I will keep them sharp as i found it a more pleasant experience when they are sharp 
However i have found the problem, my revolving centre had stopped revolving, This in turn buggered the end of the mandrel. I checked and could nor move the centre but then it went past the locked area and was ok.
I now have a buggered centre and mandrel, a trip to Axminster for a chat me thinks as they are about three weeks old. Not sure i have the receipt now though.
Oh i forgot, on the subject of sharp pencils, i hate a blunt one so i treated myself to a fancy battery operated one they are now sharp enough for darts. My wife thinks i'm sad. she doesn't understand these things.