mistergrumpy
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| posted on 21/8/07 at 06:58 PM |
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Cross Drilling Bolts
Can anyone help me? I'm trying to drill a 3mm hole through/across the shaft of an m8 bolt and it just won't have it. The 1mm drill goes
through (then snaps!) but not the 3mm. A pilot hole tends to make things worse. I'm using good drill bits that've never failed to go
through anything but I'm getting peed off now  Want them to use as swivel joints for my clutch and accelerator pedals.
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britishtrident
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| posted on 21/8/07 at 07:06 PM |
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3mm through m8 dosen't leave much solid material --- less than 2 mm each side.
Try locking 2 nuts on and drill through the flat of one nut
You can buy jigs for doing this -- can't remember who sells them
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mistergrumpy
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| posted on 21/8/07 at 07:10 PM |
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Should be right enough eh? They're not pulling a lot of weight. I'll go and try the nut thing now I think.
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theconrodkid
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| posted on 21/8/07 at 07:13 PM |
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clevis pins?
who cares who wins
pass the pork pies
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britishtrident
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| posted on 21/8/07 at 07:13 PM |
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Frost Auto Restoration do the Jig for bolts -- 17 quid
Don't seem to have the one for nuts.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 21/8/07 at 07:16 PM |
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They have the one for nuts as well part number T204 --- 21 quid.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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mistergrumpy
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| posted on 21/8/07 at 08:23 PM |
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I've got going but its like trying to drill diamonds or summat. I don't get it. I really like the clevis pin idea though. A couple of
them'd do the trick nae messing cheers conrod.
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omega 24 v6
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| posted on 21/8/07 at 09:02 PM |
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quote:
've got going but its like trying to drill diamonds or summat.
Where exactly did the bolts come from??
Are you sure they are not self tapping bolts which will be case hardened?? try rubbing them with a file and see if it skids or cuts if it skids
they're hard. Also if you look at the end of the threaded portion they look sort of rounded triangular shaped then they could be hardened
selftapping bolts as well.
If it looks wrong it probably is wrong.
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mistergrumpy
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| posted on 21/8/07 at 09:10 PM |
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Hmm. I did file a bit of a flat on but the ends are that rounded triangular shape that you mention. I've tried 3 so far and I've tried
across the head just as another area but no way they're not having it.
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omega 24 v6
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| posted on 21/8/07 at 09:20 PM |
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Another thing with self tapping bolts is that usually the heads have a flange (like a built in washer)
If it looks wrong it probably is wrong.
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mistergrumpy
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| posted on 21/8/07 at 09:24 PM |
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Nope not got that. I can't understand it. I drilled right down the centre of a different bolt yesterday with the same bit but these ones just
seem to be monsters. I'll have to rethink I think.
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omega 24 v6
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| posted on 21/8/07 at 09:34 PM |
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Any stampings/markings on the bolt head??
If it looks wrong it probably is wrong.
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craig1410
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| posted on 21/8/07 at 10:23 PM |
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Hi,
If you make a pilot hole too close to the size of the final hole then you will just knacker your larger drill as it knocks the cutting edge off it
towards the outside edge. 3mm doesn't need a pilot hole IMO.
Have you tried using drilling lubricant? I think I got mine at Halfords - comes in a spray can and is dirty brown in colour. This helps although I
usually only use it for larger holes in thick material.
Finally, are you using appropriate speed and pressure on the drill? I don't know what RPM you should be using but it is possible to use too much
pressure AND too little pressure. Smaller bits like higher speeds and less pressure but don't let it overheat. I usually know I've got it
right when I get long curly bits of metal coming off.
Sorry if some of my suggestions are a bit basic but, like you, I'm a bit surprised you are having problems.
One last thing - I have had a situation where I was cutting through a water pump shaft where I could cut most of the way through no problem but there
was a harder "core" within the shaft which was hard as hell. It was like normal steel outer around a hard tool steel inner shaft. You
don't get bolts like that do you?
HTH,
Craig.
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nick205
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| posted on 22/8/07 at 07:53 AM |
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Are you using a pillar drill and holding the bolt in a clamp or vice?
Another tip (again basic, but worth a mention) is to "peck" drill - i.e. drill a little way, then back off to allow the swarf to clear the
drill bit and hole before drilling a bit further. This becomes more inportant the deeper the hole. It could be why you're getting part way
through and snapping drill bits.
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mistergrumpy
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| posted on 22/8/07 at 08:33 AM |
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Yep its in a pillar drill and vice, markings on head are 8.8 and a couple of letters and yes I quite regularly get that solid core thing. I'm
going to try a different batch of bolts, get one from B&Q or summat and give that a try. Wonder if I've blunted the bit now keep zizzing
away at it.
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