Countersink woes

[Elnathan]

I countersink holes with a brace turned by hand.  If the countersinks had unevenly spaced flutes, they couldn't chatter....hint to toolmakers.  I use two different countersinks.  One is 5 flute, one is 3 flute.  When one begins to chatter, I simply change to the other, and the chatter marks are cleaned up, and it cuts smoothly again. 

The single flute cutters simply don't work for me.

Chris,
Do those countersinks have square shanks or do you clamp round shanks in a square chuck? Inquiring minds want to know...

[Tom Currie]

Using a 8 fluted countersick ,  I tried Metalshaper's card stock method today with a little cutting oil to do the barrel tang hole. Chattered at first,  then I added another piece of cardstock on top and tried again. WOW  .I cut the nicest cleanest countersink I have ever done !! Cuts fast too, very little pressure needed. THANKS

[Dr. Tim-Boone]

I did hear about using "toilet paper" over the hole and it would eliminate the chatter.  Apparently it does the same thing as your card stock......Don

Hmmmm, "useing toilet paper over the hole" isn't a new concept however, doing it to "eliminate the chatter", well, that's a new one on me. Even in the outhouse in -30 it don't "eliminate the chatter". I don't think toilet paper and card stock are all that interchangeable either.......but that's just me. BTW, what does this have to do with countersinking?? Strange way to highjack a thread Don.

Cody, maybe at -30 you have to use a higher speed if you want to stop the chatter   ?

[Metalshaper]

Using a 8 fluted countersick ,  I tried Metalshaper's card stock method today with a little cutting oil to do the barrel tang hole. Chattered at first,  then I added another piece of cardstock on top and tried again. WOW  .I cut the nicest cleanest countersink I have ever done !! Cuts fast too, very little pressure needed. THANKS

HA,  proof I'm not totally full of BS!!     Glad that lil' tip helped out!

Since my shop is a low tech operation, I spend a lot of effort researching older machinist techniques and manuals. The old Popular mechanics "Shop Notes" can be an wonderful source of lost techniques and shop tricks.

Respect Always
Metalshaper

[Stophel]

I countersink holes with a brace turned by hand.  If the countersinks had unevenly spaced flutes, they couldn't chatter....hint to toolmakers.  I use two different countersinks.  One is 5 flute, one is 3 flute.  When one begins to chatter, I simply change to the other, and the chatter marks are cleaned up, and it cuts smoothly again. 

The single flute cutters simply don't work for me.

Chris,
Do those countersinks have square shanks or do you clamp round shanks in a square chuck? Inquiring minds want to know...

They're just ordinary round shank countersinks.  The square chuck in the brace holds them well enough.  In fact, other than turning my ramrod hole reamer (which I did make with a square shank....no way that thing would hold with it round), that's about all I do with the brace...

[T*O*F]

What you guys really need to get is a 12 flute, FitzAll countersink. You can taper any hole from an 8-32 screw to crowning a blunderbuss.  For most holes I just hand twist it.  I don't ever recall mounting it in a brace.

[b bogart]

Wow Dave size does matter, huh?
Bruce

[J.D.]

Just to reiterate what has been said, I learned in Machine shop 101, many years ago, that the secret to good countersinks is using an odd fluted countersink to eliminate harmonics that create chatter, in addition to using the correct cutting speed for the work at hand.

Properly lubricating the countersink, and possibly using cleaning patches, card paper, or toilet paper over the hole...in warm climates, can significantly improve the quality of one's countersinks.

J.D.

[davec2]

I've been using "pilotless" or "zero flute" countersinks for years.  I have never been able to make one chatter in thick or thin material, fast or slow cutting speed.  They don't have "flutes" in the conventional sense - just a cross hole that forms a single circular cutting edge.  They are also very easy to resharpen with a stone through the hole that forms the cutting edge.  Easy to use and, as far as I am concerned, absolutely chatter proof.

http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000068412194

[jerrywh]

 DaveC2
  Link doesn't work.

[Tim Crosby]

 Is this what you are talking about?
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=8581085&PMT4NO=49986407



Tim C.

[davec2]

Tim,

Yes, that's the type -

Jerry, I tried the link from my end when I made the post, and it worked.  Now it doesn't ?  But Tim's link is good.  Several tool places carry these "zero flute" or "pilotless" counter sinks.  They come in all sizes and I use them almost exclusively now.

Dave C

[eagle24]

Old machinist trick, from out of the 40's or 50's

Place a stiff piece of card stock between the countersink and the hole.
<  Manila folder works great >  the card stock only needs to be a bit larger than you intend to go. start the counter sink and let it work its way down through the paper and into the metal.  this technique works by easing the bit/flute(s) into the metal and helps eliminate some of the harmonics and resulting chatter.

It can also be used, to clean up a countersinck after it has started to get 'chattered',, if your careful!

Hope it helps

Respect Always
Metalshaper

Thanks for a great tip.  I used the same countersink that gave me problems a few weeks ago to countersink the screws in my buttplate last night.  I took your advice and used a piece of a heavy greeting card.  Actually, I think it was a Birthday Card for my wife I bought and forgot to give her.  Already been in the dog house over that so I figured I might as well get some good out of it.  Anyway, Kudos Metalshaper!  It worked like a champ and cut a smooth clean countersink on both holes.  I did keep the speed low as well, which I had done originally, but the card stock did the trick.

[Metalshaper]

G,

 Glad I could be of some help!! 

Respect Always
Metalshaper