Which type of bolt?

Jim Titt and team-tough carry a wide variety of bolts types.  It makes me wonder why I would choose a specific bolt over another.

Jim manufactures two varieties of glue in bolts, the twist bolt in 3 lengths and 2 rod diameters and the solid leg bolt in 2 diameters and 2 lengths.  He also produces a 'traditional' hanger.  That is 11 options.

Is there a reason to choose the solid leg bolt over the twist bolt?  It looks like the solid leg bolt does not need a hammer to install.  Is the desire to not take a hammer the major deciding factor?

In my mind the reason to choose a stud bolt and hanger over a glue in is that the stud bolt is ready for use as soon as it is installed, where as the glue in needs to cure.  Although the description of the twist bolts discuss the twist bolt's mechanical attachment to the rock.

There are the 3 lengths to choose from.  I assume that the length is dictated by the rock quality.  Something like 80mm for good granite, 100mm for limestone, 150mm for sandstone?

There are two different diameters of twist bolts too.  6 mm rod (1/2 inch hole) and 8 mm rod (5/8 inch hole).  The 8mm bolts are for the ultimate in durability.   The solid leg bolts also have two widths. Under what conditions do the 6mm bolts wear out?  I do not think anyone is recommending running rope through these bolts like the metolius rap hangers.    If the worry is environmental corrosion, maybe the choice should be a titanium bolt rather then the 8mm bolt.

Lots of relevant information is provided on the Bolt Products and Team-Tough websites. The recommended bolts for specific rock type, recommended length for glue ins, test data on a large number of bolt types, etc. is all there if you look around.

 I am sure there are plenty of other uses, but large diameter glue-ins are commonly used for highline anchors.

apoet wrote: Lots of relevant information is provided on the Bolt Products and Team-Tough websites. The recommended bolts for specific rock type, recommended length for glue ins, test data on a large number of bolt types, etc. is all there if you look around.

 I am sure there are plenty of other uses, but large diameter glue-ins are commonly used for highline anchors.

Reading some of that information made me wonder what was best and why so many products?  The cases did not seem to be well laid out.  Consider " In reasonable rock we achieve around 50kN at which point the bolt breaks. In fact in an independent test, a bolt was still holding 31,4kN when testing was stopped with only 42mm of embedment. "  Why would I ever consider a longer bolt?  80mm is overkill if I understand the statement.  Perhaps I would prefer a 50mm. :)

The range of 'products' is there by design. Partly to suit climbers choices but fundamentally based on engineering criteria so really the questions are not as to why there are several products but instead what rock conditions you need to equip.

Anything welded is not recommended in corrosive environments and overall the twist leg (non welded) design is genius. Seems simple but the number of twist degrees through the anchor axis belies the thinking behind it.

Twist leg anchors have an inference fit so can be installed at any angle and won't slump or worse, drop out while the adhesive is gelling.

Anchor spec' can be matched to rock compressive strengths and also use, just a matter of a simple calculation on the back of a fag packet.

An anchor is rated for strength, not use, however it is perhaps practical to use beefier anchors for lower offs / abseil stations than runners. Softer rock use thicker bar to reduce flexing.

climber pat wrote:

Reading some of that information made me wonder what was best and why so many products?  The cases did not seem to be well laid out.  Consider " In reasonable rock we achieve around 50kN at which point the bolt breaks. In fact in an independent test, a bolt was still holding 31,4kN when testing was stopped with only 42mm of embedment. "  Why would I ever consider a longer bolt?  80mm is overkill if I understand the statement.  Perhaps I would prefer a 50mm. :)

What you will find is that instead of "minimums" that are all that is strictly required when a bolt is placed perfectly that you become more comfortable knowing you have some leeway for error.

ie Mechanical bolts don't always tighten up the way you'd like getting unexpectedly close to their minimum embed depth at times.

Even solid seeming Granite can vary in some unforeseen way and be surprisingly weak with no explanation. Bigger bolts, both longer and thicker, are needed for softer rock too.

Glue mixing is highly variable and of unknown strength (you are highly dependent on the glue for placements in roofs). Unless you have done a lot of gluing you aren't gonna be happy with a minimum depth.

And the hole has to be well cleaned for glue to adhere but its always a bit of a mystery as to what is truly going on inside the hole. Probably just inexperience again talking here.

Spend enough time hanging on bolts and thinking about what is going on inside makes one nervous. I for one only get comfortable with bolts I've placed over time when they have been used/tested enough to really know they are fine. I've seen too many bolt QC issues or unexpected rock issues over the decades IRL to  be blindly comfortable with any bolt that hasn't been tested and people that bolt a lot can trend to thicker and longer bolts over time once some unexpected failures make them "gun shy".

