Drilling out old bolts

Howdy all. I remember reading somewhere about drilling out old bolts with a larger diameter SDS bit and was wondering if anyone could confirm/ deny that such a technique works without damaging the bit? Ive drilled out a few stubborn lower sleeves and nose cones from 5 piece bolts and was wondering just how far you can push it?

What kinda bolt are you trying to drill out?

I have only drilled out sleeves and cones. Based on the amount of time and battery that took I doubt anything more substantial is feasible with standard masonry bits.

Have you looked into core drill bits?

5 peice sleeves can be drilled out. Generally you are busting or bending the sleeve up until you can retrieve the peices with a hole brush, needle nose Pliers, coat hanger, hook, etc. As opposed to actually grinding them into powder. You use the same size drill bit then can increase the size afterwards if necessary for a bigger bolt. Careful in softer stones as the sleeves will wreck the inside of your hole, only a glue in will be possible afterwards. A better method is to cut threads and use a slide hammer or hydraulic to get them out.

For stud bolts you are looking at using one of the already well documented methods, think hurley Jr. or for more work and expense a core drill setup and a larger bolt. 

When you drill out sleeves and cones, pay close attention to the bit binding up on the trashed metal parts. Use less pushing on the drill, and stop often to fish out the metal bits with a strong magnet. I use a 1/4" diameter x 1" long rare earth magnet glued into a piece of brass tubing. It's much stronger than off-the-shelf magnets on sticks at that diameter. 

First off, this is something you consider ONLY for old 3/8" 5-piece bolts where you can unscrew the bolt core itself before you start.

Short version - it works great in hard rock when the old 5-pieces are very rusty.

Long version - drilling out 5-piece sleeves & cones is highly dependent on how rusty they are. Also how powerful the drill is, the rock type, and your drill bit(s).

First - the old bolt core has to unscrew fully, if it snaps off (usually halfway down the bolt) then you have to patch and drill a new hole. You often will want small needle nose pliers to grab the upper sleeve on longer bolts. If the core comes out and the sleeve/cone/bolt are super rusty, you're in luck, and you can usually blast through the sleeve and cone no problem.

If the sleeve and cone are not rusted much, then you can have big issues depending on the rock quality and your drill. In soft rock I wouldn't even try drilling through the sleeve and cone unless you are placing glue-ins, since the probability that the sleeve and cone fragments will wallow out the hole is really high. You want to have a magnet like Greg suggests, plus a hook of some sort (I use old bike spokes, not the greatest hooks but seem to work well). The magnet is great for removing loose pieces, and it's even better for detecting where sleeve pieces are welded to the wall of the hole. A small thin screwdriver or whatever other poking/jabbing type tool you can find can be great, to help dislodge fragments welded to the hole wall.

You drill carefully to try to avoid bit binding. It's also VERY important to have a big vice-grips or something (I use a Petzl hand drill) to grab the bit with for when the drill bit binds. You want to be super careful to immediately stop drilling if the bit binds, reverse the drill and try to back it out. If it doesn't back out, try not to get frustrated, remove the power drill, then use the vice grips to wiggle/twist the bit out (sometimes with very light tapping side to side with the hammer). Even when you are really careful, there's a chance that the bit will get completely stuck.

You need to cool the bit if you drill straight on the metal for more than 10 seconds at a time - squirt water in the hole for that, or remove and squirt the bit tip, or remove and just let it air cool (for a minute or so).

As far as drill bit size - there are two options. First is to use a 3/8" to remove the old sleeve/cone, then go after remaining fragments, then drill the hole up to 1/2". This has advantages since you have leeway in going after cones/sleeve fragments that are stuck to the wall of the hole. The biggest disadvantage is the chance of the bit binding is definitely higher.

The second, "standard" way is to just use a 1/2" bit to begin with. This works great when the rock is hard enough and the old sleeves/cones are rusted enough that they disintegrate well. The rock slows down the drill bit enough that it tends to take reasonable chunks out of the metal and not bind as easily. BUT if you get pieces welded to the inside of the hole, and especially if you get fragments wallowing out the hole, then you can end up with an oversized hole. Everything is dependent on the specifics - is the rock hard enough, just how rusty the sleeve/cone is, how powerful the drill is, the drill bit design/sharpness/etc. At least if the 1/2" bit binds it's usually easier to get out, since it's larger and more easily tapped side to side with a hammer, and easier to grab with pliers/vice grips.

Also don't forget that all of this can take a lot of battery power, so think ahead on that front. That's one of the main reasons that tapping and extracting the sleeve makes a lot of sense if you are dealing with "newer" not-too-rusted old sleeves.

True on the heat thing, Greg. I got this second degree burn a few days ago in Eldo after drilling out a rusted sleeve and cone. The drill dangled and touched my leg that was against the wall - I couldn't move it quick enough, so I got branded by the tip of the SDS bit. Ouch.

