View Full Version : Tapping from a Turret

11-11-2009, 12:57 AM
With some help over the hard spots, by that I mean the work hardening spots, lol, I got this tapper built for my turret.


The shaft is located by opposing springs to the center position where it can spin freely. When I push it into the workpiece it moves to the back of the housing where it engages two hardened dowels, thereby locking it up and tapping commences.

When I hit the depth stop on the turret the tap continues to screw itself into the workpiece until the shaft clears the dowels. At that point it begins spinning with the workpiece. That's my clue to shut shut the lathe down, pull the turret back which engages two dowels in the front of the housing, and reverse the lathe.

Pretty undramatic .... but it works!:D

Here's a pic of the innards.


Now we need another for small taps.


11-11-2009, 01:24 AM
I like it. noobs could make one and like it.

good job.

11-11-2009, 01:54 AM
Very nice. Both you and that lathe have come a long way! I sure miss my turret. Odd, since I really never got around to using it much at all, but I had great plans! ;)

Ian B
11-11-2009, 02:13 AM
Ooh, that's nice!

Question; instead of using a round cross pin, did you consider using a square one (or a circular plate with 2 holes drilled in it)? Reason for this would be a cleaner break of drive when the shaft holding the tap moves forward. It looks as if a round pin will be trying to ride over the 2 fixed pins just before drive stops, and pushing the tap into the work.

Obviously not a problem with larger taps as it works, but this might be a problem with smaller taps.

Just a thought.


11-11-2009, 02:41 AM
Yeah I thought about using a square crosspin Ian. A 1/4" lathe bit would be nice, but I couldn't figure out to make the square hole ...

The circular plate with 2 holes just dawned on me. The 2 holes would slip over the dowels. Better engagment for sure. Good idea for the next one!


11-11-2009, 02:42 AM
Very nice. Both you and that lathe have come a long way! I sure miss my turret. Odd, since I really never got around to using it much at all, but I had great plans! ;)

Thanx BD. Lotta concentricity on this one and I did it all in that 4 jaw.


Mark McGrath
11-11-2009, 03:15 AM
Nice job,you have made a releasing tap holder.
The Herbert ones take your idea a bit further forward.The pins are round like yours but are spring loaded forward and the ends are angled.The high side of the angled end points in direction of rotation.When the turret stops moving forward when it hits the stop the tap is still held but gets pulled forward until the low side of the pins come out the hole.The tap holder can then rotate as it pushes the pins back against the spring pressure like a ratchet.
When you reverse the spindle the high side of the pin drops into the hole thus creating the drive to unscrew the tap.

John Stevenson
11-11-2009, 04:15 AM
Or you can use the pins to drive it and a one way roller clutch that freewheels when you come off the pins but drives when reversed.


11-11-2009, 11:07 AM
As Mark says, it's known as a releasing tap holder. All the production tooling manufacturers had a variety of this. They come up dirt cheap on ebay once in awhile, usually when the seller doesn't know what it is.

11-11-2009, 11:20 AM
You don't need a square hole, just drill a hole to clear the square bar and use a set screw to lock it in place. I think in time the dowel pins will give you trouble.

I like the tool and you did a nice job.