If an accelerometer could be added to Maslow4 then you might be able to add a datum for the z axis for the bit length when it hits the cutting surface thereby giving you an accurate depth.
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Interesting idea, I wonder if it would be sensitive enough. They aren’t expensive so it wouldn’t be too hard to add one if it works.
The stepper motor drivers that we used are super fancy and I believe that we can potentially use them for z-axis homing. I haven’t actually tried it though so I’m not totally sure it’s possible.
Adding support for a conductive touch plate is 100% on the todo list.
If the motor is on, you would just cut, and the accelerometr won’t show it
stopping.
if you are going to stop the motor, you can use a conductive touch sensor.
David Lang
My thought would be there should be SOME measurement of accelerator change if the motor is cutting OR not cutting when it hits a surface. The question I would have is if there is just too much noise with the steppers running or the router running.
I think it is worth a test though. Maybe strap a cell phone to the maslow4 and see what happens when the bit touches the cutting surface. If the data supports identification maybe it could be an idea that could use future implementation.
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A conductive sensor isnt bad BUT has its own implementation concerns and possibly more work for the end user. The accelerometer could be almost hands off (once implemented and proven to work.)
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if you can cut as fast as you can plunge, the accelerometer would not see a
difference between moving in the air and moving through the wood.
David Lang
conductive touch is a very common way of zeroing the Z for woodworking CNC
mills.
David Lang
Absolutely very common, in my opinion, the maslow4 isnt really a common X/Y gantry system with a fixed spoil board.
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I’m imagining that this would be with the router off, right? We would be sending the router bit touching the wood leading to a bump
I would anticipate some change when the workpiece is engaged. Maybe you are right and there is no accelerometer change but I have my doubts.
Maybe what we should be talking about is a load cell for the Z axis.
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Yep my initial thought was when the router was off. A bump should be able to be detected and that would tell you the point in the z travel that is the datum of the tool tip. It also should be simple to implement on the board and not require wires like a capacitive touch might.
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Fancy stepper drivers might also be able to detect the increase in current when the tip of the bit touches the wood. They do this nowadays to home 3d printers.
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right, but having a metal ruler or similar that you place under the sled and
touch off from that is very much like putting a metal z sensor under your router
on other machines (in many ways easier)
David Lang
good thinking! maybe the drivers COULD detect the increased load. I wonder if that could be implemented on the existing hardware but isnt yet.
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That’s basically what Bar is hinting at in his first reply in the thread.
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those stepper drivers don’t work well with significant EMF, which we get from
the router.
David Lang
That’s the plan, I just haven’t tested it yet so no promises 
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I volunteer for beta testing.
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There are about 100 things on my todo list as soon as we get the basics under control. First step is fixing the bugs, then there are a ton of exciting features that we can add 
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@bar I hope you know your work on smashing bugs and getting the basics under control is appreciated.
I am only brainstorming and putting the idea somewhere it wont be forgotten too easily.
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