Use IR probe to detect bed edge?

oliof

Hi everyone,
I am currently back on the cantilever track (beta testing an upcoming nice little canti design). I am contemplating going back to using an IR probe and I like the way the venerable Ormerod uses it's z probe as an X endstop, and I wonder if it could be done for Y as well ...

The basic idea is to invert the probe for Y probing, and move the bed until the sensor doesn't detect something close by anymore. I guess the issue is having to home Z before Y, which RepRapFirmware usually doesn't like me to do ...

Is this a bad idea? Anyone have suggestions how to solve the "Z before Y" conundrum?

jay_s_uk

@oliof I suppose it depends whether you want to always home Z in a certain place, then you need Y homed.
If not, then theres no reason why you can't home Z before Y

dc42

@oliof you could perhaps use stall homing to approximately home X and Y, then home Z, then use the IR sensor to home X and Y more accurately by searching for the edges of the bed.

DIY-O-Sphere

@oliof

Maybe allow unhomed movement?

M564 H0

fcwilt

@oliof said in Use IR probe to detect bed edge?:

I guess the issue is having to home Z before Y, which RepRapFirmware usually doesn't like me to do ...

I do not understand that statement.

All of my printers have Z endstop sensors and I always home Z first.

What are you referring to?

Thanks.

o_lampe

@fcwilt said in Use IR probe to detect bed edge?:

All of my printers have Z endstop sensors and I always home Z first.

Like all Deltas do...
@oliof
There is a problem with your idea:

you home Z first => probe is triggered
you move to the X-edge => probe not triggered when edge found
you move back over the bed => probe triggered again
then search for Y-edge ..... probe is already triggered => false triggering

In other words, you'd have to find the Y-edge from opposite direction. Moving out of limits from X-edge to unknown point and back to the Y-edge.
Or you'd have to redefine the probe between Z,X,Y using different endstop definition.

fcwilt

@o_lampe said in Use IR probe to detect bed edge?:

@fcwilt said in Use IR probe to detect bed edge?:

All of my printers have Z endstop sensors and I always home Z first.

Like all Deltas do...

But that doesn't explain your statement about RRF not liking homing Z first.

Thanks.

Frederick

oliof

@o_lampe said in Use IR probe to detect bed edge?:

Or you'd have to redefine the probe between Z,X,Y using different endstop definition.

of course I'd need to redefine the probe, but thanks to RRF being so dynamic that's just another line in the homing file.