Is your brush not aggressive enough? Try one of these options:

• Increase surface speed by increasing spindle RPM
• Use a coarser grit abrasive
• Increase brush diameter
• Increase fill density
• Decrease trim/filament length
• Increase pressure

Is your brush too aggressive?  Try one of these options:

• Decrease surface speed by decreasing spindle RPM
• Use a finer grit abrasive
• Increase trim/filament length
• Decrease filament diameter
• Reduce pressure

Are you looking for a smoother finish? Try one of these options:

• Decrease filament size
• Use a finer grit abrasive
• Use the brush with coolant or cutting oil
• Increase RPM
• Increase brush diameter

Are you looking for a rougher finish?  Try one of these options:

• Increase fialment size
• Use a coarser grit abrasive
• Decrease RPM
• Decrease brush diameter

Are you noticing that your brush action/marks are not uniform?  Try one of these options:

• Increase trim length/filament length
• Decrease fill density and brush face. 
• Automate the process to eliminate irregularities produced by human error

Are you looking for longer brush life?  Try one of these options:

• Increase fill density or brush face width
• Use less pressure - Brushes SHOULD NOT BE PUT UNDER EXCESSIVE PRESSURE

Are you having trouble with the brush filament smearing or melting?  Try one of these options:

• Use less pressure - Brushes SHOULD NOT BE PUT UNDER EXCESSIVE PRESSURE
• Decrease brush diameter
• Decrease RPM
• Use coolant