Mathew Newton wrote:

I'm no core drilling expert however when I hired a 150mm core drill it
came with a pilot drill bit AND a *smooth* guide bit. Hence, I drilled
right through with the pilot drill bit and then used the core drill
along with the smooth guide bit to do the biggie. The smooth guide bit
obviously didn't do any further damage to the pilot hole hence the
whole thing went through cleanly...

Mathew

Forgot to mention... here I am getting ready to do the drilling...

(Yeah I know what you're thinking - the bit does look somewhat on the
large side)

http://www.theservicepeople.com/web%...eb%20Large.jpg

Mathew