Need Help!- dropping steps

[knitehawk]

Hi guy's!

glad i found this place. it's a treasure trove of undiscovered proportions!

I have a System i got from a sign co that couldn't get it to work.
got it back to the shop and ripped out the hpgl controller, put a BOB on it, through a Computer together, and ran Mach 3.
everything was perfect and i am like a proud new father until.

i started messing around with photo vcarve.

it seams that my Z (ball screw) is dropping in a liner fashion.
in a program that was 166550 lines of up and down motion i set it up to be a max depth of 1.35mm.
when it starts out everything is fine and looks like it's working great.
however.
it seams to drop steps on the up travel of the z.
i end up at the end cutting in about 4 or so mm.

i checked the driver board (IM804) and changed it out for the h of it. still the same thing.

resolution does make a difference.
i set the rez to 1/2 (lowest these drivers will go) and the drop was over an inch over about 200 passes!
raised it up back to 1/256 and it's back to the 4mm.

i am now thinking that the motor is messed up or something, as i ripped the z apart and found a slight play in the coupler from the motor to screw, repaired that and it still does the same thing.

not sure if i'm explaining this correctly but will answer any questions asked to the best of my ability.


thanks!

[jalessi]

Knitehawk,

Try slowing the feed rate down.

P.S. More detail would help accurately diagnose the problem.

1:Feed Rate
2: Type of material being cut
3: Cutter size
4: Ballscrew tpi
5: Stepper motor torque specs
6: Power supply

Welcome to the Zone,

Jeff...

[knitehawk]

tried slowing the feed rate. it just does the same thing slower 8-)
motor is
rapid syn 23d-6309a
Static torque=150oz-in
rated current 4.6A
Voltage 2.2V
Resistance per phase .48ohms
Inductance per phase .90mH



nema 23


heres the info i have on Mach
right now.

screw looks like 2.5mm per turn

psu is a
meanwell
se-600-48
thats a 600W 48v PSU



10125.86931 steps per mm
speeds are
596.7 mm per min
68.175117 acceleration
.0069522 G's

[knitehawk]

cutter is a porter cable router
with a 45deg vtip
on a 1.56mm head
material is pine
i think i had the feed rate around 900 max but it never got to 500 because of the z travel being set so slow in mach

[jalessi]

Did you install the power supply or is it the original?

Have you tried reducing the micro stepping?

10125.86931 steps per mm may be swapping the CPU, that is a gigantic amount of step pulses to process.

Do you have a instant messenger?


Jeff...

[knitehawk]

Im804
intelligent motion
same specs as im805 but has 4A max instead of 5A

i have a current limit set at 3.6

(those are pretty neat little buggers and you can puick them up on e-bay for around $50 each)

[jalessi]

I would reduce the microstepping by a large factor.

2.5 mm TPI screws would still give a .0127mm resolution at full stepping.

Raising the current to 4.6 amps will also help.

Your steppers make all there power at a very low r.p.m.

I would also enable the Sherline mode in Mach3

See attached .jpg

What CPU is in your computer?

Jeff...

[jalessi]

If you drivers only output 4 amps set it to 4 amps.

[jalessi]

Try the other suggestions one at a time and retest g-code until issue is resolved.

[knitehawk]

nailed it.

turned out that i had an intermittent connection on one of the wires (get this) on the Y axis.
apparently there was crosstalk to the z axis screwing up the signals.
the wire was broken inside the damn insulation. (that was fun to find!)

Thanks for all the help Jeff!


just did a photocarve of the wife!
Looked great! Wish i could post pics here.