Step drill bits (where to get) ?

[birchy]

That's a countersink not a counterbore? Big difference between the two. I also had a quick search for counterbores with a combined pilot drill so that you could effectively drill and counterbore without changing tools but came up blank. I've worked in engineering for many years but have never seen such a tool. Or at least not a proper one. I guess you'd have to get a lump of tool steel and make your own or make one by grinding a suitably sized drill bit.

[dazza]

That's a countersink not a counterbore? Big difference between the two. I also had a quick search for counterbores with a combined pilot drill so that you could effectively drill and counterbore without changing tools but came up blank. I've worked in engineering for many years but have never seen such a tool. Or at least not a proper one. I guess you'd have to get a lump of tool steel and make your own or make one by grinding a suitably sized drill bit.

i must have dreamed them up then i was sure i had seen them before.ive got to use some counter sink allen bolts plan is to put in a pilot holes then manually counter sink the material on the bench drill,i can get by but would have prefered them to have that pilot guide on the bottom like those flat bottomed counter bores do

[birchy]

Sorry, I misunderstood...I thought you meant pilot DRILL and countersink combined. There are things like these, but they look a bit Mickey Mouse to be honest...

Countersink Cutter - 3/32" Rivet CC40 - Cleaveland Aircraft Tool
Buy SNAPPY 7/64" x 3/8" Twist Bit Countersink For #6 Screws Fits Festool Centrotec Chucks at Woodcraft.com

I mostly prefer to lock the work piece and then drill, change to tool and countersink. Bit of a PITA but it gives the best accuracy and squareness. If it's not too fussy, I use a cordless drill.

[dazza]

Sorry, I misunderstood...I thought you meant pilot DRILL and countersink .

its my fault fella (termonoligy how ever its spelt) its a piloted countersink im after doesnt have the drill going through it just a plain pilot on the end,ive found a few but its unlikley im gonna find the size i need so i,ll make do thanks.

[birchy]

You could customise a standard countersink by grinding it back, I suppose. You'd probably need a lathe with a grinding attachment, though.