drilling out timing bolt...

rockdemon

rockdemon

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Staff member
Hi all.

Trying to drill this bolt out but the hss drill bits arent making a dent in it. I'm going to carry on for ten minutes but i wanted to check that i wasnt missing something? Could there be a rusted particularly hard bolt in or something like that?

Rich
 
Nope the timing cover bolt that was sheared in the block. Actually managed to make a dent with the drill - but it actually has the appearance of having been welded in. The drill bit snapped when it got to about 3 mm in after about an hour of drilling. So unless someone has a bright idea i think i've just scrapped the engine, unless anybody has a bright idea?
 
I had the same problem when trying to drill out some brackets for my chassis tilter. The bolts were about 1mm wider than the holes so I had to drill them out. I broke two of my 10mm drill bits before going up to the local hardware shop and buying a better drill bit. I think it was a cobalt one, but may be wrong, it was a long time ago now.

Also, I had some cutting oil in the garage which I used on the nibbler when making all of the repair panels for Sparky. Tried that as well, and it was a lot easier.

Richard
 
The actual end of the bit is embedded and theres nothing pretruding for me to pull at. I'm guessing even the world's hardest drill bit isnt going to want to drill through an hss drill bit?

Rich
 
oh dear, I haven't had any experience with tungsten or cobalt drill bits, what I've googled so far to the question "drilling a broken drill bit" is that while the tungsten drills are just a tungsten coating on the tip of a normal HSS drill bit, some are saying that a cobalt drill bit may be a better option, and also just grinding it out with a die grinder but grinding may be a long process if using a dremel tool of such type. As you say if it has been welded before in an attempt to remove the broken stud you are probably dealing with a hard piece of weld material which is why its taking as long as it has to drill 3mm of material away. I'd be inclined to give a cobalt drill bit a go (google about it first) and I'd also think about making up a plate to act as a guide which can be bolted to the front of the block to keep a drill centered (probs about a 1/4" or 3/8" plate). You could also go the 'welding a nut on' path as the heat you put into the broken stud when welding may help to loosen the remaining broken stud.
Scott
 
Aaargh. I hate snapping drill bits off. They are very brittle so you might have some luck with a decent punch and breaking it up into bits. An investigation with a screw extractor might help with the drill, but in my experience they're rubbish for removing the studs.

If there's enough to weld a nut in then do that, the heat helps unstick it as well.

Feel for you, I've just done this job and it was proper scary drilling it out.

I went to an ironmongery and bought some quality (expensive) drills and didn't go smaller than a 4mm.
 
I meant to use the cobalt drill bit and cutting oil to drill the rest of the bolt out, I didn't realise that the drill bit was now jammed in there.

Can you get a decent pair of pin nosed pliers into the flutes and try to wind it out anti clockswise, otherwise as Midget says, try to break it up and pull it out in bits.

Best of luck with it, I don't envy you :?

Richard
 
dont think the bit is coming out unless i drill with a wider bit to give better access. it's snapped a mm or so in...
 
Have had the exact thing happen to me in the past, broken drill bit lodged in end of sheared stud.
A right pain in the @rs* But don't despair.
As others have said break up the HSS bit with a punch or similar hardened piece of steel this can take an extremely long time to do... several hours the last time I had to do this and using very narrow headed long nose pliers also mentioned above by others work the remainder of the bit end out.
After the bit is out I would most certainly use a drill guide and Tungsten drill with either oil or a good cutting fluid to drill the remainder of the stud and as I think Stina recommended in another thread use successively larger drill bits until just the original bolt threads are left in the hole which you can then break out with a right angled scriber, far better than a helicoil.

I feel your pain :(

Graeme
 
Just thinking what I mentioned earlier about using a die grinder with a grinding tip, you could just grind the broken drill bit out if it hasn't gone in too deep as you say a mm or so, then start drilling again once the hard drill bit has been ground out and even grind the hard part away until you're back to softer material, but some sort of guide would be good to prevent the drill wandering into softer aluminium as you go...hope this is of some use, any pics you can post to see where you are at so as to give us an idea for more tips we can give you?
Scott
 
So - i'll attempt to first make a plate as a guide. I'll then widen the hole to get a punch in there and try and get the bits out. Then we'll start again with a cobalt bit.

I was ready to start taking the engine out yesterday or sell to it so went for a bike ride instead.... Now i can start again with a fresh plan later in the week.

Thanks guys :)
 
Hi Rich , when you have the broken drill bit out and you've made up your guide plate and start drilling again with successively larger bits consider using an anti clockwise bit on the larger sizes to help loosen the remnants of thread . once you have a guide hole through in the dead centre the battle is won ! Don't loose heart :D
 
Hmmm - where to find a left handed cobalt bit... That's a good point.

Thinking i should be able to create a plate using a timing cover gasket as a pattern.

Rich.
 
Ah!
I presume you have actually removed the timing cover?
Had this happen with a water pump bolt!
Got a smaller diameter nut and plug welded it on,then welded a larger nut to that!
Use a higher heat setting than for sheet metal,and if poss have a practice go with a spare nut and bolt!
Giving stubborn nuts/bolts a slight tighten first can sometmes crack the grip they have in whatever it is they are stuck in!
All the best!
 
If it's slightly proud or flush with the block and you can get there, then do like Pilkie says. The heat of the welding and the subsequent contraction as it cools often allows you to turn it out with your fingers once it cools.
If it's sub-surface and the bit is broken, then you will need a centre punch, a hammer and lots of patience, plus neighbours/family that are swearing tolerant. :mrgreen: Lots of lining up and bashing on the edge of the flutes will either loosen it or break it up and then you can get it out using surgical clamps or small needle nosed pliers.

Then, you need to carefully centre the next drill and start with the smallest one you are comfortable with and reqular squirts of Q-20 or similar to lube and cool it, keep it as square to the block as you can, because if you drill through the side of the bolt it becomes a ball-ache to turn it out the block later and will require possible Helicoiling. Work your way up in steps until you are half the diameter of the bolt, and if you can get them use Left Hand twist bits because the heating and squirts of oil should have loosened it to the point where the act of drilling will turn it out all by itself. If you don't have a LH bit, then an Eezi-out will do the job with a bit more cursing for good measure.
Remember, Eezi-outs are hardened so they can work, but that makes them brittle like drill bits. Have a read of this...
http://www.brokentap.com/easy-outs.html
If all else fails, then you have this to fall back on, but it will be egine out and stripped down.....
http://en.wikipedia.org/wiki/Electrical_discharge_machining
 
Worst case scenario if you can't get it out clean and destroy the hole would be to make a simple threaded aluminium plug, drill the hole oversize and tap it, screw the plug in with loctite, redrill and re-tap the hole for the timing cover bolt, job done (that's what I'd do but I guess I've got a few more tools to hand!)
 
Another method for removing the bolt intact is to drill out maybe 3/4 to 4/5 the bolt diameter and then use a punch to collapse the remaining outer of the bolt so that the threads can be removed in one go but the ease of collapse and removal maybe a bit dependant on the grade of bolt hardness, I have used this many times but mainly on mild steel bolts.
I used this method on a Fiat many years ago with a hardened bolt and found it a bit of a pain to collapse.

Graeme
 
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