End-stop Questions: Techzone optos or mechanical & RAMPS

Hi,

I'm getting the parts together for my first reprap and I'm trying to figure out what to do for end stops.

I'm building a RAMPS electronics set, and finding in-stock opto's is tricky.

Techzone has some, but I don't know if they're compatible with RAMPS, does anyone know?

What about mechanical end stop, or limit switches, like these? Digikey has them for $0.62 each. There are many other similar switches, I didn't spend time looking for the optimum one for the purpose of this post. What wiring / firmware changes might be needed to make this work (I'm sure someone must have done this)?

they will work there is going to be a vcc, gnd and sig wire, what would make a difference is if they are normally open or normally closed. you would just have to set your firmware settings accordingly.

i have got a reply back from [ultimachine.com] he says he should have them back in stock this week for the endstop kits.

i do wish i could tell you what was more accurate though i have always wondered about that my self.

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[mike-mack.blogspot.com]

As far as I can tell with mechanical end stops the only ones that need to be very good, i.e small are on the z-axis, I have fitted 6 to mine 4 big bulky ones on the x and y and two smaller ones from ultimachine on the z-axis. They are not working yet as I still need to understand what setting I have to make in firmware, so I am running on software which isn't good as that has no memory for obvious reasons.

Please, if anybody can give me clear instructions on what to set for NCC mech endstops I would forever be in yur debt

Cheers
Rob

Here's what I've learned about mechanical endstops:

http://reprap.org/wiki/Mechanical_Endstop (<- this was oddly hard to find)

And some more information here: http://forums.reprap.org/read.php?151,75606,75891,quote=1

I haven't digested it all yet, but it may help. The second link has some RAMPS specific information.


As for what's more accurate - that'd be complicated. Switches could be more or less accuarte depending on the switch. We have some precission plunger style limit switches where I work used to aligning optics. I think they'd beat the optical switches but they're $160 each. Mechanical switches can wear old or, if they have a lever, bend. I would guess that the exact trigger point for optical stops could depend on lighting condition, temperature and dust contamination.

There're never easy answers...

I've wire up switches on perforated bread board with little trouble. You only need five components:

Required parts
Part ID Part name Quantity
R1 10k Ohm Resistor 1
R2 220 Ohm Resistor 1
R3 1k Ohm Resistor for LED 1
LED1 3mm LED 1
X1 3 pin 5.08mm pitch screw terminal or header pins1
Opto Switch 1

[reprapsource.com]

thats 7