Use of hole saw advice needed

[bncinwv]

As part of the electrical protection upgrade, I will be drilling a 2 1/2" hole into the battery compartment of the rig. For those who have experience at cutting into the unit, should the hole originate from the inside or the outside??? I am assuming the outside to minimize fragmentation but need advice as to whether my reasoning is sound or not??
Bingo

[nailbender]

I don't have any experience drilling holes where you want to, but when I drill with a hole saw I drill from both sides if possible. Drill from one side until the guide bit comes through, then complete the hole from the other side. Both sides will have clean edges that way.

[sreigle]

When fragmentation is possible I usually first cover the area with masking tape first.

[Waynem]

Masking tape really works well. Just remember that the side you are cutting from will be smooth and the other side will try to splinter, especially if you try to force it. Very light pressure and let the saw do the work. Cutting from both sides is the best and then you can rasp and file any rought spots.

[Ozzie]

What Waynem said...drill one side until you break through the surface and the pilot bit goes through the other side, then go to the other side, you have your center hole already, then finish it off. Be careful going through as the last little bit will be wanting to force the other side again. Clean out as you go, 'cause those bits will fill with foam and stop you.

[bncinwv]

Thanks guys, will follow the both sides advice while using masking tape and regular bit (saw) cleaning.
Bingo

[simonsrf]

Bingo,

Put the tool down!

Put the tool down!

OK, now move very slowly away from the tool!

Stand back!...a little further! Don't move!

Ok, now we're all a lot safer.

Whew, that was close!