Z Probe and Z Min Endstop

[Edward Boston]

I am setting up a Z Probe and have a question about the probe also being the Z min endstop.  From the documentation about Z probe, it says to disable the gamma min endstop.  I have done that and the output of M119 shows the X and Y endstops and a Probe.  No Z.  The probe is working but when I did a home all axis, the X and Y homed, but the Z didn't.  So if I want the probe to also act as the end stop, do I leave the gamma min endstop defined?  The probe is on the gamma min endstop connection.

[wolfmanjm]

generally speaking you cannot have the probe and zmin on the same pin. They are two different functions.

It is possible but you need to really understand what you are doing. I'd suggest hooking up a zmin separately.

[Edward Boston]

This doesn't make any sense at all.  All the examples show disabling the gamma min endstop to use the probe.  But you say that I should set up a seperate z min endstop?  But the probe is on the z min endstop connector.  Am I suppose to re-purpose a different set of pins for the z-min endstop?  Where is this documented?  If the z-probe module is taking over the z min endstop pin, it would seem logical it would also have to take over the z min endstop function it is taking over.

[Arthur Wolf]

On Mon, Sep 7, 2015 at 9:02 PM, Edward Boston <edlb...@gmail.com> wrote:

This doesn't make any sense at all.  All the examples show disabling the gamma min endstop to use the probe.  But you say that I should set up a seperate z min endstop?  But the probe is on the z min endstop connector.  Am I suppose to re-purpose a different set of pins for the z-min endstop?

Smoothie allows you to use any pin you want for the endstops ( though the endstop connectors have some passives that help with stability so I would recommend using one of the max endstop connectors ).
 

 Where is this documented?  If the z-probe module is taking over the z min endstop pin, it would seem logical it would also have to take over the z min endstop function it is taking over.

On Sunday, September 6, 2015 at 11:07:13 PM UTC-7, wolfmanjm wrote:

generally speaking you cannot have the probe and zmin on the same pin. They are two different functions.

It is possible but you need to really understand what you are doing. I'd suggest hooking up a zmin separately.

On Saturday, September 5, 2015 at 2:14:45 PM UTC-7, Edward Boston wrote:

I am setting up a Z Probe and have a question about the probe also being the Z min endstop.  From the documentation about Z probe, it says to disable the gamma min endstop.  I have done that and the output of M119 shows the X and Y endstops and a Probe.  No Z.  The probe is working but when I did a home all axis, the X and Y homed, but the Z didn't.  So if I want the probe to also act as the end stop, do I leave the gamma min endstop defined?  The probe is on the gamma min endstop connection.

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[Edward Boston]

Okay.  So let me see if I have this right...

If I want to use a Z Probe, following the documentation, I disconnect my existing Z Min End stop and connect the Z Probe there.

I then redefine another end stop, say Z Max, to be the Z Min end stop, connecting my existing Z Min end stop back up to the former Z Max end stop connection and thus doubling the sensors that detect the location of the bed?

Is that what you are saying?

[wolfmanjm]

No what he is saying is you can use whatever free pin you want for your zprobe. So leave zmin on zmin, select a spare unused pin and allocate it to the zprobe.

If you are only using xmin ymin zmin for endstops then you can use one of xmax ymax or zmax for the zprobe, or any spare pin on any of the headers.

What I said was you cannot have two functions using the same pin, eg you cannot have a zmin endstop and a zprobe both using the same pin.

one function per pin is the rule.

[Ed Boston]

So forgetting about the pins, I cannot have the Z probe function as both the probe and the end stop is the bottom line.  I have to have two different sensors doing the same thing, sensing the location of the bed.

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[robin bussell]

On 08/09/2015 01:28, Ed Boston wrote:
> So forgetting about the pins, I cannot have the Z probe function as both
> the probe and the end stop is the bottom line. I have to have two
> different sensors doing the same thing, sensing the location of the bed.
>

They are for different jobs ... the probe is supposed to move with the
head and is used to detect bed height at different locations so that bed
levelling can be compensated for. The end stop is usualy fixed to the
frame and used for homing or motor protection, depending on your printer
type...

Cheers,
Robin.

[Ed Boston]

Two different jobs that it seems that other firmware can do with a
single sensor. Based on the feedback, it sounds like it is too much for
Smoothieware to handle though.

[robin bussell]

On 08/09/2015 02:58, Ed Boston wrote:
> Two different jobs that it seems that other firmware can do with a
> single sensor. Based on the feedback, it sounds like it is too much for
> Smoothieware to handle though.
>

Maybe other firmware is dedicated to a single printer type?

