Cannot get good countersink with a Pillar drill!!!!!

[HAYSTACK]

Im trying to countersink 10mm holes i've drilled into sapele hard wood and I have tried numerous countersink bits.

Every one suddenly 'chutters' and ruins the the hole totally. The pillar drill is a cheap Clarke one from screwfix. It seems quite accurate for general hole drilling. I have tried changing the belt to different speeds to no avail.

What am I doing wrong? Its doing my head in!

 

[big-all]

have you tried doing the countersink with a 10mm drill bit with a depth stop

assuming you are using a mutiflute cutter because you have so many cutter faces they will be gripping at different rates as they are quite coarse and throwing sideways compared to a drill bit which will cut rather than wear away like a countersink bit

 

[HAYSTACK]

Its just to 'tidy the edge of the 10mm hole. Only by a small angled amount. I have tried it with a slightly larger drill bit but it still 'chutters' violently and rips it up unevenly. Oddly its not so bad with smaller holes. Only larger ones.

 

[Burnerman]

This may sound a bit corny, but is it possible to form the countersink first, and then drill your hole through its centre?
John

 

[HAYSTACK]

Unfortunaley not John.

I have just researched about a bit and apparently the best type of countersink is a 'Snail' de-burrer bit. These don't 'chutter' apparently. I will try one of those I guess.

 

[Burnerman]

Certainly you wont find anything better.....I've only used them on metals though, mainly due to price!
Presumably you don't have any better luck with a battery drill and an HSS countersink?
John

 

[Jackrae]

Rather than a conventional wood type countersink you could use a cross-hole countersink as used in metalwork. These look just like a tapered plug with a single cross drilled hole. They never chatter. See the first photo here
http://en.wikipedia.org/wiki/Countersink

If you want a countersink to suit a specific screw size/shape you could make your own like is shown in this youtube video
https://www.youtube.com/watch?v=3JRkfzIv8q0

 

[Norcon]

Use one of these...
http://www.axminster.co.uk/fisch-premium-hss-e-deburring-countersink

 

[HAYSTACK]

Thanks guys. I will get one of these hole through/snail bits.

Result

 

[wv62]

I'm not sure if it'll work with wood but back in a previous life when I was a toolmaker to get a good finish on a countersunk hole in metal we would put a piece of emery cloth between the job and the drill. It stopped the 'chattering' and gave a lovely smooth countersink.

 

[Burnerman]

Wow that takes me back! Must have had the same tutor......mine came from the aircraft industry.
John