Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Drill bits - which for snapped bolts?

Reply to topic
Bike Chat Forums Index -> The Workshop Goto page 1, 2  Next
View previous topic : View next topic  
Author Message

MG#43
Nova Slayer



Joined: 03 Mar 2007
Karma :

PostPosted: 17:28 - 12 Oct 2021    Post subject: Drill bits - which for snapped bolts? Reply with quote

Hi,

I've got all 8 exhaust header bolts to remove, my drill bits are already shot, as are the set (the sizes that i need right now) I bought from Aldi yesterday, of which i was expecting much, but did an ok job while they lasted.

Before i buy more I'm just wondering what tricks I'm missing here...

10 years ago a work pal leant me some Berylium tipped drill bits he said he got from QVC but were unavailable anywhere else. He swore by these when i had a similar issue, I didn't believe a word of it, when i tried it went straight through a 10mm steel bolt within a few minutes.

I cannot find such drill bits or am missing something by the name? They had a noticable grey coated tip, like they were dipped in something from out of space or something...

I may try reverse bits once the holes are nearing the whole diameter to try and avoid re-tapping them...

Let me know your approaches if you would, thanks! Mark Very Happy
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Fat Angry Scotsman
World Chat Champion



Joined: 12 Jan 2021
Karma :

PostPosted: 17:34 - 12 Oct 2021    Post subject: Reply with quote

You might have had carbide drill bits and just assumed the difference in colour was a coating but it was actually the carbide part. Carbide is dark grey.
____________________
PRESENT: 2018 BMW S1000XR SE Sport.
PAST: 2009 Kawasaki ER-6F. 2021 Zontes ZT-125U.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Nobby the Bastard
Harley Gaydar



Joined: 16 Aug 2013
Karma :

PostPosted: 17:46 - 12 Oct 2021    Post subject: Reply with quote

Ideally use reverse twist bits. Then have a tendency to undo seized.bolts.obviously you need a bi directional drill.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050
 Back to top
View user's profile Send private message You must be logged in to rate posts

virus
World Chat Champion



Joined: 17 Aug 2006
Karma :

PostPosted: 17:49 - 12 Oct 2021    Post subject: Reply with quote

You'll easily notice the difference in weight between a solid carbide drill bit and a carbide coated HSS bit. Solid carbide bits are about twice the weight.
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

sickpup
Old Timer



Joined: 21 Apr 2004
Karma :

PostPosted: 17:52 - 12 Oct 2021    Post subject: Reply with quote

Safer to weld a nut on than drill the studs.

MG#43 wrote:
Hi,

I've got all 8 exhaust header bolts to remove, my drill bits are already shot, as are the set (the sizes that i need right now) I bought from Aldi yesterday, of which i was expecting much, but did an ok job while they lasted.

Before i buy more I'm just wondering what tricks I'm missing here...



Buy a drill bit sharpener maybe?
 Back to top
View user's profile Send private message You must be logged in to rate posts

WD Forte
World Chat Champion



Joined: 17 Jun 2010
Karma :

PostPosted: 18:11 - 12 Oct 2021    Post subject: Reply with quote

Yep, tacking a nut onto a sheared off bolt/stud or oversize nut
on a rounded off head can often be a good painless option.
I reckon I've had a say 85/90% success rate this way

When I've had studs shear off despite this, the first important thing is
find and centre punch the central axis of the stud bolt as accurately as you can.
Drills wandering off axis and eating into head material can lead to depression alcoholism and drug abuse.

A 3mm pilot drill on axis will help keep later/bigger drills online

Not trusting my Aldi set for one job I nipped down to Screwfix
and bought some Cobalt bits of 3mm and 5.5mm which worked well enough with cutting fluid on 6mm bolts.
Personally I've never had much luck with easy outs and reverse bits so I tend to just helicoil the feckers
____________________
bikers smell of wee
 Back to top
View user's profile Send private message You must be logged in to rate posts

A100man
World Chat Champion



Joined: 19 Aug 2013
Karma :

PostPosted: 18:38 - 12 Oct 2021    Post subject: Reply with quote

Best drill bits I've bought locally were De Walt Extreme from Screwfix. 3mm to get started as WD says..

