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>First, levers are less accurate than buttons as there is a lot of variation in the throw.
True, but not this much. And that does not explain the repeatable dependence from speed.
>Is the Z latch backoff long enough to always back off the lever? How much travel does it take to always back off the lever?
I haven’t examined the minimum required. The specified 6mm is certainly enough. In all the tests I can hear the switch clicking both ways. It is always clearing the switch, but it seems to have a hard time figuring out when to stop when backing away.
>Can you post your Z settings?
Those are at the top of my post. Scroll the window sideways to see all of them.
I played with it some more this morning. I found that:
– Jerk setting has a noticeable effect to where it stops – as expected. When using the fast end of the machine, speed also has an effect. So, when I got different stopping positions at speeds 1000 and 2000, nothing is wrong.
– At slow latch and search velocities, it does not obey the latch backup setting, but stops as soon as the switch is cleared. This I think is the real issue.
My 1/3 – 2/3 results at speeds 500 was likely the “right-at-the-limit” setting for yesterday’s star positions. Today, I didn’t get any random results, the machine stopped either at the switch or the specified backup position.
Workaround: Don’t be ridiculously slow. 🙂 So, while you do want to fix this, it is not urgent for me.
> The deceleration should be actually starting when the switch transition occurs. Please let me know if you see evidence to the contrary – that would be a bug.
Unfortunately, I do see the contrary. These are the settings:
$z [zam] z axis mode 1 [standard] [zvm] z velocity maximum 1000.000 mm/min [zfr] z feedrate maximum 1000.000 mm/min [ztm] z travel maximum 80.000 mm [zjm] z jerk maximum 2000 mm/min^3 * 1 million [zjh] z jerk homing 5000 mm/min^3 * 1 million [zjd] z junction deviation 0.0100 mm (larger is faster) [zsn] z switch min 3 [0=off,1=homing,2=limit,3=limit+homing] [zsx] z switch max 2 [0=off,1=homing,2=limit,3=limit+homing] [zsv] z search velocity 1000.000 mm/min [zlv] z latch velocity 1000.000 mm/min [zlb] z latch backoff 25.000 mm [zzb] z zero backoff 0.000 mm tinyg [mm] ok> tinyg [mm] ok> $3 [3ma] m3 map to axis 2 [0=X,1=Y,2=Z...] [3sa] m3 step angle 1.800 deg [3tr] m3 travel per revolution 8.000 mm [3mi] m3 microsteps 2 [1,2,4,8] [3po] m3 polarity 1 [0=normal,1=reverse] [3pm] m3 power management 0 [0=remain powered,1=power down when idle] tinyg [mm] ok>Note the long zlb value. On homing, the z travels all 25mm, even though it certainly has enough time to stop. On slower zlv settings, it does stop right after the switch clears. I tried on other axis which have different settings, but their behaviour on my machine is as you say.
Btw, I was NOT correct about the latch backoff functionality. I thought the machine would start from the “bottom” of the switch and always back off the specified amount (like my z behaves now). I think I get it now, and I need to change my settings – or maybe not, I actually like the current behaviour. Fast settings produce good clearing for the switches (although not as you intended) and the homing is swift.
And if I may phrase it a bit differently, this is how I now understand homing operation (please correct me if this is (still) not right): When the homing cycle has stopped at the “bottom” of the travel, it starts backing away at the specified speed*. When the switch clears, the machine has picked up some speed, but it stops when it can*. The resulting end position has nothing to do with latch backoff value, but is a function of the speed and jerk settings.
(*: Latch velocity and jerk homing values are used)
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