Hello There. Planning for UK MechMate Build

[hanermo2]

Disagree Ger,

1.
Why will racking be an issue ?
A rigid center-driven gantry has perfect balanced push on both sides.

2.
There is zero need for not using a fully supported bed like the mechmate.

3.
There is zero need for not dropping the drive screw 40 cm, under the bed (or even over it).

4.
Ac servos do not need any planetaries - although they might perhaps be used.
Ac servos will work just like steppers, but 20x better acceleration, much better top speed, 10x more accurate.
Importantly, servos stop/fault before making major damage.

The OP looks for a *jobshop* commercial machine.
I recommended stuff for a *commercial* machine.

A mechmate cost == 8000$ to build.
In that context, the servos and 20/25 mm rails cost difference disappear.

20mm rails are more than large enough for any DIY router.

If you go with the AC servos, you're going to want to use 10:1 planetary gearboxes, with as little backlash as you can find.

There are several issues with driving a gantry from the center.
1) Racking will be an issue, unless you build a very massive structure.
2) This method requires a table that's suspended at the ends only, which will be less rigid than a fully supported table.
Using two slaved motors is easier, and works fine.