Deltas have to home to the top of the frame and use a probe on the head
for bed level compensation and auto calibration of the geometry for
instance. In a cartesian printer you could use one sensor for both jobs
I suppose, but bed probing and auto levelling evolved after simple motor
homing so they tended to be seperate too.

Fell free to merge the functions in the source if you think it's worth
it, no one is stopping you :)

Cheers,
Robin.

[Ed Boston]

I'm sorry. I guess I didn't realize that Smoothieboard/ware was just
for Delta printers. But Marlin is for both delta and non-delta and can
use a single probe for both jobs. RepRapPro also is for both delta and
non-deltas and can use a single probe. When a Delta homes to the top of
the frame, that is Z max, which is not what the probe is for, nor the
question I was asking. But I seem to have gotten my question answered
though.

[robin bussell]

On 08/09/2015 03:35, Ed Boston wrote:
> I'm sorry. I guess I didn't realize that Smoothieboard/ware was just
> for Delta printers. But Marlin is for both delta and non-delta and can
> use a single probe for both jobs. RepRapPro also is for both delta and
> non-deltas and can use a single probe. When a Delta homes to the top of
> the frame, that is Z max, which is not what the probe is for, nor the
> question I was asking. But I seem to have gotten my question answered
> though.

Smoothie does cartesian, delta, and scara too (see the "arm solutions"
section of config), but I've only ever used it for delta, and last time
I used marlin on a cartesian was pre auto bed levelling. I'm sure
someone better versed than me will let you know definitively.

Smoothie has advantages in terms of speed and versatility that will make
it worth the extra microswitch I should think, I've not regretted the
move from smaller processors one bit. Anyway it's way past my bedtime
now, I hope you find a satisfactory solution in the end.

Cheers,
Robin.

[Arthur Wolf]

On Tue, Sep 8, 2015 at 3:58 AM, Ed Boston <edlb...@gmail.com> wrote:

Two different jobs that it seems that other firmware can do with a single sensor.  Based on the feedback, it sounds like it is too much for Smoothieware to handle though.

If you want to use your probe to find the bed, you can, it's the G30 Z0 command.
 

On 9/7/2015 5:33 PM, robin bussell wrote:

On 08/09/2015 01:28, Ed Boston wrote:

So forgetting about the pins, I cannot have the Z probe function as both
the probe and the end stop is the bottom line.  I have to have two
different sensors doing the same thing, sensing the location of the bed.

They are for different jobs ...  the probe is supposed to move with the head and is used to detect bed height at different locations so that bed levelling can be compensated for. The end stop is usualy fixed to the frame and used for homing or motor protection, depending on your printer type...

Cheers,
    Robin.

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[WZ9V]

I'm getting ready to yank out my FSR setup because I just can't get reliable results with it (didn't with Marlin either so its not Smoothie).

If I have been following the various discussions here and in the delta forums properly.

Assuming I have a sensor that detects the bed when the hot end nozzle tip is 2mm above the bed.

G32 ;to setup the basic parameters (full calibration, end stops, radius)

G28  ;to re-home after calibration

G30 Z0 would then find gamma max as 2mm above the bed (the wiki suggests other methods)

So would G30 Z-2.0 be nozzle touching bed and G30 Z-1.9 be 0.1mm (paper width) above bed?

Then M500 to save, correct?


The G30 approach seems easier than the wiki suggestion of

G28
; move to 5mm above bed
G0 Z5
;  then manually jog down until nozzle is on bed or just traps a sheet of thin paper
; sets the Z homing offset based on current position
M306 Z0
G28
G0 Z1
; check nozzle is 1mm above bed
M500
; saves the results in EEPROM equivalent

[wolfmanjm]

If you choose to use G30 Z0 it is temporary an lost at the next home. (it is equivalent to G92 Z0). So you woul dneed to do it after every home.

M306 Z0 is the recommended way to do it as it needs to be done only once and is saved with M500.

G30 Z0.1 would set Z to 0.1 when the probe triggers. it effectively does G92 Z0.1 when the probe triggers.

I hope that explains it better.

[WZ9V]

OK, so while G30 can measure my gamma max it does not actually save it like the other method does.

I get if I supply a positive offset it will stop above that much above the bed but will a negative one move past 0?

I'm thinking of a probe that triggers zero before the hot end hits the bed (micro switch, etc) unlike my FSRs that are triggered at zero.