Newbie, How you decide Moving Gantry or Table ?

[Calico]

How you decide ?
correct me if I'm wrong.
if the material to be cut is heavier(moving table) then it should be moving gantry. wrong ?

rud

[ToyMaker]

rud:
that is correct: in general if the weight of the material plus table is greater than the weight of the gantry, then move the gantry.
other factors to consider are machine stiffness and desired accuracy.

robotic regards,

Tom
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“Here are all kinds of employers wanting all sorts of servants,
and all sorts of servants wanting all kinds of employers,
and they never seem to come together.”
- - Charles Dickens, English writer

[sbrpollock]

Rud:

The trade-off is that for a given amount of effort and expense, the moving table machine will be more rigid and more accurate; however for the same effort and expense the moving gantry machine will take up far less space. So, it boils down to accuracy and rigidity versus space.

[Calico]

ok thanks guys,
just to make sure... moving table is more accurate ?
and I think I can use 1 motor for moving table, compare if I'm using moving gantry may be use 2 motor.

thanks guys
i'm trying to make one, collecting parts cheap... take times.

[Torsten]

Originally Posted by Calico How you decide ? correct me if I'm wrong. if the material to be cut is heavier(moving table) then it should be moving gantry. wrong ? rud

You are correct, sort of.
The part most prone to changes in weight should be stationary so the
moving masses are more consistant for accuracy.
A lighter weight can be accelerated more rapidly for performance.
Machine Parts move towards each other, it is irrelevant wich one
actually moves the important thing is the design and support of the
elements that guide the transitions and there spacing towards each
other that have most impact on stiffness and accuracy.
Of course Floor space may also be something to consider.

[Calico]

Now what's the basic formula to choose how big the ball screw and how big the motor ? for moving table ?