Re: [CAD_CAM_EDM_DRO] Home/Limit switches : Micro switches or optical interrupters?

I feel the typical Snap switches are the better choice for most home duty equipment... They are inexpensive, easy to find, require virtually no other electronical support and have always given me a
repeatable contact within .0003".

I can't say what the repeatability is on a prox switch though I have operated MultiCam machines with them. They will need extra wiring and circuitry, that is for sure.

One thing I really remember with Prox switches was that when things went "Wrong".. really wrong, and it can and does, Guess what got pounded to death ? Yep, those more expensive limits ! The gap was
generally too small to allow space for a safe "Stop Zone" before smashing the switch. (the ultimate situation leaves enough room for "shock Absorber" dead stops on the machine)

On the other side of the coin, Some of the "levers" on the Cherry switches can be configured to allow some flexing, allowing an axis to crash into a qualified positive stop, causing no damage to the
Snap switch whatsoever, and in most cases, require no repair after such an episode.

However, I'd never argue, that if you are going to have a "Wet" environment because of coolant, running all over the place including over the switches, you might desire the sealed proximity types.
Just be sure nothing causes them to indicate incorrectly especially if you use them for "machine home" locating.

If you are doing the Snap Switch thing, be sure to get some with really tight springs ! Some are rather "Limpy"......

Chris L

Erik Reikes wrote:

> I am slowly but surely progressing on my servo CNC conversion and I
> have come to the question of limit switches.
>
> Are most people using micro switches or optical interrupters to
> determine their home position? What kind of repeatability in home
> position is required/attainable?
>
> Micro switches seem like they would be easier to implement while
> optical interrupter probably have greater accuracy and no moving
> parts. Right now I am leaning towards optical interruptors with a
> small tang mounted on my table to trigger the interrupter, but
> thought the list might have some thoughts on why microswitches are
> the greatest thing since sliced bread.
>
> TIA
>
> -Erik Reikes
>
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