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Shearing Heads Off of Old 3/8" Sleeve Anchors


Original Post
Taylor Krosbakken · · Duluth, MN · Joined Nov 2008 · Points: 448

Last weekend I was working on replacing some 3/8 in sleeve bolts and I was excited to try and remove the sleeves with a tap and extraction tool, but I never made it that far. I snapped the head of off all 6 or so bolts that I tried to loosen. The cone, sleeve, and bolt are just that corroded that they are basically just welded together. Is my only option to core drill out the whole thing with a 3/8" bit?

I was able to get one bolt out of a 1/2" sleeve bolt and I was also able to disengage the cone, but the sleeve was welded to the rock. It was sticking out a little from the rock and I wailed on it with a hammer and it wouldn't budge. I wasn't able to try and tap it, because I only had a 3/8" tap, but it doesn't seem like it would budge. After snapping off the head of the 3/8 in bolts I also wailed on those and there was nothing.

I ended up having to drill a new hole, but in the future I would like to strive for using the same hole, by removing everything, up sizing, and placing a glue in. Any ideas for removal? Just core drill? Good bit for this?

The rock is Dolomite and this was in a fairly wet part of a crag in MN. FA was in 1989 but these were  from the first rebolt, so maybe 15 years old?

Thanks for the help!

Bobby Hutton · · Gold Country CA · Joined Aug 2013 · Points: 819

What kind of bolt are you replacing the sleeves bolts with?
If you are using a glue in it is possible to drill another hole right next to the sheared off sleeve bolt and use a punch and a hammer to work the whole assembly back and forth until it is loose enough to take out with a pair of pliers. Then drill it out to the diameter of whichever glue in you are using, being careful to avoid the bit binding in the oval hole. This method of course will not work with mechanical replacement anchors because it does not yield a uniform hole. 

Tristan Bradford · · Oklahoma City, OK · Joined Mar 2015 · Points: 1,048

Using a surfactant such as a mix of dishwashing soap and rubbing alcohol tends to loosen the bond. Guys in j-tree ive helped swear by it. Using some PB blaster probably isnt out of the question in your case either. Now that you have snapped bolts, drilling them out is going to be a motherfucker. Just drill new holes and patch the old ones. Make sure you drill at least 3 inches away from the old hole. Take the liberty to move the bolts around if you can prevent rope drag/make the route better in any way. Theres a yellow tube of textured concrete patch you can buy at ace hardware. Works like a charm. If you feel so inclined, throw some tiny pieces of rock in there, or sand to make it look more rock colored. The patch material is grey.

Taylor Krosbakken · · Duluth, MN · Joined Nov 2008 · Points: 448
Bobby Hutton wrote:
What kind of bolt are you replacing the sleeves bolts with?
If you are using a glue in it is possible to drill another hole right next to the sheared off sleeve bolt and use a punch and a hammer to work the whole assembly back and forth until it is loose enough to take out with a pair of pliers. Then drill it out to the diameter of whichever glue in you are using, being careful to avoid the bit binding in the oval hole. This method of course will not work with mechanical replacement anchors because it does not yield a uniform hole.
I am currently using wave bolts for replacement.
 
Drilling next to the hole sounds like something I would be willing to try. Smallest size SDS bit is 5/32". Would you just drill on one side? all the way around? Upsizing to a 1/2" hole you would still end up with a notch on one side if you drill one hole. If you were to drill all the way around the sleeve you would end up with about a .69" irregular shaped hole.
 
Is there a hole size limit for wave bolts? how about Jim Titt bolts? Has anyone done testing on max hole size or irregular hole size. Obviously not as susceptible as any mechanical bolt, but surely there is a size and shape limit, right? A disadvantage would be you wouldn’t have the tight interference fit that mechanically holds the bolt in, but I am working on vertical walls so not as much of a concern that the bolts stays in place while curing.
 
