Re: Pendant Design, was - Spindle Motor Control?

Chris,

You make some excellent points here!

Whether any safety "authorities" would consider a USB based Estop as
fulfilling the requirements OF an estop; is NOT something I'd want to
find out AFTER an accident... Insurance companies would love to find
that the machine wasn't "wired" properly...

However, there are also rules that REQUIRE more than the "one" estop
location you mention. You've given us the "last word" on safety
before<G>; and it IS worth repeating, IMO.

Dean,
As to pendant functions, I agree with Chris that these should carry
setup and program proofing functions.(after all, the reason you are
using a pendant is so that you can get your eyes into the "action",
so to speak. Which is not where you want to be if the machine is
doing production...

But some pendants have the further ability to select a file, which
can be pretty useful on a big machine.

My questions are not is it usb, but rather is it to be tightly
integrated with some specific software package(s)? Or is it simply
a "keystroke emulator"? Does it have a display?

Because you can gain a fair bit of flexibility if you set up 3 of the
keys as: function select, numeric input, and enter.

Using these with 2 or 4 already existing jog keys for cursor control,
you can move through menus of choices which appear in the pendant
display--a 2x16 can suffice(or onscreen, but doesn't that take a bit
from the pendant idea?). The pressing of a "numeric input" key can
also be made to turn 11 keys into a numeric keypad, with decimal
point. Then pressing enter puts this value into whatever function was
needing it, whilst restoring the "numeric" keys to their other-than-
numeric functionality.

Anyway, this requires more brain in the pendant, but with todays
micros, this is not difficult to do, and will provide much more than
a simple keystroke emulator where you have to select and decide the
ONE function that each key will provide.

Having said that, there are places for both types. Pendant design is
no different than "full" program design. Do you want to have the key
do the SAME thing each time it is pressed (and therefore require more
keys; or support less functions). Or do you have fewer keys, which
can serve multiple functions, as described above?

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, CL <datac@l...> wrote:
> deanc500 wrote:
>
> >Hi, I have been contemplating a programmable hand held pendant for
> >some time now and I am at the point of laying out the keypad to
get a
> >membrane switch pad manufactured. I will be offering these in small
> >volumes at first to test the market.
> >
> Is this to be a USB device ?? I imagine so....
>
> >I would like to ask the group for
> >input on what the most useful functions would be. I agree with
Bill on
> >his choices of E-stop, on the fly feedrate override, and axis
jogging.
> >I would add "zero all axes", Home, slow/fast jog.
> >
> I guess that IF it is a "programmable" device, then "labeling"
buttons
> could be somewhat limiting.
> I like the approach taken by the X-Keys ( or Y-Keys ) by PI
engineerings
> keyboard in that the keycaps came off in order to place under them
> exactly what you want. You can look in the CCED files section and
see an
> old layout I did for Flashcut V1 in a .pdf file for their double
layer
> keypad. It does not take very long to do a nice color print of
exactly
> what one wants for buttons in Corel Draw, cut them out with an
exacto
> knife, then place them under the clear key caps. THIS is the best
option
> as it will not limit anyone or any software, but I understand the
desire
> for a membrane.....
>
> Then again, the membrane on a particular Multicam head I am
familiar
> with is absolutely shot after 5 years of use......
>
> My complaint with the off the shelf X-Keys was the
switch "feedback"...
> not a strong enough "click"..
>
> > What else would be
> >useful. I am thinking that the pendant will have room for about 12
> >functions and Estop.
> >
> I used to try to get every possible function I could into the X-
keys
> box, yet now, looking at redoing mine for Flashcut, I'll shoot for
only
> the necessary items. After all, I found out that the pendant did
not end
> up in my hand all the time anyhow. It is most used for machine or
Job
> setup, and the moments right after starting the job. Then it gets
set
> back in its holder while the job runs.
>
> Homing, Setting Zero, Jogging ( at all available rates), Setting
Part
> Zero, Move to a reference point ( like machine zero or toolchange
> location), Start Job, and finally the "ooops" Feedhold, and Reset
option.
>
> The "E-Stop" concept on it is nice, but probably best a "cover" for
> liabilities anyhow.
>
> I think it would be a shame if a person "learned" to rely on his
> pendants E-Stop" rather than on the ONE Really BIG red Kill button
he
> SHOULD have ! One might get a little too friendly with the pendant
> E-Stop, so that when a real emergency arrives, he is fumbling for a
much
> less accessable button than he should be. Also, the Real E-Stop
should
> be cutting power to the drives and spindles, not just halting the
> software. So, it has some limitations as a USB E-Stop.
>
> I learned something once about E-Stops.... Do NOT put your ONLY one
on
> or even too near to the machine. Put an E-Stop by a door exiting
the
> room, or on a pole 15 feet away in a shop scenario. Let it
Disengage a
> contactor feeding that machine. I had a fellow start a toolpath,
but
> forgot to remove his dial indicator and positioning arm from the
> spindle. The vibration was unbelievable, and the parts flying off
were
> deadly. Guess where the E-Stop was ?? NOT where anyone wanted to go
to
> get it shut down ! As everyone in the whole place was laying flat
on the
> floor dodging flying parts, I was forced to head for the Main power
> panel. Good thing I knew which breaker it was ! I don't need to
tell you
> that was the "Last Word" from our *Last Word* Indicator.
>
> So, I could do without the E-stop on the pendant... a feedhold is
> plenty. E-Stops should be BIG red locking buttons that disconnect
Power.
> I'll keep my second E-Stop mounted right by the doorway so I can
nail
> that bugger whan I am headed out in an unexpected hurry.
>
> Chris Luebke
> DATA-CUT