Login with Facebook
 ADVANCED
8 mm (~3/8) hangers on 1/2 inch Rawl 5 piece.
View Latest Posts in This Forum or All Forums
   Page 1 of 2.  1  2   Next>   Last>>
Follow replies to this topic? Notify me at the top of web site.
1

Email me.
 
 
By Brian Hestetune
From Logan, UT
Jul 30, 2013
Hi. Due to a supply issue, email exchange/phone mishap, I ended up with a box full of 8 mm hangers and 1/2 inch rawl 5 piece boolts. What I want to know is whether it is legit to couple these two? The hangers fit over the bolt and not the sleeve. From the construction of the bolts (and I'm not an engineer), it does not seem like this should be an issue. The only thing I have to go off of is:

"(besides the 5-Piece bolts; 1/2" 5-piece fit 3/8" holes on hangers)."

From ASCA's website (safeclimbing.org/education/how... )

It'd be great if anyone had any input or could redirect me to any discussion on this.

Thanks

FLAG
By M Sprague
Administrator
From New England
Jul 30, 2013
Lichen head. Me, with my usual weatherbeaten, lichen covered look from scrubbing a new route.
The threads would be grabbing less of the cone since the thickness of the hanger would be extending the sleeve. I think there would be real danger in damaging the threads while hammering it in and under initial tightening. I believe Fixe recommends against it. Thieir website has some good instructional videos about bolts and bolting.
fixehardware.com/shop/fixe-vid...

FLAG
By Kirk Miller
From Golden, CO
Jul 30, 2013
Bugaboos, 1978 <br />Photo by Ken Trout
I've always used the 1/2" powers bolts with Fixe 3/8" bolt hole hangars. When I've gone back to remove or replace them its obvious the cone has been fully threaded (and then some).
When you take them out you can also see how the squashed blue plastic spacer forms a nice seal around the bolt at the opening of the hole.

I never liked how the hangar bore directly on the blue plastic spacer when I paired the 1/2" hole hangar with 1/2" powers bolts; seemed like a recipe for future spinners.

Engaging the cone with the sleeve as deep into the bolt hole as possible seems to be a pretty good idea as well; it takes better advantage of the strength of the rock.

FLAG
By M Sprague
Administrator
From New England
Jul 30, 2013
Lichen head. Me, with my usual weatherbeaten, lichen covered look from scrubbing a new route.
See the fifth video : Power Bolt (AKA Rawl 5-Piece) Installation:
Kevin deals with this issue starting about 3 minutes in.

FLAG
By Kaylee Catmull
From Riverside, CA
Jul 30, 2013
Brian....the scenario you're describing has been utilized for decades, until recently when Fixe started producing hangers with 1/2" holes. When you match a 1/2" bolt with a 3/8" hanger, the bolt diameter is still 3/8" which is plenty strong for most applications.

FLAG
By Mike McHugh
Jul 30, 2013
Are they 8mm or 10mm? 8mm seems pretty skinny...

M Sprague wrote:
The threads would be grabbing less of the cone since the thickness of the hanger would be extending the sleeve. I think there would be real danger in damaging the threads while hammering it in and under initial tightening. I believe Fixe recommends against it. Thieir website has some good instructional videos about bolts and bolting. fixehardware.com/shop/fixe-vid...


Last I heard, Kevin recommends taking the washer out of the assembly - so the hanger takes the place of the washer. Leaves about the same amount of contact between the threads and the cone.

FLAG
By John Wilder
From Las Vegas, NV
Jul 30, 2013
yup, take the thin metal washer off the bolt- its near the thickness of the hanger, so it ends up being mostly a wash in terms of hanger thickness having any effect on the bolt. we do this all the time with ASCA replacement work.

FLAG
By 20 kN
Administrator
From Hawaii
Jul 30, 2013
Brian Hestetune wrote:
Hi. Due to a supply issue, email exchange/phone mishap, I ended up with a box full of 8 mm hangers and 1/2 inch rawl 5 piece boolts. What I want to know is whether it is legit to couple these two? The hangers fit over the bolt and not the sleeve. From the construction of the bolts (and I'm not an engineer), it does not seem like this should be an issue. The only thing I have to go off of is: "(besides the 5-Piece bolts; 1/2" 5-piece fit 3/8" holes on hangers)." From ASCA's website (safeclimbing.org/education/how... ) It'd be great if anyone had any input or could redirect me to any discussion on this. Thanks

Just dill the holes out to 1/2". I do it all the time on 12mm hangers. It works fine. The bolt is (slightly) stronger in shear if you place the hanger over the entire bolt assembly (1/2") as opposed to just the machine bolt (3/8"). I know because I have pull tested a number of sleeve bolts in a number of orientations with both 3/8" and 1/2" hangers.

