X-Axis Drive Options

[Stevo_1600]

Gday,

Just chasing everyone's opinion on which would be the most effective/accurate method for driving the X-axis on a 3mtr x1.5mtr router bed?

Either a rack and pinion arrangement or a ball/lead screw setup??

i understand for a rack and pinion drive setup, that the table would need to be driven from both sides to avoid 'racking', which then adds the extra cost of another motor,gear rack, gears etc. to the build.

Or would a ball screw, centrally driven between the gantry legs be better? This configuration would be ideal but i am unsure whether or not you can get a lead screw shaft this long?

The router is being designed for primarily cutting aluminum sheet, so is being sized to handle standard 2440x1220 sheet dims.

Any info would be greatly appreciated

cheers

[louieatienza]

I'm sure you could get a ballscrew that long, but you'd probably need one with a large diameter and it will weigh a lot. You could spin the nut instead of turning that large a screw. Or you could turn the pinions on both sides with a jack shaft.

[austin.mn]

Rack and pinion or ballscrew... . You will still end up with racking if you only center drive the gantry that is 1.5m wide (unless you really space out your linear bearings). Dual R&P is a good way to go to avoid it and properly setup can be pretty smooth. Another option you may want to look into is servobelt drive. It looks pretty simple and should make for a nice smooth machine. I had wanted to use that method for my new plasma table build, but I am going with dual drive R&P. My only real reason for doing this is that the machine I am currently working on will be the little brother to another machine that we will be building in a few months and I want use my machine as the test machine, so once I have everything figured out and finalized I will be able to copy my configuration files over to the new machine and have minimal tweaking to do.

I would check into the Servobelt system, I think there are some videos on youtube.

[born2bewilder]

I suggest you read up on this thread: Make Your Gantry Rock Solid It suggests a way to prevent racking by using an arrangement of tensioned cables and pulleys. An effective way to keep things perpendicular on wide aspect gantrys.

You may consider using a single larger motor transmitting power to both screws of a dual screw design using a timing belt. Prevents problems with motor synchronization.

[ahren]

I might humbly suggest our rack and pinion drive system for your application -- it's quite affordably priced, and we've sold quite a few to Australian customers. We even have a module 1.5 gear option so you can source racks locally from TEA to save on shipping costs.

I'd agree that dual drive is fairly important for wider gantries. Motor synchronization is really a non-issue -- Mach 3 has a "slave axis" function that works extremely well, and you'll appreciate the extra power from the second motor to keep your machine moving at a good clip. Additionally, with dual drive, you can make small adjustments to actually square your gantry prior to each run -- some folks have their machine set up to square during a homing sequence.

Best regards,

Ahren
CNCRouterParts