how to offset extruder after autohome

Hi folks,
my thanks to everyone who has helped so far.

Pretty much the last thing now till the quick and simple task of get the printing to work.

My rework has xy_min and z_max endstops which miracle of miracles are working.
The xy_min endstops are outside of the area of the bed. I could move the x_min to stop
the extruder whilst on the bed, but can't fix the y_min. ( Hint to self, Do not change the
design next time. Someone smarter made it)

I sat down today and figured out the coordinates for the usable area of bed. But having
the mech endstops outside of the xy_min is a bit of a headacre

Just discovered M207. Would it be easier to,
1. G28 Z
2. manually set z to wanted z_min
3. M207 to generate z_max_length and burn to eeprom.(This effectively generates z_min??)
4. home to wanted xyz on bed. (M206 here to make this the offset home over the bed?)
5. does the min_software_endstops get updated here to the new xyz?

Also if I have min_software_endstops greater then endstops, does the following happen?
If I autohome, the extruder goes to the mech endstops bypassing the min_software_endstops?
But if I try a manual move the min_software_endstops stops the extruder before it gets to
the mech endstops?

You need to tell us what firmware you are using. Some firmwares have ways of telling them that the min homing switches are not at position 0 on the corresponding axis, and the amount of movement (if any) beyond the homing switches that is permitted; but the details depend on what firmware you are using.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Ahh,
My apologies. I'm running marlin.

Many thanks,
Andrew

M207 sets retraction length in marlin, check M206 for setting up all offsets.
-Olaf

If i'm reading your problem correctly.

You need to change [github.com]

ie.
#define X_MAX_POS 205
#define X_MIN_POS 0 <------- change this to -15 for eg, or what ever your mm value is from 0.
#define Y_MAX_POS 205
#define Y_MIN_POS 0 <------- change this to -15 for eg, or what ever your mm value is from 0.
#define Z_MAX_POS 200
#define Z_MIN_POS 0

Then 0,0,0 is really at 0,0,0

Edited 3 time(s). Last edit at 10/05/2015 05:13AM by Dust.

Hi all,
Thanks for the responses. I tried initially using the min_pos values but wasn't sure it was working. I set up
negative values for xy min_pos but when I did an autohome, the reprapdiscount_etc_glcd 12864 displayed
what should have been neg xy min values showed as positive xy values. Maybe that is quirk of the 12864
GLCD unit.

M206 seems to do it. Can someone check if the following works?
1. Autohome extruder to xy_min and z_max
2. Move extruder to (a,b,-) on heatbed.
3. Issue m206 Xa Yb to set offset
4. M500. Write to eeprom
5. Assuming Z_min_pos = 0 > actual bed height
6. G1 Z0
7. Through pronterface or GLCD etc step extruder down till 0.2 or 0.3mm from bed
8. M206 Zc from GLCD, as positive value.
9. M500 to store to eeprom

All done? Okay the order might be a bit out of wick.

Thoughts please,
Andrew