Re: Plasma voltage servo : Mariss?

Mariss, are our needs here just to far outside of the parameters of
the comparitors, or can this be adjusted with different values of the
other components.
Thanks in advance,
Dale


-- In CAD_CAM_EDM_DRO@y..., "morgtod" <todmorg@h...> wrote:

> Hey there Dale-
> I am in the same boat as you, I am looking for the best voltages,
> dead bands and almost everything else about "voltage servo". I

have

> not hooked the circuit to my table yet, I tested the operation on

the

> bench with a scope and found out I was stuck. When building the
> circuit I installed an extra 14 pin socket with the dead band
> resistors and the step oscillator capacitor wired through it, this
> way I can vary the dead band and step rate easily by plugging in
> components instead of soldering. ( in other words I'm sure I'll be
> adjusting these ). I am using a hypertherm powermax 900 and I plan

on

> letting the software raise the torch after a cut and on a call for
> torch I'll have a relay switch control from the computer to the

servo

> circuit. Hypertherm calls for 1/16", but they call for at least
> twice that on pierce, so we are going to have to work that in
> somehow. At present I am using a floating head with Z retraction
> between cuts, this works suprisingly well except for on light metal
> wich tends to get dragged by the torch. I'm sure Mariss can help

us

> blindfolded, but I just hate to bug the guy :)
> Happy cuttin'
> Todd
>
>
> --- In CAD_CAM_EDM_DRO@y..., "aspaguy" <spaguy@l...> wrote:
> > Hi Todd, As you can see from the note in the files section, this
> > circuit was designed by Mariss, of Geckodrive fame. It was

designed

> > due to a thread in which I started when I asked why a stepper
> > couldn't be controlled by voltage variations. Mariss asked what
> the
> > voltage parameters were an the best I could do with my limited
> > knowledge is give him the info from my hypertherm manual. If

anyone

> > can correct or fine tune the circuit it would be Mariss. I'm sure
> > your added information on what is required will be helpful. What
> type
> > and model of plasma are you using? how are you conducting the
> test?,
> > by hooking the unit to a complete machine, or by varying the unit
> by
> > hand? My hypertherm manual reccomends a 1/16" distance from the
> torch
> > to the material. this may be difficult to maintain with a hand
> test.
> > A 1/16" varience may fall inside the5%. What are the voltages you
> are
> > dealing with? What seems to be the optimum voltage for the "dead
> > band"? how far outside the band do the voltages go? Does the
> voltage
> > increase when the arc distance increases or when it decreases?
> > Sorry about so many questions, some of them will no doubt help
> > Mariss, and some will help myself and others when implementing

the

> > circuit. I have built the circuit, but have not yet gotten my
> drives
> > far enough along to test it.
> > Thanks,
> >
>

Dale

> > P.S. the original thread was about a month ago and could be

found

> > easily with a search of "plasma torch height controll". Also, the
> > design was purely theoretical,and probably a great starting

place.

> > With your help, I imagine we can turn it into something really
> cool!
> > thanks
> >
>

again.

>
>
>
> > --- In CAD_CAM_EDM_DRO@y..., "morgtod" <todmorg@h...> wrote:
> > > Hi-
> > > Has anyone tried building the plasma voltage servo circuit
> > listed
> > > in the files section? I just built one and it only steps when
> the
> > > voltage is between the 5% comparator. For plasma control I

need

> > the
> > > steps to happen outside the 5% going towards center, with a +/-
> 5%
> > (
> > > or less )dead band. Any ideas on how to get there from here?
> > > Thanks
> > > Todd