David,

  Here are all three tach adapters finished machining. Took about 8
  hours per adapter.

  I was rather surprised to see two contactors wired in parallel. It
  appears to be the 3 phase for the knee motor. That huge motor can
  probably lift 500 or 600 pounds.

  I guess back when the Kasuga was built they did not have contactors
  with enough current.

  "A contactor is an electrically controlled switch used for switching
  an electrical power circuit, similar to a relay except with higher
  current ratings and a few other differences A contactor is
  controlled by a circuit which has a much lower power level than the
  switched circuit."


  I have a new invention I will upload shortly for simplifying some of
  this rat's nest :-)

  Paul Lamar


  Looks great. I switched to solid state relays, use 5vdc data to
  control, no contractors to have carbon Build up or wear out.

  David Mikesell San Jose California

  Is the idea to turn off all circuits if a limit switch opens some
  where?

  So all limit switches are in seres? What would the schematic look
  like?

  I am thinking of a Maxmite and a LED panel that tells you which limit
  switch opened.

  Or is that feature built in EMC ?  Is it in Mach 3 ?


  Paul Lamar

  You can put all limit switches in a series So if  anyone of them
  opens it goes into e stop, or if it's in homing it takes that as a
  limit to whatever axis was moving. It works that way in mach3 also
  EMC. I personally wire each one individually as an individual home
  switch and it also acts as a limit switch. And then I use software
  driven soft limits while running to make sure I never actually hit
  the switch when the machine is moving.

  David Mikesell San Jose California

  Thanks David

  I'll  think about that so more.

  What is the limit switch voltage?


  Paul Lamar

  It's a 5vdc logic circuit.

  David Mikesell San Jose California


  I guess that is the reason some of the Kasuga docs I have recommended
  running the limit switch wires in separate conduit. Unfortunately it
  was NOT adhered to on this original installation. But I will fix that
  and run them in separate conduits.

  I am guessing but that would partially explain the dozens of
  capacitors used on all the high voltage wires.


  Thanks David

  Paul Lamar

  Paul,

  You should also used shielded two strand twisted wire for the limit
  switches. You can get false signals from other wires, encoders should
  also be shielded to prevent errors.


  David Mikesell San Jose California


Personally, I wouldn't connect the limit switches to the E-Stop. It's
hard on drives, plus if your homing the machine to the limit switches,
you're stopping the drives when you do. Limit switches can be configured
to motion stop, or pull power from the drives via software and are then
not hammering the drives from the power side if the switch is hit.

  I'd also not recommend contactors (or SSR's) between the drive and
motor, a good way to blow servo drives.

I agree with shielded wiring, limit switches, encoder wiring and your
spindle wiring if it's controlled via vfd.

At least, when I built my mill it's how I did it. Ran very well, never
blew a drive. I ran my wiring in a common cable carrier with ~25' of
cable all running beside each other and no noise issues. I also star
grounded my system, which I think helped with those potential issues also.

Fwiw
Jarrett Johnson

I am not using contractors on the servo drives.

On the spindle motor I am using a Speedcom 3 phase motor controller.
I suspect the EMC software can turn that off depending on the logic.

At least I think so. The limit switches probably feed into the EMC program
and it decides  when to stop an axis drive or the spindle motor.

Is that correct David?

So far I have not found that in the EMC docs. Does not mean it is not there.
As I learn these tidbits of info I have to read the EMC docs again
and again so I learn more and more in the process.

I am saving the contactors for the 3 phase  knee motor which will not
be tied into the EMC software. It will be strictly controlled
manually. I still need a schematic for that. Either that or a good
book on 3 phase motor wiring.

Jarrett, what software did you use for your NC mill?

Paul Lamar

The limit switches and the e-stop are all independent of each other in every installation I have done. Most people do them in a series because it is easier and takes less time and less input pins on the interface board. Problem is you never know which one is triggered.

I give each one has is own 5vdc signal, and is normally wired NC so that a limit is hit, or switch failure, even if a connector or wire break it stops the mill. With each one wired independent you will get a flag indicating which system that trigger the event.

I do not use contactors or SSR's between drives and motors. I was just telling Paul I do not use contactors for anything. I use SSRs for turning on coolant pumps, actuators for tool changers. This way you can use the standard 5vdc logic signal and the ssr triggers and lets what ever voltage ac or dc you are using to do its job. No transformers for worrying about voltage spikes to the control interface or line noise.

Yes Paul, when we set up the multi-function board, there are numerous inputs just for signals. In EMC we will tell it what each pin is assigned to and whether it is in a pull up or pull down condition normally. That way any change from that state is registered and causes the action we want.

It really is pretty easy, especially someone with your background. The real trick is learning when reading these manuals on controllers and software to realize what is really pertinent to your particular installation.

When I come down and we do this, in the end you will feel like kicking yourself because it will go pretty fast and easy during the software setup. the hardest part is doing the motor tuning to set the speed, torque and revolutions per inch.

David Mikesell
San Jose, CA

So shall I replace the knee contactors with solid state switches?
Can I control them with that switch box?

I love the idea of the 5 volt logic and doing away with all that dangerous 110 Volt switching.

Do you have a schematic or do I need to program a Maximite to do it.

I assume I need at least  two of these to reverse the motor?

Still no need or intention to control it with EMC. I only need to set
the knee height once per part type.

Paul Lamar

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