.. I did also fall for the left handed drill gag too but the stud remnants never neatly backed out as it was supposed to on the one I tried.
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600
 Back to top
View user's profile Send private message You must be logged in to rate posts

MCN
Super Spammer



Joined: 22 Jul 2015
Karma :

PostPosted: 04:43 - 13 Oct 2021    Post subject: Reply with quote

For hard metal, work-harded steel, stainless steel fasteners a wonder tip is a masonry drill bit with the tip ground into a cutting edge.
(Masonry bit tips are blunt chisel edge so will not cut. They are designed to resist impact.)

Only issue is that the bit can wander.
To deal with that the sides of the carbide insert need To be trimed to the same diameter as the shank.
____________________
Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Robby
Dirty Old Man



Joined: 16 May 2002
Karma :

PostPosted: 09:15 - 15 Oct 2021    Post subject: Reply with quote

Solid carbide bits will get through anything. They are more expensive and harder to find than other bits, but you can now get them on Amazon.

Cobalt steel is fine for drilling mild steel and not as brittle as carbide.

If you are doing all 8, I would take the head off and do it in a pillar drill. Replace with mild steel studs and brass nuts to avoid this problem next time.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Fat Angry Scotsman
World Chat Champion



Joined: 12 Jan 2021
Karma :

PostPosted: 09:48 - 15 Oct 2021    Post subject: Reply with quote

Carbide is relatively inexpensive considering what it is. I get mine here:

https://www.shop-apt.co.uk/carbide-drills.html
____________________
PRESENT: 2018 BMW S1000XR SE Sport.
PAST: 2009 Kawasaki ER-6F. 2021 Zontes ZT-125U.
 Back to top
View user's profile Send private message You must be logged in to rate posts

MG#43
Nova Slayer



Joined: 03 Mar 2007
Karma :

PostPosted: 10:18 - 15 Oct 2021    Post subject: Reply with quote

Fat Angry Scotsman wrote:
Carbide is relatively inexpensive considering what it is. I get mine here:

https://www.shop-apt.co.uk/carbide-drills.html


Thanks, I think I'll try this route! Knowing the diameter I'm dealing with is an 8mm tapped, what sizes should i build up with?

2.5
4
7

thoughts?

Was planning on trying a reverse bit at this point to see if they will free themselves and avoid me re-tapping...

Will i get away with one each?

Thanks!
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

MCN
Super Spammer



Joined: 22 Jul 2015
Karma :

PostPosted: 15:45 - 15 Oct 2021    Post subject: Reply with quote

MG#43 wrote:
Fat Angry Scotsman wrote:
Carbide is relatively inexpensive considering what it is. I get mine here:

https://www.shop-apt.co.uk/carbide-drills.html


Thanks, I think I'll try this route! Knowing the diameter I'm dealing with is an 8mm tapped, what sizes should i build up with?

2.5
4
7

thoughts?

Was planning on trying a reverse bit at this point to see if they will free themselves and avoid me re-tapping...

Will i get away with one each?

Thanks!


m8 tapping size drill 6.9 -7.1mm (depending on thread pitch).

Issue of drilling to the tapping size is that as you get near to the thickness of the thread, the thread pulls away from the threaded hole and can push the drill bit off course. (If you can make a Jig to keep the drill bit in-line it can help. 10mm thick steel with your pilot hole size and a hole that you can bolt it onto the surface.)
With small 8m sizes one has to be very gentle to try and control drift off centre. If you notice the old stud begin to break away stop drilling and try to waggle the broken stud out. The effect of removing the central core of the stud is usually enough to weaken the stud's grip on the hole.
Lots of coolant and reduced pressure to help accuracy and save the drill tip/edge.
____________________
Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

virus
World Chat Champion



Joined: 17 Aug 2006
Karma :

PostPosted: 16:12 - 15 Oct 2021    Post subject: Reply with quote

Be very careful using carbide drills in a freehand pistol drill. They are brittle and will not accept any side loading like you can get away with on a HSS/Co drill. If your going to use carbide then use at least a drill guide if not a pillar drill.

