I've read that you should only use ULS glass when drilling holes through your limbs because of the tendancy for UL glass to crack. Is this always the case, or is it possible to drill through UL glass without it cracking? If so, what has been the best method for the cleanest possible hole?

I have been told that forester bits work best. I drill mine with a metal cutting bit with no problems. Make sure you have a piece of wood backing the glass when you drill thur and go slow

I drill through UL glass everyday and don't have problems. The only time I've seen issues is in areas of higher humidity where your core material or wedges pick up moisture through the limb bolt hole after the limbs are made and expand, causing the glass to split. To avoid this, seal the inside of your limb bolt hole with a Q-tip and finish or some cyno. Like James V said, back your limb up with a scrap piece of wood and drill with a sharp bit. I use a regular drill bit.

I have had one a few of my first set of limbs split in the area of the bolt hole but figured out it was the hole as south stated. ever since I seal the hole real good. I always cover my glass with backer to prevent chipping.

That's kinda what I thought. Thanks guys. Merry Christmas!