Vertical table Cnc

So i had an idea similar to this one: [vimeo.com]. Where you have a vertical table cnc mill but i want to implement the Core XY system in this. I am going to use Nema 23 motors and since the table will be moving the XY setup will be relatively lightweight for being a cnc mill. The cutting area will be 400x300mm. Do you guys think that there is any disadvantage to use the Core XY system instead of a regular cartesian belt driven system? I guess it will be affected by gravity the same way so the spindle will fall down if the steppers are unpowered, is there any way around this other then using ball screws or trapezoidals? Do you think the Core XY system will be up for the task?

No one have a input?

Gravity pull can me countered with some counterweight, but that will add moving mass to your system.

At any rate, if you look for CoreXZ it is basically a working implementation of your idea.

Hi,

Keep in mind a CNC mill is slightly different from a 3D printer.
A 3D printer needs to be fast and there's no resistance at the head.
A CNC mill don't need to be very fast because of the feed and speed
needed by the cutting bit, that requires relatively slow motion.
So, any belt system is not the best option.
You need to oversize the belts to prevent any play,
you need a kind of reduction on the motors to get enough torque.
The forces applied to the head during milling are strong
and leads to any direction. And so on...

So the best option for a CNC mill is often some screw transmission,
because it gives more torque, strong position holding,
and the travel speed corresponds to a milling requirement.

But transmission is not the only point of difference.
Motors needs to have more torque at high speed,
so a low inductance, whereas a high inductance motor
gives a 3D printer more torque at low speed to help
during fast direction changes.

You can transpose a 3D printer to a CNC cutter (plot, laser, plasma)
but mill/lathes are another world. Less speed, more weight, more stiffness...

I'm not sure the vertical position is good for a CNC mill,
because the gantry and the head weights a lot.
The raw material to be milled can be heavy too.
There must be a lot of problems to deal with,
that a horizontal table don't have.

++JM

Edited 4 time(s). Last edit at 08/24/2015 10:15AM by J-Max.