Countersink bit question.

[Rt5403]

I bought an Irwin bit from the hardware store to use on my kit. I have experienced some waviness in the chamfers. It doesn't really bother me and I'm able to mostly clean it up. I am about to put the touch hole liner in the barrel and really don't want this issue at this step. Is there a way I can keep this from happening or do I need to get a different bit?

[Hunterdude]

I am not familiar with the brand chamfer tool you have, however I have been chamfering holes for 35 plus years and can offer some tips:

#1 -Slow Down, often the slower you turn the tool, the better the cut.
#2- look at the bit and see if it looks sharp and clean any chips in the teeth.
#3 - use cutting oil, most Any oil will help, thicker is better than thinner.
#4 use fairly heavy feed down, or do not just let the tool rub, chamfering tools require firm down pressure.

When I say slow, often Less than 150 RPM, if you are wanting  a specific hole to turn out nice (like on a rifle) it's not a bad idea to drill a couple practice pilot holes same size as in rifle, and  in simular type metal to test your speed and feed rates, often going VERY slow RPM is the best fix.
   Finally, some chamfering tools are poorly designed, it's not a tool you want to go cheap on....hope this helps.

[DGB]

Hi,
Key word is SLOW rpm.
If you are using a drill press or other power tool, Keep the c'sink in contact with the part and cutting as you turn off the power. As the cutter coasts to a stop, the chatter marks should clean up.
Yes, practice this first.
All of this assumes that your countersink is of decent quality.
Good luck,
DGB

[Hunterdude]

This style is my personal favorite, made by Severance, not cheap...but good.

[J. Talbert]

Buy a M A Ford brand six flute countersink and your problems will cease.
Over the years I tried all the tricks to eliminate chatter.  Sometimes it worked and sometimes it didn’t.
Once I bought the M A Ford countersink, it just doesn’t chatter, period.

Jeff

[Clowdis]

The only countersink that I haven't had any issues with is a single flute. Never had one chatter. I've experienced problems with all the others regardless of number of flutes. A countersink will work best if you can hold the work piece in a vise and use a drill press or milling machine to run the cutter.

[Hunterdude]

I second the M A Ford as a good brand.
  Also the use of a drill press.
Many modern cordless handheld drills lack the necessary  torque at very low RPM....when the drill stalls, the natural  instinct is to pull the trigger harder = high RPM and chatter. A drill press is more likely to offer very low RPM and torque.
   As all ready mentioned,  if your drill press will not go down to say 100 Rpm? Put it in the lowest gear it has, turn off the spindle and make your cut as the spindle coasts to a stop, this is How important going slow RPM is.

[Not English]

I like to use a single flute counter sink, contrary to every one else. I agree slow speed and a drill press are key, maybe more important than type of countersink.

[davec2]

I actually read about the following tip on this board.  I didn't have much hope it would work, but it did for me.  Get the countersink lined up with the hole and then place a piece of cloth (like a patch you would use to load a round ball) between the counter sink and the work.  I put a drop of oil on the patch as well. It seemed to stop the chattering and worked like a champ.     I have also done it with heavy paper between the countersink and the work.  All the other advice also applies as well...low RPM, heavy down pressure, sharp tool...and I also have the best luck with single flute countersinks...Hope this works for you.

[44-henry]

This is the style that I like.

[kutter]

I take a regular drill bit and resharpen the point to the angle needed for the counter sink.
Not hard to do by eye comparing it to the screw head that will sit in the countersink socket.
Then dull the cutting edge on one side,,simply swipe over the sharp edge (only) with a small stone,,I use one of those diamond lap sticks.
It makes the drill bit into a nice counter sink. No chatter with the single cutting edge,,using heavy constant down pressure, good cutting lube and slow rpm..

I do the resharpening of the drill bit on a belt grinder.

[J. Talbert]

I use the M A Ford bit in my 12 volt Ryobi cordless hand drill, slow, fast it doesn’t matter.  No additional tricks required!

Just sayin…
Jeff

[Fly Navy]

What degree counter bits does everyone use?

[Rich]

If you're using a white lightn liner, the camphor is so shallow that you will not have room for clatter, etc. For a 1/4 inch liner, I use a 1/4 inch 90 Degree countersink. 

[P.W.Berkuta]

Turn the countersink SLOWLY with moderate downward pressure also a variable speed electric drill works well for this. I have used an "eggbeater" style hand powered drill and it works well but is a bit tricky to keep it true to the surface while rotating the crank - do a lot of practice countersinks you will eventually get the hang of it.

[T*O*F]

What degree counter bits does everyone use?

The one that matches the angle of the screw you're using.

[B.Habermehl]

I normally drill a small pilot hole first. Say 5/64 dia. Countersink now to nearly finish dia. I seldom have any problem with chatter. This is really useful when drilling and countersinking tang bolts. You can use a chisel mark to draw the countersink the way you need to center it perfectly in the tang. The finish drill will follow the counter sink rather than the pilot hole. BJH

[Goo]

I tried putting a patch size piece of denim fabric between the countersink and the work while I was doing the countersinking.   I found it worked for one of my countersink bits but not all of them. 

[45-110]

Denim might be to thick, I just use a cleaning patch.

[D. Taylor Sapergia]

For cutting the countersink for a White Lightning Vent Liner, I use my drill press and an 82 degree countersink.  I clamp the barrel into the table vise and the vise to the table so that the cutter is aligned with the hole.  I take the belt off the motor and turn the cutter in the chuck by hand to cut the countersink as it is only a shallow recess.  It takes about the same amount of time as typing this missive.

[Hunterdude]

For cutting the countersink for a White Lightning Vent Liner, I use my drill press and an 82 degree countersink.  I clamp the barrel into the table vise and the vise to the table so that the cutter is aligned with the hole.  I take the belt off the motor and turn the cutter in the chuck by hand to cut the countersink as it is only a shallow recess.  It takes about the same amount of time as typing this missive.

What Taylor describes above is the best way to guarantee zero chatter marks!

[Clowdis]

What degree counter bits does everyone use?

82* is the standard countersink angle.

[A.Merrill]

For cutting the countersink for a White Lightning Vent Liner, I use my drill press and an 82 degree countersink.  I clamp the barrel into the table vise and the vise to the table so that the cutter is aligned with the hole.  I take the belt off the motor and turn the cutter in the chuck by hand to cut the countersink as it is only a shallow recess.  It takes about the same amount of time as typing this missive.

I do it the same way. Much safer and accurate with no chatter.    Al

[Frozen Run]

I bought an Irwin bit from the hardware store

I own one as well, it's pretty useful in performing light duty chamfering on certain things by spinning it between your fingers. After drilling the pinhole on a ramrod tip, chamfering the entry and exit hole a little bit to create a recess to peen the pin into, maybe cleaning up cast pipes, stuff like that. As an actual countersink in a power tool it is complete rubbish.