Tempory endstop

fmeleard

Hello
I have an open question.

I would like to be able to create intermediate control points to ensure the position of the X axis

Let me explain.
My machine is very big (8 meters wide), 4 meters on the right and 4 meters on the left on the X axis.

I would like to create intermediate endstops to check at each tool change that the X axis has not moved without having to systematically travel 4 meters.

Basically, I would like to test the original endstop at the beginning (at + 4 meters) but after that, I would like to test the position from time to time only at the center.

I use HALL probes for my endstop and everything is fine, I don't know how to set up an intermediate endstop in Gcode...

I can do it in python via my raspberry by testing the probe value, but I think there is a Gcode solution that would allow me to do it.

In advance, thank you for your help
Francis

Phaedrux

Endstops are only active during G1 H1 moves, not during a normal print.
Nothing stopping you from adding an G28 X on layer change.

oliof

@Phaedrux I believe they plan to have an endstop at the center to avoid having to move the whole 8m to rehome. Should be doable but requires a couple lines of metacommands to adjust homing direction and so on.

JoergS5

@fmeleard said in Tempory endstop:

check at each tool change that the X axis has not moved without having to systematically travel 4 meters.

I would place the endstop near the tool changer. In most cases, endstops are at one end of a printer (high or low end), but this is not a must. When homing, after triggering the endstop, the position can be set to a position with G92, e.g. a middle value, so limits like M208 min and max still hold after it, if you need it.

OwenD

I think to implement this you'd probably have to have two end stops and change the configuration after initial homing
If you have an end stop in the middle with a large offset, then what happens if you restart with the tool on the negative side of the stop?
The machine is expecting to home to either a minimum or maximum end stop.
If the stop is not at the physical extreme then it can fail.
So maybe do initial homing at physical minimum then move to greater than centre stop. Then reconfigure minimum end stop to suit mid mounted stop and repeat homing?

fcwilt

@fmeleard

Is the time required to repeatedly home going to add a significant amount to the total "print" time?

If not I think you should simply accept having to home to the existing endstop.

The problem with an endstop in the middle is that the starting position for homing could be to either side of the endstop. How can you determine which direction to move?

One possible solution would be to implement a closed loop control system where the actual position is always known.

Frederick