Rebolting-How close can you space a new hole to the old one?

Hey guys! I’m in the process of fixing some routes where the extraction of the old bolts is not practical or possible in some areas so I’m going to drill new holes and chop/patch the old ones. 

Was curious what is the closest I can get to drilling next to the old hole where I am not going to compromise the new hole.

How Not 2 did some testing with the new bolt extremely close to the old bolt. I'd find the video for you but I'm about to head out. I highly recommend looking it up. I think it's an older video. 

What kind of rock is it? What kind of bolts are you placing? Why is it impractical? 

+1 for remembering that rock is a limited resource

While it's slow and annoying to replace bolts hole for hole, it is the right thing to do. If you don't have the tools, perhaps a conversation with a local bolting organization or the ASCA would be great. Happy to facilitate if you need help.

If it's really not possible, and you are placing glue-in bolts, you can pretty much put the bolt on top of the old one. This way the glue-in will cover the old bolt.

Rock type, photos, etc are all helpful for an accurate picture. 

Was disappointed in that hownot2 video years ago basically encouraging the practice of putting a hole right on top of the existing bolt. The "testing" fails to account for the original bolt rotting out into nothing and also sets you up for the inevitable of people reporting that the glue-in is "leaking rust".

The classic wisdom touted 10x the diameter of bolt size away, in hard rock I'm sure you could get away with less, but it's pretty situational. Are the existing bolts already in the optimal locations? 

I have read and adhere to the rule of keeping 10 diameters distance between the new bolt and the old bolt, hole, or edge of the rock.  So with a half inch bolt it would be 5 inches.   

DrRockso RRGwrote:

Was disappointed in that hownot2 video years ago basically encouraging the practice of putting a hole right on top of the existing bolt. The "testing" fails to account for the original bolt rotting out into nothing and also sets you up for the inevitable of people reporting that the glue-in is "leaking rust".

to combat this, I try to fill the old hole with as much cement as I can squeeze into it. If you're recessing the weld of the glue in, I was taught that you should be cementing the recess as well, so it doesn't change the outward appearance.

there's a covered and filled bolthole under the bottom of this bolt, for example. 

DrRockso RRGwrote:

Was disappointed in that hownot2 video years ago basically encouraging the practice of putting a hole right on top of the existing bolt. The "testing" fails to account for the original bolt rotting out into nothing and also sets you up for the inevitable of people reporting that the glue-in is "leaking rust".

The classic wisdom touted 10x the diameter of bolt size away, in hard rock I'm sure you could get away with less, but it's pretty situational. Are the existing bolts already in the optimal locations? 

That's because of your laziness, if you had gone to the original source you would have seen that I did test accounting for the lower bolt rusting away and it was fine (in fact HowNot2 did as well). The conventional wisdom is for two bolts sharing the load, not for the case we are discussing.

For expansion bolts which are putting stress on the rock, i could see wanting bolt spacing.  For glue ins, I can't see how it matters, other than the redundancy of being in two different sections of rock.

For rebolting, i think if you can loosen the previous expansion bolt so there's no expansive force on the rock from the old bolt, it shouldn't matter from a strength perspective. Even if you can't disengage the cone, i still think there's a low chance that it would actually make any difference.

I'm sure leaving old bolts in the wall, there's the possibility of patches failing and seeing rust streaks eventually 

Jim Tittwrote:

That's because of your laziness, if you had gone to the original source you would have seen that I did test accounting for the lower bolt rusting away and it was fine (in fact HowNot2 did as well). The conventional wisdom is for two bolts sharing the load, not for the case we are discussing.

To be clear, this is assuming that the new bolt is longer than the old,  and that the rock quality is decent.  

DrRockso RRGwrote:

Was disappointed in that hownot2 video years ago basically encouraging the practice of putting a hole right on top of the existing bolt. The "testing" fails to account for the original bolt rotting out into nothing and also sets you up for the inevitable of people reporting that the glue-in is "leaking rust".

The classic wisdom touted 10x the diameter of bolt size away, in hard rock I'm sure you could get away with less, but it's pretty situational. Are the existing bolts already in the optimal locations? 

Some of the existing bolts are in optimal locations and I am fully in scope with the practice of removing bolts and reusing holes. My situation is I am having extreme trouble remove wedges in step terrain that have lived there for 25 years in a wet humid environment and they are constructed with zinc so corrosion is my biggest enemy. I have all the bolt pulling tools including a YABR but today I just could not get a single thing to budge after going through multiple batteries spinning a single bolt attempting to cut into the sleeve to pull it. 

The old bolts are wedges that are possible to grind and push back into the hole to be covered but a new hole has to be drilled. I have room to move around where new placements can be made but I would of course like to use the original hole if it was possible or get as close to it as I can. 

I will try to get some pics here soon to show what I am dealing with. Like I said I have experience pulling and removing bolts of a variety and the process is not my issue, it is simply the bolts are corroded to the point where pulling is not possible or practical. 

This is the hownot2 video mentioned above:

https://youtu.be/8pgFzVqVEJY?si=g9m6LG5pdfJfqRCy

This method has become the standard practice across the country for many people putting in the actual work. 

