[Mizuno1]

Please excuse the ignorance with this question but I'm glad I found this site and just registered.

I'm a disabled vet trying to keep my brain going, so I reached into the I'll be an idiot bucket and now I'm building my 4th machine.

The other three were simple. Step motors, Mach3, Gecko 203v drives and a PMDX-122 board. All worked great.

The machine I'm building now is a high precision Swiss with Parker servos and Gemini drives that take step and direction.
Will also have a 3kw Parker servo that needs to run in velocity mode (I believe) for the spindle, but I need to do single point threading with this machine.

I want to use Mach4. I know that I need to go from the PC to the BOB (which I can't figure out which one I need yet either) Steve at PMDX can never be reached.
But from the BOB, I need to tie that into the servo drives which use an old parallel port. I think that I need to go from the BOB to something like this, correct?
EBAY - Parker GEM-VM50 with Mach3 Breakout Board Adapter Cable - Gemini Servo Drive CNC - - eBay item number:326260345469
But the ones for Mach4 - Which I have.
Then from there, tie into the drives.

One, is this correct?
Two, how do I go from the PC to the right BOB and what would you recommend for a BOB to the adapter, and anything else I might need to make this work?
Any thoughts?

I really appreciate your time and help,
Hope you're all having a great Memorial weekend!

Thanks,
Brian

[awerby]

You're really trying to run this thing off a parallel port?

[Mizuno1]

No, Mach4 with a ESS
Looking for recommendations as far as a BOB - a guy here that seems to be very trusted told me that the ME3 with the ESS is a good choice. I've used the PMDX-122 before and was looking at the 126 board w/ESS. But trying to get in touch with the one guy who runs PMDX is almost impossible. So IDK. The 122 board's I've used before we great. So I assume that the 126 board would be as good or better, however, if I can't get any support or even order it, then the only other one I keep hearing about is the ME3. But that board seems a bit more complex.
Would like to hear what experienced people have to say.
This build is a bit more complex. But doable.
The tough part that I'm still not getting my head wrapped around is the spindle.
I'm going to use a Parker 3kw servo with a Gemini drive that can be set up for step and direction, torque, or velocity modes.
Velocity is what I think it needs to be set up in, but I need to do single point threading.
The servo does have a 2000 line encoder.
But one: how should this integrate into the system?
two: how do you do single point threading with a spindle like this?
Once I can have a good explanation, then I can start that phase of the build.
Turning semi-micro parts.
Shafts that are .010-.025" in diameter
and .156 that have a unique thread.
This needs to be set up dead nuts so it's repeatable.

Hope this clears things up as far as what I'm doing

Brian

[joeavaerage]

Hi,
there are a couple of ways to do single point lathe threading.

Mach4 and the ESS supports lathe threading. Mach4 runs the spindle at some (programmable) speed, say 500rpm. The ESS requires an index feedback signal
which allows it to adjust it Z axis advance to perfectly match the required thread pitch and also to synchronize the start of the thread if you need to take multiple cuts
to form the thread. This works well and has been used for many years.

The basic principle is the the spindle STAY at constant speed, and thus the Z axis advances at a constant speed to form a thread. If the spindle speed varies then a
constant Z axis advance would result in a thread of slightly varying pitch. The ESS does get feedback from the spindle and can and does accommodate small variations
in spindle speed and adjust its Z axis advance to suit. What it cannot accommodate is large variations in speed. I would suggest to you that a 3kW servo in velocity mode
is about the most stable spindle you could hope for. I have no doubt you could get this combo 'dead nuts'.

There is an alternative that does not require any specific hardware support but relies on the spindle being position controlled, i.e. Step/Direction.

Lets say you called the spindle the C axis then:

g1 c3600 z-10 f3600

would result in the C axis or spindle accelerating from zero to 3600degrees/min and then decelerate to a standstill after rotating a total of 3600 degrees ie 10 turns. Meanwhile the
Z axis has advanced 10mm synchronously with the C axis, i.e. a 1mm pitch tread of 10 turns. This relies on the spindle maintaining is programmed position throughout a toolpath and
that the Z axis can move synchronously with it.....but that is when all said and done exactly what a Gcode capable machine does.....it moves multiple axes synchronously, and there is no reason that
one of those axes cannot be rotary.

I used to use an Allen Bradley servo as a spindle in my vertical mill, and I can and did use this same idea to do rigid tapping.

I think from the point of view of simplicity I would use the Mach4/ESS single point lathe threading features in the first instance. I believe you'd fin that more than satisfactory, but then if
you want to experiment with a C axis rather than a free running spindle then have at it.

