Since I had some troubles finding the optopstop components (specifically the H21LOI), and some problems with the micro switches (apparently superglue can break them) I thought it would be nice to have a (cheap) alternative.

I used the components from an old mouse. This is the model that uses a ball and has some opto couplers and (infrared) LEDs inside. Took them out, soldered them on the opto stop PCB (as described in the Wiki) and plugged it in, and this works very well. If you want to try this but need some more info, let me know, I can post some details.

Joost

its true!

i accidentally broke open the H21L0I and pulled the black thing off and it basically just contained and LED and some sort of receiver. I imagine it would be easy to make your own (or RepRap a housing for regular LED's)

cheers!

Yep it will be a LED probably IR with a photo transistor, back in the old day if you wanted a photo transistor you just carefully took the top of a regular transistor and hey presto a photo transistor, when we get to RepRap electronics would be a good item to start with as size would not be an issue.

---

Ian
[www.bitsfrombytes.com]

Ian, why do you think size is not an issue?
As far as I understand, main function of optostops is 0-position determaining. So, if we have 1mm-diameter LED and photodiode, we obtain 1-mm error in zero-position determining.

By the way, maybe good alternative way to make optostops cheaper is just use 3 instead of 6 of them? See [forums.reprap.org]

Opto's usually have a plastic cover with a thin slot to get better resolution than the size of the LEDs.

If you are using steppers then you can get four times better resolution than your end stop because you know which phase you are on.

Yes no point in more than three unless you are paranoid.

---

[www.hydraraptor.blogspot.com]

I think that the arduino code looks for all 6 end-stops though. Don't hold me to that, but that is my impression.

---

Jay

the arduino code is capable of using all 6 endstops, but it doesnt require them. you need 3 for a full machine, and 6 for doing the 'calibration' which is not required.