Last, and I am surprised no one has caught this yet, if your hangers are 8mm, they wont fit a 1/2" bolt in any orientation as 8mm is 0.31" and 3/8" is 0.375". The metric equivalent to 3/8" is roughly 10mm. However, I cant think of any manufacturers that make 8mm hangers, so I suspect yours are actually 10mm.


John Wilder wrote:
yup, take the thin metal washer off the bolt- its near the thickness of the hanger, so it ends up being mostly a wash in terms of hanger thickness having any effect on the bolt. we do this all the time with ASCA replacement work.

I know a TON of people remove the washers, and it is not a huge deal either way, but that method is less preferable and comes with a drawback. Consider the following photo:



In the photo you will notice those massive bolts have washers under them. Well, those washers are not there because the site foremen thought the bolts were going to pull through the 1.5" thick steel base. They are there to reduce the chance of the nut inadvertently loosing. The idea is that the washer provides an appropriately level surface for the nut to grip.

So, while removing the washer is not going to kill babies, the bolt is designed to be used with the washer and a 1/2" hanger and therefore I have always preferred to drill the hole out.

FLAG
 
By nbrown
From western NC
Jul 30, 2013
Top of Shortoff with the Bonsai
All of the ASCA 1/2 inchers I've used also have an additional ring/washer/spacer that can be removed instead of the flat washer. It's only about half the width of the washer but that's plenty sufficient.
The spacer ring removed.  <br />
The spacer ring removed.

FLAG
By John Wilder
From Las Vegas, NV
Jul 30, 2013
20kn- see photo above for the washer/spacer i'm talking about.

the washer proper is of course meant to stay put unless you're using 5/8" 5-piece bolts, in which case, the washer will not fit onto the hanger.

FLAG
By Brian Hestetune
From Logan, UT
Jul 31, 2013
Thanks for all of the info. The part number told me that the hangers were 8 mm fixe hangers. I measured them to be 11 mm. They do not fit the bolts very snugly at all, which I would imagine is a legitimate problem. Something seems screwy, but I'll have to wait a bit to get everything fixed up on the order. Thanks again for the help.

FLAG
By Darren Mabe
From Flagstaff, AZ
Jul 31, 2013
wham bam hand jam. Wrapping up the final moves of Twist of Fate, Oak Creek Canyon. <br /> <br />photo: Blake McCord
I think if people are going to take the responsibility of placing bolts for others to use, they should also have some understanding of basic bolt mechanics.

With 'proper' torque, the preload in the bolt joint is higher than any external forces that is intended on the bolt, and therefore the bolt shaft wont be loaded in shear. (theoretically)

in other words, expansion bolts do not act like drilled pitons.

Spinners can happen from under-torqued bolts or too shallow of holes. Spinners do act much like drilled pitons (unfortunately).

here is a simplified analogy of a bolted joint (from wiki):

FLAG
By 20 kN
Administrator
From Hawaii
Jul 31, 2013
John Wilder wrote:
20kn- see photo above for the washer/spacer i'm talking about. the washer proper is of course meant to stay put unless you're using 5/8" 5-piece bolts, in which case, the washer will not fit onto the hanger.

Ah yes, the blue piece. The formal name for that piece is the crush ring, and the little silver thing to the left of it is the extension sleeve. I dont see any problem with removing the extension sleeve on the bolt listed in the photo (but not on longer bolts). However, the crush ring is designed to compress under load and act as a lock washer. Removing it is probably worse than removing the flat washer. It wont kill anyone, but the bolt is designed to be used with all its parts in service. If you remove the crush ring the bolt is more likely to loose its preload and become a spinner, which could result in the bolt pulling if the machine bolt looses all of its thread contact with the cone. That actually happened to me in Red Rocks in 2007 in the Black Corridor, specifically, on the crux bolt of the CEL. I was able to pull the bolt by hand because it had become so loose.

