I've done this at home. Fit a cut off disc (type used in a die grinder type cut off tool) about 50mm diameter ish to an arbour and secure in to the drill press. Operate at medium speed and adjust the height of the table to allow the hole saw to be introduced correctly. Sharpen each tooth at a time and don't get it too hot. Worked a treat for me
if there worn they can be sharpened in a fashion and work.problem is the teeth are off set and wear on the sides that give the clearance . i wouldnt realy bother to be honest i have tried it
Faced with a totally knackered cutter I figured I had nothing to lose by trying to sharpen my 30mm starrett. It couldn't have gone any better TBH - I put an air cut off tool (as I'd run out of 5" slitting discs at the time) in a vice and offered the cutter at the right angle/s one tooth at a time - took about 20 mins as it was in a hell of a state. I doubt if tooth geometry is spot on but for my purposes (normally non critical holes in 10 / 12mm MS plate) it cuts as good as new and wouldn't hesitate in doing it again.