Re: [CAD_CAM_EDM_DRO] Re: PWM vs Constant current and G-rex

turbulatordude <dave_mucha@...> wrote:


I would venture to guess that only about 1-3% of the peoples running
machines would swap out what they have for the new technology.

Why ? more in's and out's I needed more extra stuff to make things
work. I finally figured a way to hobble together enough components to
make the machine work, but if I was in that building stage again, I
would have opted for the higher I/O counts.



//// HomannDesigns offers the ModIO board that will support 63 inputs and 63 outputs plus analogue I/O as well for less than a hundred bucks. Designed to work with an RS-serial port and Mach3.

////



Analogue I/O there are features that would be nice, air compressor
pressure, coolant tank level, oil lube level ? who knows. if there
was not enought of something to compelte a run, the software could
alarm or some such.

Some shops considder one bad part to be much more expensive than an
upgrade. Not many though.

And, there are home builders who have the $$ to get the newest things.

With the hundreds or maybe thousands of installations, and the fact
that there are many people that chose the high end breakout cards over
the much lower cost stuff indicates, to me, that there are people who
will spend the bux.

As to the perceived need for the faster or more capable drives ?

I think part of the answer is in Mariss's anti-lost step stepper
driver. That bit of magic will be another, very desirable unit.



/// A stepper motor with an encoder is essentially an AC servo with very poor high speed torque. For the same price as a servo. This quest for the unstallable stepper escapes me totally. Seems if the stepper is in an application that is causing it to malfunction then it would need to be replaced by a more reliable servo system. ///





But, I really have to agree with you on what to buy today.

A breakout board (I have not heard of a bad one) that extends the
parallel port to the motors is very common.

the limitation is on frequency of steps or output pulses.



//// With Mach3, The pulse rate frequency can be set as high as 45k/sec. This is ample for any system unless someone is wanting to use some ridiculous amount of encoder count resolution that no mill or router table could take advantage of. ///

I ran the math on some pulleys for a plasma or router table and there
is a limitation on encoder count and motor speed and software output
speed.

It is not hard to get around that one way or another.

For steppers it is a mute point as steppers cannot spin faster than
the software can drive them. Not and stay in a useable power range
anyway.

sorry if this reads a little disjointed, I'm Mr. Mom today and the
baby is all over.


Dave





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