PWM?
9 which is a PWM I am using for X limits
8 is unused but is not PWM
From reading that article, the PWM on 9 will be deactivated, which wont worry me as it is only used for a limit.
I don't fully understand the article fully yet, but am I to believe that pin 8 could be made to handle a servo?
I found a grbl implementation already supporting a servo:
I haven’t the parts to test it but it might possibly work for homing with the right settings and gcode
If not, then it might be a good starting place to hack on grbl.
I will have a good look at that and see what I can understand.
There needs to be a way to do it as GRBL is a very popular system and it should have this feature available.
And what is wrong with that? You know the thickness of the material. Subtract that from the known sensor value and that will give you the parameter to adjust the laser. Then the problem is knowing the thickness of your material. Do you know that before doing anything else?
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I will think about that. If that is possible it would solve a very lot of problems and only need a simple micro switch, everything else including the codes are ready from the tests I made that would only need a few adjustments.
I am using a Two Trees K-30 module, and when cutting thick materials like 20mm pine the module is almost touching the surface, so not much clearance for the switch.
I would hesitate to use microswitches. They are too variable in switching timing. I suggest an electrical contact between a metal rod and your table if it is metal or a corresponding metal plate that can be electified as one side of the switch.
After giving a lot of thought about this, I think the best solution would be to have a small point added to the laser module that is just enough to touch a metal plate that can be placed on the workpiece and then touch off on that plate each time. The thickness of the plate added to the reading to give me an exact zero measurement for which I can then use macros to set the required laser distance for focusing on which ever job I am working with.
It would be the easiest and cheapest method, just a bit of a nuisance to do each time.
It would also have the advantage of not having to be recalibrated after taking the laser module off for cleaning etc.
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Google "z-axis touch probe" (images).
They are commonly used with CNC mills, and have a standard thickness, like 10mm.
They detect detect a grounded drill bit.
Not sure if they can works with laser units.
Leo..
I have made several of those for all my milling machines, they would work fine for this job also, it is just the point on the laser module has to be very short as there is very little room to extend it. When cutting thicker materials the module is really close to the work piece, and I wouldn't want the point to touch while the head is moving as it would most likely move the work by dragging. That is why I was looking for another solution.
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