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[WolfieParticipant @wolfie]

Broken drill bit in job

[WolfieParticipant @wolfie]

Arrgh I have spent all afternoon nicely shaping a rectangle of metal which will become my steam chest and then I needed to drill a hole right through it top to bottom.

 

Drill (3/32″) got half way through and broke, not sure why although it had started to make cracking noises and now I have over half an inch of drill bit stuck in the job. How do I remove it?

[JasonBModerator @jasonb]

Whats the steam chest made from ? as you may be able to disolve the drill bit in Alum but not if its steel or Iron.

 

J

[macmarchParticipant @macmarch]

If you can, then turn it over, mark out where the hole would come out and drill from that side. It should push out the bits as you drill. Again, if you can, then use a smaller drill. You can then re-drill from the first side to straighten up.

 

[The Merry MillerParticipant @themerrymiller]

 

I shouldn’t bother Wolfie. Sling it away and buy a new one there quite cheap.

 

Len. P.

 

 

[WolfieParticipant @wolfie]

Its mild steel.

And I don’t want to chuck it away it took me all afternoon to make it grrrrrr

Trouble is, holes nearly 2″ long, it’ll be a miracle if I get two 1″ long holes to line up

[Sub MandrelParticipant @submandrel]

If you have some 3./16″ (or similar) silver steel, make a hollow tube to fit over the drill (oops- you haven’t got a 3/32″ drill handy have you?), file teeth on the end, temper and hadren to dark straw. You can then feed this down over the drill at a slowish speed until it comes out. use a bit of oil. You then need to force an oversize steel plug into the hole and start again (you may need to drill the hole right through or flat bottom it with a d-bit before plugging it..

 

I’ve done this and it works.

 

Next time you hear the cracking noise, back off the drill – that’s swarf collecting in the hole, rather than moving up the flutes.

 

Neil

[Ed DuffnerParticipant @edduffner79357]

Well, I’m a novice in engineering (ex sparky, no flames please) and it might show here with these possible solutions:

1) Add some WD-40 or easing oil and tap(as in hit lightly) the steam chest from the other side.

2) Make a long hook from a piece of stiff wire and try to pass it down through the drill flute to hook out the broken piece.

3) Make a 2 prong fork from two pieces of stiff wire or rod that engage with both flutes and try to twist the broken piece out.

All the best,

Ed.

[WolfieParticipant @wolfie]

Coordinate location???

 

Whats that??

[mgjParticipant @mgj]

Wolfie – the reason it broke was probaly because you were not withdrawing it on a deep hole to clear the swarf. (clicking crackling noise?) And that means the hole probably isn’t straight..

 

Which, if you haven’t got to the far end may well not matter. Mill it out, around the drill bit.. If you are going to hit the drill bit with the milling cutter, failing extraction by some onter means, you could easily make a mess of your cutter (depending on what it is made of) and possibly the work too.

 

Best sequence for that sort of thing I have found is to mill out the cavity. Drill the hole at the larger end – make an extension drill bit out of properly centred rod and a drill bit and loctite 2 together. Also extension centre bit. Use centre bit first. Also oil the gland hole through which the extension passes and uses as a guide.

 

That way you avoid deep hole drilling altogether.

 

I’ve never found drilling from both ends that wonderful – for me at least, even using properly held drills in a collet in a Quorn to produce a 4 facet bit, they never align absolutely perfectly. Adequately, yes, but rarely perfectly. Even with a DRO, you will have an error when hte job is reveresed end ofr end. Then of course, define perfect -.001″ clearance.(And file flat to let the air out)

 

For my money – I’m afraid I would consign that one to the scrap bin of experience – or press a bronze plug in the bottom and restart.

[mgjParticipant @mgj]

Indeed – but the problem is that there is always an error when you pick up an edge, or centre. Everything has a tolerance.

 

Again, it depends on the clearances you allow yourself. But if you wish to fit a rod into a reamed hole, the total error allowable is about.005″ each end, because you only have about .001 clearance on the smaller reamers. So there is an eccentricity in the drill chuck holding the gauge, and an error in the mechanics of finding the edge.

