Steps/mm question in Z Hi guys, I just finished modifications on my reprap (from 5mm screw to 8mm lead screw from China). Of course I changed the steps/mm in z from 8000step/mm (what I had before), to 6400steps/mm, based on 2 mm pitch and the prusa calculator. I have 0.9 degrees nema 17 and go with DRV8825 drivers and 3 jumpers underneath. The issue is that with 6400steps/mm, the axis flies over what it should move. Speed and torque are very high. In order to get it to move correctly 1 cm, I had to go as low as 800steps/mm. Speed is slow, although I modified the feedrate for Z to 300 in Marlin. Now it moves precisely 1 cm, it is slow and the driver heats up like crazy (I will use a fan for this). Could you share some of your knowledge? Is 800steps/mm correct for such a setup? https://reprap.org/forum/read.php?4,793102,793102#msg-793102 Tue, 08 Sep 2026 23:23:19 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,793102,793175#msg-793175 Re: Steps/mm question in Z https://reprap.org/forum/read.php?4,793102,793175#msg-793175
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o_lampe
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vonaurolacu25
thanks mate. as long as as 800 step/mm is moving correctly 1 cm it is clear I bought the 8mm pitch leadscrew it seems :)

Cheers!

Not really!
You got 4mm pitch leads, since the calculation above is based on 1/16 microstepping, while your DRV8825 has 1/32 microsteps ( with all jumpers set )

Was wondering about that but was not sure!]]> Roberts_Clif Reprappers Sun, 22 Oct 2017 08:05:53 -0400 https://reprap.org/forum/read.php?4,793102,793144#msg-793144 Re: Steps/mm question in Z https://reprap.org/forum/read.php?4,793102,793144#msg-793144
Quote
vonaurolacu25
thanks mate. as long as as 800 step/mm is moving correctly 1 cm it is clear I bought the 8mm pitch leadscrew it seems :)

Cheers!

Not really!
You got 4mm pitch leads, since the calculation above is based on 1/16 microstepping, while your DRV8825 has 1/32 microsteps ( with all jumpers set )]]> o_lampe Reprappers Sun, 22 Oct 2017 02:11:54 -0400 https://reprap.org/forum/read.php?4,793102,793142#msg-793142 Re: Steps/mm question in Z https://reprap.org/forum/read.php?4,793102,793142#msg-793142
Cheers!]]> vonaurolacu25 Reprappers Sun, 22 Oct 2017 01:57:52 -0400 https://reprap.org/forum/read.php?4,793102,793114#msg-793114 Re: Steps/mm question in Z https://reprap.org/forum/read.php?4,793102,793114#msg-793114
This is my 1.8°/step Stepper motor
// Typical stepper motors have 200 steps per full step/rev = 1.8°/step, so 1/16 microstepping = STEPS_PER_REVOLUTION_E = 3200
// Z Axis 3200, / 1.25mm pitch leadscrew = 200*16 /1.25 = 2560 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 3200, / 2mm pitch leadscrew = 200*16 /2 = 1600 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 3200, / 4mm pitch leadscrew = 200*16 /4 = 800 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 3200, / 8mm pitch leadscrew = 200*16 /8 = 400 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)

This is your 0.9°/step Stepper motor
// Typical stepper motors have 400 steps per full step/rev = 0.9°/step, so 1/16 microstepping = STEPS_PER_REVOLUTION_E =6400
// Z Axis 6400, / 1.25mm pitch leadscrew = 400*16 /1.25 = 5120:: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 6400, / 2mm pitch leadscrew = 400*16 /2 = 3200 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 6400, / 4mm pitch leadscrew = 400*16 /4 = 1600 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)
// Z Axis 6400, / 8mm pitch leadscrew = 400*16 /8 = 800 :: (STEPS_PER_REVOLUTION_Z / PITCH_OF_Z_ROD)

I believe you are correct unless my numbers are wrong.]]> Roberts_Clif Reprappers Sat, 21 Oct 2017 14:39:00 -0400 https://reprap.org/forum/read.php?4,793102,793102#msg-793102 Steps/mm question in Z https://reprap.org/forum/read.php?4,793102,793102#msg-793102
I just finished modifications on my reprap (from 5mm screw to 8mm lead screw from China). Of course I changed the steps/mm in z from 8000step/mm (what I had before), to 6400steps/mm, based on 2 mm pitch and the prusa calculator. I have 0.9 degrees nema 17 and go with DRV8825 drivers and 3 jumpers underneath.
The issue is that with 6400steps/mm, the axis flies over what it should move. Speed and torque are very high.
In order to get it to move correctly 1 cm, I had to go as low as 800steps/mm. Speed is slow, although I modified the feedrate for Z to 300 in Marlin.
Now it moves precisely 1 cm, it is slow and the driver heats up like crazy (I will use a fan for this).

Could you share some of your knowledge? Is 800steps/mm correct for such a setup?]]> vonaurolacu25 Reprappers Sat, 21 Oct 2017 13:03:44 -0400