Francis Haden wrote: The range of 'products' is there by design. Partly to suit climbers choices but fundamentally based on engineering criteria so really the questions are not as to why there are several products but instead what rock conditions you need to equip.

Anything welded is not recommended in corrosive environments and overall the twist leg (non welded) design is genius. Seems simple but the number of twist degrees through the anchor axis belies the thinking behind it.

Twist leg anchors have an inference fit so can be installed at any angle and won't slump or worse, drop out while the adhesive is gelling.

Anchor spec' can be matched to rock compressive strengths and also use, just a matter of a simple calculation on the back of a fag packet.

An anchor is rated for strength, not use, however it is perhaps practical to use beefier anchors for lower offs / abseil stations than runners. Softer rock use thicker bar to reduce flexing.

Interesting.

I don't see any argument for the rod bolt here at all since it is welded. (other than hammerless install).  In fact the possibility of slump during the glue setup time would be reason to quit using (selling) them.  The welded nature of the Jim's rod bolt hangers argues against their use in any corrosive environment.  

I would think the cured glue would eliminate any flexing inside the rock regardless of bolt diameter.  The glue should decouple the bolt flexing from the rock.  Certainly bolts flex as much or more holding a fall than during a rapel.  It seems to me that rapel flex should be minimal in all cases.

I realise the the interference is to hold the bolt in place while the glue sets.  Having pulled a wave bolt out that was not glued in with a funkness device,  I believe it would have easily held a fall.  Not that I recommend that in any way but the concept is similar to the old split shaft bolts.

Perhaps you could publish the back of a fag packet (assuming you are associated with team-tough) on your web site.  It would be nice to have the information before purchase. 

Harumpfster Boondoggle wrote:

What you will find is that instead of "minimums" that are all that is strictly required when a bolt is placed perfectly that you become more comfortable knowing you have some leeway for error.

ie Mechanical bolts don't always tighten up the way you'd like getting unexpectedly close to their minimum embed depth at times.

Even solid seeming Granite can vary in some unforeseen way and be surprisingly weak with no explanation. Bigger bolts, both longer and thicker, are needed for softer rock too.

Glue mixing is highly variable and of unknown strength (you are highly dependent on the glue for placements in roofs). Unless you have done a lot of gluing you aren't gonna be happy with a minimum depth.

And the hole has to be well cleaned for glue to adhere but its always a mystery as to what is truly going on inside the hole.

Spend enough time hanging on bolts and thinking about what is going on inside makes one nervous. I for one only get comfortable with bolts I've placed over time when they have been used/tested enough to really know. I've seen too many bolt QC issues or unexpected rock issues over the decades IRL to  be blindly comfortable with any bolt and people that bolt a lot can trend to thicker and longer bolts over time once some unexpected failures make them "gun shy".

I have done a fair amount of bolting including some glue ins.  Most of the glue ins I have place are wave bolts but also a few of Jim's 150 mm twist bolts.  Honestly I am trying to decide if I can go with the 80mm or 100mm bolts instead.  The rock I am working with is really very good and I would bet most people would be happy with the 80 mm.

climber pat wrote:

I have done a fair amount of bolting including some glue ins.  Most of the glue ins I have place are wave bolts but also a few of Jim's 150 mm twist bolts.  Honestly I am trying to decide if I can go with the 80mm or 100mm bolts instead.  The rock I am working with is really very good and I would bet most people would be happy with the 80 mm.

I am happy with the 80mm in granite. 

But to be honest, that there is a bit of an interference fit gives me reassurance too. Not enough experience with glue for me I guess.

climber pat wrote: Jim Titt and team-tough carry a wide variety of bolts types.  It makes me wonder why I would choose a specific bolt over another.

Jim manufactures two varieties of glue in bolts, the twist bolt in 3 lengths and 2 rod diameters and the solid leg bolt in 2 diameters and 2 lengths.  He also produces a 'traditional' hanger.  That is 11 options.

Is there a reason to choose the solid leg bolt over the twist bolt?  It looks like the solid leg bolt does not need a hammer to install.  Is the desire to not take a hammer the major deciding factor?

In my mind the reason to choose a stud bolt and hanger over a glue in is that the stud bolt is ready for use as soon as it is installed, where as the glue in needs to cure.  Although the description of the twist bolts discuss the twist bolt's mechanical attachment to the rock.

There are the 3 lengths to choose from.  I assume that the length is dictated by the rock quality.  Something like 80mm for good granite, 100mm for limestone, 150mm for sandstone?

There are two different diameters of twist bolts too.  6 mm rod (1/2 inch hole) and 8 mm rod (5/8 inch hole).  The 8mm bolts are for the ultimate in durability.   The solid leg bolts also have two widths. Under what conditions do the 6mm bolts wear out?  I do not think anyone is recommending running rope through these bolts like the metolius rap hangers.    If the worry is environmental corrosion, maybe the choice should be a titanium bolt rather then the 8mm bolt.

