Threading Die for Bagpipe Mouth Piece

Project:
Building a 9/16" by 30 TPI threading die for a local bag pipe shop

Difficulty Level (Easy, Medium, Hard, Insane):
Medium

Process:
A local bag pipe shop owner called me a couple of days ago asking if I could make him a custom die so he can thread some stock delrin with a 9/16" by 30 TPI male thread. After some research I found that a 30 TPI is a virtually non-existent pitch so there was no dies available that I could find.

I did find a matching tap but it was over $80 bucks. When I planned out how to make this die I figured if I can thread a piece of O1 tool steel to the proper size, I could mill some relief angles to make the cutting edges, harden and sharpen it and then use this custom tap to cut the inside threads of a piece of 4140 steel. Once that was tapped I would heat, quench and temper the final die so that's what I set out to do.

Unfortunately, after several hours when I had finally completed the tap I used my belt sander to cut some relief angle into the tap just to realize when I was done that I had done so at the wrong side and essentially dulled the tap beyond any use.

After I got over the disappointment, I figured I could use the Threading Insert Tool Holder that I had used to make the Milling Head Ejector Nut and skip the tap altogether.

After cutting off a 1/2" piece of 4140 on my fixed Metal Band Saw, I chucked it up, faced both sides, drilled and bored it to size and then used my 39 Tooth Gear to enable my lathe to cut 30 TPI threads.

After the bored piece was tapered on one side to make it easier to start the tap I cut the internal threads which actually worked out quite well.

Once the threads were cut, I mounted my DIY Dividing Head, set my mill to the horizontal position and drilled 6 equally spaced relief holes.

All I had to do now was heat the die with my Propane Burner, quench and temper the die, then do a final sharpening of the cutting edges as well as some cosmetic clean up and engrave the size and TPI values on the die.

Pictures:

The bag pipe piece the final threaded piece should fit into

Another view of the piece with the female thread

A piece of delrin

The 1/2" piece of 4140 I cut up to make the die out of

A 3" piece of 3/4" O1 tool steel to make the tap out of

The chart showing how to enable a 30 TPI thread on my lathe

Facing the O1 tool steel

After the O1 tool steel was threaded and tapered

Setting up my dividing head

Cutting some relief into the tap

The finished cutting end of the tap

Turning the shank down to 1/2"

The finished tap

Another view

Heating the tap

The glowing red hot tap

Quenching the tap in some old motor oil

A layer of oil smoke in my shop. I thought it looked kind of cool

The hardened tap

Drilling the die blank

Mounting it on an arbor to turn the outside to a bit under 1"

Boring the die

Another view

Threading the inside of the die

Using the tap to clean up the inside thread

Another view

Drilling some recesses to hold the die in the die holder with the set screws

The die mounted in the die holder on the tap in the vise

Another view

After the relief holes were cut; I did not have enough material along the insides and the cutting edges were too wide

Another view of the (first version) finished die

Another view

Turning the delrin to 9/16"

The new (first version) die in the holder

Close-up of the delrin turned to 9/16"

The inferior threads left with the first version die

Threading the second version die blank

The threaded die

Fitting a test piece on the die

Getting ready to drill the relief holes

Closeup of the setup

Testing how 8 relief holes would work out. I ended up deciding against it

Six relief holes looked better so I went with that

Cutting the first relief hole

After all the holes were cut

The finished, non-hardened (second version) die

Getting ready to heat the die

The glowing die just before quenching it

The hardened die

After I cleaned it up on the belt sander

Engraving the die size with a diamond tipped dremel bit

The completed 9/16" - 30 TPI die

Tools:
Lathe and accessories
Threading Insert Tool Holder
Metal Band Saw
39 Tooth Gear
DIY Dividing Head
Propane Burner
Dremel
Belt sander
Tap & die set

Materials:
3" of 3/4" O1 tool steel
Two 1/2" pieces of 1-1/4" metal (4140)

Cost:
$0.00

Time:
7 hrs

Savings:
$80.00

Conclusion:
It works and looks really nice. I'm amazed how many uses for my lathe I have discovered since I got it last summer.