Sharpening counter sinks

[Serge Nelissen]

Hello everyone,

I'm new here. Just purchased a T8 :-)

I wonder how I can sharpen a countersinck.

Anybody?

Thanks a lot!

Serge

[Ken S]

Welcome to the forum, Serge. I believe you will find your new T8 is a very versatile machine. I don't know if could be used to sharpen a countersink. I would probably start with my file drawer. If a metal file didn't do the trick, I would use an India or Arkansas file.

Enjoy your new Tormek, and keep posting.

Ken

[Jan]

Welcome to the forum, Serge! 

I think TORMEK is not entirely suitable for sharpening countersink. However, you can try the following method of freehand sharpening:

1)   Draw a line on the stone along the lowered USB
2)   Use the USB as a tool rest
3)   Align the cutting edge to the line on the stone
4)   Use the marker method to set the angle
5)   Remove the burr

Jan

[jeffs55]

Welcome to the forum, Serge! 

I think TORMEK is not entirely suitable for sharpening countersink. However, you can try the following method of freehand sharpening:

1)   Draw a line on the stone along the lowered USB
2)   Use the USB as a tool rest
3)   Align the cutting edge to the line on the stone
4)   Use the marker method to set the angle
5)   Remove the burr
I am thinking that without turning the countersink as it is being ground, you are going to create a flat or at least a concavity behind the cutting edge of the countersink. In so doing, the rest of the countersink that was not ground in sync with the edge will be a raised area. The raised area would then prevent the countersink from contacting the hole the be countersunk. Unless of course you "wallowed" out the hole by not holding the countersink at a 90 degree angle to the target. So, if I am right, then the Tormek is not the best choice for this. If however, you chucked the countersink into a drill and maintained concentric contact with the spinning grinding wheel, I can see it working although over time the size of the countersink would be reduced.       

Jan

[Jan]

Yes Jeff, you are correct, when we remove too much steel from a conical countersink cutting edge the tool may be destroyed.  Thank you for pointing it out! 

What I recommend is only to touch the stone along the edge of the tool under an angle shown by the marker method. I recommend sharpening away from the edge on a stone graded fine.

It is important to sharpen the inner side of the cutting edge also. For this I use a fine triangular ceramic file.

In this way I have prolonged the life of two countersink cutters. They do not cut iron as new but they serve quite well.

Jan

P.S.: Using the base of the scissors jig as a tool rest helps to maintain the same angle for all flutes of the countersink.

[Elden]

Which type of countersink? I agree that none would be easily done.

[Elden]

A couple more.

[Jan]

You are correct, Elden, they are many types of countersink cutters.

My experience is limited to 3-fluted countersink cutters of about 1" diameter and 90° chamfer angle.

Jan

[jeffs55]

Yes Jeff, you are correct, when we remove too much steel from a conical countersink cutting edge the tool may be destroyed.  Thank you for pointing it out! 
Jan

Jan, I just realized a problem with my comment. I am sure that you caught it but others may not have. I assumed that you were going to be sharpening on the conical part of the countersink. Whereas the proper sharpening position would be on the vertical plane which is 90 degrees to the conical portion. Well, actually it could be 45 for a 45 degree countersink or various other degrees depending on the desired outcome. In other words, the cone is half the degree of angle of the countersink. So, if you sharpen the vertical plane;  you eventually reduce the size of the countersink but do not decrease the angle of the cut. At some point if you wanted a one inch wide countersink and you have repeatedly sharpened the cutting edge from the vertical, you would come up short.

[Jan]

The attached pictures show 3-fluted countersink. The blued area shows the inner side of the cutting edge which I sharpened using fine triangular ceramic file. The red line shows the outer side of the cutting edge which I have sharpened/flattened by touching the grinding wheel.

Jan

[jeffs55]

Yes, inner edge from the inside. I am wrong again.

[Jan]

No problem, Jeff!  It is best to think about the issue from all sides.

Once Herman wrote, "I find it hard to think in three dimensions". Most certain for me is to hold the 3D object in my hand.

Jan

[Serge Nelissen]

Hi guys!

Thanks for your input.

I was talking about 3 fluted countersinks.
I thought I had to sharpen the cone, but some say I should sharpen the flat inner side. Are they right?

Thanks,

Serge

[Serge Nelissen]

I found this pic on the site of a manufacturer of professional grinding machines...

[Jan]

Serge, both sides of the cutting edges should be sharpen. The outer (conical) side can be sharpen on Tormek along the red line. The inner side shown in blue can be sharpen using a file.

Do not remove much steel from the conical outer side, touch the grindstone only.

Jan