UKC

I see all these threads of folk with computer problems, so I thought I'd seek the wisdom of all concerning problems I had today as a newbie to drilling.

The first problem is that I was drilling Moy conglomerate and the pebble part is round granite stones like from a river bed. I was having a real hard time drilling them at all, only 2 to 3 holes per battery (I was trying to avoid them but was hitting under the surface). Is this unusual or is this kind of granite much harder than anything else?

The new bolts I have are just too large at the top for a 12mm bit. So I was drilling with a 12mm, then going back and drilling the outer half with 14mm. I got half way in and the 14mm drill bit jammed. The Hilti stopped gripping the bit but this may have been a safety thing to protect the motor. The bit is still there, as no way could I get it out. Have you heard of this before or is it just my incompetence?

And suggestions welcome.

In reply to Andy Nisbet:

Andy, drilling? Hmmm. 12mm bolts should go into a 12mm hole. Sounds like the bit could be old and worn down - in diameter as well as the cutting edges... That would explain only getting 2 or 3 holes per charge as well. You should get a lot more than that even drilling 12mm. Getting the bit out - I assume you've tried hitting it?

In reply to JTM:

Yes drilling! The 12mm bit was brand new, the 14mm one was old but not too worn. I was putting a lot of force pressing the drill in to get it to bite, and apparently you don't need to do that. Possibly the poor drill was as weary as I am. Yes I tried hitting it - it is well jammed. Even got a small pair of pliers from the car but that didn't work (the pliers were pretty rusty so not surprising really)

In reply to Andy Nisbet:

The first bolt I drilled was taking a while... then I realised I had the drill in reverse!

Does sound like a dodgy bit so given you are unlikely to get it back anyway, time for a new one.

In reply to Andy Nisbet: does the HILTI not have reverse! mole grips should work if not, Special bit for Granite,check your local store. you need to keep clearing it so the bit never sticks.
Good luck.
Pete

In reply to Andy Nisbet:

I assume it is a hammer drill?

In reply to JLS:

I was using Bolt-products m12 wedge anchors (thro bolts) and they had to be hammered into the hole with a bit of effort - quite reassuring really.

In reply to Andy Nisbet:

Don't know in that case. Just occasionally - and by coincidence with 12mm bolts - I've come across the same thing, but it seems more like a few rogue bolts. If they won't fit in easily I try another. If you try bashing them in when they are tight, you end up with a real mess. What Hilti is it? To give you a rough idea, in Vallorcine granite and gneiss, my old TE10a used to manage an absolute max of 18 x 10mm holes, 70mm deep. My new TE6 does up to thirty. If I was drilling 12mm, I don't know, but I'd guess maybe 10 and 15-ish.

Maybe there's something really hard in that rock? I have come across some really hard rock up by Emosson that regularly destroyed bits after 5 or 6 holes - the cutting edges that are welded(?) in used to just snap off.

In reply to Andy Nisbet: the granite lumps will/should take a lot longer. the guys here www.supertopo.com have lots of experience. The BMC technical bloke (dan middleton) has run a drilling workshop so should be able to help.

have fun

In reply to Andy Nisbet:

Just tie off the bit then climb the rest of the route on trad as punishment...

In reply to Andy Nisbet: Sorry but i have just read your post and this has REALLY got my goat.

Good god man, what the hell are you doing ? If you are going to drill and bolt a crag, then you should be doing it with all the information technique and correct new and sharp tools to hand. Peoples lives are at stake!!

What you have just stated sounds like you do not know your hilti from your dewalt !

So what are you going to do about the stuck drill bit eh... You wont be hammering it in or taking a hacksaw to it either, nice mess you've made of that one..

Quite simply you should be following the manufacturers guide lines, for the correct placement of there products.

Any engineer worth there tools will know that if you are going to drill a hard substance with a large diameter drill then you should be starting with a smaller pilot bit eg 6mm, and then working upto your finish diameter.

Please for the sake of everyones lives and for the the sake of the rock, get a proper drill with sharp new bits of the correct diameter and stop guessing.

In reply to pete123:

Yes reverse didn't work either. The drill owner has mole grips; we may try next week. Interesting about granite; I had a feeling.

In reply to JLS:

Yes a hammer drill. We moved to 14mm because no amount of hammering got the bolts fully in. Folk have complained about the previous route I drilled with 12mm. Its just the last 1cm. So we were trying 14mm at the entrance.