And deffo wear eye protection, IF the carbide goes pop you sure as hell dont want it going in your eye.
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

WD Forte
World Chat Champion



Joined: 17 Jun 2010
Karma :

PostPosted: 16:32 - 15 Oct 2021    Post subject: Reply with quote

Going back to the original post, I'm wondering if we've got the usual
half a story.
Are we to assume all 8 bolts/studs have sheared off?
8x Rounded off heads or hex sockets maybe?

pics or gtfo
____________________
bikers smell of wee
 Back to top
View user's profile Send private message You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :

PostPosted: 18:54 - 15 Oct 2021    Post subject: Reply with quote

virus wrote:
Be very careful using carbide drills in a freehand pistol drill. They are brittle and will not accept any side loading like you can get away with on a HSS/Co drill. If your going to use carbide then use at least a drill guide if not a pillar drill.

And deffo wear eye protection, IF the carbide goes pop you sure as hell dont want it going in your eye.


As John says carbide is not meant for hand drilling and the chances of breaking are high. The chances of removing broken carbide very low.

Any good HSS drill bit will drill the bolts out. The weld-a-nut-on trick is certainly the most likely to work if you have any stud protruding.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

virus
World Chat Champion



Joined: 17 Aug 2006
Karma :

PostPosted: 22:59 - 15 Oct 2021    Post subject: Reply with quote

WD Forte wrote:
Going back to the original post, I'm wondering if we've got the usual
half a story.
Are we to assume all 8 bolts/studs have sheared off?
8x Rounded off heads or hex sockets maybe?

pics or gtfo


Seconded. Dont go ham at it with a random drill, show us some pics. Hex heads are great for this because you can easilly drill just the head off which means you can remove the collet and therefore the tension, this often means the remnant of bolt now will wind out with molegrips. If it doesnt then welding a nut over will heat it enough to break the corrosion and you can then wind it out.
____________________
own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :

PostPosted: 05:59 - 16 Oct 2021    Post subject: Reply with quote

Only bike I ever had 8 snapped exhaust studs on was a 600 Bandit. If it's one of those then drilling is the answer.

Stainless cap heads might seem like a good idea for exposed exhaust manifold bolts but only if you use the correct grade. Bandit ones used through winters rot away until the snap off with a stern look.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

MG#43
Nova Slayer



Joined: 03 Mar 2007
Karma :

PostPosted: 11:28 - 18 Oct 2021    Post subject: Reply with quote

Full story, rotten rusted bolts, i used an angle grinder to remove the bolts flush against the mounting holes. I've asked a welder to weld a bolt onto the remaining studs before and it was a 2 our out 2 fail so this is a waste of time as there was no enough stud left to work with. Previously my mechanic (car) removed two earlier in the year on another engine by drilling out then re-tapping, he charged me £50, which i was happy with, I'm not paying that x4. He used a std drill and an endless supply of drill bits. I don't have this luxury nor am I paying someone else to do this as the engine is a spare and i'll sell it on when done, i want to figure it out in a way i can sort myself and repeat. Thanks for all the responses...!



virus wrote:
WD Forte wrote:
Going back to the original post, I'm wondering if we've got the usual
half a story.
Are we to assume all 8 bolts/studs have sheared off?
8x Rounded off heads or hex sockets maybe?

pics or gtfo


Seconded. Dont go ham at it with a random drill, show us some pics. Hex heads are great for this because you can easilly drill just the head off which means you can remove the collet and therefore the tension, this often means the remnant of bolt now will wind out with molegrips. If it doesnt then welding a nut over will heat it enough to break the corrosion and you can then wind it out.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

sickpup
Old Timer



Joined: 21 Apr 2004
Karma :

PostPosted: 13:40 - 18 Oct 2021    Post subject: Reply with quote

MG#43 wrote:
I've asked a welder to weld a bolt onto the remaining studs before and it was a 2 our out 2 fail so this is a waste of time as there was no enough stud left to work with.


Next time try welding a nut on.

