Desktop size build to learn on - PCB routing / small MDF work.

[EddyCurrent]

Many years ago I used a resist pen to draw PCB's, then came photoresist but that was always out of my reach, now we are onto cnc cutting, next it will be conductive ink printing PCB's, which probably already exists. The ball screws you have are quite meaty for the size of machine you propose but that's better than too small. If you use the forum search feature you will find quite a few references to PCB making.

[JAZZCNC]

The ball screws you have are quite meaty for the size of machine you propose but that's better than too small.

Not really and at this small size machine it would be hard to find a ball screw too small but like in this case very easy to find one too big.!!

Problem with this large screw is the power required to accelerate it to full speed then de-accelerate will be high so the your creating your self more expense due to needing larger motors, drives etc while at same time costing machine performance due to lower acceleration times compared to the correct size screw and motor.
Yes it will work but at a cost that isn't always cheap in the long run.

Cutting PCB's or Aluminium the general machine design hisn't really any differant other than strength and spindle type with maybe some dedicated fixture for work holding very thin matarial. But the general principle of building one is just the same really so all you really need to do is research any well built machine.

The areas you need to focus on for PCB milling will be Accuracy of axis alignment in regards to bearing rails being on same plane and the resolution of the ball screws provide is sufficent and with minimal backlash as the tolerneces you'll mill to will probably be small.
Ridgidity of the frame and in particular the Z axis will be important as any flex will transfer directly to the cutter, the cutting forces will be generally low so strength hisn't much of a concern but often ridgidity and strength go hand in hand.

Spindle selection will be important for PCB work as you'll need very low runout and high speed for the tiny cutters you'll be using.

Good luck and golden rule is don't buy anything without asking first.!!