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TB042 Rev1 Determining Maximum Axis Velocity
Overview
The following outlines the maximum velocity of an axis while maintaining the maximum torque
Method
Where
Metric Pitch = The mm/turn of the screw
US Pitch = The turns/inch of the screw
Vmax = Maximum working velocity rapid expected
Wrpm = Working RPM of the motor Point at which the torque begins to drop
Centroid
stock Motor Centroid Part
Number Working rpm
W
rpm Example Metric
Calculations Example US
Calculations
Metric Pitch
mm/turn Rapid
mm/min US Pitch
turns/in Rapid
in/min
17 in lb DC R 10439 2300 2 540 5842 10 0 230
29 in lb DC G 10781 1500 5 08 7620 5 0 300
29 in lb DC S 10104 1500 5 080 7620 5 0 300
29 in lb DC R 10669 2200 5 080 11176 5 0 440
40 in lb DC S 10113 1500 5 080 7620 5 0 300
      Â
750 Watt AC
L 10690 3500 5 080 17780 5 0 700
1 Kw AC S 10555 3200 6 000 19200 4 234 762
2 Kw AC S 10557 2500 8 000 20000 3 175 781
3 Kw AC S 10804 1350 12 000 16200 2 12 Â 636
Examples are for maximum speed using tallest recommended
pitch
Rule Motor should be running at Wrpm when at expected rapid speed This rule assures that the motor will
produce full torque and accuracy
Speeds above recommended cause loss of torque loss of stability and loss of accuracy If this speed is too
fast for example 25 000mm/min where 16000 is recommended then the pulleys should be changed to 2/3 or
1/ 2 to reduce top speed or the ball screw should be changed to a lower pitch like 8mm or 6mm
Just setting the max speed lower in the software does not regain the loss of torque and accuracy
Obsolete Motors
Centroid
stock Motor Centroid Part
Number Working rpm
W
rpm Example Metric
Calculations Example US
Calculations
Metric Pitch
mm/turn Rapid
mm/min US Pitch
turns/in Rapid
in/min
1 Kw AC L 1 10689 3200 5 08 16256 5 0 630
1 Kw AC L 2 10689 2200 8 000 17600 3 175 690
2 2 Kw AC L
1 10688 3200 5 08 19200 5 0 760
2 2 Kw AC L
2 10688 2000 10 000 20000 2 54 780
      Â
3 Kw AC L 10715 2000 10 000 20000 2 54 780
Examples are for maximum speed using tallest recommended
pitch
DETERMINING MAXIMUM VELOCITY FOR HIGH LINE COUNT ENCODER
Maximum velocity that the Centroid system can control is based on the amount of encoder counts in a second
The limit for the control is 480 000 counts per second This limit is not reached with a standard Centroid motor
with a 2048 line encoder but if using a high line encoder 4096 lines the max speed of some motors will be
limited This limit does not apply to the spindle encoder that report velocity only
Use the equation below to find the max motor speed The Encoder Resolution
for the 4096 high line count
encoder is 16384 or 4X 4096
for high line encoder
This shaft speed is less than the maximum motor speed for all but the 3 Kw S motor which cannot spin faster
than 1350 RPM
Maximum Working Velocity with High Line Count Encoder
 Â
Working rpm W
rpm Example Metric Calculations Example US Calculations
Metric Pitch mm/turn Rapid
mm/min US Pitch turns/in Rapid
in/min
  1750 2 540 4445 10 0 175
  1750 5 08 8890 5 0 350
  1750 6 000 10500 4 234 413
  1750 8 000 14000 3 175 551
  1750 12 000 21000 2 12 825
Examples are for maximum speed using tallest recommended
pitch
Document History
Rev1 Created on 1999 09 09
by #001