drilling steel with 230v hand drill

Hi,

I am looking for advice. I am trying to drill out a 12mm diameter bolt that is about 50mm long. I only have a 650W hand drill. I have managed to drill an 8mm hole using a cobalt drill; however I have tried to enlarge the hole using a new cobalt drill, having gone in about 10mm it just does not cut anymore. I have tried my hss drills all are sharp but none are cutting, Whilst drilling I soak the hole in copious amounts of oil, I even resharpened two of my drills and still they do not cut, I have been trying to drill this bolt out for two days. I have filed a flat on an identical bolt so the bolt is not particularly hard. Is it just my hand drill is not slow enough? I just do not know what to do and helpful sugestions will be welcomed.

Regards nick

This sounds like a high tensile bolt. If it is then the 8mm drill would hve gone down the 'core'. The next drill will be trying to go through the toughened part. Drill gets hot, edge goes, bolt material work hardens. TCT drill running very slow might break the hardened skin.

I would be using slow speed on my drill. This, from memory, is about 1000rpm on a 400W hand held drill. I should point out that my drill has a 2-speed mechanical gear box so the torque is proportionally increased. If, therefore, your 650W drill has a mechanical 2-speed gearbox, then you will have more than enough power and should be able to go slowly enough.

It seems to me that the bolt has been hardened, either deliberately, or by work hardening. If the rest of the job will not be damaged by heat, then try a lot of heat to soften the bolt.

Is it possible to drive out the bolt by hammering one or other end? If seized, and the work will not be damaged, then a good dose of heat can be very beneficial in breaking the bond, especially if combined with a few good belts at either end, or if possible, a twisting motion using a pair of mole grips on any exposed part of the bolt.. Don't forget, your average car mechanic faced with jobs like this will use an oxy-acetylene cutter to heat up the bolt. I use a fine pencil flame on my propane burner initially and if necessary, a stronger about 8mm diameter flame.

I think I have read about someone using carbide tipped masonry drills for this type of work. I have never tried it myself as heat plus brute force and "higorance" have usually won.

Final thought would be to try a good soaking in penetrating fluid to see if that can free it.

Good luck,

Peter G. Shaw

Edited By Peter G. Shaw on 02/08/2013 21:19:17

Hi, are there any markings or numbers on the head of the bolt or is it a socket head bolt. This will give some idea as to whether it is a high tensile bolt or not.

Regards Nick.

For a carbide tipped masonry drill to work in steel you have to alter the cutting edge of the tip, normaly the tip is to blunt to work in steel, probably to prevent shatter when using hamer action in concrete. When change the tip to what is used in a normal drill it will work fine in hardened steel. Niko.

12mm diameter bolt that is about 50mm long. I only have a 650W hand drill.

Sounds like it's work hardened or high tensile

I have managed to drill an 8mm hole

That's the easy bit by hand, going to 10mm is a heck of a lot and 12mm can be quite dangerous if the drill grabs

A Carbide tipped Masonry drill sounds best, grind the tip so it looks right and don't let it overheat or it will come away from the shank.

Slow speed, high torque and plenty of pressure is the only way to go

A 12mm hole is really a bit too big for the human hand and should be done on a lathe etc

If it's a modern drill with electronic speed control chances are it's going too fast.

Can you borrow an old mechanical one ? failing that try blipping the trigger to keep the speed down

And watch you don't burn the drill out in frustration

Hand drills can only do so much work before they need a break, even good ones

If you've whacked a 8mm hole right through it then the swarf can clear more easily

Then it's a case of a bit at a time at 10mm

 A 10mm hole right through may let you batter it about and then unscrew

Edited By Ady1 on 03/08/2013 02:03:22

A bit of lateral thinking, to save burning out, battering, whacking or whatever I use a tool that lies in one of my tool chests for years but is invaluable for this, You it would appear that you have made a hole in the bolt so this is a tapered L/H tapered spiral thread tool work it in gently, with oil , slowly turn backwards and forwards and you will find the errant bolt will come out, Recently one of my grandsons managed to snap the head of a hex bolt on a IC engine and we succesfully removed it.
They usually come in sets of 5 different sizes, can be obtained from most of our usual suppliers or fleabay.
Good luck
Bob

i guess one question is 'why are you drilling it out'? the obvious reasons are that it is 'stuck' and early attempts to move it rounded the head so much it cant be gripped. the other reason is it has sheared off.