In reply to Redsetter:

That's fine for drilling steel, but if you do that drilling into rock, you'll get the larger bit stuck. Which by coincidence is what has happened to Andy. Drilling a smallish hole like a 12mm should be quick and easy. Obviously there is some other factor here.

Andy, maybe you should go and borrow/hire a petrol driven drill with a heavier hammer weight. I drilled quite a few 22mm holes a few years back for a short via ferrata. The Ryobi I borrowed drilled them really fast. I couldn't get one hole out of the Hilti. If you're still having problems with the diameter, consider glue-ins.

In reply to Redsetter:

You are overstating your case. I'm not leaving anything dangerous, that's why I'm asking. And all the equipment was bought by folk who know what they are doing. I'm trying to put up some easy routes with my own time and expense. The 5 I bolted last week has had double figures of ascents already.

In reply to JTM:

These are glue-ins, that's why a bigger hole doesn't matter. I just wondered if getting the bit stuck was a common problem, but it seems not. But it only got stuck when I was drilling a 14mm hole out of a 12mm hole. It seems intuitively like that could be the answer, like the bit squeezes its way in too quickly and gets stuck between sides of very hard granite. The bit (even a new one) may not have much sharp on its very edges. And I should have just drilled with 14mm and used plenty of glue; trying to have the best of both worlds could be the problem.

In reply to Andy Nisbet:

Ah, I assumed they were expansion bolts... but you don't put a 12mm glue-in into a 12mm hole - the hole must be bigger as you say for the glue. If they were 10mm glue-ins, then they'd be fine in a 12mm hole.

In reply to Andy Nisbet:

Hi Andy

I would suggest notching the opening to make sure that the bolt is slightly deeper than just flush with the surface. Also I would suggest making the inside of the bolt hole rough so that the glue is not just bonding to smooth sides of the bolt hole.

In reply to Steve Crowe:

Thanks everyone. Partly from an answer from Rab Anderson who's seen the same problem with industrial use, I'm thinking that drilling 12mm and trying to widen more than just the outer end of the hole was the mistake. This section of conglomerate happened to be 80 percent granite so it mattered. I should have just drilled 14mm because for glue it doesn't matter. Now how to get the bit out, other than tying it off as an extra runner!

In reply to JTM:

These bolts are double 6mm twisted, so there is room for glue with 12mm in 12mm. Just 25 percent of then didn't go in. But I (we) will sort it. Thanks for your comments; I'm learning.

In reply to Andy Nisbet:

George Szuca's route on Arran conglomerate had a tied off bicycle spanner for a runner.

I've never heard of a tied off drill bit.

In reply to Andy Nisbet:

This thread paints a picture - I have to see this!!!

What are you calling the route?

In reply to Andy Nisbet:

Andy, are you using Hilti SDS bits in the Hilti? I can't see how one of these could possibly slip in the chuck. If you're not using them, I suggest you try them; they are vastly superior to anything else and cut a much better hole. Sure, they are more expensive but I found that they lasted much longer and Hilti can resharpen them for you.

In reply to Andy Nisbet:

Well, fooled me at every turn there Andy! Try a big petrol drill if the Hilti isn't man enough. Also, as Chris says, I think the Hilti bits with 4 start cutting edges are much better but are about 3 times more expensive. (Jim Titt doubts this, but I've really found it to be the case.) As you say it's the safety device thst's slipping, not the bit.

In reply to Chris Shorter:

Yes I am. So there isn't a safety mechanism so that if the bit reaches something that it can't move, the system doesn't allow itself to slip?

In reply to Andy Nisbet:
Hi Andy. I will send you a detailed email about drilling this rock and the problems you have experienced later today or this evening. Cheers Neil

In reply to Ron Walker:

It could be: "stuck in the middle with you!!"

In reply to Andy Nisbet:

I have the old 24v model and I've occasionally had a drill jam if the battery is running down but I've never experienced the slipping you describe.

Have you tried contacting Hilti? I have always found them very responsive to questions.

In reply to Andy Nisbet:

Would you be so kind as to let us know where you are drilling? Exact location not required but a rough idea would be interesting

In reply to Chris Shorter:

Mine's got what Andy describes (36v model). Bit like a power screwdrver when it reaches the desired setting. Stops the motor burning out I guess.

In reply to Grimpeur ancien:

The OP says, "I was drilling Moy conglomerate".


http://www.scottishclimbs.com/wiki/Moy_Rock

In reply to Andy Nisbet:

Hi Andy

Just noticed this threead as I´m on holiday in Sicily which is a bit of an internet desert!

The bolts are supposed to be tight for the last cm, it means you can bolt overhanging rock. You fit them the last bit with a hammer!