I guess another down side would be I would use a lot more adhesive but if that means I get to use the same hole it would be worth it. I just want to make sure I am not compromising strength with a larger or misshapen hole.

Tristan Bradford wrote: Using a surfactant such as a mix of dishwashing soap and rubbing alcohol tends to loosen the bond. Guys in j-tree ive helped swear by it. Using some PB blaster probably isnt out of the question in your case either. Now that you have snapped bolts, drilling them out is going to be a motherfucker. Just drill new holes and patch the old ones. Make sure you drill at least 3 inches away from the old hole. Take the liberty to move the bolts around if you can prevent rope drag/make the route better in any way. Theres a yellow tube of textured concrete patch you can buy at ace hardware. Works like a charm. If you feel so inclined, throw some tiny pieces of rock in there, or sand to make it look more rock colored. The patch material is grey.

I will try this too. How long does something like that take to penetrate?

I had to finish the work the same day, so I already drilled new holes, taking care of both the things you brought up as well as clipping stances.

Another thing that someone with a lot of experience in a different environment said is that they do not use a breaker bar as I was and go back and forth with little movement to break the rust bond. I really only went one direction HARD. I was thinking of trying an impact wrench too that would give it a more percussive movement.
Jim Titt · · Germany · Joined Nov 2009 · Points: 490

Our larger bolt goes in a 16mm hole but up to 20mm or so is not an issue, bigger you have to start  to see about what sort of resin you are using as they will start to loose strength as it shrinks. With a pure epoxy this is less of an issue than say polyester.
If you are replacing with glue-ins and can't get the old bolt out then normally we (and every one I know) drill directly on top of the old bolt and use a resin bolt longer than the old bolt, usually 20-40mm longer. There's no reason to drill somewhere else.

Taylor Krosbakken · · Duluth, MN · Joined Nov 2008 · Points: 448

I appreciate your response Jim. I am using Vinylester (AC100).

And by "drill directly on top of the bolt" do you mean with a normal twist drill bit first to remove the sleeve or god forbid the snapped off bolt? and then upsize with a hammer drill?

Or do you mean like a separate hole but very close ("on top" laterally)? creating almost a snowman hole? do you have testing data on this?

If that's what you mean, with your bolts or wave bolts the hanger portion coming down would cover the old sleeve so it would look nice too!

One problem is if we don't get the bolt out of the sleeve, we don't know how deep the bolt goes. Unfortunately there is no standard in this area. Everything is different.

Jim Titt · · Germany · Joined Nov 2009 · Points: 490

So the new bolt lies on top of the old one and the eye covers the old one. We can't measure any difference in pull-out strength and in theory there shouldn't anyway. Just to be sure we use a longer bolt. Most Euro stuff is with 80mm bolts so maybe 70mm deep so we use 100mm glue-ins. Longer than that I doubt it matters about the length of the old bolt.
I use vinylester as well and nowadays do all the testing with it.

Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

If you "redneck core drill" a 3/8" bolt (just drill small holes around the old bolt with small SDS bits), you'll need something larger than a Wave bolt to re-use the hole. I would get some of Jim's 16mm (5/8") Twisted Leg bolts. I found that 5/32" SDS bits are super squirrelly, it's better to use 3/16" bits. You will track down the sides of the old bolt, and the biggest problem is that the little bits like to jump over to previous holes. You will also want to pay close attention to the small bits, if they break then you end up with chunks of drill bits alongside the old bolt.

Also when expanding the ragged hole for the larger bolts, the drill bit really wants to bind in the hole, so you want to be careful not to get it stuck. These kind of methods are best for when you REALLY want to re-use the original hole. Also, and this is very important, they tend not to work in soft rock since the drill bits can track out into the rock instead of along the bolt.

Finally, in the rare case where you run into very poor quality hardware store bolts, the small SDS bits can track INTO the old bolt, making it impossible to drill the old bolt out. I had that happen a few months back (the bolts were such poor quality that one anchor bolt had already snapped, and all the other bolts snapped off while trying to unscrew the nut).

