[How do I?] Drilling Into A Tap

[DoogieB]

I just noticed that a few of my metric taps do not have a point or divot at the end to allow for the usage of a spring-loaded tap guide. The taps are completely flat at the end.

I was thinking about chucking the taps in the lathe and drilling a small divot in the end for the tap guide. Obviously they are really hard, but would a carbide spotting drill work for this or would I be just wasting money?

 

[Wreck™Wreck]

You will not enjoy drilling a center in a high speed steel tap, unless the tap is large use the center on the back of the tap holder.

I broke a 1/4 NPT tap off in a part 2 weeks ago, drilled through the center of the tap with a 3/8" straight flute carbide drill and saved the part. It was slow going however.
Also royally took its toll on the drill, this part had several hours invested in it beforehand so it was worth the gamble.

 

[planeflyer21]

Sounds like trouble to me. Whenever we had taps snap off in production, the taps were burned out with the EDM machine.

I've tried to drill out a couple of tool bits over time with no joy.

 

[dirty tools]

it is not likely that you will be able to drill a pilot hole

 

[4GSR]

Get you a Kennemetal straight flute carbide drill. Hold it in a ER collet chuck. Run at 2000+ RPM and cutting oil applied. Peck at it, you might get a hole deep enough, then use your centering device.

 

[T Bredehoft]

I don't know if this will work in your case or not,
Chuck the tap in a T tap handle, they all have a center drilled hole in the back for a live (or dead) center in the tailstock.

 

[4GSR]

I don't know if this will work in your case or not,
Chuck the tap in a T tap handle, they all have a center drilled hole in the back for a live (or dead) center in the tailstock.

Good idea! I don't see why you could not power tap to get the tap started correctly and then hand tap the last few threads in a hole.

 

[kd4gij]

The easiest way would be to pick up some good taps in the size you need.

 

[Franko]

I'm not sure I've ever seen a tap with a dimple on the back for a tapping guide. I though the tapping guide was to be used with a tap wrench. Maybe I've led a sheltered life.

 

[DoogieB]

Actually I think two of my T-Handle type Starrett 93's were so old they weren't center-drilled but I fixed that myself awhile ago, I just prefer to use the Starrett 91-type if at all possible as I like the feel and better leverage.

I'll just scrap the drilling idea and make do.