Dual Steppers on y axis

Hi All,

Is there any issues/dangers running dual steppers on the y axis, I know the cohesion board can handle it?

Im building a new frame and want to use dual steppers instead of joining with a steel rod…

Thanks

Hi Craig, for a CO2 laser it is a bad idea to have 2 separate Y motors for the gantry - if they get out of sync it will send the beam where you really do not want it to go. A single motor with a shaft driving the Y rails on both ends is the correct way to do it.

That said, it is possible to slave A to Y driver if you need 2 motors. You would need to check the size of the motors to be sure it would work. Though as stated, we do not recommend doing this for a CO2 laser.

This is done all the time with the gantry on large router tables. They use separate limit switches to home to, to assure beam alignment at each power-up. Both motors drive backwards until each one hits its OWN limit switch, to eliminate any racking error that could have crept in on the last use if one of the motors skipped a beat). However, if the Cohesion board doesn’t support dual limit switches (I don’t know), you take the chance of them running out of sync and damaging your gantry if one side catches on something and loses steps, as Pete just said.

If you decide to run two motors, it would be best if the Cohesion board supported dual limit switches. You’ll have to ask them if it does. If not, then you’ll either have to manually push the gantry back against a stop on either side, to synchronize the two home positions, OR, put your limit switches in parallel, so BOTH switches have to break contact before the ‘Home Limit’ signal is sent. In this case, if one motor is running a little ahead of the other, it will grind against the stop block until the other motor catches up. As long as the physical stop is solid and doesn’t damage the gantry, slide bearings or belt drive, then it just sounds awful for a split second but may not do any damage. After all, it already did some ‘grinding’ earlier when it lost some steps in the first place by either hitting something or accelerating faster than it should.

Generally, your setup should never get out of synchronization once the motors are powered and holding. An occasional manual push of the gantry backwards against your carefully-adjusted stop blocks (to assure a parallel gantry) can just become the first step in your power-up sequence (it WILL become a little racked and out of step if you manually drag the gantry around with the power off). Unless the poo hits the fan and things bind up, two motors work just fine, same as for the large-bed router folks. If one motor FAILS, or something catches, however: minor or major ouch, depending on what happened. It’s your call, but it’s not an uncommon solution for large gantry distances.