Broken Tap

[ChrisHParticipant @chrish]

If you are a clever dick and have a tapped hole that is a bit tight you're tempted to wack a tap down it all gung-ho to clear it.

Well, I was a clever dick and now I have a broken cast steel tap stuck in an M4 tapped hole – it is one of the tool securing holes in the QC tool holder.

Fortunately, it is the last one, the one farthest from the job, so I can live without it, but would prefer to live with it being operational.

So the question is, how do I get the broken tap out?

Chris

[ChrisHParticipant @chrish]

[JasonBModerator @jasonb]

As its carbon steel use an end cutting solid carbide slotdrill in the mill to drill it out. Use a tapping size cutter and then pick the remaining teeth out once the main part of the tap is out.

J

[nigel jones 5Participant @nigeljones5]

Chris – have you tried shouting and cursing at it…thats what I do!

[John Stevenson 1Participant @johnstevenson1]

Chances are and this is from experience the carbide cutter will be toast when you are done if you get done.

How much is a new one of them ? Then if you don't get every last bit out you either snap or usually blunt the next tap down the hole – more expense.

 

Doing this for a living on equipment where expense is no problem it still gets expensive.

 

Now many are not going to like this as being too rough but it works, it's quick and it's cheap. Plus it works every time.

 

Take an angle grinder with a thin cutting disk, attack the job from the best side travelling the way of the tap, when you have a slot remove everything even it it means widening the slot, then weld up, mill or file back to shape, drill  and re-tap.

 

Don't quench at any point, allow to cool naturally and you won't get any hard spots.

Edited By John Stevenson on 04/02/2014 19:08:55

[Clive FosterParticipant @clivefoster55965]

Bin there, dunnit, got the "I killed a cutter" T-shirt too. Live with it for a while and haunt E-Bay until a suitable carbide cutter comes up at a suitable price. Five flute end-cutting ones are best if you can find them. I scored 2 for £5 (ish).

My problem was with a Dickson so holes were 3/8 thread. Bottom thread had been deformed so screwing tool retaining bolt through seriously distorted the thread. After I got the tap out my fix was to grind ou the bottom thread using a "ball on a stick" grindstone. One of a set of 4 on a card bought as a bargain 40 odd years ago.

Love to know how the thread got deformed given how hard a Dickson carrier is.

Clive

[JasonBModerator @jasonb]

Just over £1.00 for a 3mm carbide cutter from Richon, got to be worth a punt even is its a scrapper afterwards

[ian cableParticipant @iancable23486]

if its a through hole get short punch or silver steel just a couple of thou under the core diameter and give it a reasonable clout being a very small tap it will crumble, other wise take Jason B advice or find someone with a spark eroder

[Author]

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