So my suggestion to the OP, as previously stated, is to just drill the hanger out. It is easy and you maximize the installation quality, which should always be the goal of a developer considering the safety-critical nature of the application. :)

Darren Mabe wrote:
With 'proper' torque, the preload in the bolt joint is higher than any external forces that is intended on the bolt, and therefore the bolt shaft wont be loaded in shear. (theoretically)
I am confident it is possible to produce loads on a bolt, in a climbing application, which exceed the preload subjected to the bolt from the recommended tension. What I know for sure is that the recommended tension on a 3/8" wedge bolt is less than 1/6th what is required to cause the bolt to fail from overtightning.

However, very serious falls can produce as much as 20kN on the bolt, which is in excess of the failure strength of some 3/8" stud bolts. So in other words, a lead fall, if serious enough, can certainly exceed the preload. Also, I believe it is possible to load a bolt in both shear and tension at the same time. The preload may be pulling the bolt in tension, but that does not mean another external force (e.g. the hanger) cannot pull the bolt in shear at the same time.

Also, I am not so sure that the load on the bolt from a fall needs to exceed the preload in order to cause the bolt to spin and become a spinner. I suspect that how much force is required to cause the machine bolt to spin (in the case of the Power-Bolt) is a function of the coefficient of friction between the machine bolt, the sleeve and (mainly) the cone. Now, what that coefficient is, who the hell knows? I dont even know if preload would affect the coefficient of friction, although I suspect it does. So in other words, the bolt does not need to be loose to become a spinner, especially if the bottom of the hanger is not resting against the rock. I have been able to spin bolts that were properly tightened when the bottom of the hanger was sticking in the air.

Oh, and awesome pictorial, thanks for posting it. Awhile back, while talking about the bolting conference, I was trying to explain preload to someone and I was having trouble putting it in simple terms because I dident have the pictorial you posted. It does a great job visualizing something that is otherwise quite hard to visualize and explain (at least for me anyway).

FLAG
By Darren Mabe
From Flagstaff, AZ
Jul 31, 2013
wham bam hand jam. Wrapping up the final moves of Twist of Fate, Oak Creek Canyon. <br /> <br />photo: Blake McCord
I see you picked up on my tongue-in-cheek quotes, and theoretical caveat... My comments weren't too applicable to the OP, but thought I'd throw it out there. :)

20 kN wrote:
spinner

oh.. what i meant by a spinner is when the hanger spins on the shank of the bolt, and not the bolt/cone itself spinning. (which is usually from oversized holes)

ok, one more edit, How do you generate 4500 lbf onto a bolt in a climbing application?

FLAG
By Brian in SLC
Jul 31, 2013
Climbing in Smuggler's Notch
Darren Mabe wrote:
what i meant by a spinner is when the hanger spins on the shank of the bolt, and not the bolt/cone itself spinning. (which is usually from oversized holes)


Just the opposite, methinks. The bolt/cone spinning from my experience is usually from a hole that is too small. Common, as, folks don't check the diameter of their drill bits. Hole too small = oversmushin' the cone onto the bolt shaft. Voila, spinner. Especially a problem with stainless 3/8 Powerbolts.

FLAG
By kennoyce
From Layton, UT
Jul 31, 2013
Climbing at the Gallery in Red Rocks
20 kN wrote:
However, very serious falls can produce as much as 20kN on the bolt, which is in excess of the failure strength of some 3/8" stud bolts.


Just curious how you're coming up with this? The only way I can think of would be extremely unrealistic and that is to take a rope with a very high impact force (12 kN), tie it off statically just below the bolt in question, slingshot it through a biner on the bolt in question, then factor two (or as close to factor 2 as possible with the slingshot) onto it. Even in this unrealistic case, the only way to exceed 20 kN is by making sure the climber weighs more than the 80 kg mass used to determine the impact force because using the 12 kN impact force and an assumed 60% of the tension on the slingshotted side of the rope due to carabiner friction, you only get 19.2 kN.

edit to add: I'm perfectly happy to whip all day onto 3/8 stainless power-studs rated at 16 kN (assuming they're in good rock) cause there's no way I'll ever produce a force even close to that on the bolt.

FLAG
 
By kennoyce
From Layton, UT
Jul 31, 2013
Climbing at the Gallery in Red Rocks
Brian in SLC wrote:
Just the opposite, methinks. The bolt/cone spinning from my experience is usually from a hole that is too small. Common, as, folks don't check the diameter of their drill bits. Hole too small = oversmushin' the cone onto the bolt shaft. Voila, spinner. Especially a problem with stainless 3/8 Powerbolts.


