Chattering when cutting with countersink tool on lathe

[compact8]

Just can't understand why. I have tried this kind of tools with positive or zero rake angle but once the cutting area gets larger ( > 6 mm or 1/4 inch in diameter ), it will chatter. May be it's due to the backlash of the feeding screw of the tail stock but how come no such problem has been encountered when drilling even if the diameter of the hole is much bigger ( 13 mm or half an inch ) ?

 

[benmychree]

Go to a single flute countersink, problem should go away.

 

[markba633csi]

Try different speeds, and some cutting fluid
Usually slower speeds work better
Higher speeds can give a triangular or even square shaped hole
-M

 

[Aukai]

KEO Zero flute counter sinks have been good to me.

 

[MrWhoopee]

Yup, single flute or zero flute.

 

[projectnut]

I've been using either KEO or MA Ford single flute countersinks for over 35 years and have never had a problem with either brand. I switched to them after having problems with several different brands of multiflute "chatter less" countersinks.

 

[homebrewed]

It's been my experience that the amount of chatter you get is directly proportional to the number of flutes your CS has got. I've had the best results with a single flute CS and low speed. I don't peck like I do with a drill, a continuous cut works best.

Don't buy the Harbor Freight zero-flute countersinks. They dull very quickly when used on steel.

 

[BladesIIB]

Everything said above. My only tip when I don't have the right tool is to power on then power off and feed while machine is slowing down. I do this a lot on the mill when drilling countersinks. the variable speed and slowing helps reduce the chatter. If your lathe has a VFD you may need to gently hit the brake to let it hit free run for slow down.

 

[mmcmdl]

Multiple flutes are used on floating tools such as drill presses or hand drills . The flutes help the tool stay on center while the workpiece floats . The single flutes are for fixed machines such as a mill or lathe where the work piece can't move .

 

[projectnut]

Multiple flutes are used on floating tools such as drill presses or hand drills . The flutes help the tool stay on center while the workpiece floats . The single flutes are for fixed machines such as a mill or lathe where the work piece can't move .

That might be the theory, but I've had them chatter something fierce when using them in a hand drill on 316 stainless. If you have a steady hand and a good eye you can do a better job with less effort when using a single flute countersink. I have a set of MA Ford single flutes I bought back in the mid 1980's. They've only had to be sharpened twice in all Thet time. I sharpen them on the surface grinder using a Ford jig I picked up on eBay for $25.00 some 20 years ago.

I don't know if they still offer the jig, but the last time I looked a new one was in the $300.00 range. The later models came in a plastic box.