The basic reason for such a variety of bolts is no two climbers can agree on anything let alone what bolt is best! I have customers from all over the world and they all have their own idea of what works best, sometimes it´s a case of what they are used to, some bizarre engineering theory or whatever so as a manufacturer it´s easier to offer everything to cater for everybody. (There is someone who posts on here that thinks 6mm bolts are too thin for example, I could roll up with a tester and show him it would hold 44kN but it´s easier just to sell him what he wants).

Length:- I have to make them at least 70mm long (the standard says so) and the industry has decided 80mm is going to be standard, it covers just about any resin system ever used and quick-setting cement as well which is occasionally used. For really weak rock you want to go longer for sure but "really" weak is kinda flexible. The standard test block we use is for sure on the worse side of sandstone and with only 65mm glued in we still get over 30kN. With good rock (coarse granite) I´ve tested down to 25mm long and still got the required numbers but sure as shit I wouldn´t trust some stranger to install them! I actually make bolts any length, just give some indication of the standard lengths on my website, I sell a fair few 200mm long bolts and sometimes 300mm ones as well, if the customer is only installing one as an anchor and wants to be safe who am I to argue? 100mm bolts cover almost everything climbeable and that´s what sells best for sure and I wouldn´t argue against it for people who I don´t know or working with rock I´m not familiar with, on the other hand I´ve personally bolted over 700 routes and never installed anything but 6mm x 80mm bolts because I´ve glued bolts into almost everything and pull tested them. In good granite I wouldn´t blink at using something shorter.

Diameter:- Two reasons.
Some people are so used to seeing a particular style of bolt, say 10mm like a Fixe that they have trouble trusting anything thinner, 8mm rod they can cope with but 6mm is pushing their imagination even though they are equally strong (paper clips is often the description).
Rock cutting is the other problem, under high load especially repeated such as on a crux bolt and on sandstone a thinner bolt flexes more and starts to crack the rock below the bolt which looks bad, it´s actually not a problem regarding strength but you try explaining that to someone hanging on a draw staring at a crumbling crater below the bolt keeping them off the ground! In this case thicker is better and the single leg bolts are for sure the way to go. In limestone it´s normally irrelevant.
12mm single-leg bolts are suprisingly popular, I sell a fair few for sandstone areas where they are used to that sort of size from the the older bolts they used and also to highliners as under the loads they see normal bolts tend to bend too much.
Single-leg bolts you get a stronger bolt for the same hole diameter (so long as the resin holds up) so if drilling is difficult they are preferred. Twisted-leg bolts don´t work very well with glass capsule system, they can be used but single-leg ones are the way to go.

Welded or not? First off it´s more expensive.
Second while we take every care to make sure the weld isn´t a site for potential corrosion there is always a slight chance of this happening, the metal isn´t as smooth and also ha undergone some changes. I wouldn´t recommend installing one of my welded products in say coastal Thailand but anywhere else they should be fine.
Technically the usual design of welded bolts means the end of the weld will normally be the point at which the bolt fails, the metal there is at it´s weakest and usually the bolt tears across from the weld, since this only happens at test forces it´s of interest to us but not the customer in reality.

Jim Titt wrote:

...

I really appreciate the effort you put into that post. It clarified a lot for me very quickly. Thanks!

Thanks Jim for the detailed reply. Go Bolt Products and Team Tough!

https://team-tough.com/

climber pat wrote:

Interesting.

I don't see any argument for the rod bolt here at all since it is welded. (other than hammerless install).  In fact the possibility of slump during the glue setup time would be reason to quit using (selling) them.  The welded nature of the Jim's rod bolt hangers argues against their use in any corrosive environment.  

I would think the cured glue would eliminate any flexing inside the rock regardless of bolt diameter.  The glue should decouple the bolt flexing from the rock.  Certainly bolts flex as much or more holding a fall than during a rapel.  It seems to me that rapel flex should be minimal in all cases.

I realise the the interference is to hold the bolt in place while the glue sets.  Having pulled a wave bolt out that was not glued in with a funkness device,  I believe it would have easily held a fall.  Not that I recommend that in any way but the concept is similar to the old split shaft bolts.

Perhaps you could publish the back of a fag packet (assuming you are associated with team-tough) on your web site.  It would be nice to have the information before purchase. 

The calculation is based upon Uniform Bond Stress Model for this is: N = B(pi)(d)hef

Where:

N = tensile strength (N)
B = bond stress for the adhesive (N/mm²) Pi = 3.142
D = hole diameter (mm)
hef = anchor embedment depth (mm)

There are 11 models for determining glue-in anchor performance but the above is the one commonly banded about.

