Ok, so 100ft-lbs for a big mill. 135Nm. Then it seems a bicycle hydraulic brake will be sufficient. http://www.bikeradar.com/mtb/gear/ar...-brakes-24345/
That is good.

I like the look of this one + coupled with bike brake some how.http://www.ebay.com/itm/cnc-rotary-t...item232cff456c Still have not figured the dimensions of the shaft and bearings necessary.