Cobra Anchors -- Reviews?

Kevin Daniels aka KD wrote:micah i remember you now, you called me and we spoke for quite a while. our conversation was quite extensive and included allot of information that goes beyond me just stating " the cobra product is more than strong enough " that was not the statement i made at all and lacks allot of information!! i had no idea you were an administrator at mountain project or what your intentions were that said i believe your goal is to protect climbers and thats great ! mine too has always been. so I will again review the 3/8 Cobra product with my engineers, cobra engineers, my attorney and my insurance company thanks for efforts, next time please be a little more forthcoming when question me or my business and if your going to post quotes i have made make sure you include all the pertinent information that was discussed.

Kevin,

I see you are now selling both cobra and powers PS 3/8 inch bolts. Did you decide the new powers bolts are ok? (EDIT) I see that it is now only powers PS 3/8 but both powers and cobra 1/2 bolts.

Pat

slim wrote:the only 'failures' that i have seen with the older powers bolts / rawl 5 pieces have been where the installer tightened them excessively and popped the heads off. i have seen maybe 5 of these or so. going down in diameter on something where the torsional shear is so finnicky seems like a really bad idea. bolts that use nuts (as opposed to a head) for tightening are less likely to do this, but the projection of the stud is pretty non-optimal for clipping, biner hang up, etc.] it seems like going up to 1/2" would be the way to go, but there are always trade offs.

They must have had some pretty massive wrenches or a 1/2" impact. I have removed about 100 3/8" SS Power Bolts to replace with titanium. They are typically so corroded that the only way to remove them is to crank on the head until the shaft fails. I have to use a 1/2" x 28" driver, and I practically need to stand on the end to generate enough torque to break the bolt. When the bolts do fail, they never fail at the head but always along the shaft somewhere. That's just my experience though.

slim wrote:the only 'failures' that i have seen with the older powers bolts / rawl 5 pieces have been where the installer tightened them excessively and popped the heads off. i have seen maybe 5 of these or so. going down in diameter on something where the torsional shear is so finnicky seems like a really bad idea. bolts that use nuts (as opposed to a head) for tightening are less likely to do this, but the projection of the stud is pretty non-optimal for clipping, biner hang up, etc.] it seems like going up to 1/2" would be the way to go, but there are always trade offs.

Never have I been able to snap the head of a Rawl bolt. Not even with an 18" breaker bar. Studs on the other hand I've been able to snap off.

dnoB ekiM wrote: Why would we need to call them? Why can't we believe their technical literature that shows that the ultimate breaking strength is way too low? Are they disagreeing with their own literature? Really??? I don't typically call Black Diamond or Petzl to ask them how strong their products REALLY are...I rely upon their printed literature. Why is Cobra different?

Add to that, I bet that if you called Cobra to speak to an engineer, and asked them if it is okay to use their 3/8" bolts for rock climbing and human life support, they would respond with a resounding NO. Even Power's official stance is that the Power Bolt is not designed, recommended or approved for rock climbing use.

slim wrote:
the only 'failures' that i have seen with the older powers bolts / rawl 5 pieces have been where the installer tightened them excessively and popped the heads off. i have seen maybe 5 of these or so. going down in diameter on something where the torsional shear is so finnicky seems like a really bad idea. bolts that use nuts (as opposed to a head) for tightening are less likely to do this, but the projection of the stud is pretty non-optimal for clipping, biner hang up, etc.] it seems like going up to 1/2" would be the way to go, but there are always trade offs.

20kN wrote: They must have had some pretty massive wrenches or a 1/2" impact. I have removed about 100 3/8" SS Power Bolts to replace with titanium. They are typically so corroded that the only way to remove them is to crank on the head until the shaft fails. I have to use a 1/2" x 28" driver, and I practically need to stand on the end to generate enough torque to break the bolt. When the bolts do fail, they never fail at the head but always along the shaft somewhere. That's just my experience though.

rocknice2 wrote: Never have I been able to snap the head of a Rawl bolt. Not even with an 18" breaker bar. Studs on the other hand I've been able to snap off.

Slim is writing about the tightening of new sleeve bolts, during installation, and 20kN is writing about removing corroded bolts. I hope that rocknice2 is also writing about removing corroded bolts —or maybe the Rawls were just stronger.

I guess that the sleeve bolts that slim mentions would have been severely weakened by over-torquing, well before the heads were snapped off.

