The Book of NUMBERS

"Know how hard thou needest to tug it before you get release"


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 destruction test any bolt test 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 that lifts our long threaded rod that we attach to our dynamometer. 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 pull test with the other.

The Bolt Buster project is unique because of the following:

1) we try to be as sciency as we can afford with 3 samples of anything we test, AND

2) publish WITH EDITED VIDEOS all of our results,

3) we don’t manufacture any bolts and therefore are independent AF.

We have NO sponsors, and 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 bolts that are certified and rated and have been tested already in labs??? You would be surprised what we find. We also are not trying to verify lab results but instead try to test all sorts of situations we would find ourselves using these bolts. Standards and labs are trying to eliminate variables so we can get the holy grail of the MBS (minimum breaking strength) and have that number relevant to other bolts or climbing gear. That has value in the manufacturing world but doesn’t always properly inform the end user. As soon as we step outside of “normal use”, which many times can be quite common, we can get very different results, and that is what we test. We have been curious ourselves about different variables but others have asked us numerous questions that we try to explore:

  • 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)?

You would be surprised what we DON’T know about bolting as a community. We hope there is more light on our bolt knowledge after all our BoltBuster tests. You can learn more in 5 minutes watching our compilation EPISODE 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.

We do a lot of tests in concrete because it is much more convenient to set up this overly complex break test machine, install hundreds of bolts, pull them in a way that doesn’t break our gear or our bodies and film every test with 3 cameras while recording over 10 points of data for each one. As long as heads snap off, hangers bust, or welds break… our concrete substrate is not affecting our results. We also have traveled with our machines to the middle of nowhere to test granite and sandstone. When we do test these areas, we angle grind what doesn’t fully come out and cover with glue and dust our holes so you can’t really tell we were ever there.

We try not to damage any areas, but these tests also help educate those who are going to put in bolts that will stay to do a quality job or to bolt less if possible. Highliners for example were using 4 to 6 bolts for anchors, but this 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! As of writing this in March 2020 we are at 302 samples. Sometimes we get a break on retail price but no one sponsors these tests, we don’t get free gear and youtube videos for niche subjects don’t make money. (50k views in a week on my most popular video made $37, most videos are under 5k views). So I’m hoping this $10,000 project is loved by all and supported by some to help curb the cost. Please Donate something on paypal if it has really helped you out or support our Juno Coffee business we started as a side hustle to stay away from making gear. We like to be independent AF. And of course, like any good Youtuber, we have T-Shirts for sale! Thanks!

If you are a data nerd and love spreadsheets then by all means, spend your friday nights staring into our raw SPREADSHEET that we fill out when we do our tests. But our focus is making short, info packed, entertaining videos so everyone can get the jist of what bolts break at and how. In this “Book of Numbers” we include a written version of the published episodes and the corresponding bite size chart. We will update this when we publish our Bolt Buster episodes.

Watch all of our bolt videos on this PLAYLIST

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Crux Monster Bolts

About the bolt: From, these bolts are the largest rod available (12mm) which minimizes flexing for crack prone rock and gives the best bend radius for highline anchor rope if it is directly threaded through preserving more rope strength. They have an MBS of 60kn. It’s not ideal to thread ropes inside these bolts for climbing anchors because replacing these bolts can be difficult, it is better to have a large quicklink attached that can be changed out after enough rappel abrasion.

Our Results: We used Hilti Hit 500 v3 epoxy glue that was either 6 months OR 2 years and 3 months expired and basically the welds break with very few bolts coming out. Test 265 came out that was cyclic loaded very high 4 previous times as we failed to break but it was also only installed 16 hours prior in very cold temps. Test 46 was the only one in Ac100 glue but the weld broke before coming out of the hole. Except for Test 265, all the tests broke the welds, even in wet sandstone where did not have any rock failure. Epoxy and stainless steel don’t like each other very much so the bond relies on the groves but even then it still comes out eventually. We don’t quite get 60kn in most shear tests but these are great bolts, the website should maybe just be changed to reflect a more conservative number. We got some really weird low numbers when we tested in tension in concrete. Our conclusion is these welds are very inconsistent but generally high enough that I will continue to use them.


Titan Eterna

About the bolt: Certified titanium glue in bolt installed in a 14mm hole and has an interference near the top so it won’t slide out of the hole while the glue is curing. MBS is 35kn and each bolt is proof loaded to 12kn.

Our Results: We did not install these with notches but it is the recommended method. None of the bolts came out of the granite but the eye broke and it did above the MBS every time even when pulling in tension. It sparked every time it broke. They would start to bend at 8kn but they were not notched. We think we would get 10kn to 12kn before bending if it was notched.


3/8" Split Shaft

About the bolt: These are used in construction and no longer in climbing. They generally only come in zinc plated and most of these placed 10 and 20 years ago are being pulled out and replaced. ¼” button heads were pretty common and are way too tiny for today’s standards. This split shaft is threaded on the top but we had to smash it in so tightly that it mushroomed the top of the bolt making replacing the hanger in the future impossible.

Our Results: I was not shocked the head snapped in shear but was shocked that it also snapped off in tension before pulling it out. They are pretty strong but only when new as corrosion would reduce the strength over time.


Fixe Hely Glue In

About the bolt: Fixe Hardware’s newest glue in bolt is forged, made from PLX/HCR duplex stainless and fits in a 38” or 10mm hole. These do not require a notch and the shape of the shaft helps the glue grab the bolt. The eye is rounded so ropes could be ran through the eye of this glue in.

Our Results: In tension and in shear, it consistently broke right below the surface of the concrete right around MBS. Our results were fairly consistent because there is no weld to add a variable. The website shows 28kn MBS is for 3 directions but tensions didn’t give us a full 28kn every time. The episode above only shows our shear tests but our newest episodes show both shear and tension in the same episode now.

