Difference between M5 and M8 tread on the Z-axle

Hi Guys (and Girls aswell),

Yeah, yeah, i know ....... the difference is M3.

But now on the serious side: what's the difference???

The reason of my question is that i have to make a 10% correction on the Z-axle (this is a minus 10 on both X- and Y-axle) with every print i prepair in Slic3r or Cura to get the right print.

Not a deadman's problem but it should be normal to print without any correction alt all.

So the difference between X, Y and the opposit Z is 10%.
But will changing from a M5 rod to a M8 rod cover up the difference or am i heading up for a much larger difference??

For those who don't know: i have a Heacent Prusa i3 with a Melzi controller and uses Slic3r and Pronterface.

For the ever lasting glory ...... who knows the answer??

All yours,

Aad Koene.

You are going the wrong way trying to fix the issue.

Changing from m5 to m8 will make matters worst because from 1mm pitch you will go to 1.25mm so you will go up 25% not 10.

To calibrate your m5, just ask the printer to move 10mm in the z axis, measure the actual distance and the in your configuration h file change the steps per mm value using a rule of 3: if X (steps in configuration h file)=actual distance, 10 = new value.

Do this a few times until you have 10mm movement when you ask for 10mm.

M8 is harder to turn than M5 so requires more torque from the steppers
M8 is also stronger than M5, this is bad as if it has any imperfections its strong enough to compress the lm8uu and move the head.
M8 is generally much less precise than M5, as in uneven tooth distances, and non spherical rod

basically, don't use M8, It is a big step backwards

Edited 1 time(s). Last edit at 04/29/2016 04:31AM by Dust.

Oke, you two have made a point, so i won't change the pitch to 8mm.

BUT the biggest problem that remain is that the Melzi board isn't programmable, so i can't change the settings of my board.
Not unless i change the setting in the slicer ....... or build a special board to reprogram the Melzi, but that's way out of my line of knowledge.

So probably the best option is to change the board to Arduino or Ramps and start all over.

Aad.

Well that is not completely correct, read here : Melzi

your cheapest option is using an Arduino Uno as programmer, unless you fill the need to spend more than 3 bucks to upgrade your controller.

Edited 2 time(s). Last edit at 04/29/2016 08:48PM by ggherbaz.

when i started my prusa i3 with m5 thread the rule was that you don't need to configure your z at all to get your z length correct, thats other issues like incorrect 1st layer height, incorrect layer height

---

Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

m5 supposed to use 4000 steps and then adjust with slicer to correct dimensions. But I have never follow that statement, I always modify the steps to print without slicer adjustments.

@ ggherbaz: i knew about the bootloader (told that in my posting) but that's way out of my line of knowledge.
I know a few about electronics (Philips E-Lab about 1970), something about programming Apple IIe, MSX-Basic, some about CAD and a lot about technics and improvising.

Besides that ....... i'm learning a lot ev'ry day.

@Chris33: i think that when i use the height as adjustment for the Z-axle my print will fall apart, but i'm just a tenderfoot in this case.
So ..... tell me more about that .....

Aad.

Unless you've broken the atmega chip on your melzi which is doesn't sound like you have as that's what they are referring to when talking about the boot loader then it's quite straightforward to upload a new firmware to the board with the correct steps value for your z axis.

Ben

you can try to change the steps in the gcode file at the start of the file

somthing like this

M92 X80 Y80 Z4000