The first Add-on page… a 4th axis, aka A-axis.
With a 4th axis there are tons of new things to try with the cnc router, although i fist have to study the software
For a fourth axis i need a 3 and a 4 jaw chuck, so best way should be to use the ones from my lathe.
I had some old steel stock laying around from a previous project, this will become a adapter for the chucks.
One side has a groove to fit the chuck on, the other side has a 25mm hole for the shaft, and 3 holes for bolts.
Now i machined the front plate of the 4th axis, this pocket will houses a angular contact ball bearing (7205).
This bearing has a inner diameter of 25mm for the silver-steel shaft and will be for radial and axial thrust.
The axial thrust from ‘chuck to shaft’ will be converted from the chuck adapter to the inner ring of the 7205.
The shaft i used is a 25mm silver steel piece of round bar.
The only machining i did on it was drill and tap a hole, this is to secure the adapter without axial play.
To prevent the adapter from slipping round the shaft i made a small lock bolt in the adapter plate.
Now the shaft is mounted in the front plate i still need a thrust bearing on the other side.
The angular contact bearing will only handle the thrust from chuck to shaft, not the other way around…
So on the other side of the front plate i place a thrust bearing (51205).
This bearing will be locked in place by the timing gear.
The gear ratio i will use is 1:6 this because i do not need a lot of speed on the A axis, but i do like some power.
So on the shaft i used a 60 tooth T5 timing gear, but of course this needs to be machined to the required 25mm.
Now its time for the back side of the 4th axis…
This has a somewhat similar pocket, but only for a radial bearing.
The other pocket is for the stepper motor, this way i can make the a axis as small as possible.
The gear on the stepper is 10 tooth. The pocket for the stepper and its mounting holes are made slightly to big,
This way i can shift the motor a bit to tension the belt… Its a very simple methode…
And as always… a ‘making of’ video…