5bar scara Problem configuring z probe using fsr switch

Phaedrux

I assume you're working from this?

https://docs.duet3d.com/en/User_manual/Machine_configuration/Configuration_five_bar_parallel_scara

gnmrc_

@fcwilt, no the arm homes itself, then when it should do the x0 y0 move it stops

gnmrc_

@Phaedrux yes, I’m using that and I used some other forum post from 2019 I think.

fcwilt

@gnmrc_ said in Problem configuring z probe using fsr switch:

Try to be more precise - I am not there seeing what you are seeing - need to help fill in the gaps of my knowledge. Thanks.

no the arm homes itself, then when it should do the x0 y0 move it stops

Are you referring to the move to X=0 Y=0 at the end of the homing file?

That is when you get the error message about un-homed axes?

Correct?

IF that is what is happening then the G1 H1 moves are NOT homing the axes. If they were being homed the move to X=0 Y=0 would work.

When a homing move fails, that is it reaches the end of the specified travel (in your case 200) without activating the endstop switch, there is no error message - it just stops moving and the axis is still not homed.

So remove the move to X=0 Y=0 (if it is still there), re-boot the machine and click on the HomeAll button in the DWC Dashboard.

Once the movement in both axes stops. check if the X and Y home buttons have changed to indicate they are homed.

Thanks.

gnmrc_

@fcwilt yes exactly, the machine stops before the x=0 y=0 move in the homing file, but I see from the board’s leds that my endstop gets triggered,I even tested with m119 ,and the arms stops when touching their relative endstops so I do not think this is the case.
Also if I only do the G1 H1 X and G1 H1 Y moves in the homing file when it ends my x and y axis results as homed.

Gianmarco

Phaedrux

What are all the files in your system folder? It's not executing a different file than you expect is it?

gnmrc_

@Phaedrux no I checked, there is only 1 home5barscara.g

fcwilt

@gnmrc_ said in 5bar scara Problem configuring z probe using fsr switch:

@fcwilt yes exactly, the machine stops before the x=0 y=0 move in the homing file, but I see from the board’s leds that my endstop gets triggered,I even tested with m119 ,and the arms stops when touching their relative endstops so I do not think this is the case.
Also if I only do the G1 H1 X and G1 H1 Y moves in the homing file when it ends my x and y axis results as homed.

Gianmarco

Great, good to know. Thank you.

However I am still at a loss as to why the you cannot so a simple G90 followed by a plain G1 X0 Y0 unless...

OK, let's try this:

create a HomeX.g file and put just the G91 G1 H1 X200 F300 commands in it
create a HomeY.g file and put just the G91 G1 H1 Y200 F300 command sin it
re-boot the machine
click the Home X button and see if all goes well
click the Home Y button and see if all goes well
from the Console of the DWC execute an M208 and report back

Thanks very much.

Frederick

gnmrc_

@fcwilt Yeah it’s really a frustrating situation….

Ok I will try this solution and report back, but if I remember correctly it’s not possible to do an home X file and an home Y file, because reprap for a 5bar scara configuration during homing procedure will search and execute only a home5barscara.g, if this actually happens, I will create 2 macros home left and home right than put them in the homing file and see what happens.

Thanks for the help,
Gianmarco

Phaedrux

This thread is a bit long now. Can you create a summary post of the issue as it is currently and I can pass it along to DC42 to see if he has any suggestions.

fcwilt

@gnmrc_ said in 5bar scara Problem configuring z probe using fsr switch:

@fcwilt Yeah it’s really a frustrating situation….

Ok I will try this solution and report back, but if I remember correctly it’s not possible to do an home X file and an home Y file, because reprap for a 5bar scara configuration during homing procedure will search and execute only a home5barscara.g, if this actually happens, I will create 2 macros home left and home right than put them in the homing file and see what happens.

Thanks for the help,
Gianmarco

Well if that is the case that you have to have the special file then I have no idea what might be going on.