I've seen it happen either way. Too small a hole and it happens like Brian said, but in soft rock, the bolt itself can actually enlarge the hole as you pound it in, then when you try to tighten it, the bolt will hit the compressed threads and just start spinning the cone because ther's not enough friction between the rock and the cone due to the enlarged hole.

FLAG
By kennoyce
From Layton, UT
Jul 31, 2013
Climbing at the Gallery in Red Rocks
20 kN wrote:
Also, I believe it is possible to load a bolt in both shear and tension at the same time. The preload may be pulling the bolt in tension, but that does not mean another external force (e.g. the hanger) cannot pull the bolt in shear at the same time.


This is correct, but generally speaking (i.e. normal sport climbing falls) the bolt will only be loaded in tension (assuming it is installed and torqued correctly). The purpose of the preload is to create friction between the bolt hanger and the rock. This friction should take all of the shear load so that the bolt only sees tensile forces. Obviously if the load on the bolt exceeds the maximum friction between the rock and the hanger, the additional shear load will have to be held by the bolt itself. The purpose of the blue crush ring in power-bolts is to allow the bolt to pull the hanger into the rock in order to create this friction.

FLAG
By 20 kN
Administrator
From Hawaii
Jul 31, 2013
kennoyce wrote:
Just curious how you're coming up with this? The only way I can think of would be extremely unrealistic and that is to take a rope with a very high impact force (12 kN), tie it off statically just below the bolt in question, slingshot it through a biner on the bolt in question, then factor two (or as close to factor 2 as possible with the slingshot) onto it. Even in this unrealistic case, the only way to exceed 20 kN is by making sure the climber weighs more than the 80 kg mass used to determine the impact force because using the 12 kN impact force and an assumed 60% of the tension on the slingshotted side of the rope due to carabiner friction, you only get 19.2 kN. edit to add: I'm perfectly happy to whip all day onto 3/8 stainless power-studs rated at 16 kN (assuming they're in good rock) cause there's no way I'll ever produce a force even close to that on the bolt.

You're close. Consider this: the UIAA requires most carabiners to hold 20kN on the major axis, bolts to hold 20kN in tension and bolts to hold 25 in shear. Nearly all of the UIAA's certification numbers revolve around the magical number of 12kN, which is the maximum allowed impact force which a rope is allowed to subject to the test weight in a UIAA fall. They got that number from 1950's(?) military testing which proved that humans cannot withstand more than 12Gs during a parachute opening without sustaining injury.

Anyway, if a 80kg steel weight (or 100 kg flexible mass) subjects 12kN to a rope in a UIAA fall, the other side of the rope will see about 8kN and the anchor will see about 20kN. That is why draws, biners and bolts need to hold 20kN or more (22 in the case of a sling).

The Maxim Glider has an impact force rating of 10.4 kN, and with typical use and age you could certainly hit 12kN or above. And while there are not many 100kg climbers out there, they do exist. Last, you could certainly hit the magical UIAA fall factor of 1.78 in an aid climbing situation. I have caught falls close to that fall factor while aid climbing. So it is all plausible, but agreeably, highly uncommon.

That said, you dont need to hit 20kN to exceed the preload of a bolt, you can probably do that with 8kN, which is not uncommon (although above average for sure).

FLAG
By Jim Titt
From Germany
Jul 31, 2013
Darren Mabe wrote:
I think if people are going to take the responsibility of placing bolts for others to use, they should also have some understanding of basic bolt mechanics. With 'proper' torque, the preload in the bolt joint is higher than any external forces that is intended on the bolt, and therefore the bolt shaft wont be loaded in shear.


However we donīt work on the force intended for the bolt, in our application we are expecting it to hold about 4 to 5 times the load anticipated by the manufacturer. When you pull test bolts in either radial or axial directions they donīt bear any resemblance to pretty Wiki diagrams, they are a bent and mangled mess after about 7-10kN (depends on the bolt).
The manufacturers usually give (well in Europe they have to) the movement/deformation under load for both directions and it is in millimetres for the sort of forces we have to anticipate.

