Bolting Bible - Book of Numbers

The Book of Numbers

“Know how hard thou needest to tug it before you get release.”

EPISODE: 50 climbing bolts breaking in sandstone

The Bolting Bible

This is free resource by HowNOT2 and our way of contributing to the community. It's nice to understand what you are clipping and trusting with your life, even if you never plan on installing or removing bolts. We also believe that if you are going to spend time and money to bolt something, you should do it well.

This book is in a blog format. This page points to all 17 chapters, and the end of each chapter points to the next.

A downloadable PDF is available HERE.

What is Bolt Busters

BoltBuster is a project that Bobby Hutton and I built to test climbing bolts in every scenario imaginable. We learned how hydraulic systems worked and how we could use them to generate well above 100kn to be able to test to destruction any bolt we wanted to. We have one machine that looks like a bar stool for testing in tension. It has a hollow ram hydraulic cylinder on top to lift our long threaded rod to pull the bolt out of rock. To test in shear, we have a 4” hydraulic cylinder (like you would see on a tractor) that we anchor to the ground on one side and attach to our bolt victim with the other.

The Mission

1) We try to be as sciency as we can afford with 3 samples of anything we test and typically we test both shear and in tension.
2) All results are published for free in The Bolting Bible - a culmination of everything I could find about bolts online + our research
3) We share the results organized in this "Book of Numbers blog and in easy to digest videos.
4) We don’t make any products so have no incentive to bias the results.

We are funded by YOU, our viewers, not by companies trying to sell you a product. We DON’T test in a lab with small blocks of cement simulating real world situations - we just go outside and pull bolts in an as realistic scenario as possible. See behind the scenes in this EPISODE.

Why test gear that is already tested, rated and certified???? We are not trying to test to the standards. We are trying to see what happens in real world use. We feel standards organizations issue test parameters that are very narrow and designed to eliminate as many variables as possible. Which is awesome for comparing multiple manufacturers to a standard. What we have an issue with is that the end user doesn’t know that standard or the test parameters because 1) it was written in Engineer and 2) it is behind a paywall. When an end user steps out of those sometimes unrealistic guidelines, the strength can vary widely. We strive to test realistic scenarios that we as climbers and highliners find ourselves in. We also feel that independent testing is very important to keep some manufacturers honest. All that to say we are just super curious and like breaking things and finding the answers to questions like:
  • What happens if you over torque the bolt? Or don’t tighten it enough?
  • Is it bad to oversize the hole when using glue ins? Is too much glue bad?
  • What happens if you install a P shape glue in bolt backwards?
  • What happens if you pull a glue in sideways?
  • Is a ½” hanger bad on a ⅜” bolt
  • Do you install the hanger below or above the flange on the Fixe Triplex bolts?
  • Are concrete screws reliable?
  • Are the shitty ⅜” PB+ bolts rated to what they claim?
  • Are the welds weak on xyz bolts?
  • Are off brand hangers on amazon safe?
  • How strong are wave bolts WITHOUT glue?
  • What happens if you don’t clean a hole before gluing?
  • Break tests in granite vs sandstone with the same bolts?
  • What is the actual strength of AC100 vs epoxy?
  • Is expired glue safe?
  • Many bolts have 1 MBS number, what about pulling in tension?
  • Do chains drastically reduce a bolt’s strength (since it pulls higher up on the bolt)?

It's Already Been Tested

You would be surprised what we DON’T know about bolting as a community. We hope the community as a whole is better informed after all our BoltBuster tests. We think you can learn more in 5 minutes watching our compilation EPISODE (the main video at the top of this blog) about how much you hate psytrance music... or HOW bolts break than most experienced bolters. This is 50 break tests in sandstone in super slow motion at 960FPS and you will see the bolt doesn't always come out. Sometimes the hanger breaks, the rock fails or the bolt snaps.

Why Concrete?

