I could use some help

[fcwilt]

@droftarts said in I could use some help:

@mac you can use both, but there’s not much point. Homing with the Z endstop requires it to be configured with M574, and then a homing move of the axis to the endstop Homing with the probe does not need to be configured with M574 on Z (ie it doesnt need ‘M575 Z1 S2’ see M574 in the GCode dictionary) it just needs a move so the probe is over the bed, ideally in the centre, before running G30.

Ian

We are going to have to agree to disagree.

Homing with a Z probe requires homing X and Y first.

And since Z hasn't been homed it's position is unknown thus you end up with four Z relative moves (2 for X, 2 for Y) to be sure it is clear of the bed while homing X and Y.

And an endstop can home faster than a BLTouch can.

So to me faster homing and simpler code is more than enough reason to have a Z endstop - it's not like it is an expensive item.

Frederick

[droftarts]

@fcwilt said in I could use some help:

I use the Z Probe for:
setting the Z=0 Datum

I guess you home Z first to the Z endstop, then home X, then home Y, then... probe Z?

How does that work if you have a power cut, and then resume? You have no way of knowing where the X and Y is before homing Z, which homes down onto the print.

A better use for a Z endstop is as a max Z endstop, so it can recover from a power failure without hitting the print, and then continue with the print. It can also check that the Z axis is or isn't at full height during the small relative move.

And since Z hasn't been homed it's position is unknown thus you end up with four Z relative moves (2 for X, 2 for Y) to be sure it is clear of the bed while homing X and Y.

I rarely bother homing axes individually, and generally use homeall.g. That lifts Z, homes X and Y at the same time, moves to the centre and homes Z. So it's one relative move (+5mm in Z) before X and Y is homed. So yes, there's relative move where the Z axis could hit the top of travel, but it's so rarely at max Z. And if you have a max Z endstop, that small relative move can be checked.

So to me faster homing and simpler code is more than enough reason to have a Z endstop - it's not like it is an expensive item.

Faster how? You can set the Z probe speed to whatever you want. You can do a fast probe, then a slow one, just like you do with an endstop (two speeds can be set in M558 F parameter). Faster because it's less moves? Like a second faster because it doesn't lift Z before probing? But then you set Z datum to 0 after anyway, which takes extra time?

Simpler code? Homing Z after X and Y means you can move to the centre of the bed area (where most prints are actually printed) with a G1 command, and set the Z datum with G30. Two commands. I'm not seeing where that is more complex.

Expensive? Absolutely not. But unnecessary, if you already have a Z probe, and comes with extra wiring.

What I'm trying to say is please don't encourage a newbie (ie @Mac) to go down a road that suits you, but makes it harder for him to get support with at a later time, because it's not how most people do it as far as I'm aware. That axes are homed X, Y then Z if you command G28 and don't have a homeall.g, it is clearly the intention of the writer of the firmware that it happens in that order.

Ian

[A Former User]

@fcwilt knowing what it can do is helpful. Knowing how to code it so it can do those things is what I need to understand. Yes, I know, read the documentation. I'm on it, but I'm also trying to answer the question I asked at the beginning of this thread. Which has not been answered yet, because if it had, my printer would be homing, which it's not.

I'm going to unplug my BLTouch now, and chock it's demise up to some kind of objection of it, even though I enjoyed watching it go across the bed of my BLV-Anet A8 during a 16 point survey.

Mac

[A Former User]

@fcwilt I get that, and I concur.

Still . . . I loved watching mine do it's thing.

Mac

[fcwilt]

@droftarts said in I could use some help:

What I'm trying to say is please don't encourage a newbie (ie @Mac) to go down a road that suits you, but makes it harder for him to get support with at a later time, because it's not how most people do it as far as I'm aware. That axes are homed X, Y then Z if you command G28 and don't have a homeall.g, it is clearly the intention of the writer of the firmware that it happens in that order.

Ian

You are entitled to your opinion but I absolutely disagree with your view of things.

Try doing this with only a Z probe:

Auto Bed Leveling

Frederick

[fcwilt]

@mac said in I could use some help:

@fcwilt knowing what it can do is helpful. Knowing how to code it so it can do those things is what I need to understand. Yes, I know, read the documentation. I'm on it, but I'm also trying to answer the question I asked at the beginning of this thread. Which has not been answered yet, because if it had, my printer would be homing, which it's not.

I'm going to unplug my BLTouch now, and chock it's demise up to some kind of objection of it, even though I enjoyed watching it go across the bed of my BLV-Anet A8 during a 16 point survey.

Mac

Is your BLTouch not working?

Because you do want a working Z probe for the things you need to do such as setting the Z=0 Datum or Bed Leveling.

Frederick

[droftarts]

@fcwilt Check your link, it should be https://youtu.be/0U9VH40K3RY

You mean like this? https://youtu.be/ItAonH9IVy0

Ian

[A Former User]

@fcwilt For now, yes, it's unplugged. And it's going to stay that way until I can go furious olde-school on this machine, and it will print like it believes in me.

HERE'S WHAT I KNOW AT THIS VERY MOMENT:

X=HOME IS -85
Y-HOME IS -202
Z-HOME IS -138

That's how far the x-axis has to go TO THE LEFT to activate the endstop.
That's how far the y-axis has to go TOWARDS THE BACK OF THE MACHINE to activate the endstop.
That's how far the z-axis has to go DOWNWARDS to touch the bed with a old grey hair to spare.

Mac

[A Former User]

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[A Former User]

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