On Tue, 12 Dec 2017 13:57:36 +0100, Emanuel Berg
wrote:

I tried to decipher all the data on a disc for
the angle grinder. Here is the incomplete
result:

#! /bin/zsh

# Symbols that seem to indicate:
# - use safety gloves, earmuffs, and goggles
# - for cutting only
# - read the manual
# - don't use a broken disc (?)
# - use to cut Inox or SS

# EN 12413
# a DIN standard: "Safety requirements for
# bonded abrasive products"

# 125*2.0/1.0*22.23
# outer_diameter*thickness/inner_diameter*thickness
# in mm

# MAX 80 m/s
# RPM 12200
# speed when disc is at 125 mm
# when disc is at 22.23, speed is 14 m/s!
# see program below to compute this

# AS 60 T INOX - BF
# INOX is again Inox/SS
# the rest I don't know

# Fe/S/Cl = 0.1%
# Some health related chemical property?

rpm2ms () {
local diam=$1 # e.g., 125 mm
local rpm=$2 # 12200 RPM
# ---------
# 80 m/s

local diam_in_m=$(( $diam / 1000.0 ))

local pi=3.14159265

local c=$(( $diam_in_m * $pi ))
local dist_per_min=$(( $c * $rpm ))
local dist_per_s=$(( $dist_per_min / 60.0 ))

printf 'm/s = %.0f\n' $dist_per_s
}

You've got 4" x 2mm cut off disks :-)

In the last few years I have switched to 4" x 1mm cutting wheels. They
are, I believe, some sort of epoxy material impregnated with cutting
abrasive. They cut very noticeably faster then the 2mm wheels and when
they do break the don't shatter and explode all over the place.
--
Cheers,

John B.