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frankvdh
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JustSumGuy
I would avoid that, in case of a skipped step or some other malfunction you could drive your head into the bed :(
Practically every 3D printer runs on the assumption that it won't skip steps. Once printing starts, the endstops aren't checked again. So if you can't assume that every step will work correctly, you can't reliably print at all. In which case, it doesn't matter if the endstop is at the top or bottom. Typically, Delta printers have endstops at the top of each tower (plus perhaps a bed-detection probe).
Mesh bed leveling really isn't "manual"... it uses the Z end-stop (which must be triggered when the nozzle touches the bed) to probe the bed around a grid. If you use the G29 command without a probe, the nozzle will crash into the bed.
You *can* print without using a Z endstop. The printer assumes that at power-on, it is at Z=0. So use a piece of paper to set the Z height, then turn the printer on and you're good to go. But if you use Z homing (X & Y are OK) or bed levelling, the nozzle will crash into the bed.
What I do is to have the Z endstop always on. This way, an accidental home won't crash into the bed. When I want to set the Z height, I do a Z home, then manually wind the head down to grip a piece of paper.
So many ways to do it I guess :) I thought "Manual mesh" was what I do. I activate this via my LCD control panel. The system homes ALL first, then I click the knob and it starts by going to the first of nine points where I use a bit of paper and adjust via the knob by .025 (I think) up or down until I get the grip I want on the paper, then when all nine points are complete I save the mesh to eeprom.
I do this with the bed at 70c and the tip clean and at 170c this usually works well for a month or so then I have to redo it. I ordered a BLTouch the other day, see if I can fit that in the head setup.....
I am surprised the Z-Endstop does not act as a bed protector..... I have a buddy that drove his head into his Prusa i3 bed and was not around, it burned and ground the head into a hole right thru the heating traces after a few hours....