z -Endstop that doesn't need adjusting...

Hi,
I'm a 3D-printer noob, and this is my first post. I learned fast that adjusting the Z-stop is a pain, but important.
Then I had an idea:
[www.youtube.com]
It's a piece of copper tape on the glass. The clamp holds the other wire. The copper tape and the nozzle form the endstop. No adjusting needed! The regular endstop is in parallel 2mm lower for safety reasons.
Seems to work pretty well. What do you guys think? next step is all four corners and autolevel activated.

Edited 1 time(s). Last edit at 06/07/2014 01:38AM by crashsalot.

The idea was brought up before, but shot down with questions like what happens when the nozzle gets dirty or covered in plastic? Personally, that's why I haven't done it, I guarantee you I'd have plastic in the way 95% of the time.
But if it works for you, that's most excellent.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

I use this technology when milling PCB boards. Setting the dirt consideration aside, it works well. Probing is slow, of course, because you can't afford to run over the endstop trigger point.

Eventually I fixed the probing wire on the spindle, making manual actions obsolete. This even led to a feature in Teacup firmware which turns off endstop voltage during printing/milling, because this constant tiny current happened to slowly erode the mill bit :-)

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Surely the plastic on the nozzle is a bit of a none issue. you could just have a probe slightly offset to do the same job. That way it can be shimmed to suit varying initial layer height.

[www.thingiverse.com]

Nice idea, but as LMColl says, there is normally some plastic on the tip of the nozzle. It might work if you heat the nozzle to operating temperature and retract the filament before probing, and preferably wipe the nozzle too.

Another contact-type approach is to vibrate the nozzle and pick up the vibrations in the bed, or vice versa.

I did some experiments with a solenoid-activated probe on the hot end. The idea was that a spring normally holds the probe tip higher the the nozzle, until a solenoid pushes the probe down. As the head is lowered, the probe makes contact with the bed, forcing it up against the force of the solenoid. An optical sensor triggers when the back end of the probe reaches a certain height.

In the end, I abandoned that approach (and also prototype inductive, capacitive and ultrasonic height sensors) in favour of a modulated differential IR probe. Details are at [miscsolutions.wordpress.com] and the schematic and firmware are at [github.com] (the version 2 files). The use of two IR emitters instead of just one makes it relatively insensitive to the surface of the bed. It can be used for z-homing and 5-point auto bed levelling. I've supplied 50 of these to Ormerod owners already, and I am about to have another batch manufactured.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].