 

So sure, picking up by whatever method can work, but it is not as inherently acurate, and is possibly more work setting up and swapping, than doing it all from one end in this sort of situation – particularly when there is no need to introduce the error.

 

You could use a long series drill bit, though they are not very nice to use, but they do have a properly designed fast sprial to clear swarf from deep holes.

 

Or, if you have to rotate the object, and the set up is small enough, use some kind of indexing device. The Versatile Dividing Head on a Myford (or mill) does that sort of 180 dec spin pretty well. And very quickly. too.

 

 

One must do as one sees fit of course, but it is always best to use a single datum point..

 

Edited By mgj on 05/11/2011 09:30:23

[JasonBModerator @jasonb]

Lets face it you will have some float on the valve anyway so if the drill did wander slightly its not the end of the world so long as the valve rod is not binding.

 

If I were doing it I would have milled out the cavity first, taken the first part of teh hole out to 1/8″ so I could use a long centre drill to spot the other side of the cavity than drilled that out with a long series or extended drill to get the rod support hole. The larger 1/8″ hole can then have a bronze neck bush fitted as is common practice on larger models and full size.

 

In your case try and mill out teh cavity hoping teh broken drill is in teh waste, then set it up again in the 4 jaw and do like I suggest above, similar to MGJs method as well.

 

J

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Wolfie, agree with the others, that crackling sound means imminent drill breakage, so retracting the drill bit before you hear that sound, the better. The deeper you drill a hole, the more often you need to retract the drill bit to clear the swarf, and if you retract it swiftly the more swarf will be cleared.

 

Regards Nick

[mgjParticipant @mgj]

That such things- exist. Of extended drills and centres. Or you make one drilling accurately into a bit of bar accurately clocked in a 4 jaw!

 

Perhaps we have all been spoiled recently with the advent of very adequate Chinese/Taiwanese tooling, which have rendered almost everything from small milling machines (the Dore Westbury) downwards not worth making.

 

Still every now and again one does have to do it, and if truth be known, I am glad that I am sufficiently decayed as to have come from that era. Gives one a lot of flexibilty

Which I am rather needing – having just bought an HP 50g calculator, which is so vastly expensive that a decent manual is obviously beyond them. Or perhaps, it just has so many modes that even the authors (who write very good English!) forgot where they were. Even setting its clock is an adventure.

[John CoatesParticipant @johncoates48577]

Posted by Wolfie on 04/11/2011 17:19:21:

Drill (3/32″) got half way through and broke, not sure why although it had started to make cracking noises and now I have over half an inch of drill bit stuck in the job.

Can sympathise with you mate – tonight it happened to me at 9.20pm

For me it was an M6 tap. Spent blummin’ hours making this new base for a Picador grill grinding device (bought very cheap from ebay as the original base was missing)

 

Ah well the swearing is over and I’ll start perusing ebay for a new tap. Will have to get by with one M6 mechanical fixing and then Loctite the rest of the bottom base to the upper base

 

Curses! Drat! and confumbles!!

[Kerrin GalvinParticipant @kerringalvin72662]

Hi Guys,

Have you considered a spark erroder to remove either? Probably take longer to make one to do the remove the broken bits than to make the part again in Wolfie’s case, but a hunt on either the web or phone book will likely turn up somebody close by who could do the job for you. My Dad broke a tap off in a part sometime ago & had it erroded out, nice and clean, he finished the work on the hole & installed the part.

 

Mgi,

My son has the HP 50G, you can download the manual from there site, he suggest that you only grab the pages required as it consumes LOTs of paper if you download the whole thing!

 

Cheers Kerrin

[John CoatesParticipant @johncoates48577]

Hi Kerrin

 

There have been a few designs over the years in MEW but they look incredibly complicated and involve the black art of electronics, about which I know very little and usually manage to electrocute myself off the mains when changing light fittings!

 

In my case it’s only a lump out of the scrap box that has been squared, chamfered, drilled and tapped. I was fixing the flat bottom base to this with two M6 bolts so I still have one bolt hole and will use Loctite to provide the rest of the fixing strength.