Taylor Krosbakken · · Duluth, MN · Joined Nov 2008 · Points: 448

We are under no requirement to reuse the hole. I just wanted to try for aesthetic reasons. So instead of spending a bunch of time "redneck core drilling", I would much rather just drill a hole right above the old sleeve or snapped off bolt. Seems like a lot less work with basically the same result.  

Thanks again all!

Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

So Jim, what happens 50 years down the line when the old bolt rusts away to nothing and there's a void/hole/cavity where the old bolt was?

Jim Titt · · Germany · Joined Nov 2009 · Points: 490

That's why we use a longer resin bolt, even if the support below is gone there's still 30 or 40mm fixed in place at the bottom. In theory you could do the same just using a longer wedge bolt but I've never done any testing on this.

mattm · · TX · Joined Jun 2006 · Points: 1,395
Jim Titt wrote: That's why we use a longer resin bolt, even if the support below is gone there's still 30 or 40mm fixed in place at the bottom. In theory you could do the same just using a longer wedge bolt but I've never done any testing on this.

I may have a re-bolt project where numerous bolts were chopped (angle grind flush to rock) including glue ins.  Can one drill on top of these "glue shafts" as well or is it better to use 200mm spacing like an anchor?

Taylor Krosbakken · · Duluth, MN · Joined Nov 2008 · Points: 448
Greg Barnes wrote: So Jim, what happens 50 years down the line when the old bolt rusts away to nothing and there's a void/hole/cavity where the old bolt was?

You make a good point Greg. That is a bit concerning. If you got the bolt out and only had a stuck sleeve I suppose you could fill it with adhesive. And if the bolt is sheared off in the sleeve, it may take even longer than 50 years to completely disintegrate.  

What is your rule of thumb for distance between old hole and new glue in? 

Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

I usually re-use the hole and often end up using Jim's large Twisted Leg bolts for tough to remove bolts where I red neck core-drilled around them. But for moving a bolt, rule of thumb for concrete is 10 times the diameter, which is a bit less than 4" for 3/8". But it depends on the rock, you want to avoid fracture planes in some rock (particularly low to medium quality sandstone), and the particular bolt placement often calls for moving the bolt a certain direction for rock quality, surface shape/texture, or best clipping (you don't want to make a reachy clip even harder to clip). Also if you're at an anchor where you'll be installing a link to rap ring (or mussy hook), you can often position the bolt higher than the original so that the ring hangs right where the old bolt was.

Anyway, for what it's worth, I'd strongly suggest not drilling a new hole immediately next to a chopped bolt, even if that's common practice in Germany! Also limestone in wet climates can "heal" itself, so I wouldn't be surprised to see an old bolt rust away to nothing over decades, and the hole just fill in with newly deposited limestone!

Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Greg Barnes wrote: So Jim, what happens 50 years down the line when the old bolt rusts away to nothing and there's a void/hole/cavity where the old bolt was?

It´s not only in Germany where this is common practice!

The bolt spacing idea comes from a mis-interpretation of the rules regarding multiple bolts sharing the load where it is nescessary to space them so the cones of fracture don´t overlap and reduce the combined force the bolts could withstand. When there is only one bolt loaded this is no longer a valid concern and can be ignored.
Generally we are not worried about the remains of the bolt rusting away as either the things are already ancient and haven´t rusted or they are stainless steel (like rubbish ones which are starting to corrode), we simply chop them and place one above.
If the bolt below rusted away and left a void is this dangerous? Here´s a quick test I did this afternoon.
I first drilled a 12mm hole 70mm deep to represent the rusted away bolt then put a 12mm bar in it and drilled another 12mm hole 100mm deep directly above it and removed the bar to leave an 8 shaped hole. The 70mm hole I plugged with a length of hose to prevent the resin going into the hole and then installed a 12mm twisted leg bolt. 4 hours later with vinylester resin I got:-

As installed, the yellow and black is the piece of garden hose forming the "void";

5kN;

10kN;

15kN;

20kN;

25kN;

30kN;

35kN;

37.84kN The bolt failed.

