Reference Guide

Anti-Kickback.....or ‘BG’ Test?
The term ‘Anti-Kickback’ has been an industry
topic for quite some time and relates to cutting tools
such as router bits, saw blades, etc. There are several
brands of ‘Anti-Kickback’ router bits presently on the
market and all of them, it seems, would offer some
degree of safety to the end-user because they limit the
‘chip-thickness’ of the material being cut. In other
words, the cutting tool will take less of a ‘bite’, thereby
decreasing the likelihood of a kickback. While this is
true, however, it should be pointed out that there are
significant details to be considered when designing,
manufacturing and using industrial cutting tools.
1. What is ‘BG’? ‘BG’ is an acronym
for ‘Holz Berufsgenossenschaft’, the
German Woodworking Trade
Association. For the sake of worker
safety, this esteemed group has
established basic rules for the
design, manufacturing and use
of cutting tools for the wood
and plastic industries.
These basic rules concern
testing the working safety of
woodworking machine tools.
They establish test procedures
and indicate all essential
regulations and rules of
technology, which need to be taken
into account during testing. Precise
geometric design, as well as the use of high
quality materials and replacement parts complying with
DIN standards, will ensure a safe tool with a high
degree of precision in the production and the balance
of the tools. The purpose of the test is to ascertain
whether it is ensured that users or third parties, who
are handling the tools properly are, in fact, protected
as far as possible from risk to life or health.
Tools for use in wood and plastic working are classified
into two groups: manual feed operations and
mechanical feed operations.
Manual Feed Operations
‘Manual feed’ describes the holding and/or guiding by
hand of the workpiece or of a machine element
incorporating a tool. Manual feed includes the use of a
hand-operated carriage, on which the workpiece is
placed manually or clamped and the use of a
demountable power feed unit.
Tools for manual operation marked ‘BG-TEST’ are
designed according to the following rules:
a) Thickness of chip
limit with a
maximum cutting
edge projection of
1.1mm (.043"), over the total length
of the cutting profile;
b) Restricted maximum chip clearance width, including
the regrinding range as a function of the cutting flight
circle;
c) Kickback ratio must not exceed 0.25 Vr/Vs < 0.25
(where Vs = cutting velocity and Vr = kickback
velocity).
Special purpose tools which, for reasons of
speed and economy, cannot be inspected
by the German Woodworking Trade
Association may be used manually,
if they conform with the above
requirements.
Mechanical Feed
Operation
‘Mechanical feed’ means a
feed mechanism for the
workpiece or tool, which is
integrated with the machine
and where the workpiece or
machine element with
incorporated tool are held and
controlled mechanically during the
machining operation.
All the tools may be used for mechanical feed
operation. The rules that characterize manual feed
operation tools do not apply to them, except for the
manufacturer’s label and maximum permitted speed.
The basic rules applying to manual feed operations do
not apply to router bits with diameters smaller
than 16mm.
2. ‘BG’ Form vs ‘BG’ Test - ‘BG’ Form is a term
indicating cutting tools which have the same general
circular shape of ‘BG’ Test tools, but which do not
comply with the strict regulations governing ‘BG’ Test
as outlined above. (1.1mm cutting edge projection,
restricted maximum chip clearance width etc.) There is
a significant difference between the two.
IMPORTANT NOTE: Unless specified otherwise, all
router bits over 16MM (5/8") diameter in this catalog
are ‘BG-TEST’. This does not apply to CNC, Insert and
tools with larger than 1/2" shank diameter.
ROTATION
1.1mm
(.043")
ROTATION
‘BG’
Non ‘BG’
ROUTER BITS
VIII