Help a noob with his Z height issue

[Verkeer]

Hi all,
Thanks for reading.
I bought a printer that was built/modified by a supposed expert, it's a Prusa i3 MK1 rework.

All measurements in mm.

So I've been printing for a couple of months and noticed recently that I have an issue with my eventual height when printing.
I printed a cube that was designed as X150 x Y150 x Z150, to check that the steps were actually set correctly
and my measurements look like this at the end: 152 x 153 x 127.
Yeah the Z has actually gone up waay less than was supposed to.
The screen shows 150 at the end.

When I home the axes and move Z up to 150 with the screen, it goes up to about 150.
I created a gcode file to do the same, to home everything and move Z up to 150 and it went up to 153.
At first I thought the firmware just had the incorrect steps calculated and that I had to fix that,
but now the new gcode file takes Z up more than it was supposed to.

Any help will be appreciated.

Please and Thank you

[Roberts_Clif]

Sounds like you might be missing a stepper motor jumper

https://reprap.org/wiki/Prusa_i3_Rew...#Motors_wiring

[Verkeer]

Sounds like you might be missing a stepper motor jumper

https://reprap.org/wiki/Prusa_i3_Rew...#Motors_wiring

Thank you for the info. I've checked and all the motors have all 3 jumpers intact.

[Roberts_Clif]

Knew it was a long shot.

Post your 3D Printer specs, along with which firmware you are using.
You may need to calibrate your steps per mm on your Z-Axis

[Verkeer]

Knew it was a long shot.

Post your 3D Printer specs, along with which firmware you are using.
You may need to calibrate your steps per mm on your Z-Axis

Eh it was worth a try, thank you.
Which specs are you referring to?

I've got two Prusa i3's.
Below you can see I tried printing two tubes, 100mm in height. The white one printed 100%, the green came out to 74mm.
Not sure about the other printer that got it right, but the questionable prints are coming from the machine that has
Marlin 1.1.9

Steps currently on Z axis is set to 8000 steps/mm
So my initial question was why 150mm comes out to 127mm, and fixing steps should then be on 9448
Now the new print was at 100mm and came out to 74mm, so then changing Z should be on 10810...
Thinking something else is wrong.

20200721_192820.jpg

[Roberts_Clif]

This is the tricky part of calibrating your 3D Printers, For each step on your an axis will move a precise distance.
So if we print a calibration model then do some math, we can adjust to create that prefect size model.


https://www.thingiverse.com/thing:195604