Countersink gage

[mklotz]

I've wondered about the uses of 60 deg countersinks myself. I can't remember ever seeing a screw with a 60 deg included angle. Lathe centers are 60 deg on metal lathes and I guess the same on wood lathes. For metal we use center drills that have the required angle. I'm not a woodworker so I don't know how those folks make center holes for their lathe work. Regardless, they're advertised as "countersinks", not center drills, so I would expect the intended application is seating screws.

When I drive Robertson screws I use an electric drill with an adjustable clutch. The clutch slips before the head of the screw is torqued off.

The other type of screw that can be held on the driver is the hex-head self-tapping screw, e.g.,

https://www.amazon.com/Swordfish-315...tapping+screws

driven by a magnetic nut-driver, e.g.,

https://www.amazon.com/DEWALT-DW2235...tic+hex+driver

Not suitable for fine woodworking but, as I said, that's not my passion; my woodworking is more construction-grade.

[Frank S]

As near as I can recall My grand pa used the 60° countersink only when he was pinning pieces together with tenons the 60° included angle gives a tighter tap in fit also allows for a smaller surface profile in the finished product.
I know at times he would bore tapered holes of around 10° for those times when he really wanted something to never move this way he could have larger diameter tenons without having the large surface profile

[Jon]

Congratulations mklotz - your Countersink Gage is the Homemade Tool of the Week!

We had a clear winner last week with rossbotic's excellent Machine Tool Dial Making Fixture, and this week was the exact opposite. One of these days I'll end up wearing a straitjacket in a white padded room, mumbling incoherently about utility vs. ingenuity, pondering my recent diagnosis of Homemade Tool of the Week Selection Dysphoria Syndrome.

Other nice entries this week include an Engine Tilter by brianhw, a Horizontal Mortising Machine by Marc Broussard, a clever Broach by astroracer, LED Lights by mattthemuppet, Bar Clamps by Tuomas, and a Lathe Alarm by mklotz. Especially notable was the Tool & Cutter Grinder by tonyfoale, which was quadruple-documented with text, photos, video, and even a spreadsheet. It will be a difficult candidate to beat for the January Best Documented Build award, and we may see future builds based upon the information presented.

The Countersink Gage, though very simple, surfaced an often-ignored but critical issue over 8°, and also garnered an unusually large number of Thanks votes. But ultimately what pushed it over the line was the followup, in which mklotz applied "assistance and encouragement" to rgsparber to publish a new design of the same tool. rgsparber's build, published 10 hours after the weekly award cutoff time, is unavailable for this award, and who knows what will happen in the coming week. Nevertheless, this is a clear demonstration of a valuable meta-quality of a tool builder: not only is it socially acceptable for others to build your idea, but they're encouraged to do so, with your assistance.

This is your 7th Homemade Tool of the Week win. Here are all of your other winning entries:

Bore Measurement Gauge by mklotz

tags: gauge, dial indicator, measurement

Miniature Indexing Faceplate by mklotz

tags: indexing unit, collet

Pocket Tools by mklotz

tags: magnet, measurement

Bench Block Clamping Setup by mklotz

tags: clamp, V-block

Model Cement Mixer by mklotz

tags: mixer, cement

Sphere Drilling Jig by mklotz

tags: jig, drilling

You'll be receiving a $25 online gift card, in your choice of Amazon, PayPal, Giftrocket, or bitcoin. Please PM me your current email address and gift card choice and I'll get it sent over right away.


Congrats again and nice job

[Toolmaker51]

Marv's gauge is a quick check and sorting device. I can't offer much on the crazy range of countersink angles. The highest 100* and 120* offer broad contact and a thin head for threaded fasteners and rivets in sheet materials, i.e. aircraft. The only 60*s I recall using were considered 'center reamers' as in correcting mis-located spot drilling, and other limited use. Part of course, must be clamped.

Inspection wise, determining angle of countersinks is a little trickier. 82* and 90*, use corner of a flexible rule or paper. The 90* might show daylight, but will be parallel to the edges of the scale. 82* won't touch at the bottom. There are small angle gauges about size of pitch gauge leaves that range 5* to 100*[?]. Easily made though by a number of methods.
Inspection dictates proper angle, diameter, or occasionally depth per drawings. Some prefer digital calipers for diameter. I get repeatable measurements using pin gauges. Better brands have a minimal corner radius. Whatever the tolerance range, that's the pins to select. The largest shouldn't 'fall' into the countersink when slid over it, smallest has to. At extremes, zero an indicator on pin set on adjacent surface, then positioned in the c'sink. If largest allowable diameter reads lower, the c'sink is oversize.

[Toolmaker51]

Congratulations mklotz - your Countersink Gage is the Homemade Tool of the Week!...One of these days I'll end up wearing a straitjacket in a white padded room, mumbling incoherently about utility vs. ingenuity, pondering my recent diagnosis of Homemade Tool of the Week Selection Dysphoria Syndrome.

Long as you can recall, spell, pronounce, and describe the Homemade Tool of the Week Selection Dysphoria Syndrome diagnosis, you'll be fine. Just fly low of Nurse Ratched. Randle and Chief won't be there to warn you.