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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Original Post - Sep 15, 2010 - 09:27pm PT
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Today, I tested a method of pulling out 3/8" wedge anchors. Drilled and tapped a 3/8" hole in the end of a piece of 15/16 all- thread. A 15/16" bolt would work better but being cheap, I used what I had. I welded a nut on the end so I guess it is a bolt now. I used a pipe tee, a second nut and a couple washers too. My sources tell me that the tension on a bolt with good clean threads can be estimated by:
Torque = (0.2) x (tension force) x (bolt diameter)
T = 0.2 F D
Fine threads don't produce more tension for given torque, they just damage easier. Knowing the force you think will pull the bolt, you can resize the system accordingly.
I drilled a 3/8” hole 2.5” deep and pounded in a zinc plated carbon steel bolt. I was too cheap to buy a stainless one but if you give me a stainless one, drill the hole and offer me a decent beer - I’ll test a stainless one for you. I didn’t have two wrenches big enough and handy so I used a pipe wrench. Hold the bolt and turn the nut. Definitely took a bit of grunting but not too hard to do. It broke at the neck just as I expected but I consider it a success since I got most, if not all, of the bolt out.
I have some load cells that I could set up to measure the force on the bolt but it didn’t seem important enough. You might have to by a 6-pack and pizza to get me to do that.
Don't forget to put everything on a leash so you don't lose everything when the bolt pops.
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Steve Grossman
Trad climber
Seattle, WA
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Sep 15, 2010 - 11:37pm PT
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Nice simple puller! It would be interesting to see how often you get a crater. I wonder if being able to work the tapped center bolt side to side would be useful?
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Delhi Dog
climber
Good Question...
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Sep 15, 2010 - 11:58pm PT
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Yep you need better beer judging by the one on your rock there...
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Spider Savage
Mountain climber
SoCal
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Sep 16, 2010 - 01:16am PT
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Probably should consider upgrading to Pabst. That should work perfectly.
Nice bolt puller! There's a market for those. Some people don't have access to a drill press, tap & die set.
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Mighty Hiker
climber
Vancouver, B.C.
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Sep 16, 2010 - 01:22am PT
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Would the test results vary if you had better equipment (beer)?
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Sep 16, 2010 - 10:21am PT
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It would be interesting to see how often you get a crater.
By crater I'm assuming you mean failure cone. I thought about this and I think that if the depth to the wedge is greater than the radius of the pipe fitting, you shouldn't get a cone. This might not be the case if the rock has defects or a crystalline structure that fails at something other than 45 degrees. The 45 degree cone happens because the rock is quite strong in compression and weak in tension. If the bolt is shallow, a heavy washer with a 3/8" hole might be the solution.
I was once hired to help replace a cast iron column in the basement of a brick building on Union Square in SF. We had to jack the load off (that sounds a bit off topic) but not go too far so we didn't crack the brick walls. We strain gauged the column. We gave the jack a pump and checked the strain. When we didn't get a change in strain with a pump of the jack, we had jacked it off so to speak.
Anyway, that last paragraph has little to do with failure cones except that we had a pressure gauge and knew what the load was. The load was a fair bit more than we had anticipated. We had predicted the load based on a 45 degree wedge of brick wall being lifted but when we increased the angle to the natural angle of the brick stack, we got the right answer.
.... keep spalling to a minimum.
The photo makes the edge spalling look worse than it is, perhaps because it is a planar, polished surface. Since my life wasn't at stake I was a bit sloppy starting the hole. The edge shouldn't spall with a wedge anchor if it is pulled straight out. The bolt doesn't really touch the sides of the hole except at the wedge. This isn't true for a cast in concrete anchor or a glued in anchor like the image below.
As for the beer, all I can say is it's cheap. Have you tried 7-11's new in house brand "Game Day?" That's what I drink on Sunday.
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Steve Grossman
Trad climber
Seattle, WA
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Sep 16, 2010 - 11:26am PT
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Brings a new twist to Drunk on Game Day! Every day is Game Day!
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k-man
Gym climber
SCruz
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Sep 16, 2010 - 12:17pm PT
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Get a load of that drill in the first pic. And...Miller Lite?
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Sep 16, 2010 - 02:52pm PT
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Miller Lite?
Yeah, well, until we can get Schlitz again.
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adatesman
Trad climber
philadelphia, pa
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Sep 16, 2010 - 03:56pm PT
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If you switched over to using Acme-threaded all-thread and nut you'll probably find that it works with much less effort (60 degree V-thread isn't terribly efficient in applying force).
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couchmaster
climber
pdx
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Sep 16, 2010 - 04:34pm PT
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Nice work. Would you say that you got all of the threaded part of the bolt out and the unthreaded part stayed in? If that is the case, then perhaps a 2nd jig with clearance for that part would fully pull the bolt out.
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SteveW
Trad climber
The state of confusion
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Sep 16, 2010 - 04:57pm PT
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Banquo, yer doin' some good stuff!
a big THANKS!!!!!!
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healyje
Trad climber
Portland, Oregon
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Sep 16, 2010 - 05:16pm PT
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Nice work!
If you switched over to using Acme-threaded all-thread and nut Aric, where would one get less than 12' of the stuff?
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k-man
Gym climber
SCruz
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Sep 16, 2010 - 05:20pm PT
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Dude. You are killing me. First Schlitz, and now...
Doughnut Nation! Whoa, my hero. Love that place ...
BTW, great job on the puller.
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Sep 16, 2010 - 06:02pm PT
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Would you say that you got all of the threaded part of the bolt out and the unthreaded part stayed in
The only stuff left in the hole is the expander cone (pointed small end out) and the expansion sleeve. You can see these in the first photo. It just occurred to me that if I punch the cone back in, I might be able to fish the sleeve and cone out with a magnet. I'll try it later at home.
