Burning out drill bits, FAST

I’ve been working in rock that’s mostly quartz, so I know its hard.  Previously, I might get about 7 holes.  Now I’m getting like 2.  I thought my bits were the same but now I’m trying to determine what the change is.  The tips are being ripped off, not just dulled.  Any thoughts from the gallery?

Curtis Baird wrote:

I’ve been working in rock that’s mostly quartz, so I know its hard.  Previously, I might get about 7 holes.  Now I’m getting like 2.  I thought my bits were the same but now I’m trying to determine what the change is.  The tips are being ripped off, not just dulled.  Any thoughts from the gallery?

I've drilled a fair bit of quartzite and had as few as 1 or 2 holes per bit. Tried many brands, styles, and tips, and settled on cheap and plentiful since extra dollars doesn't seem to translate to significantly longer bit life. 

Make sure you're keeping the bit cool. Drill in short bursts and wait in between. While you're waiting, clean dust from the hole to help keep the bit cool on the next burst.

Another trick is to pre-drill with a smaller diameter (and therefore cheaper) bit, then drill a second time with the intended diameter. This saves the bigger bit for more holes, and it doesn't really matter if the shoulders on the smaller bit wear out more quickly. 

Would a diamond bit really not work longer than carbide? Has anyone tried those? They are super expensive, of course.

Your drill may be hitting with less impact force. In really hard rock, the power of the “punch” normally correlates with life of the bit. If you noticed a fall off, seems possible your drill may need servicing?

Curtis Baird wrote:

I’ve been working in rock that’s mostly quartz, so I know its hard.  Previously, I might get about 7 holes.  Now I’m getting like 2.  I thought my bits were the same but now I’m trying to determine what the change is.  The tips are being ripped off, not just dulled.  Any thoughts from the gallery?

- bad batch of bits?

- harder than usual rock?

Quarzite is like sandstone in that there is a big range in actual hardness. 

In general it is all hard but some of it is just rediculous. There can be a good bit of variation on a single climb. Go slow to get the best life. Change the bit if the hole is too tight.

Power drill or by hand?

If by hand:  my partner breaks the carbide tip way more often than I do, which I believe is because he hits harder than I do.

If by power:  maybe you are pressing harder than you did before?  I doubt that's the answer, though.

Bit is likely overheating due to, as mentioned above, weak drill with more spin than impact.  What drill and how old?

Drilling quartzite recently, here’s what I found...

Basic chisel tip bits work better than the 4 cutter bits. The narrower and more even/plain the carbide tip the better. These are usually the cheaper bits too. Don’t push too hard, let the drill do the work and make sure the bit is bouncing off the back of the hole. Failure is most commonly due to overheating the tip and causing the carbide to rip off, so cool the bit periodically (I bring a little water bottle on my harness now but spit works too). Also a lower power drill (18v versus 36v, or comparing the impact energy) will take longer for each hole but the bits will last longer.
In really really really hard spots drilling a 1/4” pilot hole first is sometimes the only way to go. But if you do this you really have to drill gently when boring it out to 3/8” or 1/2” because the bit will usually bind some. 

Bill Schick wrote:

Bit is likely overheating due to, as mentioned above, weak drill with more spin than impact.  What drill and how old?

Bosch 18v Bulldog.  Brand new last year.  Was also happening with my buddy’s 36v Bosch.  Very possible I’m pushing to hard, cause I’m not paying attention hanging on that tiny hook.

Curtis Baird wrote:

Bosch 18v Bulldog.  Brand new last year.  Was also happening with my buddy’s 36v Bosch.  Very possible I’m pushing to hard, cause I’m not paying attention hanging on that tiny hook.

In that case, indeed, patience. Go a half inch at a time and pause, and let the drill do the work. No need to push super hard.

Little Man wrote:

 Hilti KB3 or KB TZ are the best way to go, but if you're using anything other than that, you'll want to be sure that hole is perfect. 

