84/91mm Combo Tool in Mods

[WoodMan]

I have drilled quite a few 84mm combo tools. I use cheap 7/32 drill bits i buy at Walmart. Heat is the enemy i run my drill press as slow i can. When the bit gets starts to get hot i let it cool some drilling more. It is slow but it works. I tried using oil while drilling but then my bits did not cut very well. Using charcoal lighter fluid worked pretty good it helped keep the bit cool and it still cut well. Just go slow.

Do you mean 7/64"?  7/32" would be far too big.

[Mike 56]

Yes you are right it is 7/64. 7/64 bits a little bigger than a 2.5 but they work fine. 7/64 bits are  easier to come by here in the US.
Mike

[WoodMan]

I have drilled quite a few 84mm combo tools. I use cheap 7/32 drill bits i buy at Walmart. Heat is the enemy i run my drill press as slow i can. When the bit gets starts to get hot i let it cool some drilling more. It is slow but it works. I tried using oil while drilling but then my bits did not cut very well. Using charcoal lighter fluid worked pretty good it helped keep the bit cool and it still cut well. Just go slow.

When you say "go slow" do you mean to use a slow rotational speed on the drill, or use a slow feed, or both?

[Mike 56]

Both the Swiss steel is very hard and heats up fast if you don't over heat the bit it will keep cutting and not burn up or break. When the bit is about to go though you have to go even slower so the bit does not hang up and break. If you are careful you can get one hole with a new bit. The bits i buy come in two packs that way i have a back up.
pc