Background
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I was using an inductive sensor as my main Z_min sensor. I was unable to use it as bed leveling sensor because I was using a very thin and
...Show more soft steel plate under the glass. This lead to several issues: the glass itself is not perfect. The steel plate under it was not flat even when compressed so both the steel and glass does not represent the REAL printing surface. Only a touching probe can give you that!!!
I like the idea of the piezo - but also plan to use PEI in the future and I would not like to touch a hot nozzle to that surface.
I like a lot the BLTouch - but the real thing is too expensive to my tastes and the clones are not that reliable and not so cheap as well.
I do not like the bulky thing, with movable wires and such, when using a servo and a mechanical end-stop. Also I do not trust the repeatability of the servo positioning.
I fall in love with these two designs:
[Robscar Thing](https://www.thingiverse.com/thing:2841443)
[Jupacreations Thing](https://www.thingiverse.com/thing:2197895)
Cheap as heck, simple, reliable, no dependency on servo position (the servo just raise the probe when not in use). But both are bulky and very specific to their owners printers.
So I started designing something I could just put in place of my old inductive sensor at my Hypercube Evolution. That is compact enough for any other printer (different fixation designs on demand! Just ask me.). The size is based o the BLTouch footprint.
Key Features
===========
Some key features (this list is based on Jupacreations design description!):
* It can be used on all bed surfaces.
* It is not sensitive to temperature changes. **
* What you see is what you get during the working and setup.
* High accuracy and repeatability (better then anything at least at this price range! ;-) )
* Lowest price possible with ready to buy products. (I had everything at hand...)
** Well... it is sensitive to temperature... But my fault: I put the thing right at the heat flow path of the hot end cooling fan! Do not do that!!!! I am working on a solution :D
Bill of Materials
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You will only need:
* 1x Micro Servo (e.g. TowerPro SG90)
* 1x Optical Endstop TCST2103 (RepRap Standard)
* 2x M3x10 to fix the optical endstop.
* 1x M3x30 as the probe
* 2x self cutting screws (2x8) fix the servo
* 1x Cheap made in China gift pen spring that fits the M3x30 screw.
* Some 4 wire cable **
** I like to use old USB cables for this! It is very common to have the micro USB damaged from use ao the cable is good, felxible, shileded and have nice and stadard colors. Use black and red for feed and the other two for each signal :D.
Instructions
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1. Print Main and Flag (flag MUST be black or painted black!) parts and test if the flag move freely.
2. Put the spring (cut something like 10mm long) at the M3x30 and screw it to the flag mounted to the Main until the head is flush with