I agree this might be a contributing factor. With 5-piece powers bolts I get maybe 7 holes before they start getting too small. With the KB3 I get maybe 15 (I way over drill the depth of the hole). Looking at your location I would also expect your drilling in difficult stances and maybe pressing too hard.

You mean like this?

https://www.mountainproject.com/forum/topic/114230853/how-do-you-drill-really-hard-rock-diamonnd-drills

Consider also that not allowing dust to clear from hole as you drill gauls out the hole to larger diameter that will be less secure for an expansion bolt - and overheats the bit - bad workmanship.  Not saying that’s what is happening, but something to be aware of.

Little Man wrote:

Try Makita basic SDS bits (D-00929-25). You can find them in 25 packs on line for roughly $2 a bit which is how I buy them. Though, prices may have gone up. I've used just about every brand and style SDS between work and climbing and found that the Makita brand bits last the longest and work best in hard quartzite. Any brand works well in the soft Carolina granite and southern sandstone but even the Makita bits seem to be best. I've used them in the hardest quartzite around with no problem after having issues with all the other big brand bits. And, they're just about the cheapest out there too (when you buy them in the 25 pack)! I think it has to do with their wide flute which allow for more efficient dust extraction. Also, there's a technique to drilling that hard stone. Those expensive bits made for dealing with rebar may be good in concrete but I have found them to be less than ideal in hard rock as they don't extract the dust as efficiently. Like others said above, in hard quartzite, let the drill do the work and don't try to push too hard. Pull it out every 1/2" of so and let it clear the hole. If the rock is real hard and your bit has already seen a few holes, go in the hole with a fresh bit after drilling with a worn bit to make sure it's perfect. You'll get more life out of the worn bit and greatly reduce the chance of a bad bolt. Lower quality bolts like the Powers stud and others similar to it really don't play well with a slightly worn bit in harder rock like quartzite. Hilti KB3 or KB TZ are the best way to go, but if you're using anything other than that, you'll want to be sure that hole is perfect. 

Lots of good advice here! Also, I second using the Kb3. Especially the TZs for super hard stone because they fit a little less tightly in the hole than the regular Kb3.

Derek DeBruin wrote:

In that case, indeed, patience. Go a half inch at a time and pause, and let the drill do the work. No need to push super hard.

I had a similar problem with my old Bosch in super hard quartzite just outside of Linville. Only got 1 or 2 holes per bit at best. Switched to a small 12 volt (panasonic at the time, later a Milwaukee M12) and instantly got many more holes per bit (same ones). I don't know the mechanics but I assumed it had to do with a less aggressive hammer design.

nbrown wrote:

I had a similar problem with my old Bosch in super hard quartzite just outside of Linville. Only got 1 or 2 holes per bit at best. Switched to a small 12 volt (panasonic at the time, later a Milwaukee M12) and instantly got many more holes per bit (same ones). I don't know the mechanics but I assumed it had to do with a less aggressive hammer design.

I had the pleasure of using a Milwaukee M12 last year and seriously considering getting one of my own as a result. 

I have had good luck with the bosch bulldog xtreme bits in quartzite. I usually rotate 2 or 3 drill bits at a time to keep them from overheating, and cleaning the hole more often. I have also tried dipping them in water but found just rotating bits works well, takes a bit of patience but if the bit gets too hot its done. I have gotten as many as 10 holes with the bosch bits in quartzite, this was using a bosch 18v drill.

I think I'd just resort to toproping. The cost/benefit analysis here doesn't seem positive 

Claudine Longet wrote:

I think I'd just resort to toproping. The cost/benefit analysis here doesn't seem positive 

Well... my girlfriend dumped me, I have no social life, and I work 10 days a month full time.  So I gotta do something with my money and time.

Derek DeBruin wrote:

I had the pleasure of using a Milwaukee M12 last year and seriously considering getting one of my own as a result. 

It was great back in NC, but I had to buy a bigger drill when I moved Colorado. They seem to have a different idea on what well-bolted means here... and my old M12 just couldn't handle drillin' so many holes.