Setup for squaring twin X-axis gantry

[Ger21]

Clamp one side so that it can't move, then push very hard on the other side. I wouldn't be surprised if it moves at least 1 mm.

Another thing to consider, is that when you apply power to the steppers, that they'll usually "jump" to the nearest full step. If one moves one way, and the other moves the other way, then they'll be twisting the gantry out of aquare, although the amount would be very, very small.

If it's as rigid as you say, then one switch would be fine. But you need to make sure that the gantry is perfectly perpendicular to the axis is moving along.
If you go with two switches, you need to position them so that they get the gantry perfectly square. Both methods require very precise measuring and fabricating.

[JAZZCNC]

I wouldn't be surprised if it moves at least 1 mm.

Wow Gerry your getting all Metricated now, Watch it you'll be speaking with Yorkshire Mans accent before you know it. . Lol

Eddy every thing Gerry says but I'll also point out the affect of inertia pushing the gantry can lead to error that without home switches on each axis you'll never know about untill the error as accumulated enough to rack the gantry and stall ONE motor. The Mess that can come from this is sickening if it happens at high speed which it often does because that's when torque is lowest.!!

Another way and one I know Gerry used or maybe still does is to bump upto a hard stop on each axis which squares gantry and use this as machine Home position. Then just occesionally bump upto stops to realign.!!

Another way is to permantently fit cheap dial indicator at each side and use these to check if it's losing position.

[Clive S]

Wow Gerry your getting all Metricated now, Watch it you'll be speaking with Yorkshire Mans accent before you know it

And I thought it was the official system over there, but I have had a few glasses of vino http://www.nist.gov/pml/wmd/metric/upload/1136a.pdf ..Clive