So just edit that one homing file and after the two G1 H1 commands add a M208.

I want to know what the M208 "thinks" at that point.

Thanks.

Frederick

gnmrc_

@Phaedrux ok thanks so:

I’ve built a 5bar scara arm, I can home the 2 arms in the home5barscara.g but when I try to do a G0/G1 move to set the hotend position to the center to home z, the arms overshoots the required position. If I only home the arms than send a G92 Z## the arm works as expected.

In this thread there are also the config and homing files, plus the videos of the machine behaviour.

Thanks for the help,
Gianmarco.

gnmrc_

@fcwilt Ok, I’m going to report back asap.

Thanks,
Gianmarco

gnmrc_

@fcwilt so this is what I get from m208:

g28
Axis limits (mm)s X-162.7:250.0, Y-108.5:250.0, Z0.0:200.0
Axis limits (mm)s X-162.7:250.0, Y-108.5:250.0, Z0.0:200.0
Error: Failed to home axes Z

Thanks for the help,
Gianmarco

fcwilt

@gnmrc_ said in 5bar scara Problem configuring z probe using fsr switch:

@fcwilt so this is what I get from m208:

g28
Axis limits (mm)s X-162.7:250.0, Y-108.5:250.0, Z0.0:200.0
Axis limits (mm)s X-162.7:250.0, Y-108.5:250.0, Z0.0:200.0
Error: Failed to home axes Z

Thanks for the help,
Gianmarco

Thanks. That all looks normal.

It seems that your kind of printer has some unique requirements - like changing the name of of HomeALL.g to something else.

So who knows what else is going on. In a "normal" printer you would have some code to home the Z axis in your HomeALL.g file. But after the X and Y are homed they can move to wherever is needed to home Z.

But in your case to move to X=0 Y=0 you have to force Z to be homed with a G92 - which makes no sense to me at all.

I gather from your config.g file you have a Z Probe which, in theory, would be used to home Z.

Since the G92 allows you to move to X=0 Y=0 have you tried adding the code to home Z with the probe?

Can you specify in G92 close to the actual position of Z? If so you can still move forward and home Z with the probe and the actual Z position would finally be established.

Or maybe you have to home Z first somehow?

Just out of curiosity what took you down the path to a SCARA printer in the first place?

Frederick

Phaedrux

if you send G30 on it's own does it attempt to use the probe?

gnmrc_

@Phaedrux Yes, the heated bed is moved up, but due to the zprobe not being inside the bed area the heated bed crash. But if I manually activate the probe the homing is completed.

fcwilt

@gnmrc_ said in 5bar scara Problem configuring z probe using fsr switch:

@Phaedrux Yes, the heated bed is moved up, but due to the zprobe not being inside the bed area the heated bed crash. But if I manually activate the probe the homing is completed.

One "disadvantage" of homing Z with the probe is X and Y need to home first so the probe can be moved into position.

I don't like that so all of my printers have a physical Z endstop switch or sensor so I can home Z first thing and be sure it is safely out of the way when homing X and Y.

Then I use the Z probe for setting the Z=0 Datum, leveling the bed, creating the height map, etc.

Have you consider going that way - adding a endstop switch to the Z axis - it sounds like it might solve all of your problems.

Frederick

gnmrc_

@fcwilt yes in the homing file I tried to use a dummy G92 comand to trick the machine in to moving, but with no success. There is something that I’m missing but I can’t figure it out.

So I wanted to build a SCARA printer because I think that there is a lot of unexpressed potential in this kinematic but due to it’s complexity there aren’t a lot of people that wants to build one of this printers and improve them. This type of printers are left in an embrional state, particularly the 5bar one, the only 2 guys that I have seen make them work are Joerg and Pontus Borg but 3/4years have passed since the last videos and post about those printers.

Thanks for the help,
Gianmarco

gnmrc_

@fcwilt for semplicity of wiring I would prefere to have only the probe, but due to all this problems I’m really considering this solution.

Gianmarco