Which endstop. Microswitch or stall detection?
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I agree with that, with one caveat:
@Danal said in Which endstop. Microswitch or stall detection?:
Non-Delta XY doesn't need to be very precise, so optical, snap switch, stall detect all work. Z needs to be optical or a good switch.
If you want to use the resume-after-power-fail functionality, then you need to be able to re-home X and Y (and ideally Z) to the same positions as before you started the print; so then you do need repeatable endstops.
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I guess we ought to add a couple more options to complete the list. Firstly there are these which is what I currently use for Z homing https://www.metrol.co.jp/ec/contact-switch_cs?gclid=CjwKCAjwvOHzBRBoEiwA48i6Aia0mpbKJrQVI626sR3oOE8VQCsAjM_hfVqfWi002W6rRRY8-M05nRoCT68QAvD_BwE
The way I do it is a bit tricky to implement from a mechanical point of view because the switch is connected to the nozzle mount, so the nozzle itself is the Z probe. It's a bit tricky because the nozzle must be constrained from any movement in X or Y but free to move (albeit only by 0.3mm or so) in Z.
These switches aren't cheap though and would be overkill for X or Y (but they do come with optional LEDs which as Mark said, are handy).
Another option is two insulated contacts coming together to complete a circuit, which is as simple as it gets. One contact on the carriage, the other on the frame. The contacts need to be non corroding - so gold or silver plated.
I'm currently working on another variant for my Z axis using that technique. I've just spent the princely sum of £1.26 on these https://www.ebay.co.uk/itm/Flat-Disc-and-Post-Earring-Findings-Pack-of-10-Make-your-Own-Earrings/112606214351?ssPageName=STRK%3AMEBIDX%3AIT&var=413683787505&_trksid=p2060353.m2749.l2649 which might make suitable contacts. It's still a bit tricky to implement from a mechanical point of view but if it works, then in theory the Z offset will be zero (although in practice it might be a few um).
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To that last point, I'm working on multi tool alignment on tool-changing printers. Right now, the simplest way to measure Z seems to be to wire the nozzle and a touchplate. Metal-to-metal contact.
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@Danal said in Which endstop. Microswitch or stall detection?:
To that last point, I'm working on multi tool alignment on tool-changing printers. Right now, the simplest way to measure Z seems to be to wire the nozzle and a touchplate. Metal-to-metal contact.
How do you plan to clean any filament debris from the nozzle?
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@dc42 said in Which endstop. Microswitch or stall detection?:
@Danal said in Which endstop. Microswitch or stall detection?:
To that last point, I'm working on multi tool alignment on tool-changing printers. Right now, the simplest way to measure Z seems to be to wire the nozzle and a touchplate. Metal-to-metal contact.
How do you plan to clean any filament debris from the nozzle?
The toolchanger wipes the nozzle when it mounts it, as a normal part of printing, to avoid blobs and such. So far, debris has been a very low failure rate.
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@jens55 said in Which endstop. Microswitch or stall detection?:
Consensus seens to be that stall detection is not as accurate as s switch.
Super accuracy of x/y homing is not a goal for my Core X/Y since I don't need to resume from power outrages. As for Z, the printer has a BlTouch which works great also for Z homing. This minimalist approach simplifies the hardware and works great for me.
The case may be different for other kinematics such as Deltas where a tower homing errors may tilt their plan and invalidate their previously acquired compensation mesh.
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I'm using opto switches in all three axes. The Z=0 is adjusted using a differential screw so small tweaks to the bed position can easily be made. It much simpler than putting a sensor on the extruder carriage, and since the printer is stable, like the bed leveling, it doesn't have to be readjusted.
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@mrehorstdmd said in Which endstop. Microswitch or stall detection?:
It much simpler than putting a sensor on the extruder carriage,
Do you use a sensor for mesh compensation or is your mechanical frame accurate enough as is?
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@zapta No sensors, no mesh compensation. Built like a tank and very stable. Bed is flat and leveled on a kinematic mount. On numerous occasions I have dragged it up basement stairs, loaded it into my car, taken it back out and started printing with no adjustments.
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Any way we can use the "dual" sensor for homing? I'd like to do the switch (opto or mechanical) + stall detection as a backup. During the homing process, if something goes wrong (print left on the bed is a good example), it would be cool to "cancel" homing on stall detection.