Getting the drill stuck enlarging the hole is normal, mostly you just wrench the whole drill (machine and all) outwards and they come o.k.

Notching the eye in is neither nescessary nor desirable.

When you drill never force the drill in, you get a not-round hole which is a bit small, only apply enough force to make the hammer action work and let the drill do the job.

I´m off to drill some more rock!

Jim

In reply to jimtitt:

Of course I'm just learning, so take nothing I say too literally. I sometimes found the bolts so tight that no amount of hammering fitted them in. On the first route I drilled, some of the bolts just wouldn't go in despite violent hammering - the bolts are safe but worrying to subsequent climbers who have commented. I think it's not just me, as the locals here have started drilling the top with 14mm so they fit easily. The argument is that because you're glueing, it doesn't matter. The conglomerate at Moy is extremely hard granite in quite a soft matrix.

One hole I was drilling, I hit granite (I presume) and no matter how I tried I just could not drill any further. I used a whole battery charge and did not get in. But it was the last 1-2cm so we decided just to use a shorter bolt (but we haven't placed any yet). Even drilling with a brand new bit is hard sometimes at Moy Rock. I didn't try drilling that hole with a new bit.

I didn't want to apply too much force (drill and all) to try and get the bit out because it wasn't my drill. So it might work. But the bit was very stuck. Folks here suggested hitting it with a hammer but the hammer just bounced off like the bit was set in stone (which it was). My guess is that because the granite pebbles are so hard, the bit has distorted very slightly between two pebbles and that has jammed it.

I may well have forced the drill in too much, especially when enlarging the hole, also gone in too far with the 14mm instead of just the top.

The route is gently overhanging, which made life harder, but I had used nuts to hold me in place. And yes much of the route could be protected trad (scary though becasue the odd pebble does pop), but the start would be dangerous before you reached the corner-crack and you would still need a lower-off. So it seemed right to bolt it all. So the jammed bit is near a good nut placement, which is totally weird to me as a trad climber, but it is not a trad cliff.

I am working next week so it will be another week before I try to salvage something. Drilling the bit out could take a while as the rock is very hard (and I'm not!)

In reply to Andy Nisbet: I'll start by stating that I have no experience in placing bolts for climbing but loads in using resin and expansion bolts in industrial use.

If you need to enlarge a drill hole then you want a fairly big difference in drill bit sizes (say 6mm - 12mm) especially in the type of rock you describe where the drill will rip through the soft matrix and effectively cam into the harder chunks.

If you need a larger hole at the start you would be better off drilling the 14mm bit first and then drilling the rest with the 12mm. This would prevent the drill jamming.

The bit that's slipping is the clutch - its designed to slip at a set torque, both to protect the drill and the user.

You don't need to load the drill, the bit doesn't cut like a metal drill, it relies on the thousands of impacts from the drill to chip off tiny bits of rock/concrete which are then removed by the rotating action. Loading it wont increase the amount of impacts, has a minimal effect on the force of the impact (it does direct more of it into the rock but not much) but it does make the motor work much harder and therefore massively affects battery life.

As for removing the bit, time and repeated tapping with a hammer. Don't smash s**t out of it as this will just drive it into the rock like a giant nail. Tap the end then either side, use the drill to try and turn it either way but with no load and just repeat. I once spent about 3 hours in the early hours of the morning trying to remove a jammed bit - perseverance will win.

In reply to spearing05:

Thanks. That makes a lot of sense, and ties in with what I found. I hadn't thought about drilling a short 14mm hole first (I know Jim reckons you don't need to). Plenty for me to work on next time.

In reply to Andy Nisbet:

wrt the jammed bit, tie it off?

In reply to Andy Nisbet:

I presume it's an SDS bit, in which case maybe you could get more torque to remove it by using a large adjustable spanner on the SDS grooves rather than the drill itself? Just an idea - no personal experience of doing so.

In reply to john arran:

Yes an SDS bit. Andy Wilby, whose drill it is, has offered to go the crag and supervise. He doesn't want to attach the drill cold as it might damage it. But he has a mole wrench which might work. Otherwise he'll supervise me drilling it out. Thanks for suggestions; I'll get it drilled eventually. You might see me later in the year - I haven't forgotten about Les Enfants de la Dalle, even if I have to bring a new partner each time.

