Power tapping tap holders

[jjr2001]

Tapping over 150 holes made power tapping a requirement for my 2000 mill project.
I used 5/8" drill rod for the adapters.
Each blank was 2" long.
Turned a taper on the nose of each blank.
Drilled/reamed the hole for the tap in the tapered end while still in the chuck.
Reversed the partially completed tool in the chuck.
Turned down the shaft to 1/2" for use in my drill press, mill, or portable drill motor.
Moved the part to the mill to drill the set screw hole. Note that while I had it in the mill vise
I drilled the set screw hole all the way through. Now I have an extra hole in case I need a spare set screw threaded hole.

Made one for 10-32 and another for 1/4-20.
Added one blank to be used for whatever in the future.

Cheers, JR

[Paul Jones]

JR,

Nice addition to your new Sherline 2000 mill. Smart idea drilling the set screw hole all the way through. Over time the first threaded hole may become worn or stripped-out in the brass material.

Paul

[mklotz]

There's another good reason for drilling all the way through with the tap drill. If the hole the tap drill is intersecting is small, the tapered tip of the tap may not be able to make full threads to the intersection before bottoming out on the opposite side of the hole. A through hole provides a place for the tapered tip to go. A bottoming tap might solve the problem but keeping a full selection of tap types can get expensive.

[jjr2001]

Thanks guys, Good points for tapping and tool making. I do prefer to either
drill deep or drill through holes when tapping. Bottom taps are ok when there is
no other choice but going deep or all the way through works best for me.

Cheers, JR

[petertha]

Nice parts JR. I was just drawing up a similar holder, but more for hand tapping teeny, sensitive taps floating/sliding within jaws grips or loose collet.

I'm curious about the 'power' aspect of your holders. You mentioned using your drill press. So dumb question but what is the tap holder providing that you would not similarly have by gripping the shank of the tap directly with the chuck?

[jjr2001]

Nice parts JR. I was just drawing up a similar holder, but more for hand tapping teeny, sensitive taps floating/sliding within jaws grips or loose collet.

I'm curious about the 'power' aspect of your holders. You mentioned using your drill press. So dumb question but what is the tap holder providing that you would not similarly have by gripping the shank of the tap directly with the chuck?

Hello petertha,
The tap holder has a much better gripping surface with the 1/2" shank for the drill press chuck. Tap shanks are extremely hard and can slip in the jaws of a drill press chuck. The diameter of the tool holders also helps the chuck grip it. Then the set screw in the nose of the tap holder prevents the tap from turning.
In over 200 holes tapped my holder never slipped.

If the hardened tap slips in the chuck jaws it can ruin them so there is a bit of safety added.

Cheers, JR

[Ralphxyz]

Where did you get taps that would stand being power driven? Links appreciated.

Most hardware store taps will not take the power for long.

Thanks for posting.

Ralph

[petertha]

Ah, hardened tap shanks - makes sense. I must admit I've always wondered about this aspect because drill shanks must also be hardened, but maybe not to same degree? Anyway, gripping them directly is probably not great for chuck jaw health if it does spin or catch. That's a lot of holes, good job!

[jjr2001]

Hi Ralph, well since the pallet is aluminum it does not take too tough a tap. I have used 1/4" Craftsman (from a 40 year old set) to tap 100 + holes in an aluminum pallet I made for my mini mill. Never failed, it just kept on tappin..

The tap I just used for the 10-32 holes was from Dad's tool box. It is a Nachi GH3 made in Japan tap. Not sure how old it is but it is still sharp.

Cheers, JR

[Ralphxyz]

Thanks JR.

Ralph