I also guess that the difficulty of breaking the shaft of a corroded sleeve bolt is due to corrosion resisting the transfer of torque from the bolt's threaded shaft to the cone at the tip. Perhaps corrosion glues the shaft to the cone, so that turning the hex head counter-clockwise, to push the cone forward and release tension on the sleeve is difficult. Turning the hex head clockwise, to pull the cone back and create more tension on the sleeve (and thus break the shaft) is likewise difficult. Corrosion may also glue the sleeve to the rock and resist turning of the bolt. The difficulty of removing or breaking a corroded bolt, even by using a long wrench, belies the bolt's impaired ability to hold a fall.

Given all the things mentioned about what can happen to bolts during installation, as well as for prolonging service life, half-inch-thick stainless steel is the way to go. Use long ones in limestone and sandstone. If properly installed, Ti glue-ins are even better.

Yes when removing the sleeve type bolts, Powers/Rawl 5 piece, the corrosion between the bolt and sleeve act like glue. Thre is usually less rust at the thread cone area. At least that's been my experience here on the northeast.

If we are not breaking the head when removing the bolt its never going to break upon installation. The weakest point is the root of the thread, whether it's a bolt or a stud. When installing a bolt, over torquing will stripe or snap the thread at the cone, deep inside the hole. In the case of stud at the nut.

So when the bolt is corroded around the sleeve, it inhibits the torque from reaching the cone. This has a better chance of snapping at the head than installing does.

The only way I can see how one might snap a hex head is if the bolt hole was drilled crooked and then the installer tried to tighten it straight. Maybe.

Anyway bolts are way way better than studs.

M Sprague wrote: Is this just the non-SS versions that are being discontinued? Kevin's note seems to be indicating that. If so, what is the problem? People shouldn't be using non- stainless anyway. I would be glad to see him stop selling the plated stuff. I use Powers SS 1/2 x 2 3/4, 5 Piece Bolt #R5930 for good granite (occasionally Fixe SS 3/8" Wedge Bolts for slabs) and Fixe or Wave SS glue-ins for more porous rock like schist.

If you already use classic wedge anchor, the length can be a very serious factor to influence the strength of the anchor.  Using anchors of 2'' may be very dangerous if the first layer of the stone is weak.

Have you ever tried to use rather concrete screw like the Powers Wedge Bolt Type SS316 ?  or the Hilti HUS3-S ?  Following our experience with the Powers one (we use his European version), we have had excellent results. And for removing, there is noting easyer than a concrete screw...   Anyway, it won't work obviously in porous stone but who would like to use mechanical anchors in porous stones???  Another advantage of the concrete screw is his behavior under shock loads.  Not only it has a good dynamic behavior recognized by the different international approvals but it has a plastic behavior of partial failure that isn't described in the classic norms but that exists and give you another layer of security.  (During a shock failure, the tensile forces applied on the concrete screw that tries to screw off increase terribly the friction and as a result, the concrete screw hasn't got an instant failure like wedge anchors or the Powerbolts or similar anchors but a partial failure followed by a plastic behavior if it's not a pure tensile forces.  And usually, at the time, the shock is gone, the concrete screw is still in the wall, while bigger wedge anchors or similar would have failed.  This we know from a large number of explosion tests made with various systems connected with those concrete screw.

Yves De Lathouwer wrote:

If you already use classic wedge anchor, the length can be a very serious factor to influence the strength of the anchor.  Using anchors of 2'' may be very dangerous if the first layer of the stone is weak.

Have you ever tried to use rather concrete screw like the Powers Wedge Bolt Type SS316 ?  or the Hilti HUS3-S ?  Following our experience with the Powers one (we use his European version), we have had excellent results. And for removing, there is noting easyer than a concrete screw...   Anyway, it won't work obviously in porous stone but who would like to use mechanical anchors in porous stones???  Another advantage of the concrete screw is his behavior under shock loads.  Not only it has a good dynamic behavior recognized by the different international approvals but it has a plastic behavior of partial failure that isn't described in the classic norms but that exists and give you another layer of security.  (During a shock failure, the tensile forces applied on the concrete screw that tries to screw off increase terribly the friction and as a result, the concrete screw hasn't got an instant failure like wedge anchors or the Powerbolts or similar anchors but a partial failure followed by a plastic behavior if it's not a pure tensile forces.  And usually, at the time, the shock is gone, the concrete screw is still in the wall, while bigger wedge anchors or similar would have failed.  This we know from a large number of explosion tests made with various systems connected with those concrete screw.

Screw -in concrete anchors have proved to be poor (or unusable) in rock, in particular the stainless steel versions as the threads are softer than most rock (limestone and granites) and rip of or gall badly and no longer grip. The physical difficulty of actually installing them by hand is another major drawback and climbers have tried drilling the holes oversize to overcome this with the invitable results that they hold even less. No one has ever got consistently reliable results in testing to the standard in rock and for this reason their use is strongly discouraged, conventional wedge bolts are far superior. In sandstone (the only rock they can be reasonably installed in) they work loose.

