I have a requirement for some M6 internally threaded through holes. In the past I have done this same job by drilling holes and tapping with a standard tap followed by a bottoming tap.I usually produce about 80 pieces. As you can see this is a tedious and monotonous task.
This time I am seriously considering doing this job by internal thread milling on the lathe.
I am wondering if anyone on this group has ever contemplated doing the same? I have the means of grinding a carbide milling cutter so that will not be an issue. The parts are about 6mm through.

Dick

Charles,
I owned two Tapmatic tappers some years ago. They are nice to use and I wish I still had them. They are very expensive to buy even on the used market. It is not cost effective for me and the job I have.
Dick

?

Dick,
If you set up the Uni as a mill/drill press and use a spiral point tap
you could knock these out pretty quickly, if you have a reversing motor.
With the standard Uni motors removing the tap will take a bit of hand
cranking. How much cranking depends on the depth of the hole.
For through holes a spiral point tap is what you want. For blind holes
use a spiral flute tap.
Elliot

--
Elliot Nesterman
elliot@...
www.ajoure.net

"The finest jewel cannot disguise a flawed character."

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Hello Dick and Elliot:

I had a lot of holes to tap in plastic and built a reversing tapper from a cordless drill:

The switch is a DPDT push button to reverse the drill.

Then when I was at my brother-in-law's we needed to tap a bunch of holes so we built a crank to clamp on his drill press spindle:

Guided tapping is the way to go, I try to avoid hand tapping at all cost!

Good luck, Carl.

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Hi Tim:

I remember the stamping die shop I was in hired a mold maker from LA. In die sets they drill holes for springs and call for flat bottoms. Not used to die work the mold maker tried to start the hole with the flat bottom drill, it walked all over the die set. We then told him to drill to depth with a regular drill and then remove the corners with a flat bottom drill.

Carl.

Probably not what you are looking for, but I use this. ?An easy conversion to a reversing electric drill.

A long time ago we had this discussion. In England the three taps are Taper, Second & Plug and a bottoming tap is usually made by grinding the point and lead off a pug tap so you can tap all the way to the bottom of a blind hole.

In America the three taps are Taper, Second & Bottoming. Hence confusion. I have decided to call them First, Second & Third. Should be clear enough to everyone.

To add to the confusion a lot of sets these days do not cut the full thread form until you use the third one. I often use a taper tap, the first one, to cut full threads in thin materials. Sometimes that won't work now.

Ages ago I had to tap a lot of M6 holes in a bit of framework. The holes were drilled in a pillar drill, and then I used a pistol drill to run the tap through, forward and reverse, BUT that was in Al alloy. In steel you would need specialised tap, not sure just what, spiral point, spiral flute, but there are taps to do the job.

On Fri, Feb 24, 2023 at 05:57 PM, Bill in OKC too wrote:

drill to depth with a regular drill and then remove the corners with a flat bottom drill.

I was assured long ago that a flat bottom drill is made from a slightly bigger drill, with the cutting edges ground off the flutes, and the end flattened. Never seen anyone take the trouble, perhaps because there's only one company I've worked with who had a cylindrical grinder.

? This link should take you to a listing for an American Gator tapping tool that can be used on a mill or drill press, ect. Might fit your need.
John