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MG#43 |
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MG#43 Nova Slayer
Joined: 03 Mar 2007 Karma :
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Posted: 17:28 - 12 Oct 2021 Post subject: Drill bits - which for snapped bolts? |
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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 |
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Fat Angry Scotsman |
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Fat Angry Scotsman World Chat Champion
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Nobby the Bastard |
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Nobby the Bastard Harley Gaydar
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virus |
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virus World Chat Champion
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sickpup |
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sickpup Old Timer
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WD Forte |
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WD Forte World Chat Champion
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A100man |
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A100man World Chat Champion
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MCN |
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MCN Super Spammer
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Robby |
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Robby Dirty Old Man
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Fat Angry Scotsman |
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Fat Angry Scotsman World Chat Champion
Joined: 12 Jan 2021 Karma :
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Posted: 09:48 - 15 Oct 2021 Post subject: |
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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. |
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MG#43 |
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MG#43 Nova Slayer
Joined: 03 Mar 2007 Karma :
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Posted: 10:18 - 15 Oct 2021 Post subject: |
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Fat Angry Scotsman wrote: | |
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! |
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MCN |
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MCN Super Spammer
Joined: 22 Jul 2015 Karma :
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Posted: 15:45 - 15 Oct 2021 Post subject: |
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MG#43 wrote: | Fat Angry Scotsman wrote: | |
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. |
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virus |
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virus World Chat Champion
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WD Forte |
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WD Forte World Chat Champion
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Pete. |
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Pete. Super Spammer
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virus |
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virus World Chat Champion
Joined: 17 Aug 2006 Karma :
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Posted: 22:59 - 15 Oct 2021 Post subject: |
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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. |
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Pete. |
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Pete. Super Spammer
Joined: 22 Aug 2006 Karma :
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Posted: 05:59 - 16 Oct 2021 Post subject: |
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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 |
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MG#43 |
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MG#43 Nova Slayer
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sickpup |
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sickpup Old Timer
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MG#43 |
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MG#43 Nova Slayer
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Polarbear |
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Polarbear Super Spammer
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Posted: 17:24 - 18 Oct 2021 Post subject: |
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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. ____________________ Triumph Trophy Launch Edition |
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 21:41 - 18 Oct 2021 Post subject: |
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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. |
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kramdra |
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kramdra World Chat Champion
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Fat Angry Scotsman |
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Fat Angry Scotsman World Chat Champion
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Pete. |
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Pete. Super Spammer
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Old Thread Alert!
The last post was made 2 years, 162 days ago. Instead of replying here, would creating a new thread be more useful? |
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