After getting thy hole hammered, make sure thou cleanest it really well."
Holes matter a “whole” lot! You have to know where to put them, what pattern to put them in, how to drill them and what diameter they need to be, even sometimes accurate to within 0.1mm. And did you know that if they aren’t super sterile clean, at least for glue in bolts, they could fail at a dangerously low force? Keep in mind drilling a hole is a permanent deformation to the rock, so be intentional before you swiss cheese our public land. See here all the things you need to get your holes drilled out.
Chapter 1 - HIGHLINE Bolt Placement
Things to consider before installing highline anchors:
1. Where do you want your master point to be? It will be in the center of your bolting pattern so choose carefully. And remember you don’t want more than a 45 degree angle on your anchor legs so it doesn’t put exponential force on the bolts, rather than sharing the load evenly.
2. Is the anchor going to serve more than 1 highline? How can the bolts be placed to best be pulled in multiple angles?
3. Will the hangers sit flat against the rock?
4. Will there be a weird hump between the bolts and the masterpoint causing unwanted friction?
5. How far back from the edge will the bolts be?
In hard rock it can be a foot or two away from edge but if it is too close then it can put the master point too far beyond the edge making rigging a bitch.
In soft rock it is important to stay away from the edge even 6 to 10 feet back in some cases but then the master point will need extending
6. What Pattern will you use?
Straight line - Careful, this is how they harvest quarry stone. This can score rock and make it susceptible to fracturing. Know your rock. STRAIGHT LINE PATTERNS DON’T EQUALIZE on top of cliffs but being pulled straight out of cliffs may equalize better.
Equilateral Triangles equalize best if on top of a cliff. The bolt most direct in line (the center bolt) and the closest bolt sees the most force. Those two principles cancel each other out for the most part if you do an equilateral triangle, with the center bolt being furthest back.
7. How close, or far, should the bolts be apart from each other?
The force is spread at a 45 degree angle through the rock. You can see an example in this photo of a piece of sandstone that broke while pulling a short mechanical bolt straight out in a bolt buster test. If your bolts are too close together, the same sections of rock will be seeing forces from two different bolts. It’s also important to not be too close to areas of the rock that you hear are bad when you checked with your hammer. The longer your bolt, the bigger your cone will be, so the further your spacing will need to be. The expansion anchor industry has established a minimum of 10 anchor diameters apart from each other (½” x 10 = 5” or 12mm x 10 = 120mm apart minimum) but I’m not sure diameter really has much to do with it. For most climbing situations, a hand width apart is fine but in softer or fractured rock it is better to spread them out twice as far.
8. How many bolts will you use?
HIGHLINING - 2 bolts is redundant and 3 bolts is common for highline anchors. 4 bolts are overkill and often make it difficult to equalize which means only 2 or 3 bolts see all the forces anyways. Check out Equalization is NOT a myth for more information.
CLIMBING - Things to consider: How high is the route? Where are the cruxes? What is the complexity of the installation? See The Book of Climbing Anchors to learn more.
9. What are the regional trends and is it correct? Don't do anything drastically different than others have done in the area without fully understanding why they did it.
Chapter 2 - Climbing Bolt Placements
Things to consider before installing climbing bolts, or a list of things you can complain about on the next route you climb.
To avoid rock failure, place bolts an appropriate distance from rock edges, further in softer rocks.
Avoid placements that weaken your carabiner by loading it over edges or rock imperfections.
Plan placements to avoid rope drag. Keep bolts on a sport route in line to avoid the friction of the rope redirecting back and forth across the route.
Avoid placing anchor bolts too far from the cliff edge, forcing the rope to rub.
When bolting sport routes, find good clipping stances, then make sure to place the bolt so most climbers will be able to reach it. If you are 6’6” don’t place it as high as you can so a shorter climber will be able to comfortably use the same stance to clip the bolt.
Consider when a quickdraw is hung on the bolt that it won’t be in the way of a key hand or foot hold as you climb past.
Place top anchors so they protect as much of the route as possible. If the route wanders place the anchor in the middle point of the traverse to prevent big swings on top rope.
Hitting the ground or ledges is bad. Place bolts to avoid this.