FLAG
By Darren Mabe
From Flagstaff, AZ
Jul 31, 2013
wham bam hand jam. Wrapping up the final moves of Twist of Fate, Oak Creek Canyon. <br /> <br />photo: Blake McCord
Jim Titt wrote:
However we donīt work on the force intended for the bolt, in our application we are expecting it to hold about 4 to 5 times the load anticipated by the manufacturer. When you pull test bolts in either radial or axial directions they donīt bear any resemblance to pretty Wiki diagrams, they are a bent and mangled mess after about 7-10kN (depends on the bolt). The manufacturers usually give (well in Europe they have to) the movement/deformation under load for both directions and it is in millimetres for the sort of forces we have to anticipate.

oh geez. what part of simplified analogy did you not understand? When I said intended force, i meant whatever force was going to be put on them when you're falling on them, etc. How come I never hear about bolts being pulled out, mangled, and broken at the crags from people falling on them? did i miss something?

FLAG
By Jim Titt
From Germany
Aug 1, 2013
Darren Mabe wrote:
oh geez. what part of simplified analogy did you not understand? When I said intended force, i meant whatever force was going to be put on them when you're falling on them, etc. How come I never hear about bolts being pulled out, mangled, and broken at the crags from people falling on them? did i miss something?


Well I guess itīs a difference of what one means by intended;- the force the bolt designer meant it to be used at, the force the faller might impose or the force bolts are supposed to be able to hold in a rock climbing application. Iīve tested hundreds of bolts but only to the requirements for certification to EN/UIAA and exactly where the preload is overcome is never really an issue since it certainly is before either achieving the standard or anchor failure.
The friction between the hanger and the rock depends mainly on the preload (and rock coefficient) and the point at which the hanger shifts and the bolt itself becomes loaded is for most bolts in the 6 to 8kN level which is in the common falls region but not the worst case which is what most people consider.
All of the above relies on the load being applied perfectly radially which in many climbing areas is never the case since some people actually climb overhanging rock where the mechanism of bolt failure is completely different.

FLAG
By Darren Mabe
From Flagstaff, AZ
Aug 1, 2013
wham bam hand jam. Wrapping up the final moves of Twist of Fate, Oak Creek Canyon. <br /> <br />photo: Blake McCord
Jim Titt wrote:
Well I guess itīs a difference of what one means by intended;- the force the bolt designer meant it to be used at, the force the faller might impose or the force bolts are supposed to be able to hold in a rock climbing application. Iīve tested hundreds of bolts but only to the requirements for certification to EN/UIAA and exactly where the preload is overcome is never really an issue since it certainly is before either achieving the standard or anchor failure. The friction between the hanger and the rock depends mainly on the preload (and rock coefficient) and the point at which the hanger shifts and the bolt itself becomes loaded is for most bolts in the 6 to 8kN level which is in the common falls region but not the worst case which is what most people consider. All of the above relies on the load being applied perfectly radially which in many climbing areas is never the case since some people actually climb overhanging rock where the mechanism of bolt failure is completely different.

Good info!

FLAG
By Jim Titt
From Germany
Aug 1, 2013
Iīve just done a radial pull test on a 12mm Fischer bolt (similar to the Powers) installed and torqued to the manufacturers specs. With a hanger which fits over the sleeve (13mm hole) the hanger starts to shift at 3.4kN. The movement smooths the rock underneath by grinding off the crystals and the resistance drops to about 2kN. Fundamentally the preload of the bolt forcing the hanger onto the rock performs no strength related function when the bolt is used in the manner directed by the manufacturers as the plastic crush sleeve plays a considerable role on how much of the tightening torque is involved in forcing the hanger onto the rock.
In fact with this design of bolt you can tighten to the design torque with the hanger some distance from the rock and exactly how much pressure you achieve in normal practice is going to be luck of the draw depending on how deep you pre-set the bolt.

Changing to a hanger with a smaller hole so it doesnīt fit over the sleeve and pre-setting the bolt below the surface the hanger starts to slide at 6,9kN which is in general agreement with the clamping force applied and the coeff of friction between rock and steel.

With a wedge bolt the tightening torque is always functions to clamp the hanger to the rock surface and the frictional effect is around 8kN, after this bolt set and deformation take over and the hanger is loose.

FLAG
 
By Chris Vinson
Aug 13, 2013

FLAG
By snowdenroad
Sep 10, 2013
bolts
How about using 3/8 bolts on hangers with a 1/2" hole?

FLAG


Follow replies to this topic? Notify me at the top of web site.
1

Email me.
Page 1 of 2.  1  2   Next>   Last>>