4th axis brake enquiry

[marbles]

Hi,

I'm starting to mill some larger blocks of hardwood on my 4th axis using rotary indexing machining and I can see from the play in the wood when roughing at the extents of the block that the issue will only accelerate as I mill out to the edge of the stock. I've not had this problem with continuous 4th axis machining as i've been parallel milling down the centre line of the axis where there is least radial load on the stock.

I've not really looked into this it only occurred to me tonight that maybe what I need is to be able to lock off the 4th axis between indexed rotations. Looking at my 4th i'll have to attach a brake rotor to the back of my 72t pulley.
How have people solved this problem before?

Anybody got a neat solution or a link?

ps since the 4th was built i've changed the design a bit but its a standard belt and pulley set up with a nema 34 and an er32 shaft