The cross slide (X axis) servo motor has a 14mm dia shaft and I have a 16t toothed pulley. This mates with the 32t pulley on the cross slide ballscrew. However, it's only about 15mm outer diameter. So clearly I will need to make up a stepped adaptor. This will fit on the servo motor shaft, engaging with the 5mm key and locking in place with an M6 grub screw.
Machining the pulley:
The belt guides on this pulley are superfluous. The larger pulley has them, so they can come off this one for starters. They are only staked lightly in place, so doesn't take much to pull them off.
16t pulley fits the 4-jaw nicely. Dial it in carefully, using the machined boss...
And drill it out with a nice, sharp 7.5mm HSSCo drill.
And face it off
Looks good
Machining the spindle adaptor:
A piece of mystery steel from the window ledge. Skim it off so that it's concentric. Difficult to get a good finish with a carbide tool when you are manually feeding it.
Bore it out 14mm with carbide boring bar and CCGT06 polished insert.
Bottom line is - does it fit? Yep, nice sliding fit.
Turn it round and pick up on the outer diameter I've just skimmed so it's set up concentric with the internal bore.
Nice blue chips - you don't get chip breaking unless you get enough heat into the swarf. And the ribbons you can get with girly surface speeds can be lethal.
Spot on diameter, now chamfer the edges
Loctite clone adhesive to bond the pulley to the shaft, although it was a fairly tight push fit anyway. That's not going anywhere.
Keyway:
The key stands out 2mm from the shaft
Now to machine the keyway in the adaptor. None of this messing about with slotting - I'll mill a radial slot instead.
Mount the adaptor vertically with a vee block
Pick up the bore centre and the top surface with the Renishaw probe
4mm carbide end mill, 0.5mm either side of centre (in X) to a radius of 9mm from the centre line (in Y) and a depth of 16mm ie 4xd (in Z). Trial fit looks good:
Drill 5mm for M6 tap.
M6 grub screw. Job done! I knew it would be a fiddly business but it allows me to drive the cross slide ballscrew with a 2:1 reduction.
Getting there. Lots of fiddly bits done now.....
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