Replace the optical switch with a mechanical switch?

[Luis E. Rodriguez]

http://www.pp3dp.com/index.php?option=com_content&view=article&id=204:replace-the-optical-switch-with-a-mechanical-switch&catid=43:blog&Itemid=55

Why is this important? I've never had a problem with homing. Just curious.

Luis E. Rodriguez

[Paul Jehlen]

Darkhouse commented that they were experiencing quality issues with the optical sensors and were switching production over to a mechanical solution.

The machines that shipped were tested to ensure quality/reliability - they probably have a large bin of rejects.

--
Regards,
Paul Jehlen

Mechanical Engineer
San Francisco Bay Area

[Luis E. Rodriguez]

Cool, thanks. I won't bother until I experience something. Only thing I've noticed is the four corners it thinks are corners are off a bit from the actual.

Luis E. Rodriguez

[Paul Jehlen]

That's a different issue - once the machine initializes, the end stops are not used. The Y axis (IIRC), is offset about 3mm - you'll notice it if you send the print head to center and reference the two bed screws.

[Dave M.]

I hope they are good mechanical switches! I haven't had a problem
with my opto sensors, nor have I ever had a problem on any of the ones
I've used on machines in the past. It would be interesting to see why
they were having problems. One thing I found interesting about the
printer that I have is that they colored the ABS black where it breaks
the light beam. I'm not sure why they didn't just replace this part
with sheetmetal or something.

Another question that comes to mind is whether or not they designed
their board to use both optos and mechanical switches, or just optos.
If it's the latter, then I wonder if they have proper debouncing
circuitry in place. They could easily deal with this in firmware, but
then that means everyone would have to ship their printers in.

I guess the bottom line is, I hope that I don't have a problem. :)

On Feb 11, 2:07 pm, Paul Jehlen <paul.jeh...@gmail.com> wrote:
> Darkhouse commented that they were experiencing quality issues with the
> optical sensors and were switching production over to a mechanical solution.
>
> The machines that shipped were tested to ensure quality/reliability - they
> probably have a large bin of rejects.
>
> On Fri, Feb 11, 2011 at 12:16 PM, Luis E. Rodriguez <
>

> lrodriguezm...@gmail.com> wrote:
>
> >http://www.pp3dp.com/index.php?option=com_content&view=article&id=204...
>
> > <http://www.pp3dp.com/index.php?option=com_content&view=article&id=204...>Why

[Luis E. Rodriguez]

"We use mechanical switch to replace optical one is just because the mechanical one is more reliable. As your limited switches run well, I don't think you need to change the mechanical one. "

I didn't ask but it would seem it does. I'm not worried about it, I've had no problems. A few stripped filament episodes but that is it.

I can't seem to make heads or tails of the new ROM update feature being the same thing as firmware updates or not!? The last firmware update that allowed the build platform to stay kn after a build is moot. I print on proto boards anyway, heat isn't a factor.

Luis E. Rodriguez

[Paul Jehlen]

They're calling "Firmware" the stuff that handles basic I/O and motion control. ROM is also onboard the printer, but runs the machines "programs" - I believe it's just semantics, but I think we'd can call them the same thing. Their MCU has a fair bit of eeprom storage - this is probably what they're writing to (which doesn't require a bootloader or a factory reflash).

As for the opto sensors... I imagine if it were as simple as replacing with a sheet metal part (which would be more expensive than a printed plastic part), they would have done so instead of switching to a different OTS component. I think they did consider mechanical switches as they had the plastics parts in their replacement part folder well before coming out with the blog post.