Messages

You were right about the relief angle Jan! It now cuts like crazy

Here is the proof with the marker: https://www.dropbox.com/s/dn9dwqv05fwynkv/jig-19.jpg?dl=0

Serge

Hello Jan,

Any idea how a relief angle can be achieved? I have no idea (yet).

Serge

Hello Jan,

Any idea how a m

Since the jig can't move sideways during sharpening and because countersinks are hard, a standard grinding stone soon shows scores. Therefore I think a black stone is recommended.

I did a few tests... although the cones are perfectly sharpened, the sinks don't cut well. I know why: in between 2 flutes, the sink drops to the grinding stone and the cutting edge is rounded. I see 2 solutions:
1 after sharpening the cone, sharpen the inner side of the cutting edges with the jig in a 90° position and at the edge of the grinding stone. Difficult to do well!
2 modify the jig so it retracts the sink just at the cutting edge. I don't know yet how to do that

Oh, I forgot the last picture... This is how it looks like as a whole:

https://www.dropbox.com/s/htttsm12riyq7r4/Jig-18.jpg?dl=0

Here it is!

Assemble 2 tool supports like this...
Pic 1 normal view
Pic 2 top view
Pic 3 front view
Pic 4 side view
Pic 5 bottom view

A steel tube, 12mm external, 10mm internal diameter
Pic 6

Place the tube in the upper tool support. Stick out in front 1mm to avoid friction with the tool support. Pay attention that the tool support has been shortened 15mm (otherwise long counter sinks won't fit)
Pic 7

The tube should stick out about 15mm at the back.
Pic 8

Make an 'L', as wide as the sharpening stone, height 77mm, as deep as the tool support. And 2 bolts 3mm diam. Pay attention to the white line, this will be the reference to the top of the tool support.
Pic 9

Fix the 'L' to the upper tool support. The height of the 'L' above the upper tool support must be 51.5mm (explanation later)
Pic 10

Make a ruler, 30 cm long, 4 cm high, 4-5mm thick and provide a hook.
Pic 11

This is the ring between the grinding stone and the machine. We are going to use it to set a correct angle of the tool support so that the axis of the countersink goes through the axis of the grinding stone. This ring is 36mm in diameter And the height of the axis of the countersink is 33.5mm. 33.5 + 36/2 = 51.5mm. This is the height of the 'L'.
Pic 12

Now, use the ruler you made, put it on the 'ring' and align the tool support with the ruler. Now we are sure the axis of the counter sink goes through the axis of the machine. This is needed to correctly set the horizontal angle for the counter sink conus.
Pic 13

Then, take a steel bar, 10mm diam. ⅜ thread in front for a chuck, M10 thread at the end. Fix a chuck as short as possible (I found one from Makita).
Pic 14

Place the steel bar with chuck in the jig.
Pic 15

Place a spring, a washer and a nut.
Pic 16

Assemble and fix a hand wheel. Ready!
Pic 17

Pictures: https://www.dropbox.com/sh/veofqyl9pnkzfcq/AACdxjfexZaYbzP5bZqOfHeoa?dl=0

How does it work? Tomorrow...

Serge

Prototype almost ready!
Pictures follow soon.

Serge

I'm going to make my own jig...
When it's finished I'll show pictures 

Jan... shapen by hand? No jig availale?

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

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

Hello everyone,

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

I wonder how I can sharpen a countersinck.

Anybody?

Thanks a lot!

Serge