Re: [CAD_CAM_EDM_DRO] Bridgeport CNC Mill???

Hi Hanermo

> He would go from a single source of very expensive parts (the original
> Anilam stuff, which is what I referred to) to a single source of hw, the
> pico systems stuff, that ONLY works on EMC2.

No matter how you go you end up single sourcing parts. For instance if
you went for Gecko drives, no others would be physically compatible.

> However..
> EMC is limited in terms of hw speed, unless you go into the expensive
> stuff, just as you said.
> The mentioned servo loop update time, 20 khz max, is low for high
> resolution stuff.

I think you are confusing pulse rate and servo update rate. 1KHz servo
rate is plenty fast enough for this application. Resolution is not
affected by the servo update rate. Higher resolution means that your
encoder counter hardware has to run faster. Both Mesa and Jon's hardware
will count at several MHz.

> The high end stuff is not well documented, and making any changes into
> the screen stuff is hard, practically impossible, unilke with mach3
> screen designer.

IMHO that is the biggest disadvantage of EMC. No two machines have the
same requirements and it is very handy to be able to customize the
screen layout to suit. For instance on my mill I have one page dedicated
to different forms of probing and center finding. I do a lot of one-offs
so this is really handy. It would be useless for a production machine.

> EMC installed base for higher end stuff is very, very low.

How high end are you talking? There are some serious EMC setups out
there but there are also a lot of more mid-range installations. Would
you consider my lathe high end? It is a Colchester Triumph 2000 with
10HP spindle and 3 speed electronically controlled gearbox. Servos are
about 750W and have 1000 line (4000CPR) encoders. It works extremely
well on EMC (with 1kHz update rate). I also have two electronic
handwheels so it can be used like a manual.

The mill running Mach3 is a converted Series 1 CNC Bridgeport. It has 3
handwheels.

> Plugins are few and far between.

What exactly do you want to do? EMC's Hardware Abstraction Layer
combined with ClassicLadder allow you to do a heck of a lot. For
instance it easily controls the sequencing needed for the electronically
controlled gearbox.

> As an example, I am using 100-200 kHz hw update rate and will be using 1
> Mh to 2 Mhz, in the near future.
> On a lathe, with a Centipede, and mach3.

That is pulse rate, not servo loop rate. 1MHz servo update rate would be
insanely fast. Not even an ultra light voice coil actuated positioning
system would need that.

One really big advantage of EMC with servos is that you have true closed
loop control. Even after an estop it knows exactly where the machine is
so you can resume machining immediately without having to re-home. This
sounds pretty minor but for a home/small workshop this is quite
important and encourages safe working practices. With my lathe, if I
want to reach in to clear some swarf or pick up a part that I have just
parted off I usually estop the machine. I seldom estop my mill (running
Mach3) because of the hassle of re-homing. If I suspect something is
going wrong with some code on the lathe I'll immediately estop it. With
the mill I'll hesitate. That has resulted in some nasty crashes.

Les