SELECTION OF RIGHT MOTOR
The stepper motor must provide sucient torque to turn the lead screw in all positions. De-
pending on the machine, more or less power is required. In general it can be said that the nec-
essary forces are smaller than e.g. on a milling machine.
For normal hobby machines with 400-600mm distance a Nema24 motor with 3-4A current
should be sucient. Larger machines might need more power.
Do not underestimate the force a motor can generate on a threaded spindle. A Nema24 motor
with 2.2 Nm torque on a 4mm spindle generates a thrust of about 1400N, which corresponds
to a weight of 140 kg pulling on the bed slide!
Step rate of the drive on the Z axis:
The control can only supply a nite clock rate, which is directly linked to the pulses of the spin-
dle encoder. The recommended 400 pulses per revolution of the encoder and 400-800 steps/
revolution of the stepper motor are used to ensure correct operation up to a spindle speed of
3000 rpm. If you deviate strongly from this, malfunctions may occur.
Transmission via toothed belt on the Z-axis
The available torque can be increased by a transmission, a smaller motor can be used, but at
the expense of speed. Stepper motors have lower torques at higher speeds, the curve drops
sharply at higher speeds. So if high speeds are required, it is more of a disadvantage to trans-
late: In the end they do not necessarily get more torque.
Pay attention to backlash-free variants of timing belts, e.g. a HTD prole.
Only use transmission in straight ratios, 2:1, 4:1, etc.
The step rate on the motor driver should then be selected accordingly, see table below. Ob-
serve the maximum speed of stepper motors, this is usually in the range of 800-1400 rpm with
a noteworthy torque. With a ratio of 2:1, only half the speed is available. At 700 rpm on a lead-
screw with 2mm pitch, a maximum of 2x700 = 1400 mm/min feed rate is still possible.
In comparison, an untranslated drive delivers 2800 mm/min here.
X-Axis
The ELS does not require high speeds on the X-axis, so a transmission is easier there, and the
step rate can also be set higher to increase the resolution even further. We recommend 1600
steps/rev at 1:1 and 800 steps/rev at 2:1 on the X-axis should almost always be possible. So a
smaller motor can also be used, which often ts better on the X-axis.
Resolution
The number of steps of the drive should be adapted to the leadscrew pitch so that a resolution
of at least 0.01 mm is achieved per step (leadscrew pitch/step rate). Refer to the tables below
for step rate recommendations.
We are happy to help you with the design, please contact us if you have any questions!
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