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The Book of Concrete Screws

The Bolting Bible

The Book of Anatomy

Welcome to our free course as our way of contributing to the bolting 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. Also, if someone is going to spend their time and money to bolt something, I assume, they probably want to do it as good as possible. Hopefully the Bolting Bible gives you the tools you need to do a great job. Get it?

Our courses are A-Z content in blog format, glued together with an over arching blog we call a text book. A blog format is easy to read, easy to update, and easy to translate. Be sure to begin at the TEXTBOOK and at the end of each episode we'll point you to the next.


Screwing Rock?

These work similar to normal wood screws. Pre-drill a hole and the threads bite into the sides of hole. The screws have a cutting thread of harder steel at the tip and the rest of the threads just follow along. This does require a quality impact drill with a ⅜” drive (NOT ¼” like so many are) as it takes quite a bit of torque to get them in, but you won’t need a hammer. The hole doesn’t have to be super clean like glue in bolts require, but you should blow out the dust before installing them, or you may not get it all the way in as the dust in the bottom stops it. Adding some water can help lubricate and cool when installed in harder rock and the bolt could be compromised if trying to install this in a super hard rock. These are NOT safe in softer rock.

A ⅜” bolt requires a ⅜” hole (overdrill the length by ¼”) and should be used with a hanger that has a ⅜” hole even though it can feel tight getting it on there. Don’t try to hold the hanger while using your drill to put the bolt in the hole. The threads can grab the hanger and spin around so fast that it could break your hand! The Titen HD’s are the work horse in BoltBusters but we found using a hanger with a ½” hole that it would peel off the bolt sometimes in our tension tests, albeit, above 30kn. We use these a lot in BoltBusters to anchor down our hydraulic testers and to test all sorts of hangers as they are easy to remove. We even reused the same holes (in concrete) during our hanger tests over a dozen times and it was still stronger than our hangers even though the hole was being clearly compromised. Any hanger test video has these bolts and they are how we test hangers that go to 60kn. It did break once in shear at 46kn on test 66 and after reusing the same hole enough in concrete it will come out like in this VIDEO (at very high forces) Pulling in tension snapped the head off at 43kn as you can see in test 142 (amazing slow mo at 1:15) but it is hard to do as the hangers typically fail first. Some are concerned that after many freeze/thaw cycles these bolts will become loose over time but there hasn’t been enough examples of this problem for us to be concerned about it. These are the easiest bolt to remove and replace from a bolt stewards perspective. They come in zinc plated steel, 304 SS, and 316SS. Please use a stainless that is right for your area.

Keep in mind this is a newer fad and the ASCA or any old school bolter does not currently approve of these for the good reason that extensive science has not been done specifically for climbing. Local areas may frown upon this more than others for cultural reasons and these are NOT good in sandstone as it won’t hold up to cyclic loading in soft rock. However, they have been used by several climbers in solid rock without any signs of issues and are often used in highly regulated construction. The TitenHD bolts have also been very impressive in Bolt Buster tests.

A hanger is how you interface with a bolt. Unless you glue a "P" into the rock, every other bolt needs a way to clipped a carabiner or have a rope connected to it. Standard hangers start as a flat oval-ish shaped metal pancake is stamped with a big hole you clip to and a small hole for the bolt and then folded into shape. Some hangers are welded stock rod into a similar shape as a standard one. The idea is to have a rounder surface for your carabiners and even your ropes if you want to run them directly into the hanger.


How strong are concrete screws? It really depends on the rock it is in, but here are the tests we have done with Simpson's Strong-tie Titen HD's. Most of our uses cases are temporary so we have a lot more plated steel (PS) bolts tested than the stainless you would use for a permanent anchor. IF the bolt holds, we can get between 42kn and 52kn before the head shears off. 4" pulled in tension held A LOT more than the 3".

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