I second Greg's comment on only drilling out 3/8 5 piece.

Even extremely rusty sleeves can be pulled in the 1/2 inch size if you tap most of the sleeve.

Using a DoDad or similar tool with a draw stud for the sleeve and the cone makes for an easier job. Paying close attention that your draw stud is not turning and expanding  the sleeve is crucial. Hence the DoDad tool.

Gents, lots of great advice- thanks! Seriously,  this is an awesome example of shared experience saving many hours of frustration when just trying to do a good deed (which few will ever appreciate,  right?) Just out of curiosity,  I've seen some SDS bits now with a "x" profile vice the traditional spade bit. Do these work any better or worse for this task?

Glad to hear that all the rigamorol getting that darn upper sleeve out with the tap and threaded rod was worth it. 

Jesse Morehouse wrote: Just out of curiosity,  I've seen some SDS bits now with a "x" profile vice the traditional spade bit. Do these work any better or worse for this task? 

Yes, the 4-cutter bits (solid carbide head) tend to work better, but probably just because they don't bind up as easily.

Gregger Man wrote: True on the heat thing, Greg. I got this second degree burn a few days ago in Eldo after drilling out a rusted sleeve and cone. The drill dangled and touched my leg that was against the wall - I couldn't move it quick enough, so I got branded by the tip of the SDS bit. Ouch.

drill bit condom - stay safe out there...  ;-)

edit: it's a piece of garden hose

Gregger Man wrote: True on the heat thing, Greg. I got this second degree burn a few days ago in Eldo after drilling out a rusted sleeve and cone. The drill dangled and touched my leg that was against the wall - I couldn't move it quick enough, so I got branded by the tip of the SDS bit. Ouch.

Sounds like you need a drill bit condom for guaranteed safe drilling.  A short section of pvc longer than the bit on bungee will keep that smokin hot bit off you and your stuff, especially the rope.  

Went back for more on Saturday. This one got a bit warm, wouldn't ya say?:

I discovered something - if you decide to drill through a 3/8" 5-piece, you still need to disengage the cone. If the cone is firmly holding that sleeve in place, you will have to grind up every bit of it as you drill the new 1/2" hole. If you shove the cone to the back of the hole, you at least have a chance at getting the sleeve out in two big chunks, which saves a lot of battery power. I had neglected to charge one of my batteries Saturday morning because the indicator light still said '3 bars'. It only lasted two holes. Time for some new batteries, I think.

I now drill out 3/8 5-pieces from the get go. I've never had much luck with the tapping threads on the sleeves. For me, they seem to come out 1/8" or 3/16"  at a time, horribly frustrating and slow.

Key is to use Bosch "Xtreme" bits. These have a solid carbide tip somehow welded onto the shaft and seem far more durable than other SDS bits which have a slice of carbide slotted into a slot. I tried a 4-square tip rated for rebar, this cut quickly through metal at first but a chunk broke off quite soon, disappointing. I've recently seen some newer 4-square designs, these may be better?????

I just pull the bolt, remove any sleeve bits that are easy to extract, and start drilling with 3/8" Xtreme bit.

I'm not noticing any benefit from disengaging the cone from the sleeve, though as Greg says, if the sleeve is free from the cone logically there's less holding the sleeve in place (just rust) and more chance it may come loose from the hole in larger pieces. I'll watch out for this.

1. This bit will plow through the rock and sleeve quite happily. If slowly. At some point the remains of the sleeve lose integrity and the bit will probably bind on a fragment. Immediately stop drilling. Don't even bother reversing the drill, this sometimes works but it's hard on the drill clutch.
2. Remove the drill from the bit, clamp large vice grips to the bit, wiggle the bit to and fro to free up the bit and then draw it out while wiggling, it will probably come out with metal fragments.
**Binding or not, it's good to regularly stop and clean out the hole, with blower and with magnet-on-a-stick.**
3. The cone seems to be made of a more brittle steel than the sleeve and fragments surprisingly easily. These fragments may bind or may simply disintegrate. Once the cone is gone pale rock dust will start flying out of the hole.
4. Clean the hole.
5. Remove 3/8" bit from the drill, install 1/2" SDS bit. Take care to orient the drill in line with the existing 3/8 hole, Once the hole is started the bit will naturally want to follow the hole. There may yet be sleeve parts left and the bit may yet bind, so be wary. If so, repeat step 2.
6. So far using this technique I've been getting good tight holes for new 1/2' bolts, no wallowing.    

Crusher
Thanks for the detailed explanation. If one was planning on using glue ins do you see a down side to doing all drilling with a 1/2" bit as wallowing might arguably be desirable? 

Jesse Morehouse, if you are placing glue-ins, the 1/2" bit works fine. A tad more easy to bind due to the larger diameter, but still works. the only downside I see is that more glue will be needed per hole.

I just drill the stone out around the old bolt and replace with an epoxy bolt. hot drill bit burns are so much fun on lead..