Re: Connectors, switches etc.

>> I like Proximity switches.
> How do these work?

Proximity switches and photo sensors offer not contact and not
mechanical means of switching. mechanical switches will fail for a
variety of reasons. a held down switch will be a PITA until replaced.

> What is a contactor?

This is a relay of specific purpose design.
All relays have three ratings on closure (completing a circuit) one
is for DC voltage, one for AC voltage and one for inductive loads. As
professor Marriss has taught us, inductive loads are like short
circuits until the motor starts spinning. a typical AC motor will
draw upwards of 5 times the FLA rating when starting.

The arc will melt the contacts of lessor units and the burnt contacts
will add resistance leading to heat and premature failure.

if you are just switching end switches, on/off switches, vaccumme
present switches or any other low power, low voltage control signals,
most relays will work fine. it's hard to find relays with less than
an amp capacity and more often 10 amps is the norm.

Here you might use a dual/tri or quad pole relay. you can use one to
light a panel light to indicate status on your panel.

The great thing is that you can switch 5 volts on one set of contacts
and 110 volts on another on the same relay with no problem.

>What is the momentary switch for?

A lot of designs use a momentary to close a relay (or contactor) to
get things to start. Figure a momentary switch that puts power on
the relay's coil, and through one set of contacts that same power is
put on the same coil feeding itself. when you push the momentary the
coil pulls in and when the contacts close, power is fed to the coil
through that set of contacts, keeping the coil energised. any drop
in voltage and the coil power is lost shutting down the relay. you
could wire in 1,000 switches in series to interupt that signal, but
remember, they all have to have contact to let it start in the first
place.

hth
Dave

>
> Oh ya! Looking at the pics of the machine. How did you attach the

linear

> guides to the extrusion? Custom T-slot nut(s) or????
>
> Thanks,
>
> Jay