[dneisler]

I have a cnc fusion deluxe kit with ballscrews and a Gecko 203 controller setup and ready to go just need steppers.

X & Y 425 oz nema 23's
Z - 600+ Nema 34

Should I go bigger/smaller and why?
Just trying to get best performace possible and not have to have a spring on my Z axis.

[project5k]

well i dont know what would be "best" but i'm gonna try and run 500oz-in on all 3 axis.. i think that 400 might be a little much on x and y.. the whole thing about it is that you want enough to move the mass, and start and stop and whatnot, but if you go too big you start running into resonance issues and having to get bigger drivers (current carrying ability) there has been a really good discussion of dampening resonance on here, do a search for it.. one person made something that followed the "rattler" design, a dampner thats used on the front of an engine and reports from him and others say that it was very effective... but you wont know for sure what your resonance issues will be till you get it all put together and try it...

if you want the "best performance possable" then you should really look into servos.. but this is just like what the mechanic said in mad max... speed is a question of money.... how fast do you want to go?


my cncfusion kit is listed as "out for delievery" on the ups site this morning.. so i'm all excited...

[dneisler]

I have gecko 203's so my drivers should be fine. As for speed I would be happy with rapids of 20-40 IPM, not that I will use them that fast.

[project5k]

that should be doable... thats 100-200 rpm on the motor, direct coupled. i dont know the gecko drivers as i've never had one to play with, but your looking at 333-666 steps per second full stepping which should be no problem... I'm guessing here, and would like to know more, but i would bet that your planning to at least half step, if not going to even smaller graduations... still shouldnt be a problem....

as for the gecko's, whats thier current per phase max? V-in max? just thinking about what it will take to drive that 600 nema 34... oh, and what powersupply do you have/ planning to get?

[dneisler]

70v power supply

G203V 10-Microstep Drive
7A 80VDC
Short-circuit protection
Reversed-polarity protection
Over-temperature protection
Over-voltage protection
Optoisolated Step, Dir and Disable Inputs
Optoisolator Common is ground

2.5V, 3.3V and 5V logic compatible inputs
Recirculate mode while motor is stopped
350 kHz maximum Step pulse frequency
Top settable Adjust trimpot
Power and Error LED indicators
No user settable jumpers inside

Internal socketed fuse
Power-on reset
20 kHz switching frequency
Same size and terminal pin-out as the G201

http://www.geckodrive.com/product.cfm?pid=38

[project5k]

oh wow, ok, yea your golden... well i cant say from experience yet, but i've read about guys running 200-300 oz motors on x and y.. they'd have to have a longer ramp up and down, but your 425's shouldnt have any problems at all.. as for the z, i would think that 600 would be fine.. but you will be starting and stopping that 80 something pound head up and down..

can i ask why you dont want to do the spring on z?

[dneisler]

one less thing to deal with, I may end up doing it anyway.

[project5k]

ok, i understand... less is more.. well personally i plan to run some kind of weight compensation on my head.. i lean towards a gas shock/spring rather than the counterweight just cause its that much less mass i have to move.. i would think that performance-wise the spring would be a good idea.. and longevity of the machine.. taking some of the weight off the bottom bearings on the z axis screw should allow it to live a little longer....

it sounds like your on the right track to me, at this point the only thing i can say is try it and see, if you start dropping steps when z tries to go up, then look at the spring...

[dneisler]

I have read some people using 400oz nema 34's on the Z with no issues, so think more is better I considered using a 900oz nema 34 just so I have no issues moving the head up. I am just trying to build a good reliable machine.

[patndel]

Hey Donald,

I'm running 425 oz steppers on my X3 for all 3 axies X and Y direct drive and the Z axis 2:1 (timing belts). I've got the gecko 201's sitting packed away in a box, as I am still using a xylotex drive. the motors are wired in parallel to get back within the parameters.

The X and Y run happily all day everyday at 25 IPM and the Z at 20IPM. I've tuned them down to account for the lack in power from the drive. I guess I'm trying to illustrate the worst case here, that there is no issue pushing that 80lb head up and down the slide with a nema 23 geared down

I did buy a pair of gas struts, they too are still sitting in a box. There are mixed feelings about using them. On occassion I've forgotten to released the Z lock on the slide, and the head still came down, only realised it was locked when the motor buzzed trying to drive it back up.

Big is not always better the larger motors tend to have a highier inductance, which corresponds to the maximum rpm you'll get out of them before the torque drops away drastically.

Pat

[Trey54]

Hi, I have an X3 that I'd like to convert to CNC. Are the Gecko 201 drivers better than xylotex? Also, where did you purchase your stepper motors from? Thanks

[Oldmanandhistoy]

Hi, I have an X3 that I'd like to convert to CNC. Are the Gecko 201 drivers better than xylotex? Also, where did you purchase your stepper motors from? Thanks

Hi Tray54,

The Gecko 201 is superior to the Xylotex in every way specification wise. Quality and reliability wise I can’t comment other than I have a Xylotex and it was very reliable. If you have the funds go for the Gecko’s.

John

[tauntdesigns]

Howdy,

I went for the Gecko G203v for drivers and 425 oz/in steppers for X & Y and 640 oz/in stepper for Z.
I'm wiring the 425 oz/in steppers parallel and the 640 oz/in stepper series.
I'm using a 65vdc-15amp power supply for the drives.
I went with CNC4PC C11G BOB powered by 5v-4amp,12v-1amp wall wart.

I'm in the process of building the control box right now.
Jack

[nda22]

I'm in the process of turning on my X3. I put 275 oz/in steppers with 203's on all axis. The X and Y would do 200 ipm (direct drive) but I slowed it down to 100 to be safe. the Z would move at 40-50 but I lost steps so I had to slow it down to 10 ipm (2:1 timing pulley). I'm not counter balancing the head yet but I plan to.

Nick