2 motors on xaxis with rack + pin

[ger21]

If you use Mach2/3 to control your machine, all you have to do is check a box in the software to slave one axis to the other. You should also have a seperate home switch on each side, and Mach2/3 will square the machine when you home it.

[DEEDEE]

Great to hear that Ger,

I havnt got mach as yet, how ever i think i will get it, could you also tell me do you think 300 oz inch steppers are good enough for the job, i was wanting to direct drive them as it saves me allot of agro trying to use gearboxes or pullies to get them geardown,

Thanks for your Help, much appreciated :-)

[ger21]

I've never used rack and pinion, but from what I've read, they should work fine IF you gear them down at least 3:1. I'm not sure how well they will work direct drive.

You can download MAch2 or Mach3 and start using it right away, to see how it works. At the end of the install, if you uncheck the box that says load driver, it'll run in simulation mode. It's free for use with less than 1000 lines of g-code.

[mxtras]

ger21 -

3:1 - is this a decent rule of thumb for R&P?

Scott

[ger21]

Originally Posted by mxtras ger21 - 3:1 - is this a decent rule of thumb for R&P? Scott

Not sure, but you want to gear it to get decent resolution.

[Al_The_Man]

One method I use enables me to get the lowest inertia ratio and fastest accel/decel rates and that is to find out the top rpm of your motors, the travel/rev of the pinion, and the desired top feed rate and go with the highest reduction ratio you can, in keeping with the method you intend to use for gearing etc.
BTW here is a sizing program I have used for quite a while, I believe this is the only site you can get it now, it was originally put out by Emerson (Emersize) in the 90's.
The advantage is you can enter you own 3rd party motors and amps.
http://www.macphersoncontrol.com/navbar/mcptools.html
Al.

[bobgerman]

A good commercial dual motor system will use servo/encoder Vs steppers to avoid the issue of missed steps. I work in a shop with all kinds of CNC equipment (mostly Amada) The press brake back guages use dual servos...we also have a shear using a cross-over shaft to keep the guages locked together. If you're useing rack and pinion (on both sides) it would be as simple as just adding an idler shaft anywhere convenient to lock the two sides together.