opto endstop boards?

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On Thu, 2007-05-31 at 15:46 -0400, Zach 'Hoeken' Smith wrote:
> how many do we need for a full reprap machine? i recall seeing the
> number three somewhere, but wouldnt that only be for the minimum?
> also there are two connectors on the board, so it would make sense for
> there to be 6 required (3 mins, 3 maxes)

We only use 3 in the current design. That's all we have flags and
brackets for in the BOM. Suggestions Adrian?

Vik :v)

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Ello,

After wiring up Darwin, I'm an advocate for using only 3 endstops to establish the home positions (the minimum requirement). Those extra three max-endstops are of course completely possible, but can be made virtual in the software (yet to be implemented it think?). Software replacing hardware... 1's & 0's cost less and you don't have to wire em ;-)

eD

"Software replacing hardware... 1's & 0's cost less and you don't have to wire em ;-)"

Yup, they do take cycles though and if you're running a heavily interrupt driven app that can get to be a problem.

Sorry for the delay - exam marking.

Vik Olliver wrote:
> On Thu, 2007-05-31 at 15:46 -0400, Zach 'Hoeken' Smith wrote:
>> how many do we need for a full reprap machine? i recall seeing the
>> number three somewhere, but wouldnt that only be for the minimum?
>> also there are two connectors on the board, so it would make sense for
>> there to be 6 required (3 mins, 3 maxes)
>
> We only use 3 in the current design. That's all we have flags and
> brackets for in the BOM. Suggestions Adrian?

We have never used the far endstops. The props file knows the axis
lengths, and in all our runs we've never driven off the end. And if you
do, the motors just stall anyway, which is not a major disaster.

We should set the drag bars in the stepper exerciser prog so that full
length is full length; again easy from the props file.

--

Best wishes

Adrian

Dr Adrian Bowyer
[staff.bath.ac.uk]
[reprap.org]
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interesting, although i'll probably be using 6 as they're cheap and makes me feel safer. plus, i'd like to experiment with a auto-calibration system where it starts at one end, goes all the way until it hits the other endstop, counts the steps, and then figures out the step size based on the user supplied length of the travel.

good to know that you can get by with only 3 though.

Ed wrote:
> After wiring up Darwin, I'm an advocate for using only 3 endstops to establish the home positions (the minimum requirement). Those extra three max-endstops are of course completely possible, but can be made virtual in the software (yet to be implemented it think?). Software replacing hardware... 1's & 0's cost less and you don't have to wire em ;-)

Yeah, I built six into my RepStrap. Three of them have never been
triggered a single time (except during testing). In that sense they're
a bit of a pointless addon -- they were really intended as a
precautionary feature in case the software goes crazy or something. It
would be rather unfortunate to have an unattended RepRap go slightly
insane and crash the head into a wall. I think we should leave them in
the design but for lazy and brave people, just don't solder them in or
mount them.

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