Craig

[Mizuno1]

Hi Craig,
Thanks for the explanation.
Please excuse the ignorance on my part as I've built 3 great machines, but NEVER needed a live spindle.
The Parker drives can either run in step and direction or velocity. Not both. So how can I set a spindle speed in Mach4 to cut the OD of a part, then change to step and direction using the g1 code you mentioned above? or is that capable in velocity mode?
Use to be pretty good with g-code, I'll get back to it after a while. But surgery after surgery and work has had me running ragged for many years so I've forgotten a lot.
Can I set a code to just run at a feed rate in step & direction for an axis drive instead of an "S" code in velocity?

Thanks,
Brian

[joeavaerage]

Hi,

The Parker drives can either run in step and direction or velocity. Not both.

In the sense that a servo can only run in one mode at a time you are correct. My Allen Bradley servo, like my Delta servos, servos can operate in dual-mode. With one signal input pin asserted
the servo operates in Step/Direction mode and with that pin de-asserted it operates in analogue velocity mode. Thus with my machine I would use velocity mode mostly as I used the servo as a free running
spindle motor, but when I wanted to do rigid tapping I would switch to the spindle being the C axis.

I suspect that were you to investigate the Parker drives you'll find that they too can be programmed to dual-mode as well.

As it turns out you can in fact run your spindle in Step/Direction mode permanently. I've never used it so cannot report more than that its there. See the attached pics of the Mach4 Control plugin Spindle Tab
and the ESS Spindle Tab.

I always imagined that a Step/Direction servo that has an ever steadily increasing count would spin at constant rpm. The only limit I could think of is that Mach4 counts in 32 bit integer fashion
and thus the largest step count could be:
max step count= 2³²-1
=4294967295 and at 8000 count/rev (2000 line encoder) that is 536,000 revolutions before the counter would overflow, and that is 176hours at full 3000 rpm say. More than enough.

I think initially I would use just velocity mode, i.e. use 's' word in the Gcode file. I think that will be sufficient to thread in a highly acceptable fashion. Get comfortable with that before getting
too carried away. There are other options but start simple and work up to those. For instance in Mach4 there are up to six Out-of-Band (OB) axes which can be controlled independently of each other
but not synchronized with X,Y,Z,A,B,C. They are controlled by what amount to jog commands.....and there is a velocity jog....so that opens up even more choices, but don't go down a rabbit hole yet....
there is still plenty of time to get really lost and bamboozled yet!

Craig

[Mizuno1]

That's an awesome post.
Knew I had the right guy.!
Ok
I need to let all of that sink in.
Writing a spec page to the guys at Parker this week.
I'll include what you posted and ask them.
These guys are very good and have 30+ years of work with the legacy drives.
I'll let you know what they said if my head doesn't explode first!
???? ???? ???? ???? ???? ???? ???? ???? ???? ????
Thanks brother !
Brian

Hi,



In the sense that a servo can only run in one mode at a time you are correct. My Allen Bradley servo, like my Delta servos, servos can operate in dual-mode. With one signal input pin asserted
the servo operates in Step/Direction mode and with that pin de-asserted it operates in analogue velocity mode. Thus with my machine I would use velocity mode mostly as I used the servo as a free running
spindle motor, but when I wanted to do rigid tapping I would switch to the spindle being the C axis.

I suspect that were you to investigate the Parker drives you'll find that they too can be programmed to dual-mode as well.

As it turns out you can in fact run your spindle in Step/Direction mode permanently. I've never used it so cannot report more than that its there. See the attached pics of the Mach4 Control plugin Spindle Tab
and the ESS Spindle Tab.

I always imagined that a Step/Direction servo that has an ever steadily increasing count would spin at constant rpm. The only limit I could think of is that Mach4 counts in 32 bit integer fashion
and thus the largest step count could be:
max step count= 2³²-1
=4294967295 and at 8000 count/rev (2000 line encoder) that is 536,000 revolutions before the counter would overflow, and that is 176hours at full 3000 rpm say. More than enough.

I think initially I would use just velocity mode, i.e. use 's' word in the Gcode file. I think that will be sufficient to thread in a highly acceptable fashion. Get comfortable with that before getting
too carried away. There are other options but start simple and work up to those. For instance in Mach4 there are up to six Out-of-Band (OB) axes which can be controlled independently of each other
but not synchronized with X,Y,Z,A,B,C. They are controlled by what amount to jog commands.....and there is a velocity jog....so that opens up even more choices, but don't go down a rabbit hole yet....
there is still plenty of time to get really lost and bamboozled yet!

Craig