4th axis improvements to the YOOCNC 6040Z+S80 CNC

Why?

I want to be able to machine larger diamter parts on the 4th axis of my 6040Z-S80 machine.
Because the space below the gantry was limited to about 110mm, the original plan was to machine larger side-plates that hold the gantry higher.

However that would mean making the entire machine less rigid.

What?

Closer inspection shows a much better path.
The bed of the machine consists of 4 plates, each 120mm in width.
They can be removed individually.
The 4th axis (a chinese build 100mm K11 chuck on a 50:1 harmonic drive) needs 110mm of width and has the center of rotation at 65mm above ground.



...

Without the T-slot plate it sits a -20mm and thus the center of rotation is at 55mm. Perfect.

I can mount it to the t-slot plates on the left and right.
The edge of one of them makes sure it is perfectly square and parallel to the X axis.

The only problem are the chucks.
They extend beyond the 100mm circle.
So I will have to cut slots into the T-slot plates left and right of it.

...

Luckily the traperoidal spindle that drives the Y-axis gantry has enough clearance to not collide witgh the chucks.
Mounting some plastic foil onto the t-slot sides will prevent them and the bearings to get covered in dust and shavings.

 This is what is looks from below the bed.