Chip-limited tooling

Old style tooling tended to pull the hand in to the cutters, often resulting in serious amputations. Although limited cutter projection tooling will not prevent an accident it is designed and constructed to significantly reduce the extent of an injury if the worker touches the cutters. If injuries do occur they are likely to be lacerations requiring stitches rather than amputations.

What does limited cutter projection tooling look like

Old illegal cutter blocks

Risk of ejected cutters from square block as well as serious hand injuries when no chip limitation:

Square block, no chip limitation, cutter held by single bolt
Example 1 - Old illegal square block. In addition to not having chip limitation, the cutter is held in place by only a single bolt so has a risk of being ejected.
NLS cutter block, no chip limitation
Example 2 - Old illegal NLS cutter block with no chip limitation
Cutter block, no dummy profile
Example 3 - Old illegal cutter block without any dummy profile for chip limitation
Detail of Cutter block with no dummy profile
Example 4 (Closeup of Example 3) - No dummy profile for chip limitation

Chip limited tooling

An example of limited cutter projection tooling for use on a hand fed machine (marked MAN on tool body). This cutter block has chip limitation from a dummy profile as well as secure fixing arrangements for the blade to prevent the risk of ejection, this being two side bolts and centre bolt for a locking wedge.

Chip limited tooling cutting block
Detail of chip limited tooling cutting block

Benefits of chip-limited tooling

The limiter reduces the depth of cut so 'kick backs' are less likely to occur.

Ejection of the tools was common with the old style cutters as they were only held in place by the friction from clamping bolts. Chip limited tooling has two ways of securing the cutters, preventing ejection.

The reduced depth produces a better finish, so less sanding is required, reducing the health risk and improving production.

Chip limited tooling is much better balanced so there is less vibration when it runs. This has the following benefits:

  • With high revolution machines such as CNC routers vibrating tools can be ejected with serious consequences;
  • Less vibration means there will be also be a reduction in noise levels. In addition, noise levels will also be reduced if the tool body is made from aluminium, a feature of some chip limited tools. Lighter aluminium bodies also reduce forces on the motor during braking as well as making the tools easier and safer to handle.
  • Less vibration means that the tool cuts more efficiently so it can therefore have a three to four times longer tool life. In addition, there will be an improved finish and less wear on the shaft and bearings of the machine.

The old style tooling requires a lot more skill and time to set up correctly. Chip limited tooling is simpler to set up and therefore reduces down time during changeover. Also, as it is more likely to be right first time less timber is wasted. One head can also have several different profiles which also reduces set up times.

These hand-fed machines should have been fitted with limited cutter projection tooling after 5 December 2003:

  • vertical spindle moulding machines, even if fitted with a power feed. This is because power feeds are easy to remove and only provide some protection if set low to the table, ie when machining small pieces
  • single end tenoners
  • rotary knife and copy lathes, unless they are fitted with fixed and/or interlocked guards that prevent ejection of, or contact with, tools.
  • other machines that can be fitted with moulding tools, such as pull-over cross-cut saws.

For more information visit the Tooling for use with hand-fed woodworking machines WIS37(Revision 1) website.

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Updated 2021-07-06