Countersink cutter

I have to machine large countersink holes in 8, 12 and 20mm steel plate, up to 38mm x 90 degrees with a Sieg X3 mill.

My options are to buy or make a countersink cutter. Which way to go ?

Have seen 40mm HSS single flute cutters on e-bay. Are 1 flute cutters any good >

Also 2,3,4, or 6 flute cutters. Which are better ? (Would like a replaceable carbide insert cutter but expensive). Does anyone have any expeience or suggestions ?

Paul.

Edited By Paul Lousick on 04/09/2013 14:13:07

Edited By Paul Lousick on 04/09/2013 14:14:01

I can only speak from personal experience, which suggests that the fewer the flutes, the less likely the countersink is to chatter. My choice would be a single-flute cutter in HSS. What do more experienced engineers think?

Generally speaking ... odd numbers of flutes [cutting edges] seem less prone to chatter than even numbers.

For your job, I tend to agree with Mike ...

MichaelG.

I'd vote for a single flute, I'd even consider making one from silver steel, although it will have to be treated gently.

Don't bother with the ones that have a hole through a cone, they are really only deburring tools IME.

The hole size is important too - a 36mm countersink on a 30mm hole isn't a tough task, but one on a 12mm hole is very different!

Neil

A small boring head or fly cutter with a shaped tool would do the job the cheapest if You have the tools, just not the fastest.

Thanks for the feedback.

Saw a 40mm HSS single flute cutter on flee-bay for $45 will give it a try. Otherwise may make one with carbide inserts.

Regards, Paul

A countersink that big is a recipe for mega-chatter on a small mill like the Seig.

You need to run the tool as slow as 20rpm to get a clean (not 50p piece) profile with a single tooth cutter.

When doing large countersinks in the past - on big machines I might add - I would turn the spindle by hand for the last cuts as the spindles could not go slow enough.

Have fun.....by hand I mean with a big spanner or tommy bar

Trevor

Edited By Trevor Wright on 05/09/2013 13:02:10

I have also been known to profile the pocket on the CNC because it was less hassle.......

Trevor

My home made cutter would be a conically ended d-bit, so very unlikley to rpocuce an out of round hole, but yes run slowly.

Neil

Thanks for the advice. I can only have a go at producing a decent countersink hole. If not successful will have to find a larger machine.

Regards, Paul.