Diy built 5 x 9 ft. router that has a gantry that is vibrating when is moving.

Hi Need idea about solution to make my gantry stop shaking .
My servo don't gerk or vibrate . the gantry is moving from back to front. when making part , the part as nuch ,
the gantry is square with the y axe .
I need some clue !
Go see it , Thanks
https://photos.app.goo.gl/bTsU16J6G1sCd1Gm9

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Hi,
as far as I can see your gantry is in two pieces with one rail on each and the ballscre/ballnut in between. I would guess the vibration is because
the two halves of your gantry are flexing in the opposite direction, one half going back towards the rear of the machine while the other half is flexing forward
to the front of the machine.

Try grabbing the bottom of the spindle and pull it towards the front of the machine. How much force does it take to twist the gantry by 0.1 inch? It should take many
tens of pounds-force but looks like its not that stiff and more than a few pounds would cause the deflection. I think your gantry is twisting like a soggy noodle.

Craig