Yves De Lathouwer wrote:

If you already use classic wedge anchor, the length can be a very serious factor to influence the strength of the anchor.  Using anchors of 2'' may be very dangerous if the first layer of the stone is weak.

Have you ever tried to use rather concrete screw like the Powers Wedge Bolt Type SS316 ?  or the Hilti HUS3-S ?  Following our experience with the Powers one (we use his European version), we have had excellent results. And for removing, there is noting easyer than a concrete screw...   Anyway, it won't work obviously in porous stone but who would like to use mechanical anchors in porous stones???  Another advantage of the concrete screw is his behavior under shock loads.  Not only it has a good dynamic behavior recognized by the different international approvals but it has a plastic behavior of partial failure that isn't described in the classic norms but that exists and give you another layer of security.  (During a shock failure, the tensile forces applied on the concrete screw that tries to screw off increase terribly the friction and as a result, the concrete screw hasn't got an instant failure like wedge anchors or the Powerbolts or similar anchors but a partial failure followed by a plastic behavior if it's not a pure tensile forces.  And usually, at the time, the shock is gone, the concrete screw is still in the wall, while bigger wedge anchors or similar would have failed.  This we know from a large number of explosion tests made with various systems connected with those concrete screw.

We've been using the Simpson Titen 316 (and the zinc-plated version) screw in granite for the past two years. The main reasons for using them were their ease of replacement, lack of loosening, and relatively low cost, though it is also nice that those screws can be placed very close together for a top anchor station.  

https://www.strongtie.com/products/go/anchors/titenhdss

But as Jim says, they can be hard to screw in. We've found some ways to make this easier though. I haven't tested them, but perhaps Mark H- will pipe in here with his test results. From what I saw of the results, they held higher forces in granite than some of the standard anchor bolts. 

Jon Nelson wrote: We've been using the Simpson Titen 316 (and the zinc-plated version) screw in granite for the past two years. The main reasons for using them were their ease of replacement, lack of loosening, and relatively low cost, though it is also nice that those screws can be placed very close together for a top anchor station.  

https://www.strongtie.com/products/go/anchors/titenhdss

But as Jim says, they can be hard to screw in. We've found some ways to make this easier though. I haven't tested them, but perhaps Mark H- will pipe in here with his test results. From what I saw of the results, they held higher forces in granite than some of the standard anchor bolts. 

Sketchy.

Hello all

As Jon N mentioned, I have undertaken a focused study of screw anchorage in natural stone substrates. In industry, I have had the opportunity to place several hundred in concrete. Jim is correct that use in stone can be a different and somewhat problematic issue. I totally agree that the Powers and ITW products do not work well in hard stone.

The Simpson Titen HD has a much improved thread which is sharper and harder with an excellent lead in thread cutting tip. I have placed many 2” models in good granite by hand with success. In 2017 or so they introduced a 316 stainless model. Concurrently, advances in lightweight impact drivers have allowed easy install.

I own and maintain calibrated testing equipment, and have begun comparative tests in various rock types. Recently, I tensile tested the 3/8” x 2 .5” Titen ss in Darrington granite to 12,400 lbf without failure of stone or bolt (test rig broke). The granite in question has an approximate unconstrained compressive strength of 3800-4200 psi.

This installation took about 12 seconds with the impact wrench, with added benefit of not needing a hammer. The key to installation in hard rock is to fill the bore hole with water that acts as a lubricant and cutting fluid.

These values approach or exceed glue ins, particularly when you consider the small diameter, depth, and relative low cost. These bolts are available throughout the USA by Simpson distributors. I ordered the last batch through HomeDepot by special order at 3.44 each.

As they are easy to pull and inspect for thread damage, and they do not loosen under use (based on observations over several years), I would encourage further research and testing by interested parties. I personally plan on testing in sandstone, gneiss, limestone, basalt, and other native pnw stones.

M. Hanna

A Fixe video showing what appears to be a Hilti HUS screw in


https://m.youtube.com/watch?v=tBRY1h3z1Mg

They don't loosen under use yet the video you post shows the guy unscrewing it by hand. No thanks. 

Is Fixe marketing those as a removable bolt concept similar to Petzl and ClimbTech?

Also, Fixe's installation videos are totally bunk. They barely clean any of their holes, plus the glue in they place in a different video looks like a gooey mess. I like to keep that glue tight!

