For $4tr, what’s a good setting for .5” ACME lead screw w/ 10 teeth per inch?
$4tr setting for .5” ACME lead screw w/ 10 TPI.
From the original Synthetos forum (2011–2025)
10 tpi (threads per inch, I would be worried if the screw had teeth ;) means it will travel 1/10" or 2.54mm per revolution. $4tr=2.54
Thanks. Got it:
Direct drive Z axis Stepper motor setup (with motor 4 as Z axis)
1.8 degree per step motor = 200 full steps per 360 degrees
set to 1/4 microsteps ($4mi=4) 800 microsteps per 360 degrees
if using a 10 teeth per inch ACME lead screw, 8000 microsteps = 1 inch of travel
$4tr=? (travel per rev in mm)
convert to mm:
1 millimeter is .0393701 of an inch
or
1 inch = 25.4 millimeters
314.960 micro steps = 1mm of travel
800 microsteps / 314.960 microsteps = 2.540 mm of travel per revolution
$4tr=2.540
Well yes, but the only parameter being set is $ztr, travel per one revolution.
If the pitch is 10 Threads per Inch, a nut, or the Z axis Lead Screw Nut, will move 1/10" per revolution, or 2.54mm =$ztr
tinyG does all the distance per step and distance per microstep calcs for you, based on the $_sa = 1.8 degrees ( which is 360 degrees/200 steps) and the $_mi microsteps per step parameter.
If you want tinyG to use smaller steps, eg $_mi=8, you just set that parameter and tinyG computes a new distance per microstep,
$_mi=4 is recommended because 1/314.960mm is already really fine precision for typical milling.
Driving a laser engraver or a 3D printer may introduce additional considerations.
Thanks again. Even clearer now.
This topic is from the original forum (January 2015). Your reply starts a new discussion linked to it.
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