What's the best drill bit to use for broken stud?

wobbler65

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Have to remove a broken stud on my 06 GSA , bottom bolt on the diagonal bar under the tank that then links to the rear frame and goes into the engine block , it snapped just below the surface so cannot get a nut onto it or weld , tried ez out and its been well soaked with penetrating stuff , have managed to drill 20mm out but still have 20mm to go and im getting through drill bits like their smarties .

read loads on technique etc and have started small and then large but the last 20mm is out of reach for my small drill bits and I really do not want to have to take the engine out .

If im lucky I will be able to retap to M10 but if not have next size on standby ,

whats the best drill type to use , hss , cobalt etc as this bugger has to come out at the weekend so I can put the old girl back on the road after a year out .
 
You need long drills not easy to find dormer presto are some of the best Iv got a few try the web someone must sell them but don't buy cheap ones I bent a drill bit the other day they should snap not bend lol :confused:
 
Have to remove a broken stud on my 06 GSA , bottom bolt on the diagonal bar under the tank that then links to the rear frame and goes into the engine block , it snapped just below the surface so cannot get a nut onto it or weld , tried ez out and its been well soaked with penetrating stuff , have managed to drill 20mm out but still have 20mm to go and im getting through drill bits like their smarties .

read loads on technique etc and have started small and then large but the last 20mm is out of reach for my small drill bits and I really do not want to have to take the engine out .

If im lucky I will be able to retap to M10 but if not have next size on standby ,

whats the best drill type to use , hss , cobalt etc as this bugger has to come out at the weekend so I can put the old girl back on the road after a year out .

Why we're you taking that bolt out in the first place,

Slow the drill right down spray cooling oil on take your time, have some coffee in between, had to drill two bolts out on my gs 1150 rear frame took three days to do one, the other was halve a day for some reason,
I used aldi bits I've got a few boxes handy just in case
 
I find that cheap bits tend to shatter on awkward jobs like this. A fragment jammed down the hole is game over for drilling.
I've had success with re ground masonry drills. Grind the tip to a metal cutting profile and use LOTS of cutting /cooling oil.
If the newly drilled out hole isn't too large a thread insert can help. Something like a Timesert fastened in with high strength thread lock. This is an example http://www.carrlane.com/Catalog/ind...006280B1713050245221E0107070F1A3C3B285356445B I have not used this brand.


Sent from a widget that can't spell.
 
I can't add to that post for some reason. It helps a lot if you can make a jig block or plate to keep the drill aligned. Also masonry can be more easily found in longer lengths


Sent from a widget that can't spell.
 
Dormer HSS drill bits and discard as soon as they lose their edge. Start drilling with a centre bit. Then use a 3mm bit to the required depth. Work upwards in 1mm sizes. Drill as slowly as possible with a firm pressure applied to the drill. Use plenty of cutting fluid or a thin oil. If you are doing it correctly, the swarf should come off like spiral springs.

The mistake most make is that they drill too fast with blunt bits and no cutting fluid.
 
thanks guys

all really helpful , only reason the bolt had to come out was to get to the alternator which had seized and had the usual issues with corroded bolts on the alternator cover that wouldn't come off and bugger all space to get to anything .

This will not beat me and she will ride again.
 
Cobalt steel bits, loads and loads of coolant, slow speed and gentle pressure not over forcing the bit. Ideally use a left handed drill bit if you can get one with the chuck rotating backwards so if it bites it might turn out the threaded part if you are lucky.
 
If you are asking this question, you should not be attempting the job, but leave it to a pro, who would find it easier to do if you haven't already made a rat's-ringpiece of the job by following 'advice' from a few non-pros on a forum....... :D
 
Big problems happen when the bits blunt then burnish the cutting face, its just a few thou but can be proper hard, sometimes centre punching the burnished face can encourage the new bit to bite again, once its cutting again, keep it slow, keep it cool.
 
you can get a left handed drill bit (not a wind up)when you drill the stud they normally unscrew the stud as they grip


http://www.ebay.co.uk/itm/Left-Hand...Home_Garden_PowerTools_SM&hash=item3a907bad8a

are you suggesting that as the drill 'bites' into the stud it'll wind it out??

Best of luck with that one mate :bow - a drill chuck only just holds the drill bit to create drive, if it held it any tighter it'd snap your wrist if it 'snagged'

back to the problem- why not use a 'stud extractor'?? now one of these may just get it out if you have not knackered it already. these extractors get TIGHTER the further you can wind it in, in fact that tight that the stud gives up and starts turning out
 
are you suggesting that as the drill 'bites' into the stud it'll wind it out??

Best of luck with that one mate :bow - a drill chuck only just holds the drill bit to create drive, if it held it any tighter it'd snap your wrist if it 'snagged'

back to the problem- why not use a 'stud extractor'?? now one of these may just get it out if you have not knackered it already. these extractors get TIGHTER the further you can wind it in, in fact that tight that the stud gives up and starts turning out



they can turn the stud out, once you have drilled it sufficiently to remove the pressure, they won't generally though, stud extractors will only work, if you can get a good purchase on and you can heat the stud up to a cherry red, but if you could do that, then you should have before the stud snapped,

on Gs'ers I normally just end up drilling progressively bigger, until I can either pick the remaining threads out and re Tap, or if it's slightly off centre, drilled out to helicoil size and re Tapped,

a good centre punch is an essential start, get it in the centre of the stud and keeping it straight and true is much easier,

had to drill out 6 studs this morning on a boxster, not fun!
 


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