Flappy machine - Advise needed please!

[cncJim]

I suppose you have to first establish exactly where the flexing is taking place, it's maybe not where you first think of.

Valid point - I admit the only reason for picking on the gantry as being the issue is based on my complex scientific testing - I grabbed the spindle, yanked it around until it flexed! I all feels very rigid except for flexing the spindle up and down.

What about attaching a wide piece of aluminium extrusion or box section from one side piece to the other then fasten supported rail to that.

That could work really well! Thanks for the idea :)