When putting in anchors for a climb that will only/mostly be top roped, consider the safety of those walking to the cliff edge to set up the climb.
Chapter 3 - Drilling Basics
Here are some pointers for drilling holes regardless if you are hand drilling or power drilling.
1. Drill the hole long enough. In almost every situation, there is no such thing as too deep other than you are wasting battery life, drill bit life or glue. IT IS VERY BAD IF THE HOLE IS TOO SHALLOW. Just like relationships, if it is too shallow it isn’t going to last. A bolt sticking up out of the rock is not safe to use and difficult to remove. If it is even 95% deep enough it will look like it is in the rock but the hanger will be spinning and that always raises a red flag on the integrity of the bolt to someone who wants to use it.
TIP: Put duct tape on your drill bit or your wire brush to verify that you are deep enough.
2. Drill it straight.
Mechanical bolts will have a hanger and it is important that the hanger sits flat against the rock.
Glue in bolts have conflicting information online. FixeHardware says in this video to tilt them backwards for leverage. Bolt-Products website (scroll halfway down) did a test showing stakes in the ground do better if installed straight in. I believe glue in bolts act much like ice screws where the threads are supposed to do the work, not the leverage. Ice screws are recommended to be tilted 10 to 15 degrees towards the direction of pull so it doesn’t leverage the top of the ice but allows all the threads to be pulled on. So just drill glue ins straight in for soft rock and let the entire shaft and glue do the holding rather than the angle.
3. Test the spot
Set the hanger (if using hangers) where you think you will drill the hole to make sure it sits flat and nice. If you really like the spot and only a few crystals are stopping you, you can chip them away, but just be sure the end product… the hanger… will sit nicely.
After drilling the hole an ⅛”, stop and check everything again. Do you like the spot? Does your hanger sit nicely? Did the rock feel/sound solid? If you goof, ⅛” it isn’t a deal breaker, but if you drill all the way and then realize there was a mistake, then it is just slop.
4. Bring Backups
It really sucks if you don’t have a backup drill/batteries or backup bit or backup glue tip or even backup hardware in case you miscounted or dropped one and you can’t finish bolting. The impact that bolts have on an area has been debated, but everyone agrees a half drilled or half installed bolt is bullshit.
5. Drill Bits
A 4-point bit drills faster and saves energy or batteries rather than a 2-point bit. They also make a rounder hole which is important for some bolts such as those overpriced petzl removable bolts.
Fresh bits are important because the tip/shoulders get worn down on old bits and you get an undersized hole. If the hole is too small, then you have to smash your mechanical bolt in harder which can damage it or the glue in will not have as much glue surrounding the rod.
Battery powered hammer drills and Petzl Rocpec hand drills require SDS-Plus drill bits, “special direct system”. These kind have the grooves at the top so the drill can hammer and rotate the bit. Not all SDS bits are created equal. SDS-Plus is 10mm shank and SDS-Max is 18mm. So make sure you know what you are buying.
Size matters - the usable length and overall length are generally different by 2” because of the shank, or the part that goes into the drill. Remember that a 6” drill bit only has 4” that is usable.
It helps to understand all 5 parts:
Shank: has two sets of grooves so the bit doesn’t fall out and helps during hammering.
Land - raised portion of the spiral (similar to the crest or peak of a wave).
Flute - the spiral groove which facilitates the removal of the concrete dust as the hole is being drilled.
Head and Tip - these work together to break up the rock. The carbide is brazed onto the head to harden the tip of the SDS bit to assist in the breaking of the rock.
Chapter 4 - Hand Drilling
There are some places that do not allow power tools, such as National Parks in the USA. However, if it is legal and ethical to install bolts, you can do it the ol’ fashion way… by hand!
1. You need a handle. The poor man’s method is to duct tape the shank with about 50 wraps but the efficient way is to use a Petzl Rocpec , designed for SDS drill bits or the high quality D/5 Hurricane Drill which is designed for both SDS and HSS bits.
2. You need a hammer… obviously. You can use any 12oz construction hammer but the Yosemite Hammer has an attachment cord and an eye to attach a carabiner to for clipping and the occasional yanking.
