Drill out bolt - broken bit.

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Tue 1 Feb 2005 20:17
Drill out bolt - broken bit. - SimonJ
Had to drill out a bolt to remove (wouldnt turn at all, despite alot of persuasion, but rather remove the head.)

Head dropped off and item removed. I then had a small hole drilled all the way through the bolt, but cant get last bit out, before I can try the new bolt. To make matters worse I have now broken off a small drill bit in the hole!

Left job for today - going dark.

Any idea of how to proceed?

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Tue 1 Feb 2005 20:40
Drill out bolt - broken bit. - Hugo {P}
I assume you're using bolt removers. These are tapered LH thread screws you can get from any motor factors.

Suggest you give it a good soaking in wd 40 before you go back to it. Then drill a fresh hole and try again.

If this doesn't work, use a firm bit to drill a series of shallow holes in line to get a slot. Use a big hefty slotted square shafted screwdriver with a spanner to give extra leverage to ease the rest of the bolt out.

When you do this use a rocking motion on the remainder of the bolt to loosen it.

Hugo

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Tue 1 Feb 2005 21:20
Drill out bolt - broken bit. - storme
nice answer,,,every one should print that for later needs :)
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Tue 1 Feb 2005 21:27
Drill out bolt - broken bit. - Civic8
You didnt mention what bolt you are trying to remove.From your post it sounds like head bolt..But could be meant as (easier to remove with head off)Please specify what you mean!
--
Steve
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Wed 2 Feb 2005 08:51
Drill out bolt - broken bit. - Cliff Pope
" Head dropped off and item removed. I then had a small hole drilled all the way through the bolt, but cant get last bit out, before I can try the new bolt. To make matters worse I have now broken off a small drill bit in the hole!"

Some definitions needed here for clarification:

"Head" = cylinder head or head of bolt?
"bit - (1)" = bit of the bolt, or drill bit?
"bit (2)" = drill bit, as stated. But when you say broken off, do you mean it is now stuck in the middle of the stump of the bolt?

At the point when you had got most of the bolt out, was there any thread available, despite the stump still being in place?

What I am getting at is, what kind of bolt is this? How loaded is it? Is it vital to get all the stump out, or is it lightly stressed and partial threading would do? (Not if cylinder head, obviously!)

If you now have a broken drill bit jammed in the bolt stump, then you have a problem. I have been there, and all too often the next stage is just a succession of broken bits, because they are very hard and brittle and impossible to drill into.
If it was only a small pilot hole you may be able to drill another hole at the side, but that will limit your scope for widening the hole in order to use a sizable extractor. If the extractor is not as large as possible it will snap too, and they also are impossible to drill out.
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Wed 2 Feb 2005 12:03
Drill out bolt - broken bit. - SimonJ
All sorted.

Was brake disk bolt in hub. On inspection this morning drill bit was not stuck solid in the hole (see daylight in the gaps). With a pit patience i could tap the drill bit with a punch to loosen it, and push it back from the hole in the other side of the hub. Came out quite easily.

Hole drilled was smaller than original bolt. Redrilled with correct size bit, and rethreaded to fit replacement (original) bolt.

Not as bad as first feared! Question is though, why was the bolt so hard to come out when it should only be tightened to 10nM
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Wed 2 Feb 2005 18:56
Drill out bolt - broken bit. - mjm
Temperature cycling, corrosion, brake dust, salt spray, all sorts of reasons. The main thing is you got it out ok.
ps Sometimes the gods of car diy just don't like you-------
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Wed 2 Feb 2005 21:05
Drill out bolt - broken bit. - Richard J
If a nut or bolt is seized; I find it usually works best to 'shock' the fastening undone. No, I don't mean creep up behind and say 'boo', but to apply a sharp heavy tap to the wrench. If you just apply increased leverage with a large pipe or suchlike, you're more likely to shear the thing off. I think the technical explanation is that you have to overcome the 'sticking' caused by rust or paint or whatever. I bought one of those impact wrenches sold for undoing wheel nuts for about £25 from machine mart and these are brilliant for undoing rusty suspension bolts etc.(Comes with a selection of proper impact sockets too.)
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Wed 2 Feb 2005 23:40
Drill out bolt - broken bit. - Aprilia
If a nut or bolt is seized; I find it usually
works best to 'shock' the fastening undone.
I bought one of those impact wrenches sold for undoing
wheel nuts for about £25....


