Graduating markings

Advice please, fellow swarf makers. Have had a spell of making Hemingway kits, and have (some) pieces that need graduation markings engraved on them. The Hemingway graduating tool supplies a piece of 3/16" dia HSS, but I need to know suitable angles to grind it to for optimum use with minimum wear, not wanting ruts that look like a tractor tyre has been through them. I am considering an included angle of about 30 degrees; would that be about right? Flat top, or should it have a bit of rake? Grind to a point, or leave a slight flat? All suggestions gratefully considered. TIA.

From memory, always suspect, GHT: 40 deg included angle 2 thou tip flat cut to 5 thou deep

Rob

Edited By Robert B on 12/03/2021 20:18:46

According to the GHT book you are very close.

Included angle 40 to 45°
Side clearances 5°
Back rake 5 to 7°
Tip width 0.002"
Cut Depth 0.004"

This will produce a line approx 0.005" wide in steel, with a suggestion to cut slightly deeper in cast iron.

Phil

Most grateful for your response. Wonderful. Thank you

I engraved some dials for a little lathe a few weeks ago using this:

I was pleasantly surprised with the results which can be seen in my album "Record ML-10 lathe".

Rik

Neat approach, Rik. I don't know the angles on those tips, but it looks around 40º.

35 degrees

Emgee

I did some using some carbide inserts the same as Rik's on the cross slide dial and the tailstick on the Smart & Brown model A. They are VCGT 160401, came in a job lot and are too sharp for normal use (0.5mm rad tip).

Edited By old mart on 24/03/2021 21:23:54