How to put in a bolt

In many years of climbing I have never placed (or participated) in placing a bolt. But the time has come. There is this route that is too runout and I want to retro bolt it... JUST KIDDING.

I am going to place 4 bolts in my back yard for a slack line for the kids. Can I drill 4 holes in granite without a hammer drill? Can I use a regular drill? Is there a special drill bit or do I use a regular masons bit? any tips on how to drill the holes would be great. Same goes for placing the bolts. Any tips would be great.

Thanks

Do you really have two solid granite locations in your backyard? If so that is awesome. If they are just landscaping boulders then I would be a little careful since a slackline can generate quite a bit of force.

I can't comment on the bolts but I can tell you how I set up anchors in my backyard for a slackline. I took a huge eyebolt(maybe 8-12 inches long) and dug a hole with a posthole digger making sure it was wider at the bottom than the top. Rig up a piece of wood or something to hold the eyebolt where you want and fill the hole the concrete. In the end the eyebolt protuded maybe an inch or so out of the concrete, which is mostly just the eye of the bolt.

Also pay attention the the height of the eyebolt you want the top sunk below ground level so that you can safely mow over the top. To do a slackline I have an A-frame made out of wood that I can pull out to raise the slackline. You could make the aframe or use something like this from gibbon.
gibbon-slacklines.com/en/pr…

They are landscaping boulders but they are fairly big. They are 4x4 at least. I imagine they each weigh a few hundred pounds. I plan on using two at each end. I was worried about the force of a 200lb person bouncing on them but I was thinking they would be ok.

I had thought of putting the 4x4 post in the ground but figured the wood would flex.

Hammer drill is definitely the way to go. You can probably rent one for a few $. You can also buy a non-cordless version at Home Depot or wherever for cheap as well. Bolts are pretty straightforward, I'd use some Powers 5-piece (you can get them, and hangers from Fixe), pick the diameter you want (3/8" probably fine), depth (3-3/4"?), drill the hole slightly deeper than the length of the bolt, blow out the dust, assemble the bolt and hanger, tap it in, tighten it...you'e done.

"Rotary Hammer" is what you're looking for. big difference between rotary hammer and a hammer drill. Place them perpendicular to the direction of pull if possible and over-drill the hole by a tad so you can cut off, tap it into the hole and patch it if you ever want to remove them. Also dont mix bits and bolts. in other words dont drill with a 10mm bit and then use a 3/8" bolt bc it fits.

Lots of videos, etc on the subject but here's on on the diff between drill types:

youtube.com/watch?v=6UMY4lk…

Mut wrote:They are landscaping boulders but they are fairly big. They are 4x4 at least. I imagine they each weigh a few hundred pounds. I plan on using two at each end. I was worried about the force of a 200lb person bouncing on them but I was thinking they would be ok

Since boulders really need 3 dimensions... assuming they're actually 4x4x4 each would weigh about 10,000 lbs. Or, if we assume they're about spherical with a cross-section (diameter) of 4 ft, we'd get about 5,000 lbs.

Yup, probably won't be going anywhere.

Jack Ubaek wrote: Place them perpendicular to the direction of pull if possible

I'm not sure this is correct. It is probably at the level of doesn't matter -- but my understanding is that a properly placed bolt will be as strong or stronger on tension as shear. And that tension distributes the force over more of the rock than shear -- which concentrates the force at the lip of the hole.

I've used my jeep and a tree on each end and believe it or not, my jeep moves enough to create slack. I weigh 190. Make sure they are big boulders.

Use a rotory hammer with an sds bit... I have a Ryobi Lithium Ion rotory hammer and it drills through granite like butter. It's so simple a caveman can do it.

Slacklines can create incredible forces on the anchors due to the geometry, and can easily exceed the strength of typical climbing hardware. If it's only a couple feet off the ground then the consequences of anchor failure aren't too bad, but better if it doesn't. You might want to check out the info on slackline.com.. Also: slacklineexpress.com/highli…

Just a note about cleaning out bolt holes: It is very important when placing bolts to clean the holes well. Don't just blow them out. Use a tube brush (available in many hardware stores)in them also - blow, brush, blow, brush, blow. Just blowing out a hole leaves a lot of dust still in there stuck to the sides. For blowing them out, a piece of tubing long enough to get your face out of the way works OK, but a blow bulb is even better as it doesn't introduce moisture like your breath does.

For 4. Bolts you can easily hand drill the holes using a 2 to 4 lb hammer. Buy a few sds drill bits from fixe and hold them vice grips so you don't smash your hand

A can of DustOff works really well for blowing out the hole. You don't need to get your face/eyes in the vicinity of the hole or introduce moisture, as with a blow tube.

I'm not sure what kind of slacklining you'll be doing but if there is any possibility that you'll be tricklining, I'd definitely choose 1/2" bolts. The loads the anchors see while doing any sort of body bounce are insane.

youtube.com/watch?v=6TxGv8f…
and 8kn standing tension on a trickline is fairly low.

Can you not some how sling the boulders. Once you have them to height and apply tension to the slackline they shouldn't slide down. Drilling into landscaping boulders seems silly if you every want to sell your place. If there is cracks in to rocks use passive pro that you can remove later.

Capt. Impatient wrote:Drilling into landscaping boulders seems silly if you every want to sell your place.

As long as he over-drills the holes, he should have no problem hiding the holes at a later date.

I snapped a nylon slackline right off while walking a 30m line (actually, sling material, not a proper slackline). Also, I pulled up the neighbours car out of the ditch singlehandedly all by myself using the same principle. The force on the line is pretty high when you´re bouncing around on the middle.

If you aren't super attached to the idea of using bolts and you can easily dig in the soil where you live you should make a couple deadman ground anchors hooked up to a saw-horse sorta thing. I've had this system going for a couple of years now and it has worked perfectly.

No-tree/rock slackline anchor

Does the A frame method reduce the tension/force on the anchor?