Re: stepper vs. servo

Les,

Well then let's just confine ourselves to the second half of my
statement. Steppers, once tuned--and I disagree with your assertion
that "tuning" is required--need no further attention. (steppers DO
need proper "selection". But not tuning.)

Now let's address your second assertion, in a fun way:

No matter how carefully you set up SERVOS, one day you will hit a
particular set of circumstances that will make them lose steps. It is
most likely to happen if you are demonstrating the machine or just
finishing a very expensive and time consuming job..."

But you won't know it! Only when the part is rejected because it
doesn't meet spec will you find that the following error ALWAYS
PRESENT with servos, has caused the actual toolpath to be other than
intended... Because the g320 and similar can be off by up to 128 steps
(encoder counts, really) before a fault is issued...

If you're going to defend things by using worst case scenarios, let's
apply them across BOTH systems being considered...

Ballendo

>In CCED, Les Newell <lesnewell@f...> wrote:
> I am afraid I have to disagree with this one. Steppers do require
> tuning. For best performance you need to spend quite a lot of time
> playing with acceleration and max pulse rate.
> Steppers are easy to tune if you run them well within their

capabilities

> just as servos can be easy to tune roughly right. Getting top
> performance from either takes time and care.
>
>
> I personally would go for servos. No matter how carefully you set

up

> steppers, one day you will hit a particular set of circumstances

that

> will make them lose steps. It is most likely to happen if you are
> demonstrating the machine or just finishing a very expensive and

time

> consuming job...
>
> Les
>
> ballendo wrote:
>
> > 1a) Servos require tuning, and they may require additional tuning
> > over time. Steppers won't.