Horizontal Hangers

About the hanger: Fixe Hardware’s sells a hanger designed for climbing lower offs. You add one quicklink to these and the rope will run parallel to the rock rather than getting smashed against it. They do sell these with welded rings inside. If two of these are spaced too far apart on an anchor it causes a rope to get gnarly twists in it. We tested PS accidently and not their 304SS hanger which is rated for 26kn. Please only use stainless steel!

Our Results: We installed these with Simpson Titen HD concrete screws like we did for all our hangers. They are ⅜” and fit in a ⅜” hanger and a ⅜” hole and easily removable so perfect for testing hangers. There is no point in testing this in tension, but our shear tests were all consistently about 2kn above MBS.


Dewalt Power-studs

About the bolt: Dewalt makes a quality stainless steel wedge bolt that comes with a stainless washer and nut.

Our Results: It was very difficult to break these because if the hanger wasn’t failing, our concrete was, or our original hydraulic wasn’t strong enough. Test 79 we were able to break it at 60kn and that was lucky with a 30kn hanger! We love Fixe hangers. This bolt is awesome for hard rock, but didn’t do so well in our sandstone tests which will be in a separate episode. They are about $3 a piece on Amazon.


3/8" Red Head

About the bolt: Red Head is a cheap brand and their plated steel bolts are tempting to use because they are so cheap. A similar bolt was installed in the Blue Mountains in soft rock and killed someone. Short wedge bolts in general should not be installed in soft rock. This VIDEO shows how easy they removed them.

Our Results: Brand new, these did break near 20kn but cyclic loading and time would wear these out. Please use quality brands like Dewalt or from our climbing bolt manufacturers and only use this style in hard rock. The hanger we attached regularly gets 40kn so let's use a bolt that utilizes that value.


Fusion Hangers

About the hanger: These are found on Amazon for $5 a piece. They are a brand I have never heard of before but look legit and is 304SS.

Our Results: Tested with the TitenHD concrete screws which were bomber for our hanger tests. We did not test these in tension because we didn’t feel it was worth it. MBS is 30kn but one of our tests was slightly below that. They seem fine if people want to use them but I would rather buy a PLX from Fixe for $3.35 which are twice as strong in our tests and more corrosion resistant.


Fixe Glue Ins with Hilti Glue

About the bolt: Fixe Hardware has sold these bolts for years. They are a great glue in with a nice bend radius and welded really well. These do require a notch and that does help keep the weld covered from exposure. I believe they are making these bolts all PLX from now on. They cost about $9 each.

Our Results: We installed these 10mm bolts in a ½” hole into our concrete slab with the weld facing away from the force. Epoxy does not stick to stainless at all, so the bolt has notches, but it still fully pulled out of the glue, albeit at very high force. Only some of our tension tests broke the weld. The epoxy was 4 months expired but gave good results. We cannot recommend expired glue since that is really hard to determine how long is super safe enough. Don’t risk people’s lives to save $20.


Fixe Glue Ins with Liquid Rock 500

About the glue: Liquid rock 500 is an affordable epoxy with decent working times. We accidently found out that it will not come out of the tube when it is cold out. Hilit glue has been popular so we tested the same Fixe Glue in bolts as the test above, but with them in Liquid Rock 500 to see if it held about the same.

Our Results: The weld broke each time and the bolt did not come out of the glue. There is no point in testing in shear if the weld is going to just break. We also did other bolts in tension and shear and the bolts would break before coming out. This glue is fantastic if you are not wearing a puffy jacket! Dries way quicker than Set XP which is what I use to use. I like how it uses a normal caulk gun.


Wave Bolts with Dirty Holes

About the bolt: Wave bolts are very popular 6mm continuous stainless rods bent with a wave shape on the shaft. They fit in 1/2” holes but require a lot of smashing with a hammer to get them in. They even have a tendency to bend while you hit them. The small bend radius reduces the strength of ropes threaded through them but is better for carabiners clipped to them than sharp hangers. Rarely are they installed with the intention of ropes being threaded inside of them.

Our Results: We tested the wave bolt with ac100 glue which is a very common glue used with these, BUT we did NOT clean the hole to see if the glue would come out in a cylinder like we have seen in some photos we shared in the Book of Holes section. Nothing seemed compromised and we got the same results as clean holes except the 22kn result was because I had an air bubble when installing that bolt. That shows how important it is that the entire hole is filled with properly mixed glue. Holes SHOULD be cleaned but this was interesting it did not affect this test. With results like this it wasn’t worth testing dirty holes in this context in shear.


Wave Bolts with AC100 Glue

About the bolt: Wave bolts are very popular 6mm continuous stainless rods bent with a wave shape on the shaft. They fit in 1/2” holes but require a lot of smashing with a hammer to get them in. They even have a tendency to bend while you hit them. The small bend radius reduces the strength of ropes threaded through them but is better for carabiners clipped to them than sharp hangers. Rarely are they installed with the intention of ropes being threaded inside of them.

Our Results: We tested the wave bolt with ac100 glue which is a very common glue used with these, we DID clean the hole unlike the test on the previous page. We got consistent results in tension as the previous test and the bolt, even with it’s wave shape, does not stick to the glue once a certain force is achieved. I’m impressed with the shear strength and the bolt was breaking and pulling out around the same force so I assume epoxy would have the similar results. In theory, epoxy glue would last longer than ac100 but it is more runny and the ac100 is more user friendly though your working time is short!


If you have feedback, additional information, more correct information, or just good ol' typos that need fixing, please email me at or leave a comment below.


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