Taylor and Rockso
 
 I provided the link to simply illustrate that others were thinking about the screw in technology. I'm not endorsing the video or certifying the installer's competency. The Fixe video(s) are generally ridiculous... Bunk is a gross understatement :)
 
Based on my observations over about 7 years, the Titens do not loosen even in freeze thaw conditions we have in the PNW.  As the video installer likely didn't snug the bolt onto the hanger (it is an ad for a removable hanger after all…), no surprise in easy removal.  It's also good to note that many other mechanical anchors that are in common use have threaded fittings that have the potential to loosen (Triplex, Wedgies, etc.)

Much like the common ice screw, the cut thread maximizes engagement area and distributes the load completely through the bore hole. This results in glue in like performance in a small package.
 
I think the screw in Titen HDSS represents an interesting innovation in that it strikes a balance between ease of inspection and installation, strength, cost, availability, and corrosion resistance.

As a professional industrial roof anchor consultant and route developer going on 25 years, this topic is very meaningful to me, and I have spent quite a bit of time and my own resources in researching the evolution of what we do at work and on the cliffs for “permanent” anchorages. Previously, they were only available in zinc plated, which was a deal breaker other than temporary installations (ground up).

In this case, my preliminary opinion is that Simpson got this one right. Rather than crusading for immediate adoption in all cases, I would like to see where this goes, and do a lot more testing in various stones.

On the industrial front, you might be interested to know that Titens have generally eclipsed many adhesive anchors for all of the above stated reasons (west coast).

I encourage you to seek out a distributor and install a handful in sample stone of your locality to get some firsthand experience. Would love to hear your results. If anyone is in the Seattle area and has a chunk of stone they would like to see tested, I'm happy to do it.

Cheers,
M.Hanna

An added distinction here is that it is one thing to be concerned about a nut unscrewing on a bolt, allowing complete failure upon loosening 1/4", another thing entirely to be concerned about an entire 3" screw coming unscrewed.

If Fixe had used a standard hanger in the video, the entire screw would have to be unscrewed for the hanger to come off. As it was, they had to first loosen it with a wrench.  DrRockso has apparently confused loosening with unscrewing. At any rate, there is no way I could unscrew one of the Titens with my fingers even after loosening with a wrench.

Yves De Lathouwer wrote:

If you already use classic wedge anchor, the length can be a very serious factor to influence the strength of the anchor.  Using anchors of 2'' may be very dangerous if the first layer of the stone is weak.

Have you ever tried to use rather concrete screw like the Powers Wedge Bolt Type SS316 ?  or the Hilti HUS3-S ?  Following our experience with the Powers one (we use his European version), we have had excellent results. And for removing, there is noting easyer than a concrete screw...   Anyway, it won't work obviously in porous stone but who would like to use mechanical anchors in porous stones???  Another advantage of the concrete screw is his behavior under shock loads.  Not only it has a good dynamic behavior recognized by the different international approvals but it has a plastic behavior of partial failure that isn't described in the classic norms but that exists and give you another layer of security.  (During a shock failure, the tensile forces applied on the concrete screw that tries to screw off increase terribly the friction and as a result, the concrete screw hasn't got an instant failure like wedge anchors or the Powerbolts or similar anchors but a partial failure followed by a plastic behavior if it's not a pure tensile forces.  And usually, at the time, the shock is gone, the concrete screw is still in the wall, while bigger wedge anchors or similar would have failed.  This we know from a large number of explosion tests made with various systems connected with those concrete screw.

I have since moved to pretty much exclusively using Jim's 8mm glue-in Twist bolts, even in granite. I have no experience with those screws. I am no longer a fan of plate type hangers, so I probably wouldn't use the screws if that is what they require.

Don’t get me wrong I really like glue ins from a performance perspective but around here we do a lot of hand drilling and a 5/8 or 1/2x 4” hole in granite is a problem. Particularly ground up style which is my preference.  A 316 stainless 3/8” x 2.5”with similar performance (and way superior to many other types) is a valid idea. My main point is that bolt choice is a very specific process to the substrate ,local style and ethics. As long as strength and corrosion resistance are the predominant criteria, there may be several acceptable designs.

I think we climbers would benefit to be well informed of anchoring evolution and innovation even if they are run to ground as not suited to the climbing arena. Whether we like to admit it or not these changes come from the construction industry where design criteria and code compliance form the basis for acceptance.

M. Hanna

Something to bear in mind with fixings intended for industrial use is that once a sharp (and relatively thin) bolt hanger is attached and the assembly loaded, the performance may be so low that it cannot meet sufficient strength margins for climbing applications. The hanger causes bending underneath the nut with subsequent shearing through the shaft, unlike industrial flanges that are designed thick enough not cause this and can maintain the loading in the designed direction. Strengths specified on the 'box' may have certain design assumptions that do not apply to use as rock climbing anchors.

Point being that anything borrowed from construction purposes ought to be tested under climbing certification conditions.