Changing The Spindle Speed - Proxxon FF 500 CNC Commissioning Manual

12.5. Changing the spindle speed

Setting the spindle speed is necessary so that the cutting speed of the tool can be
adapted to the characteristics of the material to be machined and to the tool
geometry.
Large tool diameters at equal rotational speed also mean a large circumferential
speed and thus potentially a too large cutting speed. Conversely, the same is also
true for small tool diameters.
This makes it necessary to be able to vary the rotational speed. To do so, a belt drive
guides the motor power at the milling cutter to the spindle. This is a two-stage
gearbox with an intermediate gear for general speed reduction and two ratchet
wheels with respectively different diameters in pairs. These are connected by two
poly-V belts that are excellently suited for this purpose due to their quiet running and
transfer characteristics. The respectively required spindle speeds can be realised by
shifting the belts. A total of 6 spindle speeds can be set: 180, 350, 550, 800, 1,300
and 2,500/min.
The sketch on the right shows the respective belt pulley combinations of the
individual rotational speeds; necessary rotational speeds for different milling cutter
sizes and materials can be read directly in the table on the gear case.
2500 / min
1300 / min
800 / min
550 / min
350 / min
180 / min
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