MiamiCuse wrote:

I need to drill a 5/8" diameter hole through a laminated beam that is 16"
deep. This beam is sitting 10 feet above the floor across a room support
part of the roof. So I will be standing on a bench drilling from below
pushing the drill up.

I need this hole to be perfectly vertical as I will be passing a rod through
for a ceiling fan.

I know in the past when I had to drill through something much thinner like a
2x4, I often end up with a slanted hole.

What can I do to ensure my drill is perfectly vertical?

I cannot afford to make a mistake and redrill.

Thanks,

MC

Personally I would avoid drilling through the beam that way and would
instead hang the fan along the side of the beam. If I were going to the
trouble of deep drilling through the beam, I would be going large enough
to feed 1/2" rigid metal conduit through to allow the power to feed
through "invisibly". With a beam like that you can support a fan rated
box from the beam with a couple lag screws if you're going to be routing
power to the box along the beam anyway.