Dual Drive Gantry Question?

[Syphontek]

I'm almost finished the cad work on my plasma table (60"x50"), and I want to use 2-Nema 23, 276 oz-in stepper motors to drive the gantry. The question I have has to do with the wiring to the drive control (Gecko Drive 201). Would both these motors be wired in parallel off one Gecko Drive 201 or would each motor have its own?

I'm ready to order my three Nema 23 Motors (1 for x-axis, 2 for y-axis), but I'm not sure if I need to order 2-Gecko Drives or 3-Gecko Drives?

Thanks
Syphontek (CNC Rookie)

[freak_brain]

I use a gecko for each motor. I have 4 geckos for a three axis machine



Allen

[standles]

Thanks for asking that question.

I am in the formative stages of my own design and was wondering the same thing.

I was looking at doing this for my x axis since it was the longer axis and I was assuming would help eliminate racking of the gantry by driving both sides.

In your setup is your long axis the Y? If not then why double drive the shorte axis?

Steven

[freak_brain]

If memory serves me correctly, I ask Marris (Gecko drive guru) this question and he told me that I had to have a gecko for each motor.

I also notice you made no mention of a "Z" axis on your machine. Are not going to use any type of THC? I am just curious if you came up with some other way of maintaining torch heigth.

Allen

[Syphontek]

Thanks for the replies.

I've changed my strategy of attack since I posted this question. My changes involve only two motors instead of three, one for x-axis and one for y-axis. One motor will drive both sides of the gantry simultaneously but I think I will need 1-Nema 34 Motor instead of 2-Nema 23 motors. I’ve attached a small drawing of what I'm thinking.

freak_brain you asked about my z-axis, since this is going to be for plasma cutting only and not cnc milling I plan on using a pneumatic cylinder for the plasma head down position.

Oh before I forget to mention, going back to the drawing I've attached I plan on using two proxy switches as belt detects. I know I didn't show it on the drawing but each belt will have its own proxy switch and if for some reason a belt brakes the machine will shut down as a safety to prevent anything from being damaged.

[freak_brain]

When I started this process I went through all of the design possibilities, including the one you are talking about in your picture. That design, in my opinion, will not save you that much money and will prove to be more of a liability. It actually may cost you more money, two screws, two belts, a nema 34 motor etc.. The two motors and two racks work very well. and is easier than you may think to setup.

As for the "Z" axis. The reason for a "Z" axis on a plasma cutter is to maintain the proper torch heigth throughout any cut. Another words, it would actually follow warpped material by moving "Z" up or down.

Allen

[jcc3inc]

Gentlemen,

My two cents' worth; why not use rack and pinion? It is more economical, can run faster, is very adequate in terms of precision, tolerates dirt much better, and is easy to sync the dual side drives! A leadscrew has a critical speed limitation, as you may already know.

Regards,
Jack C.

[Syphontek]

Originally Posted by freak_brain When I started this process I went through all of the design possibilities, including the one you are talking about in your picture. That design, in my opinion, will not save you that much money and will prove to be more of a liability. It actually may cost you more money, two screws, two belts, a nema 34 motor etc.. The two motors and two racks work very well. and is easier than you may think to setup. As for the "Z" axis. The reason for a "Z" axis on a plasma cutter is to maintain the proper torch heigth throughout any cut. Another words, it would actually follow warpped material by moving "Z" up or down. Allen

Oops I never even considered the possibility of warped material, so I guess I'll need a z-axis motor.

I'm a millwright\Fluid power technician by trade and I specialize in hydraulics, pneumatics and PLC's. My automation and design experience usually consists of cylinders and PLC's, so I guess when it to CNC designs I'll have to change my way of thinking.

I've worked around CNC equipment but never tried to design anything CNC so it's kind of new to me, thanks for the input!

[ger21]

For your z-axis, you'll also need a Torch Height Control board like thos at www.campbelldesigns or www.candcnc.com

[Syphontek]

Looking for a bit more input. From what I've been reading so far it looks to me that I will need to purchase:

1) 4-stepper motors
2) 4-motor drive's,
3) 1-Breakout Board
4) 1-Torch Height Control
5) 1-24v-80v power supply


Is there anything I am missing besides the obvious, limit switches, wire etc.

[freak_brain]

You are most likely going to need a bridge rectifyer a capacitor and a 5vdc power from somewhere. Geckos require 5vdc before they will work. You can get 5v from your computer or do like I did and just purchased a power supply for my 5v needs. you can purchase your breakout board and the power supply here

http://www.cnc4pc.com/

The bridge rectifyer and capacitor (speaking as a non technical non electric guy) will convert your AC power output to DC and the capacitor will filter it. I guess that is assuming your power supply outputs AC. Also, when converting AC to DC your voltage will go up, I think the conversion is 1.4:1. So you can factor that in when checking voltage. You will also need some resistors if you are using geckos drives. It uses the resistors to set the proper amps for your motor. You will need to have your motors or know what motors you are using before getting the resistors. I think that about covers the major stuff.

One last note. Depending on your motor, one power supply may not be enough. Maybe ask on of the guru's on here about power supply needs after you decide on your motors

Allen

[freak_brain]

here is a power supply I use. Seems to work ok for me