As you have cut the bolts flush, I really have no idea why you would do this the answer is to weld a nut on.
 Back to top
View user's profile Send private message You must be logged in to rate posts

MG#43
Nova Slayer



Joined: 03 Mar 2007
Karma :

PostPosted: 15:04 - 18 Oct 2021    Post subject: Reply with quote

As I said I witnessed this on 8-10mm of rusted remaining thread, it may seem like the most obvious thing to you, but 1: no welding gear, 2: i'd need to take the engine to someone who has welding gear. 3: I've been down this road before as I said and it failed, to state it would work 8 times out of 8 when i've already seen it failed 2/2 times would not be a sensible approach, but of course in theory you are right, but we need to think beyond that now.... Very Happy

sickpup wrote:
MG#43 wrote:
I've asked a welder to weld a bolt onto the remaining studs before and it was a 2 our out 2 fail so this is a waste of time as there was no enough stud left to work with.


Next time try welding a nut on.

As you have cut the bolts flush, I really have no idea why you would do this the answer is to weld a nut on.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Polarbear
Super Spammer



Joined: 24 Feb 2007
Karma :

PostPosted: 17:24 - 18 Oct 2021    Post subject: Reply with quote

I'm a fan of cobalt drills. Because as said they aren't as brittle as carbide but better than HSS. Plenty of cutting fluid and don't overheat them.

Just don't buy a set of drills from ebay for £4.99 and expect them to do anything other than resemble plasticine. Thumbs Up
____________________
Triumph Trophy Launch Edition
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

stinkwheel
Bovine Proctologist



Joined: 12 Jul 2004
Karma :

PostPosted: 21:41 - 18 Oct 2021    Post subject: Reply with quote

A carbide centre drill can be handy to get a start right in the centre or to punch through a hardened skin if you've overheated a stainless fitting by spinning a drill on it. It'll only drill in a couple of mm but will bust through anything, if you break it, it's unlikely to leave much stuck in the hole.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.
 Back to top
View user's profile Send private message You must be logged in to rate posts

kramdra
World Chat Champion



Joined: 28 Oct 2010
Karma :

PostPosted: 17:14 - 09 Nov 2021    Post subject: Re: Drill bits - which for snapped bolts? Reply with quote

The tapping drill for M8 is 6.8mm, not 7.1mm as mentioned earlier.

@Stinky where are you buying carbide centre drills cheap enough for abuse in a cordless?

MG#43 wrote:

Before i buy more I'm just wondering what tricks I'm missing here...


Cheap aldi/lidl drills are adequate but if your using them wrong the last thing you want is harder and more brittle bits. It sounds like you are running them without adequate pressure, or, too fast for the pressure you can apply. This heats up the bit and blunts. You need decent thickness of chips to remove the heat. If the chips are paper thin or powder your drills will not last. Cobalt and carbide are less sensitive to overheating but are not requited if HSS are used properly.

The benefit of carbide is it will not bend. HSS is very bendy. You get a very straight start to the hole which will guide a normal drill. I use 2 and 3mm carbide stub drillls for piloting holes, often in a cordless.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Fat Angry Scotsman
World Chat Champion



Joined: 12 Jan 2021
Karma :

PostPosted: 17:36 - 09 Nov 2021    Post subject: Re: Drill bits - which for snapped bolts? Reply with quote

kramdra wrote:
The tapping drill for M8 is 6.8mm, not 7.1mm


Only if you're tapping an M8 x 1.25 coarse thread. The M8 x 1.00 fine thread uses 7.0mm.
____________________
PRESENT: 2018 BMW S1000XR SE Sport.
PAST: 2009 Kawasaki ER-6F. 2021 Zontes ZT-125U.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :

PostPosted: 18:38 - 09 Nov 2021    Post subject: Re: Drill bits - which for snapped bolts? Reply with quote

Fat Angry Scotsman wrote:
kramdra wrote:
The tapping drill for M8 is 6.8mm, not 7.1mm


Only if you're tapping an M8 x 1.25 coarse thread. The M8 x 1.00 fine thread uses 7.0mm.


Yeah? Ever seen one?
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts
Old Thread Alert!

The last post was made 2 years, 139 days ago. Instead of replying here, would creating a new thread be more useful?
  Display posts from previous:   
This page may contain affiliate links, which means we may earn a small commission if a visitor clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 

Debug Mode: ON - Server: birks (www) - Page Generation Time: 0.10 Sec - Server Load: 0.17 - MySQL Queries: 17 - Page Size: 140.48 Kb