We have done a lot of tests in concrete because it was convenient. As you can imagine, setting up our break test machines, installing the bolts, pulling them in a way that doesn’t break our gear or our bodies and filming 3 angles on every test and recording it all on the spread sheet, takes a long long time. And most of the time the bolt or hanger fails not the rock, So we tested in concrete and if we had a failure influenced by the concrete we add it to the list of things to break when we test in real rock. When we do test in real rock, we make sure it is in the middle of nowhere and of no use to anyone, and when finished, we remove everything we can and camouflage the remaining metal.

While we try not to damage any areas, we balance that against the value these tests have to those who are going to put in bolts. We hope that because of these test there will be less bolts that will last much longer. Highliners for example were using 4 to 6 bolts for each anchor, but our research has clearly shown that we can use 2 or 3 now.

Our goal is to break 1000 bolts and not any more of our break test equipment! All of our tests we have done so far are organized below and associated with the video if available. We have been able to answer some common questions and address some persistent myths as well as make the Bolting Bible way more complete than version 1, before Bolt Busters. A huge thank you to all who have donated so far towards this form of edutainment. Not only has it helped pay the bills but it makes us so STOKED to know that other people care about our project to donate money. 100% of your donations go back into the channel and break tests.

Bolt Busters

Here is all of our results of our tests with the associated episode available next to the data.

Tables of Contents


Main Episode with most tests

Correcting our hangframe results

Episode coming soon. Can't believe I haven't made one about these yet! We love them.

This is about 1/2" Dewalt Powerstuds. Will make a video about 3/8" soon.

Episode with all 30 tests

Episode coming soon!

Twist Bolt Episode

We broke 2x 1/2" bolts in limestone. MBS is 11kN.
In Tension - 14.12kN
In Shear - 13.48kN
Uncertified Titanium U Bolts in limestone
Shear 55.90 and 32.93 - rock failed each time - liquid rock 500 glue
Tension 54.10 and 51.53 - bolt broke then rock failed - Ac100 Equivalent glue

Fixe Titanium U Bolt in limestone
Shear 41.59 - Bolt Broke - liquid rock 500 glue
Tension 34.25 - Bolt Broke - Ac100 Equivalent glue
Galvanized eye bolts are lasting longer near the ocean than 304 Stainless. The chemistry gets nerdy which we cover in the Book of Metal but here our results after testing in crappy limestone with liquid roc 500 glue cured overnight while cold out for our shear tests and Sorbat Vinylester for in tension.
Cosiroc 304SS 10mm x 115mm - 36.53kN and 33.32kn (both pulled out)
Cosiroc Galvanized 10mm x 115mm - 53.32kN (eye broke) and 13.69kN (rock failed)
Cosiroc Galvanized 12mm x 140mm - 35.15kN and 54.81kN (both pulled out)
LONG 1/2" x 8" galvanized - pulled out at 57.58kN and then NO glue pulled out at 11.26kN
Galvanized 3/8" x 6" 36.87kN (pulled out)
Cosiroc 304SS 12mm x 140mm - 36.51kN (pulled out)
Cosiroc Galvanized 12mm x 140mm - 51.36kN and 46.14kN (pulled out)

Eye Bolts Tested Episode

TIG welded glue in P shape bolts with the weld on the back side pulled out before the welds broke in all of our tests. Rated for 25kn MBS. We used liquid roc 500 glue, cured overnight while it was cold out. The limestone rock in the mine we tested this in was fractured and failing in all of our shear tests.
Tension 41.53kN, 32.22kN, 54.23kN
Shear 52.26kN, 44.69kN, 50.14kN

Juniper Bolt Break Test Episode

Tension 42.14kN, 42.10kN, 47.70kN (43.98kN avg)
Shear 45.88kN, 51.32kN, 44.88kN (47.36kN avg)

Can you drill a hole next to another hole for glue ins?

What's Next?

Chapter #14 - Bolting for Climbing