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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 
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 < 
  (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.