The theoretical strength of an expansion bolt is the tensile strength of the material (rock compressive strength) multiplied by the cross sectional area (CSA) in which CSA represents the bolt diameter.

I am not affiliated with Team Tough however Jim has the above info on his Bolt Products website.

Flexing glue-ins is a particular issue in soft rock (sandstone) and developers in places like Australia will not use something like 6mm bar based anchors for this reason. It's just to minimise rock crushing over time.

The problem with that model is it is only good for the resin/rock interface and doesn´t consider either the engagement of the resin in the bolt or rock strength. Normally resin/rock is going to be the last point of failure except with very weak rock (or a badly cleaned hole) and then the actual embedded depth at the time of failure isn´t then the length of the bolt so it´s very difficult to produce a model. The "classic" explanation for rock failure is a cone of rock starting at the deepest point breaking out but in reality the bolt stretches slightly and the area nearest the surface is loaded highest and a shallow cone breaks out first, then another deeper cone and so on until the actual amount of bolt still glued in is short enough that the resin pulls out of the hole.
Soft rocks, particularly sandstones and conglomerates are so variable there is no way of realistically modelling what the can hold and testing is the only way to know.
In hard rock like limestone and granite with a well-designed bolt (good engagement with the mortar) bolts are always stronger than one would think!

Thanks for all the information. I think I will go with the 6X80 mm twist bolt for the granite near me where I can use a power drill.

There is a large wilderness study area near me that prohibits all bolting that has a lot of work inch bolts from before the WSA designation.  There is legislation coming this year to change the are into a wilderness area which would allow hand drilled bolts.  Is there any chance of getting glue in bolts that work in a 3/8 inch hole.  The time and effort to hand drill 1/2
 holes is significantly more than a 3/8 inch hole.

Yes, Bolt Products makes 8mm solid leg bolts, and there's also the Fixe Hely. These bolts are both intended for 10mm holes, hopefully Jim will chime in with whether or not you need to use a 10mm bit to have enough epoxy for proper curing (10mm is slightly larger than 3/8") - although I'd bet that many hand drilled 3/8" holes may be just as large as a power drilled 10mm hole.

Here's the options compared to a 2.25" stainless 5-piece with Fixe hanger. Left to right, BP solid leg 8 x 80mm, Fixe Hely, BP solid leg 8 x 60mm, 3/8" x 2.25" Power-Bolt. The standard length for the 8mm solid legs is 80mm (or longer) - the 60mm solid leg is a sample length, I don't know if Jim would make those normally or just did the sample for us. We were looking for options for water streaks in Tuolumne where ice fall smashes regular hangers (and for a few where long periods of immersion in running water have made the stainless 5-piece start looking a bit odd as far as surface color).

The 8mm solid leg bolts are listed here: bolt-products.com/Protectio…

climber pat wrote: Thanks for all the information. I think I will go with the 6X80 mm twist bolt for the granite near me where I can use a power drill.

There is a large wilderness study area near me that prohibits all bolting that has a lot of work inch bolts from before the WSA designation.  There is legislation coming this year to change the are into a wilderness area which would allow hand drilled bolts.  Is there any chance of getting glue in bolts that work in a 3/8 inch hole.  The time and effort to hand drill 1/2
 holes is significantly more than a 3/8 inch hole.

Not a problem with our 8mm bolts, we actually tested them in 9mm holes and the short ones for Greg in a 3/8" hole as well, in fact that´s when I started messing about to see exactly how short they could be and still get the standard. As I´ve said, in Europe I have to make them 70mm long as a minimum and everybody including me makes them 80mm to cover ourselves, we see the standard of some peoples bolting and sometimes wish they were even longer! I´ve a couple of non-EU customers who bolt granite slabs where I also supply 60mm bolts like I did to Greg (and twisted ones) but sure as shit I want to know the guy installing them knows what he´s doing, I don´t need to see one of my bolts which has failed all over the internet just to save someone drilling a bit deeper!

When I got my twisted bolts independently tested the technician actually screwed it up and didn´t drill the hole deep enough so only 65mm was in the concete block, the lab offered to do it again but I didn´t bother, straight out pull it got over 30kN using polyester resin before it came out.

Jim Titt wrote:

 I also supply 60mm bolts like I did to Greg (and twisted ones) but sure as shit I want to know the guy installing them knows what he´s doing, I don´t need to see one of my bolts which has failed all over the internet just to save someone drilling a bit deeper!

Ha, try hand drilling a dozen in a day and get back to me. :D

Harumpfster Boondoggle wrote:

Ha, try hand drilling a dozen in a day and get back to me. :D

If yer weak place less!

Jim Titt wrote:

If yer weak place less!

:P

One of beauties of Jim's bolts is it is easy to shorten them for hard rock.