 

Mind you I did have to scrap a £70 three phase motor during my last tap snapping episode when I lost one putting an M5 thread in the motor spindle. That’s still sitting on the shelf!

 

John

[mgjParticipant @mgj]

Taps – there are 2 tricks.

 

1st is to only advance a litlte at a time before reversing and clearing. This I ALWAYS do, and I have never broken a tap. (or pack hole full of grease, which squirts out with the swarf)

 

Second is not to believe many of the tapping drill guides. Many that I have seen quote a 80%+ amount of engagement, which is unnecessary and makes tapping far too forceful an excercise. 75% engagement is plenty, and makes all the difference in the world, without affecting strength. (I suspect this has more do to with my not breaking taps than the blatant lie above, especially when I run most of my taps in under power with a small Bosch cordless – has a clutch.. Not my idea – Tubal Cain again) The guides for many of the ME threads are particulary bad for this.

 

HP50g. Thanks. I have the manuals and the guides – its just that you have to guess which mode you are in vids-a-vis hte book of words! But its very good and far better than the Ti89 when you do have the hang of the small bit you are using!!

[John CoatesParticipant @johncoates48577]

Actually thinking about it now the fact the two M6 holes were blind and I didn’t remove the workpiece from the mill/drill between drilling the core and tapping (to maintain register) probably had something to do with it

[Steve WithnellParticipant @stevewithnell34426]

I’d it toss it. Put it down to experience and apply your learning to making a new one! Unless off course your hobby is removing broken drills from steel You will make the second faster than you made the first. I’ve not come across a steel steam chest before, normally cast iron or some form of gunmetal, but that’s a casual observation.

 

I’ve done this twice now and both times it took 2-3 times longer to get the broken tap out than to make a new one and even when I did succeed, the part was then not as good as it ought to have been.

 

 

[Gordon WParticipant @gordonw]

Wolfie, I’ve just been reading an old ME, about 1952, One tip, from a very esteemed writer, is to grind the drill with one land slightly longer than the other, (that is standard for me). This makes the drill cut slightly bigger and so make the broken bit easier to remove !

[John Stevenson 1Participant @johnstevenson1]

Chuck the bastard.

You might have half a days work in it already but by the time you finish messing with it you will have a full day into it, at the least and a bodged up job at best or it will still go in the scrap bin.

 

Then put the whole episode down to experience.

 

Might sound harsh but it’s not, it’s experiences like this that develop skills and the second attempt will go faster than the first so even that is showing skill development.

 

If it was an expensive or rare casting then it’s worth spending time but bar stock parts just are not worth the effort.

 

Anyone who hasn’t broken a drill or tap whilst learning or even after hasn’t done anything.

 

John S.

 

[ Who broke a M4 tap into an expensive part last week, last hole as well. I was going to have it professionally spark eroded but the customer told me it was only for a securing clip and accepted a new hole to one side – Phew !! ]

[WolfieParticipant @wolfie]

Lots of interesting advice there however theres a couple of added spokes in works that mean I really don’t want to chuck it.

 

1. I don’t have a milling machine (although working on that)

and 2. I don’t have another piece of metal big enough to make a new one without sending off mail order

I think I’ll go down the route of making the cavity and hope the broken bit comes out with it.

[JasonBModerator @jasonb]

Should still be able to do it on the lathe or even stitch drill and saw/file out the cavity. Once thats done set it up in the 4 jaw and do the drilling in the lathe, drill and ream the 3/32nd hole first then open up the stuffing gland cavity.

 

You can now tackle the hole at the other end, as I said a long centre drill is best but you could even grind a point on a bit of 3/32 rod and use that as a long punch to get a start dimple on the far side of the cavity. Then drill the hole, the advantage of having the cavity done is that you don’t have to back the drill off much to clear the flutes as the swarf can drop out into the cavity.

 

This is what you really want

J

Edited By JasonB on 06/11/2011 20:27:54

[WolfieParticipant @wolfie]

A picture is worth a thousand words! Brilliant. Whats that metal, and where do I get some?

[Author]

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