dual drive x-axis?

**fasteddy** · 07-06-2009

Hi all..

Was hoping to drive my x-axis with a dual drive. Anyone know if it is possible to run two motors from a single controller point? I had originally thought of a dual pulley system but it is rigidity and accuracy I am after and not sure that is the way to go..

Really would like to drive twin ball/lead screws on my x-axis (2 meter x-axis x 1.3 y-axis meter work area, floating gantry)..

Any suggestions will be very welcome as this is my first cnc project...

ta..!

**John S** · 07-06-2009

Two motors, two drivers and slave the axis.

Two motors on one driver is asking for problems, a belt and pulleys over 1.3M is also asking for problems.

Your size basically restricts your choices.

Using two motors / one drive makes the driver the weakest link which they normally are, any problems will take the drive out so you will have to buy a new drive, that's the cost of doing it correctly in the first place.

.

**fasteddy** · 07-06-2009

Thanks John..

Does that mean I will need a 4 axis controller? 1 for the z, 1 for the y and 2 for the x-axis? If so, could you recommend one or do I have to decide on which motors first..? This is my weakest area of non-expertise so any advice would be v helpful..

**fasteddy** · 08-06-2009

Sorry everyone, just noticed the thread by Hiltonsteve, 3 below mine, asking exactly the same thing..! There are more than enough answers there to sort me out... Sigh.. Looks like I was wide asleep again!!!

**fasteddy** · 09-06-2009

Have finally settled on a single motor, single leadscrew, but with extra bearings and rails under the gantry. I know I know... Pictures..! I will try to put a couple of sketches together tonight and post them..

Have listened carefully to everyone's if, buts and maybe's about dual driving and have to agree that a single drive is much less prone to errors, and belts are, in my experience, another added layer of mischief..

But I do think it important to stabilize the gantry as any yaw will not be acceptable. To this end I have come up with a way of using additional track and bearings (as these are so cheap) to give extra guides to the gantry...

Pics later..!

**BillTodd** · 09-06-2009

But I do think it important to stabilize the gantry as any yaw will not be acceptable.

What about a cable (or two) wrapped around pulleys (like a drawing board) ?

**Smiler** · 09-06-2009

Originally Posted by BillTodd

What about a cable (or two) wrapped around pulleys (like a drawing board) ?

Apparently works incredibly well too!

Jeff.

**fasteddy** · 10-06-2009

Any pics of that? Will do some sketches of my thoughts later, gotta 3 year old with tonsillitis to sort out today..!

**BillTodd** · 10-06-2009

One method:
(pinched from http://www.cnczone.com/forums/showth...le+rack&page=4)

**fasteddy** · 10-06-2009

The cable design looks funky! But I am still unconvinced by using an active system, I would be concerned about slippage, stretching etc.. Not sure if I have uploaded the image properly in this reply, but if I have you will see that I have added two tracks under, and attached to the bed. There are bearing runners attached to the inside of the gantry base that locate onto the tracks.

Have not drawn it yet (have not finished designing it) but the base of the unit (the whole CNC will sit on top of it), will also have another pair of tracks that will fit to the bottom of unit, that will locate to a further pair of bearing runners attached to the underside of the gantry for further stabilization...

Hope this is clear, if not ask away and will try to further clarify it. I like this principle as it is passive and cheap..

Have to apologize for offering the link on my first post of the build videos that first wowed me into all of this... This is the proper link http://buildyourcnc.com/step1.aspx (cant seem to make it a link, having one of those days...) which shows every step of the build in videos (best watched at 2am when web traffic is light, yawn...)