Re: Need advice on upgrading 2 existing CNCs

Thanks to all that responded.

I didn't really want to brand my machine as specifically being a
ShopBot for personal reasons...guess you let the cat out of the bag,
Bob.

I am running a very unique machine. It is a hybrid 5' X 16' machine
with a 5X8 5HP Colombo mill and a 5X8 Hypertherm plasma setup. I
custom ordered it that way to suit my unique needs. I am currently
running 5 Vexta 2-phase steppers with 3.6 and 7.2:1 gearboxes.

Yes it is possible to A) JOG a ShopBot with rack and pinion drives
at 30 inches per second and cut 3/4" MDF in one pass at 10" per
second. It is also possible to run at those speeds with adequate
torque with steppers. I have seen it on a ShopBot and the new Alpha
machines will do it. They run the Oriental AlphaStep steppers with
feedback and the torque band is at a higher speed. It is a new
offering from Oriental that they consider a cross between a stepper
and a servo.

My machine will need more bracing than it currently has. It is a PRT
machine, not an old PR. Between the plasma CNC, MIG and TIG welders
I can fabricate all the bracing that I need.

No...I do not plan on running the plasma faster than 6"/sec.
Especially with Hypertherm's new 'Fine Cut' consumables which let
you cut thinner materials at slower speeds. My main objective is on
the mill side of things. I am looking to cut 3D reliefs in foam and
mahogany at a faster rate. One file I run takes 2.5hrs to complete
with a speed of 2IPS on the XY and 1IPS on the Z at a 5/16" maximum
depth in mahogany. Any faster and I lose steps. I have toyed with
ramping and other tweaks to no avail. Plain and simple, time is
money. If I can cut at 8IPS on all 3 axes, then I would be extremely
happy. The new SB Alpha machine can do this...and this was
demonstrated at the last Jamboree.

Where I am stuck is it will cost me almost the price of a new
ShopBot for me to upgrade my current rig. I do not want to spend
that kind of money, plus have to trade in my original control box
(stipulation of upgrade)...and then have old steppers laying around
to boot. I am looking for a robust and economical solution to this
dilemma either with servos or with the new Oriental hybrid motors.

I am just not sure what software and hardware combination I would
need to get the job done. Mach2 software looks like the ticket &
Mach2 hardware with plasma board and breakout looks like it might be
the right way to go as well. Now that I think about it, I don't
think that Geckos will work with the new Alpha motor's feedback
functionality. So a brushed servo might be an option for me...Any
ideas on selecting a servo that will make the grade for this app?

Any help is appreciated.

Thanks!
-Brady

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "caudlet" <thom@t...> wrote:
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "braidmeister"
> <braidmeister@y...> wrote:
> > At the moment I am running Vexta 2-phase motors putting out
about
> > 305in/lbs ea. I believe that they are either NEMA 32 or 34 size.
I
> >>
> > My 1st thought is to look into servos, but I have concerns with
> > there being interference with the Hypertherm plasma cutter
machine.
> > I am also at a loss how to properly select a servo that will be
> > closest in mounting, torque and target speed. The other option
is a
> > hybrid type stepper like Oriental's AlphaStep or Animatic's
> > SmartMotor with feedback like a servo.
> >
> > Can someone tell me if a servo will reliably run on a plasma
> machine?
>
> I can address that directly. I am running a servo/stepper mixed
> machine. The gantry is run by two servo's driven with Gecko
340's;
> the X is an identical servo with another 340 and the Z axis with
> integrated THC, is a stepper with 201 driver. The whole thing is
> hooked to a PC (8' away) running MACH2. I don't get missing steps
or
> bad cuts. My plasma is an old noisy HF start Miller 500.
>
> The secret is proper grounding of the table and plasma and total
> isolation of the controller and PC. Another dirty little secret
is
> that I mounted my drives close to each motor so the encoder leads
are
> less than 8". I made sure the Gecko's had nice big filter caps on
> the raw DC and that the step and direction lines were buffered and
> run in shielded cable up to each Gecko.
>
> The Hypertherm is a a MUCH quieter machine than my old Miller.
> As Jon pointed out, my upper IPM limit (200IPM) is a function of
my
> leadscrews and the whipping if I try to exceed that. I used 7'
3/4"
> ballscrews for the best reason: I got them real cheap. My motors
are
> not brusers either being only 23 frame 120 oz/in Units with 3:1
belt
> reduction. I could easily get 300 or 400 IPM if my ballscrews
would
> take it. My next machine will be either a rack and pinion or a
> toothed belt drive setup, and while I am too chicken to run at 600
IPM
> (10" /sec), I would like to be able to move at 250 or 300 on long
> rapids. Moving a 100lb gantry (it was originally designed to be a
> combo router and plasma....bad idea) at 600 IPM would make me want
to
> soil myself. There are two many times I have had to reach in and
> grab a piece that hangs in the cut before the head has a chance to
> move back over it. I fear I am not quick enough to do that with a
> machine moving at 10"/sec
>
> I would faint and fall in it if I had to spend 7 grand to retro
fit
> my machine. I only have about half that in it to begin with
> including software!
>
> Pop over to the MACH1MACH2CNC group and talk with some other
> Torchheads (and router guys) that can show you how to get close to
> what you want for a lot less. How about complete Torch Height
> Control with dynamic corner sensing and anti-dive features AND the
> software to run the machine (Controller software) for about 500
> bucks? Check out www.sheetcam.com for a ultra low cost (free
while
> in beta) CAM program with extensive plasma features (will work for
> router too).
> >
> > What would you suggest, a hybrid stepper with feedback or servo
for
> > both machines?
> >
> > What kind of ballpark $ am I looking at to upgrade the hardware
on
> > one machine? (Steppers~Servos/power supply/Geckos etc)
> >
> > Where would you recommend that I purchase my motors to get the
best
> > deal?
> >
> > Any and all help is greatly appreciated!
> > Thanks!
> > -B
>
> There have been a lot of servo motors on ebay from time to time.
You
> need to stay with DC brushed perminate magnet units. Don't worry
if
> the encoders are not the right count or are missing. Rotary
encoders
> are cheap. Even DC PM motors can be used for servo if you can
figure
> a way to mount an encoder. A lot of the industrial DC motors
(like
> the Reliance Micro 100 series) have a rear shaft and mounting
holes
> for an encoder.
>
> You are welcome to contact me off-list if you need specific help.
>
> Also take a look at www.campbelldesigns.com (Bob answered you
earlier
> and is a friend)