In reply to Andy Nisbet: I don't think anybody has mentioned this yet, apologies if they have; I always blow the dust out of the hole before inserting the bolt. Hilti manufacture a dust blower, sounds hi-tech but it is just a large tube with a plunger, and a hose to put in the hole, a bit like a bike pump. This makes a world of difference when inserting the bolt and also makes the final fixing safer as the bolt is gripping the stone, not the dust in the hole left over from the drilling.
Secondly, expanding a hole from 12 to 14mm is likely to trap the bit, there is simply not enough of a difference in diameter between the two holes. If you feel the need to pilot the hole then use a much smaller drill bit to do this, 5 or 6mm would be fine. Having said that there is normally no need to drill a pilot hole if you are using a quality, newish drill bit. I have drilled thousands of 22mm holes for glue-in threaded sleeves, sometimes in granite, and I never pilot the hole.
Thirdly, decent drills have a safety clutch that prevents damage to the users wrist and to the drill. Sounds like this is what helped to released the bit.
Is this the crag that Will was looking to develop before his tragic death on the Ben ?
Cheers and good luck with the routes.
Andy

In reply to AndyP:

Yes, the first two routes were either side of Will's route. I was taught to blow out the dust with a bicycle pump, cheaper for Scots, and which seems to work. I wasn't piloting the hole, just that the last section of bolt wasn't going in, so I was expanding the outside of the hole (too deeply!). But I should have drilled a shallow 14mm hole first, then the 12mm, because the other way round jams the bit (so the thread told me). Sheppy explained to me that if the bit is at all worn it might drill 11.95mm and the bolt then not fit. But the alternative which the locals seem to prefer is to drill 13mm and that seems to solve the problem. The drill is apparently fine, so it was a safety clutch kicking in. The thread has taught me a lot and the route should be completed the week after next (I'm working next week) - best 5+ on the crag.

In reply to Andy Nisbet:

>"the bit was set in stone"

Are there any young page boys live in the area?

"Excalibur" would seem the obvious route name.

In reply to JLS:


Yeah! Or 'A bit stuck here'.

Hoping for some photos when you do the route, Andy

In reply to JLS:

Excellent choice. The crag is so popular that it's only 50/50 I'll climb it first. By the time I've waited overnight for the glue to set, someone is likely to have climbed it! I could hang a mousetrap on the first bolt.

In reply to Andy Nisbet:

Padlocking a saucepan over it has been tried and tested!

In reply to Andy Nisbet:

Tape on the first bolt is a gentlemanly alternative...

Although I wait overnight for glue to set, my mate M is an expert on setting times. You've hardly had time to finish your cup of tea before he's back out there again, bagging the FA!

Mick

To help remove the stuck drill bit set the SDS drill on to rotary stop so its on hammer / impact only.

The shaking should loosen it.

In reply to Richard Wilson:

Sounds good. I'll suggest it.

In reply to john arran: Adjustable spanner does work, use a good one though, something like a Bacho or similar as the cheep ones wont stay tight enough. Be careful as with a good grip it is possible to twist the end. You can also use the drill as a kind of slide hammer (with only a very limited amount of slide) to tug the bit out.

In reply to Andy Nisbet:

A tag of material showing its a project works very well around here. People respect the work that bolting takes. Do you have to wait over night anyway? I've not done the actual bolting but helped clean and prepare a wall for some sports routes and my friends followed Hilti's advice on the glue setting and it was just a few hours. They drilled in the morning had lunch and did some other routes elsewhere on the crag and then went back and 'sent' in the afternoon sunshine!

BTW, on Finnish granite my mates were only getting IIRC 3 or 4 holes per battery. Our Aussie friend was saying back home in the Blue Mountains he could equip a the 30 metre pitch with 10 plus bolts in it with the same drill and battery. Shows how much difference the rock can make.

In reply to Andy Nisbet:

Try removing the drill bit with some stillsons borrowed off a plumber if you have none. Pull them the opposote way to the drill rotating in case it is the screw on the drill that is jamming.

If all else fails, larksfoot or clove hitch a sling on the drill and use it as a runner.

In reply to Andy Nisbet:
I'm 99% certain your bit has hit the side of a hidden granite pebble at an oblique angle and failed to bite into it, thus drilling along the side of it until the bit was forced to bend and seized up against the side of the hole. My colleagues at work have exactly this problem when trying to drill holes through walls of granite farmhouses for cables - you're lucky the bit didn't break. All advice given by others above is worth trying to free it. I'd hate to drill into granite conglomerate, it's bad enough drilling into the solid granite we have here (reputed to be the hardest in britain, a significant percentage of the granite kerbs and steps in London are made of it). If you've not looked yet read the boltproducts website.