If you switched over to using Acme-threaded all-thread...
Yeah, I have a hand pump and hollow core hydraulic cylinder that does an easy job of it but I was looking for the cheapest solution. I'd have to buy acme threads.
As George used to tell me, "any fool can spend money."
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adatesman
Trad climber
philadelphia, pa
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Sep 16, 2010 - 09:10pm PT
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If you switched over to using Acme-threaded all-thread and nut Aric, where would one get less than 12' of the stuff?
McMaster has 6" lengths of 1"-5 Acme threaded rod for $13. Not as cheap as V-thread, but would work work better since it puts the flank of the thread more in line with the direction of force. A buttress thread would be even better, but no idea where to find either a rod or nut with that threadform. :-(
If you switched over to using Acme-threaded all-thread...
Yeah, I have a hand pump and hollow core hydraulic cylinder that does an easy job of it but I was looking for the cheapest solution. I'd have to buy acme threads.
As George used to tell me, "any fool can spend money."
Don't get me wrong; if you have the threaded rod and nut sitting around anyway there's no reason not to use them. It's just that if you have to buy the parts you can end up with something that works better for not much more money.
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Sep 17, 2010 - 04:17pm PT
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something that works better for not much more money
I've used acme threads before and they do work well. they might resist damage better too.
Today's lunch time goof off. Went out the the granite block and punched the cone down but the collar stayed in place either because it didn't have enough spring to retract to a small enough diameter or/and it was too melded to the rock inside the hole. I got out the hammer and drill and beat the heck out of it for awhile which did little except compact the metal into the bottom of the hole. I then got an electric drill and high speed bit and tried to drill it out but didn't have much luck. The cone might be spinning.
So, to replace the bolt we would have to have a deep enough hole (or short enough new bolt) to leave the cone and wedge in place or drill a bigger hole. The bigger hole route has two alternatives I can think of just now:
1) Pull/break bolt as above, hand drill hole to 1/2 inch, hope you can loosen and fish out the remnants of the old bolt and replace with 1/2".
2) Buy one of these
http://www.drillcogroup.com/removal.html
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Sep 22, 2010 - 07:30pm PT
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I had another try at removing the wedge and sleeve of the bolt from the bottom of the hole. I found a 1/2" diamond hole saw intended for cutting holes in tile but it was too short to reach the bottom of the hole. The shaft only had three flats so I filed the three remaining sides flat and it fit a 9mm hex socket nicely. Drilling down to the remnants of bolt was very fast but things went slowly from there. I eventually got past the metal and pulled all the remaining bits out. It seems that the hole saw didn't follow the old hole very well and by the time I got to the bottom I was off quit a bit. I actually sawed the wedge at the end of the bolt in half lengthwise and the hole ended up not round at the bottom although at the surface it looks great. The diamond grit wasn't happy going through the metal and the bit was pretty much shot by the time I was done. I suppose it would be possible to do this twisting back and forth by hand but it would take an unreasonable amount of time. I think the hole saw would track better if the bolt was still there and running through the center but you would need a much longer one for that.
Fail:
1) too hard to do
2) The bit didn't last
3) The bottom of the hole isn't round and wouldn't be useful for a new bolt.
4) You have to keep the bit cool with water and it would be a huge mess in the field.
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Juan Maderita
Trad climber
San Diego, CA
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Banquo,
In regard to the original post: Maybe I'm missing something. How is the puller device any different from simply applying a wrench (or breaker bar w/ 6-point socket) and overtorqueing until the wedge anchor snaps off?
It seems that the utilizing the puller is a complex method to do the simplest task.
In actual field use, rebolters would find that many wedge anchors have the threads on the tip deliberately smashed to prevent removal of the nut and theft of the hanger. On my installations, a small bead is welded at the tip for the same purpose. The extra step of filing the damaged part would be required, prior to attaching a puller.
My experience with breaking wedge anchors by overtorqueing has yielded differing results. One set of approx. ten, 3/8" carbon steel snapped at the cone 80% of instances. Another time, a set of approx. seven 3/8" wedge anchors snapped at the threads, nearly flush with the rock. Many other individual 3/8" wedge anchors always snapped at the threads, nearly flush with the rock. I suspect that results may vary by manufacturer and/or by type of steel.
When broken at the threaded portion of the bolt, removal can only be accomplished by core drilling. Core drilling is not practical (or legal) for most rebolters, requiring expensive diamond core bits, power drilling, and water.
Are you familiar with Jim Titt's work on the subject?
http://www.bolt-products.com/SustainableBolting.htm
His company sells core drills and a compact water system:
http://www.bolt-products.com/Accesories.htm
It's always interesting to read your testing info, thanks. The research and discussions are a service to the climbing community.
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Banquo
Trad climber
Morgan Hill, CA (Mo' Hill)
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Topic Author's Reply - Nov 2, 2010 - 02:06pm PT
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Juan-
I haven't tried just overtorquing the existing nut but it's interesting to hear that you have had some success with that. Just overtorquing the nut has to apply some torque to the bolt shaft. My thought was to apply pure tension to the bolt and no torque even though I am not sure it makes much difference. I managed this but it requires two wrenches and hardware. Damaged bolts and welded nuts are a whole nother problem of course. Mine is probably not yet an entirely practical solution.
I hadn't seen Jim Titt's website but he is doing pretty much what I was thinking of. I did find a US company that sells similar core bits but as I recall, they didn't sell small enough ones.The diamond bits are sure a pain and a mess. Seems like something could be made in carbide or even hard steel that would work - pretty small market tough. Something that looks like the Rawl Saber-tooth Self Drilling Anchors. They don't make these anymore but there are some on ebay.
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