Yep, I'm completely addicted now. Work is suffering, I'm getting no sleep, the bank manager thinks there's been a robbery...

Lol, when I was drawing that long connection bracket I could hear you in my head saying "that's too long" :-D

As an alternative to mounting the 10mm plate on the front of the gantry could I instead mount the ball screw on the gantry supports like this and put a thin (5mm?) plate with a slot on the front? That gets the screw closer to the z-axis back plate and the gantry gets the full support of a 10mm plate on the back.

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I've had to significantly increase the size of the base to accommodate the new rails. I can't really afford a full sheet across the whole base but I've added corner supports all around the bottom and the top has 200mm wide plate running the full length. All plate is 10mm thick and will be thoroughly bolted to the 45x90 heavy extrusion.

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I actually feel like I didn't do to badly with the redesign if I only needed to move the screw, perhaps there's hope for this machine yet