daedalusminos
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- Thread starter 8ob
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hotponyshoes
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Ah, an 8.1mm drill bit might be a bit big then!
What's the plan?
Drill to thread root dia. and pick the remaining bits out? I would think that if they are so stuck that heat followed by an extractor or left hand bit won't get them out then a pick won't either.
You could drill out to 8mm to remove all the bolt and then drill/tap m10 (or probably tap m10 corse without having to redrill) but I don't know if the disks would then need drilling out to suit each time?
Probably worth fitting helicoils/serts anyway if you don't want it happening again?
123hotchef
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dont use carbide it will break and mess up your day! ask me how I know
hotponyshoes
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The trick with decent carbide is to get it spinning so fast it doesn't have time too break.
premmington
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2 axis CNC mill would be the tool of choice in my mind!
Centering this up on a drill press - would be nightmare
8ob
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I could use the new discs as a drilling jig if I spun up some drilling bushes, I can cut the broken bolts down with the gas axe. I have tried to mill off the top of the bolts but they are way to hard for any of the cutters I have here.
There are four of these hubs to do.
There are four of these hubs to do.
God mode restorations
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I have drilled 12.9 HT studs and bolts with cobalt at a very slow speed. Took a while but definitely doable
123hotchef
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hum i have broken them on the lathe too
Agroshield
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Presumably the holes in the disk are aligned with the bolts. If the bolts are too corroded to pick up their centre from the OD, I wonder if they could be leveraged into helping locate the bolt centres using a bush. You'd just have to get the rotational position of the disk correct and clamp or tack it into place.
Anything you do has to be better than a blind guess with a centre punch.
Edit: 8ob types faster than me!
A decent cobalt drill will go through those bolts without any issue. Even HSS would, but it's not likely to last as long.
As has been suggested, I'd use the new disc as a guide, but I'd concentrate on just getting two bolts drilled first, then bolt the disc in place for doing the rest.
As it's only M8 bolts, I'd probably just go straight for a 6.8mm drill, then run a tap through to clear out the threads.
Despite carbide being very tough, it's quite brittle, so any jamming is likely to result in breakage.
As has been suggested, I'd use the new disc as a guide, but I'd concentrate on just getting two bolts drilled first, then bolt the disc in place for doing the rest.
As it's only M8 bolts, I'd probably just go straight for a 6.8mm drill, then run a tap through to clear out the threads.
Despite carbide being very tough, it's quite brittle, so any jamming is likely to result in breakage.
Screwdriver
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If it was me using my limited tooling and experience, I'd chop them down with a Dremel cutoff wheel and grind the stub with a small grinding wheel. Centre punch the concave surface (the bolt position should be visible) and drill it out to tap size.
Kram
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These are excellent, hard but not brittle.
Centre drills, swisstech from zoro are very good but more expensive now.
Centre drills, swisstech from zoro are very good but more expensive now.
I found their recent stuff to be brittle, chip easily, need constant resharpening. Nothing like old Dormer which were great. I have a set from about 1980.
Arclikeharrypotter
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Dormer, guhring, titex, would be brands I’d look at. You’d probably be fine with a dormer A002, but if you want something with cobalt look at dormer A777.
Trevorleach
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Done loads of them, so many it makes me shudder just looking at the pics, what you have there actually looks real good.
You have enough shank left there to either weld an m8/10 nut onto and undo that way or use one of the tapered stud removal tools, 5/16-8mm is the size you need.
When they are real bad you have a bolt that the shank is so waisted, as you undo the head it shears off leaving a ****ty little stub, then its a tapered chisel to remove the bulk of the remains, die grinder to get the remains flat, then dot punch and drill away.
Think the bolts are std M8 8.8 Iirc tightening torque was 30nm ie nowt special
It sounds real bad but the new holes do not have to be perfect so long as the bolt tightens it will be just fine, ie the work would make an engineer cry but will hold just fine.
You have enough shank left there to either weld an m8/10 nut onto and undo that way or use one of the tapered stud removal tools, 5/16-8mm is the size you need.
When they are real bad you have a bolt that the shank is so waisted, as you undo the head it shears off leaving a ****ty little stub, then its a tapered chisel to remove the bulk of the remains, die grinder to get the remains flat, then dot punch and drill away.
Think the bolts are std M8 8.8 Iirc tightening torque was 30nm ie nowt special
It sounds real bad but the new holes do not have to be perfect so long as the bolt tightens it will be just fine, ie the work would make an engineer cry but will hold just fine.
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Moose McAlpine
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These are what i use. They drill through everything i chuck at them, last for ages. I've used them to drill out 12.9 bolts with no issue. You can get them in jobber length too. Got me out of many binds.
I could use the new discs as a drilling jig if I spun up some drilling bushes, I can cut the broken bolts down with the gas axe. I have tried to mill off the top of the bolts but they are way to hard for any of the cutters I have here.
There are four of these hubs to do.
I'm all for DIY, but I think I might be reaching for the Yellow Pages and "general engineers" - clamped on a locating bush on a decent sized mill and clock it round for each bolt - repeat for each hub - once set up, should be reasonably quick. Remove the remnants, drill out, helicoil, done.
Or days with a drill press, even a big 'un . . . and wasting time that could be spent better elsewhere.
