit, vvvv Thanks for the heads up. Email sent:)
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kunlun_shan
Mountain climber
SF, CA
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Apr 20, 2017 - 06:56pm PT
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BLUEBLOCR, Taco PM does NOT work.... send edavidso an email to merlinrockgear@gmail.com, per his request a couple posts up.
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karabin museum
Trad climber
phoenix, az
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Apr 20, 2017 - 08:28pm PT
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..........email sent!
:)
:)
:)
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nutstory
climber
Ajaccio, Corsica, France
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Apr 22, 2017 - 01:46am PT
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I promise super photos as soon as I get my sample ;-)
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'Pass the Pitons' Pete
Big Wall climber
like Ontario, Canada, eh?
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Apr 22, 2017 - 05:32am PT
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Tom's Valley Giants are tried and tested by yours truly and many many others. They are superbly crafted and highly recommended!
It's great that Tom is producing them again. Get 'em while you can.
Tom - I'm hoping you'll please be able to return that #9 to me this spring, the one where the spring had come undone.
See you on the Bridge for beers?
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Tom
Big Wall climber
San Luis Obispo CA
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Apr 22, 2017 - 03:49pm PT
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Yeah, PTPP. Early to mid-May?
I would like to see photos of a Merlin8 cam pulled to destruction, in a testing frame that doesn't restrict a big cam's lobe's natural tendency to buckle sideways. That is a big cam's failure mode, not some sort of in-plane breakage of the material. The testing frame photo above looks like it would restrict lateral deflection of the lobes, and not accurately reflect structural behavior in the real world.
A more accurate test of a big cam's strength would be with it almost fully opened, and not half-compressed. Any cam is going to be stronger compressed, as opposed to being fully open. People use cams fully open, and a testing regimen should reflect that.
Furthermore, a rectilinear testing frame is not going to induce the same off-axis loads that a real crack would. Those off-axis loads dramatically increase the lateral loads on a big cam's lobes, and cause them to bend and buckle sideways earlier than predicted in a laboratory test. Depending on how thick the cam lobes are, a rigid, rectilinear frame would tend to stabilize the lobes, in a manner, again, that would not exist in the real world.
And, how is a climber supposed to fully control how his gear is loaded? I've bootied enough "fixed" cams to know that even small ones get adversely loaded in ways the user never intended. Jaybro mentioned above that a Cloud Nine cam's rigid stem bar can be bent sideways during use. PTPP bent and deformed a super lightweight magnesium MVG12 while aiding on it, simply by pulling awkwardly in the awkward Neitzsche chimney. If you had to bail during a storm, or were forced into a emergency hanging bivi, would you want to rely on a "pusher piece" that is not full strength?
10 kN strength for a big cam, in the laboratory, probably translates to something like half that in the real world. The strength of a super lightweight cam can be compared to a tiny brass nut, or a tenuously tapped beak or rurp.
If it was easy to reduce the weight of a structure without reducing its strength, super-expensive materials like carbon-fiber composites and titanium alloys would never have been developed.
There is nothing wrong with climbing gear of relatively low strength. That, after all, is the entire point of aid climbing. But, a climber must recognize the limitations of that sort of gear, and usually include other, stronger, gear on their rack. When I used my own super lightweight, magnesium cams in Yosemite, I always had full-strength Valley Giants, as well. I would never had taken just the magnesium cams, because that would have been irresponsible, and WVB would have given me a ticket for "reckless endangerment" if he had been summoned to come save me.
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edavidso
Trad climber
Oakland, CA
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Apr 24, 2017 - 11:03pm PT
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Tom, thanks for keeping me honest here. You bring up some good points, some of which have been addressed earlier in this thread.
I've pulled a couple #8's to destruction with the load frame I posted a picture of. Both were tested at a crack size of 8", which is the max opening on my current setup. It does not restrict buckling and the first #8 I tested was an old prototype from a few years ago that indeed failed in buckling. I tested a new #8 yesterday and it failed at the handle loop at 11 kN before buckling. Heat from the silver soldering annealed the 304 wire rope and led to that failure. I'll bump up the wire rope size on the handle loop to address. Aside from the broken handle loop, the cam suffered no other damage and was perfectly operable after the test. Cams of any size will fail at their weakest point. However, large cams are much more susceptible to failure by buckling and out-of-plane bending. As mentioned, both of these failure modes get worse as the cam is opened farther.
Double axle cams help reduce buckling failures by having a shorter unsupported span between the near axle and point of contact with rock. This actually helps quite a bit since buckling load goes as the inverse of length squared. Double axle cams also are indirectly more resistant to buckling by having a much larger range than single axle designs. In other words, for an 8" crack, a Merlin #8 is in the middle of its range and a VG9 will be at the edge of its safe range. None of this means that the Merlin cams are immune to buckling, it just means I can make the lobes a little lighter compared with a single axle cam. Eccentric loading leads to earlier buckling failures. Out-of-plane bending leads to eccentric loading and therefore earlier buckling failures. To prevent this type of failure in a normal climbing situation, always make sure that the cam is able to rotate to be in line with the direction of a fall. Lobes that are trapped and unable to rotate are more likely to bend in a fall, which will lead to eccentric loading and buckling. Poor cam placements can lead to failure well below rated load. Using a cam with a bent lobe will also result in eccentric loading and failure below rated load. This goes for all cams but is especially important to remember for large cams.
Here's a picture of the #8 I tested to failure yesterday.
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Rhodo-Router
Gym climber
sawatch choss
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Apr 27, 2017 - 06:45pm PT
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Email sent... projects- awaiting large units.
Thanks!
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edavidso
Trad climber
Oakland, CA
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Apr 27, 2017 - 10:15pm PT
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Nutstory sent me this cool graphic and said I could post it:
If only it were that easy to make these things!
I just completed another pull test using the same cam I tested last time but with a larger diameter wire rope on the thumb loop. Since this was a test, I decided to also try a coarser stitch on the sling. This time the thumb loop held but the stitching gave out at 12 kN. Still no buckling but this was in an 8" crack. The cam was still operable after the test minus the sling. Finite element analysis shows that buckling will occur in a 9" crack at 79% the buckling load of an 8" crack. So if this thing was on the verge of buckling (i.e. assume buckling failure at 12 kN), then it will buckle at 9.5 kN in a 9" crack. At this point, the cam is looking rather tipped out or similar to how a VG9 would look in an 8" crack. Someday I will test in a 9" crack but will have to make a new, larger crack simulator so that will not be for some time. I think I'm done breaking good cams for a bit.
Some bad news on the manufacturing front. There are only two custom parts in these cams that I do not make myself and those are the torsion springs and the axles. I've been having a shop make the axles for me and they've produced a few good batches of axles over the past few years. I ordered 100 axles a couple months ago and a month ago was told they were on machines and would ship out soon. That's the last I heard from them despite several emails and phone calls and no axles have appeared in the mail. So I'm afraid I'll probably have to source these from another shop, which means they're probably about a month out. I have enough axles to make only a few cams at the moment. I'm sorry for the delay. There is still some chance axles will appear but it's looking less likely by the day. Thanks for your patience!
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