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Autofocus behavior

Posted: Sat Oct 09, 2021 8:18 pm
by Marian Scheja
Hi everyone,

i have a question about my autofocus behavior (RDC6445GT5).
I have a Z bed with limit switch (NO) on top position which is wired to Z- limit input.
I installed the red pen type autofocus sensor (there is is a NPN NO inductive sensor inside).
As recommended i wired it in parallel to the Z- Limit.

Reset is enabled for X, Y and Z. This works as intended.
Z-Axis travel is limited to 250mm (Breadth)

After reset (homing) the Z table is on top position and i can move it down by 250mm before the controller limits further movement. -> Good
If i use autofocus on an object (i.e. 100mm), it touches the pen-sensor twice, lowers the table by the set focal distance (i.e. 10mm) and sets the Z coordinate to zero.
But after that operation the controller allows travel down by 250mm which would crash my machine. -> Dangerous
The travel should be limited to the remaining 140mm of travel (250mm -100mm -10mm = 140mm).

In user settings -> focus -> "focus sensor": ich can choose between "z limit" and "Probe".
Currently "z limit" is selected.

If i select "probe", the behavior is even more strange: Table moves up, touches probe or z-limit, moves down till i cancel the operation (i don't want to crash the bed). Even if i touch the probe by hand while the bed is moving down nothing happens.
Wiring the probe to "z+", it is not recognized by the controller. I even tried the "in1" which apparently has no function at all.

Is this a fault in my controller/firmware, or do you experience the same behavior with other controllers (6445g/s, 6442, others)
(for testing you should temporary limit the travel (breath) to a smaller value to prevent crashing your machine)

Btw. i have made pictures of the disassembled pen-probe. Maybe it is useful to someone.

Re: Autofocus behavior

Posted: Fri Dec 03, 2021 11:09 am
by Jerry Camel
I don't have an answer to your question, unfortunately, but I did want to thank you for the parts breakdown photo. That was useful.

Re: Autofocus behavior

Posted: Fri Dec 03, 2021 4:26 pm
by Pete Cyr
I am unsure from your post if the controller is moving the bed uncommanded by the user or you are indication it is possible for the user to drive the bed into the laser head and crash the system.

"But after that operation the controller allows travel down by 250mm which would crash my machine."

Assume you have positioned you material on the machine bed
Assume you have positioned the autofocus device over the material to be lasered
Assume you have initiated the auto focus feature

You are now ready to laser the material.
If you move the bed up or down you will be out of focus
After you initiate the autofocus function 9ssuming it works) you have established the programed focal distance you entered in the controller between the lens and the material to be lasered.
if you move the have to start over.
The System will not automatically establish autofocus after you move the bed - that is a user function every time

You can crash the bed and the head easily - the system will not prevent you from doing foolish things