I am in the process of building a Rep Rap Prusa 3D printer, and I have this habit of trying to re-invent the wheel. I started researching electronics and really disliked everything I found,

I had originally ordered some gen 2.1 Opto boards, which I decided were too large for the printed clamps.

After some research I found the most recent End-stop http://reprap.org/wiki/Gen7_Endstop_1.3.1, looks like somebody's after-thought.

So I decided to design my own....

Step 1: The Design

I started with the schematic from the Gen 7 end-stop and went from there. My biggest problem with the schematic is that the output signal (probably) will not give a 5v high output, according to my math the output will range from 0- 3.7v. I'm sot sure what a digital input pin on an arduino will accept as a high but I would rather the output could go the full 5 volts.

I used the same photo-interrupter TCST2103 and corresponding current limiting resistor as well as the pull up resistor for the photo-transistor.

It needed to have an led for debug purposes but I couldn't decide on the final wiring, so I left 3 different component landings near the end of the board. The idea is for the builder to use whatever landings they feel necessary: led on all the time, led on when the sensor is blocked and led on when the sensor is not blocked. Use the 2nd one with caution because it will also have an output high of 3.7 volts.

The board was carefully sized to fit onto a Prusa End-stop holder with minimal overhang. The connector is placed at the end of the board so the wires can be routed out of the way.

Board Parts:
The board (3 ordered from http://oshpark.com/ for around $5)
TCST2103 Photo-interrupter
blue led (surface mount 0805)
180 ohm resistor (surface mount 0805)
2.2k ohm resistor (surface mount 0805)
2 - 1k ohm resistor (surface mount 0805)
Plus a complete assembly of a ~.1" pitch male/female connector (don't forget pins), or solder wires directly to the board. This project was designed to use a 2.5mm pitch JST connector.

Mounting Parts(assuming mounting to Prusa):
Printed end-stop holder
2 - M3X18 screws or similar
3 - M3 nuts
2 - non conductive spacers or small diameter washers to space the board from the printed holder
M3X25 screw
<p>Hi. Great job on the article. I'll get right to the point. I'm working on a special project. If you haven't already noticed. It's 1984 again. The Rep Rap community is our modern day &quot;Home brew&quot;. The tech world is on the edge of a new renaissance, and I'm betting everything that 3D printing tech will lead the way. I'm aiming to be the next Apple, and I'm looking for my Wozniak. From what i read you could be him. If you're interested please contact me at searlsinc@icloud.com and let talk. &quot;Those crazy enough to believe they can change the world will.&quot; Regards. </p>
good job! <br>Your design of optical end-stops selling on ebay.com (http://www.ebay.com/itm/3pcs-Opto-Endstop-Switch-Kit-for-CNC-3D-Printer-RepRap-Makerbot-Prusa-Mendel-/390591025467?pt=Kunststoffe_Chemie&amp;hash=item5af10a113b) and i am buying :) <br>Could you add a sketch of dimensions with holes. thank you.
<p>For those who are looking for this answer: https://grabcad.com/library/opto-endstop-tcst2103-1</p>
great work! is your rep rap completed then?
Nope, every time I get involver in a project I feel that I have to &quot;re-invent the wheel&quot;. My most recent snag was slipping belts for which I spent several days machining aluminum belt tensioners.
<strong>Jason-B:</strong> You go right on ahead and <em>re-invent the wheel</em>, I like your thought processes!

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