sliding gantry or sliding Base ?

[Ricardoco]

Hello Folks,

sorry if this question has been discussed before, if so, i couldnt find it :)

I am currently thinking out my Design and I am not sure how to make the X Axis.

Either the whole Gantry slides, or the Gantry is fixed and the "Baseplate" slides (lack of the right english word, sry) ?

Ok sliding Gantry will give you almost double the working X travel for a given length of rail so how much workable area do you need

I will probably use 600mm TBR20 supported round rails for x and y, so thats what the size will be.

Anybody has empiric experience comparing the two methods ??

With Moving Gantry you will get 600mm travel and 600mm working X axis minus the thickness of the gantry and the spindle offset, i can do pics if you need them, with the moving X worksurface you will get 300mm workable area/length if you want 600mm workable area then you will need 1200mm rails. and possibly a bigger area to put the machine in than you have..

Regards Rick

[JohnJ]

I am aware that the machine footprint will be almost double the length if i am not using a sliding gantry.

My question is, is the advantage in structural rigidity worth it , or are there arguments against it, except the larger machine footprint.
I am mostly interested in

Anybody has empiric experience comparing the two methods ?

If i go with sliding baseplate, i obviously will use longer rails on the X axis.

*edit*
Regarding the mounting question of the supported Rails,
i probably will just use 40x80 Profile where the rails are, and just mount the rails with t nuts, as the spacing of the TBR20 is 40mm.
Any arguments against that ?
I want to avoid machining that large adapter plates.

Thanks,

Regards,
Clemens