Personally I think it is a perfectly acceptable technique  and infinitely better than spraying bolts all over the place and leaving disguised holes to catch out the next guy.
mattm · · TX · Joined Jun 2006 · Points: 1,395

Jims efforts absolutely make my day right now.  I have a future project with well north of 50 chopped bolts that were going to a major PITA to move.  This makes life infinitely easier.  

Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

Matt, are you going to use glue-ins? Do you know how long the original bolts were?

Jim, I would think that this technique would be sketchy with mechanical bolts, the most common situation in the U.S. would be a plated 3/8" bolt that snapped off replaced with a 1/2" stainless bolt, and the plated bolt would be expected to rust away to nothing eventually.

Edit: and the old bolt might be of the same length or longer than the new 1/2" stainless bolt placed alongside it - seems like a very bad idea to me!

mattm · · TX · Joined Jun 2006 · Points: 1,395
Greg Barnes wrote: Matt, are you going to use glue-ins? Do you know how long the original bolts were?

Jim, I would think that this technique would be sketchy with mechanical bolts, the most common situation in the U.S. would be a plated 3/8" bolt that snapped off replaced with a 1/2" stainless bolt, and the plated bolt would be expected to rust away to nothing eventually.

Edit: and the old bolt might be of the same length or longer than the new 1/2" stainless bolt placed alongside it - seems like a very bad idea to me!

100% glue ins for the re-bolt.  Chopped bolts vary from glue ins to 3/8 SS wedges to 3/8 PS 5 Pieces.  Many placements can be re-located but there were several where the location did NOT have a lot of wiggle room.  One of Jim's 12x150mm will do will in these spots as that will more than cover length variation.  

Jim Titt · · Germany · Joined Nov 2009 · Points: 490
Greg Barnes wrote: Matt, are you going to use glue-ins? Do you know how long the original bolts were?

Jim, I would think that this technique would be sketchy with mechanical bolts, the most common situation in the U.S. would be a plated 3/8" bolt that snapped off replaced with a 1/2" stainless bolt, and the plated bolt would be expected to rust away to nothing eventually.

Edit: and the old bolt might be of the same length or longer than the new 1/2" stainless bolt placed alongside it - seems like a very bad idea to me!

Well you could always get one of the original bolts out and assume the rest were the same length or as Matt says, just use something really long. In my opinion it´s unlikely anything over 100mm is nescessary but in the morning I shall do the same test with a shorter glue-in than the mechanical bolt and see. Loaded radially it´s hard to see how the glue-in is going to shift down into the old hole and fail, if I can I´ll cut into the block from today and see what´s happened inside the hole.

Axial tests I did a few years back the depth wasn´t critical, I just recommend the glue-in is longer to cover myself really!

With mechanical bolts the critical thing would be get the contact point deeper than the old bolt obviously, 10mm wedge bolts come up to 210mm long and 12mm 240mm long as standard items and I doubt back in the day anyone was planting bolts that long!
Bobby Hutton · · Gold Country CA · Joined Aug 2013 · Points: 819
Jim Titt wrote: Here´s a quick test I did this afternoon.

Jim, thanks so much for sharing that technique and your test. That is a much more elegant solution than drilling another hole.
Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

Tough to tell bolt length in the U.S. since a fair number of old rusty 3/8" bolts are about 100mm/4" long (occasionally longer), while most are in the range of 75-80mm. The bolt length stamps on the heads of the bolts are a newer development, so they're not much use. Also it's common to have different length bolts (and even different type bolts) on the same route.

I would think that lower quality rock would be more susceptible to long-term issues with a bolt next to a void...and any bolt next to a void still seems pretty sketchy to me!

Guideline #1: Don't be a jerk.

Fixed Hardware: Bolts & Anchors
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