3. Use gloves! The thicker the better for when you occasionally miss the head of the drill.
4. Use eye protection! You can literally feel things hitting you in the face when hammering a rock. You don’t want rock shards in your eyes. You can use sun glasses, you will look cooler when explaining you are trying to create a hole in granite the same way they did 200 years ago.
5. How long does it take?
A 4 ¾” x ½” bolt hole takes approximately 1000 hits in hard Yosemite granite. Counting is a great way to keep the stoke high. Try to hit it at least 50x before resting your arm. Find and keep a rhythm to the hitting rather than pretending you are the road-runner on crack and getting tired 20 seconds later.
It takes about 45 minutes to an hour for a single 4 ¾” x ½” bolt hole in hard Yosemite granite. Softer rock can be much much quicker but you may have to drill for a longer bolt.
6. Keep it straight - As you get tired, you may have a tendency to not keep the drill straight. If the drill isn’t perfectly straight, it will be dragging against the sides of the hole and the friction that creates can really slow down momentum. It’s also very important to keep a drill straight so the hole stays true to size.
7. Don’t give it a courtesy tap, hit the drill with some umpf! You're not trying to make noise, you are trying to burrow a hole in rock!
8. Keep the hole clean periodically. Maybe after 100 to 200 hits. If you don’t, you are just pounding dust… literally!
9. Use the most important resource on the planet… friends! If the anchor is safe to “hang out” at and easy access for everyone, take turns. Hitting 100x and switching can speed things up and not feel like such a burden.
10. Keep it attached to you. Wouldn’t it suck if your hammer or drill rolled off the cliff or fell out of your hands?
11. Use fresh bits. This is especially important for hand drilling. That extra $10 won’t seem like much if you are only half done after 1000 hits because you are using a worn out bit.
12. Don’t slack off! Install a ½” or 12mm bolt if you plan to highline on it, but ⅜” bolts are fine for climbing applications.
Chapter 5 - Power Drilling
1. Hammer drill vs rotary hammer drill - rock isn’t threatened by a normal drill spinning, you need a hammer drill. However, a normal “hammer drill” only has 2 cam/discs/gears spinning and tapping each other and is designed for “light masonry”. Unless you are drilling into some really poor quality rock, you will want a rotary hammer drill. Those have pistons which chisel the rock while spinning. Hammer drills have a normal chuck in which a smooth shank fits in and Rotary Hammer drills require SDS bits. You can buy the best at Bosch or save some money and buy the one from Makita that works just as well (i’m very happy with it) or Milwaukee has a great one too for the same price (Bobby Hutton really likes this drill).
2. Keep it straight - it’s common for people to think a drill is straight and it be completely at an angle. With all the vibration and noise, you really have to be intentional to keep that drill perpendicular to the rock. There’s no fixing a hole drilled at an angle after you see the hanger doesn’t sit flush with the rock!
3. Check your work after the first 2 seconds of drilling. Make sure that it is where you want it. Don’t check once and drill twice. Let's avoid swiss cheese rocks by being mindful about checking our work.
4. Don’t push hard. Let the drill do the work.
5. Don’t be afraid to pull out. To help clear the debris, just pull the bit out periodically while it’s spinning. Not the entire time like you are trying to have sex with the rock, but you don’t want to just leave it in the hole for 3 straight minutes either. :)
6. Know your batteries and bring enough. Don’t run out of juice and not be able to finish.
7. Know your target length. You don’t always want to drill the full length of the bit so know how much of the shaft has to be buried and keep an eye at that spot. Many drills have a measuring stick built into the handle called a “depth stop”. Or you could go fancy and put duct tape on the drill bit to identify the right depth. Just don’t drill too shallow, it can create major problems. Remember notched glue ins need to have a deeper hole than glue ins with no notch.
This episode covers what was in this chapter. Watch every bolt video on this PLAYLIST
If you have feedback, additional information, more correct information, or just good ol' typos that need fixing, please email me at email@example.com or leave a comment below.
It costs about $10k a year to operate HNTH and no we don't make money on youtube. Please spot us $20 on paypal/venmo or support us per episode on Patreon.