Collaboration
ART
BEAUTY & WELLNESS
CRAFT
CULTURE & HISTORY
ENTERTAINMENT
ENVIRONMENT
FOOD & DRINKS
REVERSE ENGINEERING
SCIENCES
SPORTS
TECHNOLOGY
WEARABLES
Cross-Hole Countersinks: A Slanting Hole Through the Cone Makes One Spiral Shearing Lip (Taylor, 1903)
John M. Taylor · Public domain
Forge

Created by

Forge

13. November 2026NO
0
0
0
0
0

Cross-Hole Countersinks: A Slanting Hole Through the Cone Makes One Spiral Shearing Lip (Taylor, 1903)

John M. Taylor of Hartford, Connecticut, received US 724,520, dated 7 April 1903, for a countersink that shears wood smoothly. Its conical head has a hole drilled through it at a slant that crosses the axis and reaches the point. One edge of that hole is the cutting lip, a spiral curve from the point out to the rim, and the chips go straight out through the hole to the back. A short band behind the cone guides it. We turn a set of three from tool steel and harden them. The patent gives no sizes; every size here is ours.
Intermediate
About 1 day

Instructions

1

Where the slanting hole must go

Loading Jupyter Notebook...
2

Read US 724,520

"One of the outer edges of the wall of the opening forms a cutting-lip 8, which is of spiral formation, whereby it is effective to make a shear cut, and terminates in a shoulder 9, forming an entering or cutting point 4 at the apex of the conical head 2."
3

Turn the blanks

From octagonal tool steel big enough for each head, turn three blanks: a 90 degree cone 2 to a sharp point, 12, 16 and 20 mm across at its base; a band 5 2 mm long at that diameter as the guide; a truncated cone 6 down to an 8 mm shank 50 mm long. File three flats on each shank's end for the chuck. Heat each to a cherry red and let it cool slowly in the air, to soften it for drilling.

Materials for this step:

Octagonal Tool Steel BarOctagonal Tool Steel Bar2 pieces

Tools needed:

Metal LatheMetal Lathe
Lathe Chuck 3-JawLathe Chuck 3-Jaw
Lathe Cutting ToolLathe Cutting Tool
Parting ToolParting Tool
ProtractorProtractor
Digital Caliper 6-InchDigital Caliper 6-Inch
File SetFile Set
ForgeForge
Forge TongsForge Tongs
Safety GlassesSafety Glasses
4

Drill the slanting opening 7

Hold a blank in the machine vice tilted so the drill meets the cone's side at 35 degrees to the tool's axis, aimed to cross the axis just behind the point (the notebook gives how far). Drill through with a drill 0.45 of the head across: 5.5, 7 and 9 mm, so the hole breaks out through the point on one side and out of the back cone on the other. Open the back of the hole a little larger, so it tapers towards the shank.

Tools needed:

Drill PressDrill Press
Machine ViceMachine Vice
ProtractorProtractor
Drill Bit SetDrill Bit Set
Digital Caliper 6-InchDigital Caliper 6-Inch
5

File the lip 8

With a round needle file, clean the hole's edge on the side that leads as the countersink turns, leaving it sharp from the point to the band: that is the spiral cutting lip. File a little relief on the cone just behind it, and leave the shoulder 9 at the point.

Tools needed:

Needle File SetNeedle File Set
Machine ViceMachine Vice
Bench GrinderBench Grinder
6

Harden and temper

Heat each head to a cherry red, until a magnet no longer sticks, and quench it point first in water, moving it about. Rub it bright with a stone, heat the shank gently 20 mm behind the head, and quench again as soon as a light straw colour reaches the cutting lip.

Tools needed:

ForgeForge
Forge TongsForge Tongs
Small MagnetSmall Magnet
Quench BucketQuench Bucket
WaterWater
Sharpening StoneSharpening Stone
Welding GlovesWelding Gloves
Safety GlassesSafety Glasses
7

Hone and test

Hone the lip lightly with the stone. Drill a few screw holes in hardwood and countersink them in the drill: the cone should cut a smooth bell without chatter and the chips should come out of the hole at the back.

Tools needed:

Sharpening StoneSharpening Stone
Cordless DrillCordless Drill
Drill Bit SetDrill Bit Set
Hardwood BoardHardwood Board
Safety GlassesSafety Glasses
8

Troubleshooting

Countersink troubleshooting.

Flow

Loading...
9

History and honest limits

**John M. Taylor** of Hartford, Connecticut, US 724,520, dated 7 April 1903, filed 7 November 1901. He claimed "a countersink having a cone-shaped head provided with an opening crossing diagonally to the axis within the length of the tool and intersecting the apex of the cone, said opening having a curved edge forming a cutting-lip", and a two-part shank for brace or chuck. We make one-piece shanks for a chuck. He gives no sizes, angle or steel; our 90 degree cones, sizes and the house hardening are ours.

Materials

1

Tools Required

22

This blueprint makes

Thumbnail
Placeholder

Countersink Drill Bit Set

Free

325
0

Related Blueprints

These blueprints share knowledge with this one — techniques, materials, or principles that connect them in the learning graph.

Wood Chisels and Gouges Forged from Tool Steel

Wood Chisels and Gouges Forged from Tool Steel

by ForgeNO

Blacksmith

24
0
0
0
0
0

CC0 Public Domain

This blueprint is released under CC0. You are free to copy, modify, distribute, and use this work for any purpose, without asking permission.

Support the Maker by purchasing products through their Blueprint where they earn a Maker Commission set by Vendors, or create a new iteration of this Blueprint and include it as a connection in your own Blueprint to share revenue.

Discussion

(0)

Log in to join the discussion

Loading comments...