You could try tapping an 8mm copper rod through the hole you have and apply heat to that. That may let you get the bolt hot enough to break the bond without damaging the component. Then remove the rod, Could you then put an 8mm bolt all the way through, put a nut on the top and bottom to clamp the 12mm bolt tightly enought to let you undo it? I hesitate to suggest 'easy out' because if you break one of those in the hole you will be in even more trouble. The tapered square ones rather than the left hand thread ones can be driven out from the other end if they do break.

if you do have a clear hole through, could you use one of those carbide 'rod' saws to cut a slit in the side? there's only 2mm to cut. Or a junior hacksaw?

hope some of these random ideas inspire a solution for you.

-russ

If the bolt is too hard too drill out any further a Dremel type drill with a grinding wheel may save the day if you have or can borrow one. Colin

Nick,

What is the bolt fastened into, is it a large chunk of metal / casting /axle /frame?.. I have released a few rusted / seized bolts over the years & one trick I used was to heat the bolt to dull / cherry red then quickly cool the surrounding area with cold water this should then release any seized material due to shock temperature change, as you already have a hole in the bolt , if it 's not right through, heat the bolt then pour some ice cold water down the hole this should cause shock contraction of the remaining wall thickness & any overspill will do the same to the surrounding material, thus breaking any grip between the threads...obviously this shock change in temp' would / can cause some fracture in thin or important surrounding work, but if it's not critical ..go for it!

George

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NO NO

NOOOOOOOOOOOOOOOOOO

Do NOT use these things, they are the devils spawn.

Just examine how they are made ? A LH thread with a slow taper.

All that happens is as you screw in the hard tapered tool just wedges the stub or bolt even harder into the hole.

The more you tighten the more it wedges in, until finally being a hard and brittle tool, it breaks.

Now they do work IF the bolt stud isn't tight but the problem is knowing at what point you use these and what point you don't.

A good check is to knock the tang of a file in and turn the file with a spanner, if it's loose enough then the stud will come out if it rounds the tang then the tapereddogfacedswearingatthecat excuse of a stud extractor will only make it worse.

I had a similar prob yesterday, cut off a rod end with an angle grinder and it left the bar end glass hard, but managed to get a dimple thru' the hard bit with a reground masonry drill bit. If you have a hammer drill try a rod in the hole on hammer setting, sometimes works. Important - cool the drill machine by running free for a few seconds between cuts, let plenty of cold air thru'.

I've used the re ground masonry bit, so that gets the thumbs up from me. A note (which may be teaching me granny...) if you are using a mains drill with an electronic speed control for long periods at reduced speed then the cooling fan is also operating at reduced speed. Result burnt out drill. So if this is the case then take plenty of time.

David.

Anyone know the best way to cool a hand drill when it's working hard and getting too hot?

Stop it and let it rest

or

Run it at a higher speed under zero load to circulate lots of air

Edited By Ady1 on 03/08/2013 10:30:34

If the drill machine gets hot DO NOT just stop it, a sure way to melt it. Let it run free 'till the exiting air feels cool.

Hi - Are you able to weld a lever onto the remains of the bolt? The heat will break the 'bond' and you'll be able to wind out the thread with the lever. - Regards Mick

I would help if Nick were to provide more details and perhaps a photograph as several people have requested.

I'v got a set of Snap On stud removers, better than eazy outs, and they usually work, they consist of splined steel rods that are driven into a hole down the centre of the stud, a hex driver fits on the rod, and just unscrew with a spanner. Have you tried knocking something square into the 8 mm hole, and backing it out. Try the carbide drill, if you get it right, you should just need to pick the metal out of the thread in the hole. Ian S C