Hole for hole is preferable from a workmanship standpoint, but obviously this method is way faster.  

Time will tell how many of these bolts end up leaking rust, but from a strength perspective, the Hownot2 tests and Jim Titt's tests show there's nothing to be concerned about.

If you value workmanship and going hole for hole above time and numbers, maybe try core drilling the wedge bolts out.  You can buy a solid core drilling setup from hownot2.com, the 13mm core bits work well for 3/8 wedge bolts 

You can also try drilling through the old bolts themselves, though you will wear through carbide bits and have to deal with the metal shavings. Having some small strong magnets superglued to a bic pen helps with this.

Jim Daywrote:

This is the hownot2 video mentioned above:

https://youtu.be/8pgFzVqVEJY?si=g9m6LG5pdfJfqRCy

This method has become the standard practice across the country for many people putting in the actual work. 

Hole for hole is preferable from a workmanship standpoint, but obviously this method is way faster.  

Time will tell how many of these bolts end up leaking rust, but from a strength perspective, the Hownot2 tests and Jim Titt's tests show there's nothing to be concerned about.

If you value workmanship and going hole for hole above time and numbers, maybe try core drilling the wedge bolts out.  You can buy a solid core drilling setup from hownot2.com, the 13mm core bits work well for 3/8 wedge bolts 

I'm not sure what qualifies as  "putting in the actual work", but no one does this locally and after replacing approximately 1200 bolts mostly hole for hole, I wouldn't recommend this as best practice without a number of caveats. A couple of tests in a controlled environment in high quality rock or concrete hardly shows that this method is best practice or acceptable in every instance.  I'd caution folks against doing this in low compressive strength sandstone and also encourage that even in harder rock that the new bolt be an inch and a half longer than the old.  

Regarding leaking rust,  this is obviously case specific,  but there's no need to wait for time to tell,  there's thousands of examples of rust streaking, the problem becomes when people assume that the streaking is coming from the glue in itself rather than the old bolt. In porous rock the patch does not seal the hole entirely.  

I haven't had the chance to try this out yet but this seems like a promising method for reusing holes since we're all assuming you're using glue ins.

https://www.mountainproject.com/forum/topic/200660913/hybrid-bolt-removal-technique-when-using-glue-in-replacements

Jim Daywrote:

This is the hownot2….

This method has become the standard practice across the country for many people putting in the actual work. 

I don’t think that is correct, and I don’t think it’s good to encourage that as standard practice. I think it can be a good option when things go wrong, or actual standard practices fail.

As someone “putting in the actual work” across the southwest, that’s not what I do, nor what I see as standard practice. Shameless self promotion… in the last 12 months I have personally replaced several hundred bolts across Colorado, Wyoming, Nevada, Arizona, Utah and New Mexico, and have directly supported the replacement of over 1,000 additional bolts in the last year through helping to facilitate rebolting clinics/events. More than 90% of the time extracting the old bolt, and reusing the original hole. I think this is and definitely should be the “standard practice”.

Diego: if interested, I would be happy to talk with you about some strategies to get the old wedge bolts out. Over the last 10 years I’ve done a lot of rebolting, and through practice, and watching other experienced folks have learned a bunch of tips and tricks. I’m also the person who shipped you the YABR. If the bolts are in really bad shape, some of them may break, but that still leaves you in a better place than starting out grinding them off. It sounds like you are able to knock them back in the hole and get them to turn. If that’s the case, you can almost certainly get them out.

Positioning either with gear or hooks, or running a taught line that keeps you against the wall will be the biggest help on steep climbs. Putting a little lateral load on the bolts as you’re spinning makes a huge difference in damaging the cone. I’ll send you an email if interested in some other tips/tricks.

I said "standard practice for many people" not "standard practice for everyone".  For instance, I know that most of the rebolters in Central Texas go straight to this method for replacing zinc 5 piece bolts.  Hundreds, if not thousands, of bolts have been replaced like this in Texas limestone over the last few years.  

I usually go hole for hole, but I've done this method on several occasions using pure epoxy to cover the old bolt (similar to George M's picture above), sealing the old bolt in the wall.  Haven't seen any rust streaks from them yet, not sure how many decades or centuries it would take for rusty water to find it's way past the epoxy seal but it's not happening anytime soon.

Lots of different ways to skin the cat. A core drill rig is a good solution. Red neck core drill method is very helpful for difficult to spin wedge bolts. 

If i break a wedge bolt accidently trying to spin it and the location is ideal i will place the new hole right on top of the old one. This is a method i have fairly recently adopted. I am happier removing the old bolt completely but if I break the bolt i would rather stack the new hole than add to the Swiss cheeze factor. I am confident that Jim Titt knows what he is talking about.

Diego- for fixing your wedge bolt problem,  alternatively- greggerman posted a thread recently where you just drill a 3/16" or 1/4" hole along the bottom of the wedge bolt, then attach a YABR and pull. 

 It will come out!  And you can replace with a glue in.

Edit- didn't notice Dan already mentioned this hybrid method above.  Thanks Dan