couple 'o questions about endstops and custom dimensions

so i have a few questions about the duet (this might be the wrong place to ask).

1) if i wanted to use mechanical endstops (microswitches) on all 3 axes (X,Y, & Z) instead of the opto endstops, how would i go about this?
can i just wire in the endstops into the duet board? do i need to modify the config.g file or the firmware directly?

2) i am using the duet to power a custom printer (not the ormerod), therefore the axes and bed dimensions are all different. what would i need to change in platform.h exactly? must i only change the axes dimensions? what about the absolute position of the y axis (extruder) in relation to the other 2 axes - how do i account for that? is it already accounted for in the firmware/when the printer is homed...? see the sketch to understand what i mean.... the extruder axis is not in the middle of the printer but offset.


Images...

Hi Raplel, I can answer question 1 for you. This will be based around the Ormerod.
It' best done in stages.
1) Fit a MicroSwitch to your X-axis.
2) Look at my X-axis MicroSwitch mounting in ThingyVerse, that you may need dependant on the type of MicroSwitch you will be using. There's a wiring diagram there, or on the Z-axis mount.
3) Alter either your config.g file (global setting) to use a switch instead of probe all the time, by altering the M558 command to M558 P0.
or if you still want to use the probe for Z....
Alter the homex.g file, by adding M558 P0 at the beginning, and then M558 P? (what ever setting it is before you start the alteration dependant on the probe you are using now) at the end of the file.
4) Prove it's good... Test it...
5) Look at my Z-axis MicroSwitch bracket on ThingyVerse, and fit a similar arrrangement to your machine. Again there is a wiring diagram. There's a sample Gcode file there that you will have to adjust to suit your switch.

I no longer use a probe... Just my MicroSwitches. They have proved reliable, repeatable, and simple.

Hope that helps,
Kim...

Edited 2 time(s). Last edit at 05/26/2014 09:33AM by KimBrown.

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Regarding point 2, if you use my firmware fork then you can use the M208 command to set both upper and lower limits of axis travel, which are also the values assumed when an endstop is triggered. This will allow you to set up your extruder offset.

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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].

thanks KimBrown ill give that a go!

dc42 - is your firmware relatively easy to set up for multiple (3) extruders? the 3 nozzles are mounted on the extruder carriage i sketched.

Sorry, I don't support multiple extruder yet, although I will when I get my Ormerod multi-extruder kit.

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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].

so are you saying in order to define the limits of axis travel i need to use your version of the firmware? could i not use tony's (think3dprint3d) multiextruder firmware? or does M208 only work with yours?

M208 can be used to set the limit of positive travel with all builds of the firmware. Only my build supports setting the negative limit at present. Perhaps you can persuade Tony to merge in the changes needed,

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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].

If fitting a Duet to a different printer, there should just be a few settings that need changing. Endstop switches should should work straight away (just do M558 P0 as mentioned to disable ir probing). However, X needs to be a "min" endstop and Y a "max" endstop for them to work properly. If you need to change that, you will need a recompile of the firmware.

Apart from setting the "printer dimensions" with M208, you would also need to set the "extruder steps per millimeter" with the M92 command, as the defaults are all hardcoded for a stock Ormerod and would likely be different on another printer.