Need Help!- reccomended drill size before reaming

[john scott]

Experts ,
I need to (hand) ream some 8mm holes in steel plate.
Don't know the material spec - it's fairly hard - i can file it and drill it , but it is too hard to (hand) hacksaw easily.

Plate thickness is 8mm , so i'm reaming through - and there's no problem with chip clearance.

What size drill would you reccomend ?

thanks in advance - johns

[Perfect Circle]

0.014 to 0.025 smaller than the reamer size or as close as you can get under near that. AND make sure that your drill is sharp and does NOT run out..use an indicator if you want to make sure that your drill is running true. Other than that keep it wet with some cutting fluid.
Good Luck~!

[john scott]

Thank-you Perfect , that's perfect !

just checking - that's 14 to 25 thousandths of an inch , or microns of a metre ?

johns

[Perfect Circle]

Yup thats 0.014-0.025 thousandths of an inch.
Are you going to use a center in the machine to guide the reamer?
AKA keep the reamer perp. to the matl.

[john scott]

Thank-you again !!

No , this isn't the sort of job i can just get under ths spindle
to drill and ream - it's truly hand-work on a piece of plate which is integral part
of the machine structure , and the drilling is all pistol drill stuff :*(

Fortunately it is down-hand - so i can clamp a pre-drilled block on first to keep the tool perp. to the plate. For the drill size - i'll creep up on it
with a succession of drills. ( and a good dollop of patience... )

[Perfect Circle]

Aye I've been there ...Fun stuff~!
Well good luck and try not to snap your wrist with that drill.