Bevel Angle - Challenge CHAMPION 370 XT Operator's Manual

The machine seems to strain while cutting. This strain can be heard in the hydraulic motor.
The knife makes a "rougher" sound as it passes through stock.
Nicks are visible on the cutting edge of the knife.

10.1.3 Bevel Angle

The most appropriate bevel angle depends upon four factors.
1. The length of time desired between sharpening
2. Physical properties of the stock being cut (hardness, impurities, density)
3. Power output of machine
4. Amount of clamp pressure applied
1. Length of Time Between Sharpening
Under identical cutting conditions, knives with larger bevel angles will require sharpening less
frequently than knives with smaller bevel angles. There is more material supporting the
cutting edge of larger bevel angles.
2. Physical Properties of Stock
In general a smaller bevel achieves a better quality cut. Hard, dense, and impure papers,
however, will dull a small angle bevel quickly. Impurities may put nicks on the cutting edge.
As a result, cut quality is lost quickly, and knives require sharpening often. Therefore, a
larger angle bevel should be chosen for such materials. Soft materials can be cut with small
angle bevels without adversely affecting sharpening frequency.
3. Power Output of Machine
As the bevel angle increases, more power is required to push the knife through stock. If a
bevel angle is too large for a machine, the machine may take excessive wear-and-tear and
may stall part way through the cut cycle. Although the knife will require sharpening less
often, the machine may incur costly damage.
4. Amount of Clamp Pressure Applied
As clamp pressure increases, the pile density increases. As discussed in 2, above, more
dense materials are harder to cut. This presents a dilemma. Higher clamping pressures are
used to reduce draw when cutting with large angle bevels. While higher bevel angles
increase the lifetime of the knife, high pressure clamping increases the material's density and
detracts from knife life. As a result, a compromise must be made between knife life and cut
quality.
10.1.4 Helpful Suggestions
If your shop is large enough to purchase more than one set of knives, the following
suggestions may be helpful. A set consists of 3 knives, one in the machine, one back up,
and one at the grinder.
If you cut a variety of stocks (easy and hard to cut), purchase two sets of knives. One set
should be beveled at around 21
Use the smaller angle bevel to cut softer stocks at lower clamping pressures. Begin by
cutting the most pure, easy to cut stocks. As the knife dulls, begin cutting the less pure of the
softer stocks.
Use the larger bevel to cut harder more dense stocks at higher clamping pressures. Begin by
cutting the softer and most pure of the hard stocks. Then move to cutting the harder and less
pure of the hard stocks.
0 and the other around 23
10.0 Routine Maintenance/Adjustments
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