I might get one of those. I have a CP Air pneumatic impact wrench, but it is old and worn. These new electric ones look quite tempting.
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Thu 3 Feb 2005 08:31
Drill out bolt - broken bit. - Cliff Pope
I agree Richard. Impact wrenches are wonderfull. In a limited space, or if you haven't got one, carefully applied hammer blow is often effective. Either hitting the bolt axially, or sideways with a cold chisel. One is not trying to break it, just give the short sharp shock that frees it from corrosive locking.
It is often well worth applying WD40 etc as soon as any movement has been achieved, and then leaving it. Sometimes doing the bolt up again a fraction, and then undoing, works too. This is useful if the bolt feels very tight even when broken out. Working it backwards and forwards, with plenty of WD40, helps it to loosen up and minimises the risk of fracture.
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Fri 4 Feb 2005 09:10
Drill out bolt - broken bit. - Claude
I did this years ago, partly drilled out a cylinder head stud, it broke off down the hole and then I broke the drill bit in the bottom of the hole. So for a very long time I drove around with a slightly warped cylinder head and a lot of gasket compound until eventually I had the engine rebuilt. At that point the remains of the broken stud, together with the broken drill bit, were removed by spark erosion in a few minutes. So, as far as I'm concerned, that has to be the most effective solution.
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Fri 4 Feb 2005 09:23
Drill out bolt - broken bit. - AR-CoolC
removed by spark erosion in a few minutes

Whats that then??
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Fri 4 Feb 2005 10:43
Drill out bolt - broken bit. - martint123
Whats that then??

Absolutely brilliant (if expensive)

www.wmccm.co.uk/WMCCM/DesktopDefault.aspx?tabindex...8
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Fri 4 Feb 2005 13:39
Drill out bolt - broken bit. - Claude
For example www.sheenspark.co.uk but you will get lots of responses on Google if you type 'spark erosion'
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Sat 12 Feb 2005 15:03
Drill out bolt - broken bit. - madux
Been there done this loads of times in the past - usually with steel bolts sheared off in (Japanese) aluminium casings.
I've heard spark-erosion described as a sort of "reverse osmosis",
which I think is like un-welding something.
Best thing to do is hang around outside your local engineering shop until you see a guy in overalls having a fag-break. For a tenner, he'll put 4 million volts through your bolt in his tea-break!
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Sat 12 Feb 2005 16:06
Drill out bolt - broken bit. - buzbee
Spark erosion is machining process using a specially shaped piece of metal and controlled current and movement. It needs proper setting up on a jig. You do not just flash it.
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Sat 12 Feb 2005 16:09
Drill out bolt - broken bit. - buzbee
oops! Just looked at martint123's link above. That explains it all.
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Thu 20 Jun 2013 21:13
Drill out bolt - broken bit. - Jackk39

xxxx can remove broken bolts atc even with broken extractors. Equipment very dear so Cheapest to send items to them they also do Helicoils

(Edit - no free advertising.)

Edited by Avant on 21/06/2013 at 23:16

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Sat 22 Jun 2013 00:31
Drill out bolt - broken bit. - focussed

I was trained to use a spark erosion machine during my apprenticeship - truly amazing what can be done with one of these. Drill and tap a threaded hole in hardened die steel, and as said before remove broken drills and taps, machine an internal spline in hardened steel, very specialist and expensive machinery, if I remember correctly the machine was Swiss made.

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Sun 23 Jun 2013 07:58
Drill out bolt - broken bit. - Peter.N.

I have had a 100% sucess rate by welding a nut onto the broken bolt, even if its broken off flush you can still weld through the middle of the nut. The heat helps to release it and the nut gives you much better purchase and it doesn't take long.

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Mon 24 Jun 2013 14:41
Drill out bolt - broken bit. - Duncan112

These can also be a life saver!! http://www.tracytools.com/hs-drill-sets?product_id=707

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Mon 24 Jun 2013 19:18
Drill out bolt - broken bit. - galileo

Another option for broken drill bits I used was a hollow diamond tipped drill - drilled cleanly round the outside of the broken bit. Only cost £9.99 on Ebay.

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