Help with Prusa homing and endstops

Hi there

I have nearly finished building my Prusa,

Plastic Parts from Nophead
Sanguinololu bought assembled with firmware pre-loaded from Think3d
Extruder bought assembled from Genesis Machines
Dell core 2 XP
Pronterface


I tested the motors with mechanical end stops installed using X + Y 100,10,1 commands from Pronterface, the motors responded seemingly correctly and on the last test stopped after hitting the endstops (mostly)

But I'm not really sure what I'm doing and would appreciate some help and advice

How would I get the motors to a permanent fixed home position and set the Z axis so that the extruder tip is just above the plate?

If the board came with pre-loaded firmware do I need to reinstall and re calibrate ?

I'm being cautious because I ended up jamming the extruder into the plate and wedging the plate into rods a few times

Thanks in advance

Simon

gnomadix Wrote:
-------------------------------------------------------
> I tested the motors with mechanical end stops
> installed using X + Y 100,10,1 commands from
> Pronterface, the motors responded seemingly
> correctly and on the last test stopped after
> hitting the endstops (mostly)
They will get to the stop, reverse just a little then go back to the endstop more slowly. This is normal.

> > How would I get the motors to a permanent fixed
> home position and set the Z axis so that the
> extruder tip is just above the plate?
You would adjust the position of the endstops or flags so the axis stops where you want it.
For Z, you also need to make sure the bed is level in reference to the nozzle head.

> If the board came with pre-loaded firmware do I
> need to reinstall and re calibrate ?
As you're working on calibrating, you will need to upload the modified firmware to the board. Most likely you'll need to upload several times as you fine tune the settings. Especially if you do each axis at a time. Don't forget to disconnect from pronterface each time you upload the firmware otherwise Arduino (or other SW you use) to upload won't be able to.

Thanks Grog,

for your clear answers: that worked a treat, so I was much more confident
about setting the axis after that

The Z axis worked fine but the X axis moved in the opposite direction when pressing home,
but I think I can change the "const bool X_ENDSTOP_INVERT = false;" to true in Sprinter

Best
Simon

Just to report:

Glen from Genesismachines (who sold me the Hot end)sent me this email:

"To calibrate the axis tell it to move then mesure how much it moved.
steps per mm value in the config.h = ( distance it moved / what I told
it to move ) * steps per mm value"

and re: inverted endstop

"Find this line in configuration.h
const bool INVERT_X_DIR = false;
Change it to true."

As a Noob I feel that a clear online walkthrough of a building a standardised version of the Prusa
with a few variations for the choices of (maybe pre-assembled)electronics/hot end would be useful for the
inexperienced. I'm not sure if I'm confident enough to put it toghether yet but I might give it a go

Best
Simon

For assembly instructions, I hightly recommend Gary Hodgson's instructions