NOTES:
1.       Bit Diam.         Max Speed

 3 to 9mm           24,000 RPM
10 to 35mm       18,000 RPM
38 to 50mm        16,000 RPM
56mm plus         12,000 RPM

2. Bearing care:

Ball bearings should be cleaned in solvent and dipped in light oil after use

3. Burning:

Feeding the bit too slowly causes fiction and burning.
Blunt cutters will also cause fiction and burning.
Blunt cutters will also cause burning aggravated by a fast feed rate.