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Z probe stays triggered too long

Posted by kasperhangard 
Z probe stays triggered too long
October 15, 2017 06:25AM
Hi Guys. I have just installed a Capacitive proximity sensor as a probe for my printer, but i am having some trouble with it.
This is the PROBE
I have wired it like THIS
I have disabled the pullup resistor in marlin for the z probe and z min.

It does seem to work, it lights up when it sees nothing, and the light turns off when it sees an object, but the distance seems to "stick".
When i move a object towards the sensor, i triggers at around 1cm away. But when i move the object away from the sensor, it only stops triggering at around 3cm.

Shouldn't it trigger and open at the same distance?

The product of this problem means that when i home Z, it goes down to the bed correctly, but is triggered so long that when the printer moves up, to find the precise distance, it never goes down again because of the probe triggering.

Series diagram showing how to sensor acts from open to triggered to open, based on the distance to the object
[T] = triggered Sensor
[O] = Open sensor
| = 1CM
# = Object

EDIT: I dont know how to format this correctly, so i attached a screenshot. Sorry about that.

Edited 1 time(s). Last edit at 10/15/2017 06:26AM by kasperhangard.
open | download - Capture.PNG (1.4 KB)
Re: Z probe stays triggered too long
October 16, 2017 07:02AM
I've not played with a Capacitance Proximity Sensor so cant say if that is normal or not

but I do know that in Marlin in the file Configuration_adv.h is
#define Z_HOME_BUMP_MM 2

So you can make this larger and get past the still triggered point. Then it should re home slowly.

Edited 1 time(s). Last edit at 10/16/2017 07:05AM by Dust.
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