DIY gone wrong

[Hertford Stargazer]

I thought I'd be clever and add an extra pair of tube rings to the dovetail bar which mounts my Evo 150, I've never felt comfortable with those two little bolts supporting all that weight. So to cut a long story short I drilled a pilot hole in the dovetail bar for one of the new rings only for the drill to snap just as it's breaking through the other side.

I've tried everything to remove the broken bit so I can drill the full sized hole and all to no avail. I've just ordered a new bar from FLO in a moment of surrender but any ideas as to how I can salvage the old one? 

Thanks
 

[Alien 13]

I would drill it from the other side with a slightly larger bit, the broken piece will either spin out or if still stuck should be able to be punched through with a hammer/nail.

Alan

[Tinker1947]

I would try to knock it back through, if you can flatten the tip first might help....

[Hertford Stargazer]

Hi Alan, thanks for the suggestions. I tried a bigger drill but it gets pushed to one side and starts to drill down the side of the broken bit. I also tried a hammer and punch, gentle tapping didn't work so I got a little frustrated, gave it one big whack which shattered the punch and the hammer hit my thumb leaving a blood blister and some nice bruising

I think it might have welded itself in there. 
 

[kendg]

You could always try a little heat to the dovetail before tapping out the drill bit.

Might help and probably can't hurt. 

[Davey-T]

You could try one or other of these  perhaps, probably need a pillar drill and clamp to hold it.

Dave

http://www.diy.com/departments/ptx-diamond-coated-tile-ceramic-holesaw-dia-10mm/702708_BQ.prd

https://www.machinemart.co.uk/p/cht468-516in-spot-weld-drill/

[Hertford Stargazer]

Thanks Tinker1947 and kendg,

I didn't think of heating it, I've done enough damage for one day so I'll try that tomorrow when I have more time.
 

[Hertford Stargazer]

15 minutes ago, Davey-T said:

You could try one or other of these  perhaps, probably need a pillar drill and clamp to hold it.

Dave

http://www.diy.com/departments/ptx-diamond-coated-tile-ceramic-holesaw-dia-10mm/702708_BQ.prd

https://www.machinemart.co.uk/p/cht468-516in-spot-weld-drill/

 

Thanks Dave, I do have a pillar drill which is why I thought nothing could possibly go wrong 

 

[Davey-T]

1 minute ago, Hertford Stargazer said:

 

Thanks Dave, I do have a pillar drill which is why I thought nothing could possibly go wrong 

 

They do a 6mm hollow diamond one, not designed for ally but should last long enough for one hole

Dave

[Knighty2112]

Can you get onto the shaft of the drill bit still where it snapped? If so tigten a pair of good mole grips on the drill bit and then twist it out the opposite way that the drill was going in to the metal. If you can't latch on like this then either a big pin punch should knock it out with a but of persuasion. Good luck! 

[bottletopburly]

bigger hammer works every time lol

[Hertford Stargazer]

24 minutes ago, Davey-T said:

They do a 6mm hollow diamond one, not designed for ally but should last long enough for one hole

Dave

Seeing that link has given me an idea, I have my late fathers toolmakers cabinet in my shed/workshop, when I was looking for a punch earlier I came across a selection of mills, I wonder if one of them might do the trick as some of them have hollow centers.

 

25 minutes ago, Knighty2112 said:

Can you get onto the shaft of the drill bit still where it snapped? If so tigten a pair of good mole grips on the drill bit and then twist it out the opposite way that the drill was going in to the metal. If you can't latch on like this then either a big pin punch should knock it out with a but of persuasion. Good luck!

Thanks for the suggestion, the only protruding part was the end of the drill on the underside of the dovetail bar, I gripped it with pliers to try and twist it out but it just disintegrated.

 

1 minute ago, bottletopburly said:

bigger hammer works every time lol

I don't think my thumb could take anymore 

 

[Physopto]

Put the plate in a bucket filled with diesel and let it soak for a day. Then use a vice to push out the broken drill bit from the breakout side. Use a socket around the hole to allow the tool top push out the broken bit, or you can use a bit of very soft wood. So a drill bit the same size can be used as the punch with its flutes cut off.  order is drill bit punch on the breakout side then plate then socket or wood in the vice. Gently screw in the vice and it should start to pop out. Wear goggles for safety.

The drill bit shank is softer than the fluted bit so it should deform on the broken bit slightly as you tighten the vice and give a bit grip. I have done it many times and it will work if done correctly.

Best of luck.

Derek

[kev]

Re the thumb. Rather than heating it, shouldnt you be cooling it by putting it under a cold water tap?

(sorry couldnt resist)

 

[Stub Mandrel]

Aluminium dovetail steel/HSS drill bit?

Get some alum (off ebay, die supply craft shop or elsewhere) make up a decent strnegth solution and soak in it for a day or three.

Drill bit will disintegrate and fall out. Works with taps too.

[Starlight 1]

  I can think of only one drill that harder them the one you are trying to get out  that will be a slow job as you can not get it hot and that a masonary bit it will work.

[Hertford Stargazer]

Some great suggestions, many thanks everyone 

I think I might try the Alum method first as it seems less dangerous taking into consideration my track record.
 

[8kids]

Put the nail punch into the pillar drill chuck and use it as a press.