Moving or fixed Gantry ??

[xairflyer]

Just looking for views from people who have experience with both fixed and moving Gantry designs.

I have always thought that moving Gantry increases the chance of movement in the Z axis for and aft.

What are the pro's and cons of each version.

[MrBean]

For a very small machine, I'd go with moving table, as the bearings the gantry would ride on would take up a lot of the Y axis. If it's a larger design, then moving gantry's got to be the way to go. Imagine you want a cutting area of around X=4' * Y=6'. For moving table the Y axis would have to be double the cut required (12'). If you had moving gantry and the gantry bearings were say, 12" length span, then you'd need 7' for the Y axis instead of 12'

That's how I view it.

Regards Terry.....

[smabhyan]

Moving Gantry design is used for machines with large X-axis stroke. Normally the X-axis stroke should be beyond 10 meters or more.
It also implies that the workpieces are large and heavy.

In case of small machines, Moving Gantry design is used only in special cases like impeller machining etc. (usually 5-axis machines).

If the Y-axis stroke is also large (say 5 to 6 meters), then the X-axis needs two ballscrews (two motors and two measuring systems) and a software to keep skew in control.

[ger21]

If the Y-axis stroke is also large (say 5 to 6 meters), then the X-axis needs two ballscrews (two motors and two measuring systems) and a software to keep skew in control.

Or two screws mechanically linked and driven by one motor.

[xairflyer]

I can see what your saying Terry fixed gantry machines have to be bigger to allow for the stroke of the table under the gantry.

Iw ould think that for smaller machines (under 3ft square) then a fixed gantry would be easier to build and get set up.

Don't think I would be too keen on a moving Gantry using the roller bearing method, but with linear rails to would be ok.