Thread: Weldon Countersink Sharpening Jig.

Hi Guys,

Some of you may or may not remember me making a jig to sharpen Weldon countersinks and similar tools.

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This is the jig in question !

Well I needed to use it the other day, and found that the nylon screw at the back had seized up and I couldn't turn it, to sharpen a countersink.

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This is the nylon screw and the aluminium housing it goes into.

So having stripped it down I set to and made a new screw out of steel.
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This is the array of bits that I ended up with.

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The piece of doner metal was a hub for another project, hence the three partial holes in it. I chucked it up in the three jaw and turned it down to suit an M30 by 1.25 thread, drilled it 12 mm and then bored it out to suit 1/2" inch. I drilled and tapped three holes at 120 degree intervals round the outside for M5 grub screws.

I used a piece of chromed 1/2" steel bar from a line printer for the shaft, putting a 3/8" inch by 24 tpi screw on the end to suit the Rohm 1/2" inch chuck.

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This is how it looks now. What's more it is now much smoother than it was with the plastic screw.
I haven’t tried it out yet but a least I've recovered a nice MT2 to 3/8 X 24 adaptor.

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These are the two items recovered. The 1" inch tool adaptor is basically scrap metal. In fact it might even have come from the scrap yard. It looks to have had a hard life

Thanks Guys.

Great work as usual John,

I read your informative earlier thread - //metalworkforums.com/f65/t1985...58#post1899858 and I have a couple of questions. How does the jig perform when grinding actual Weldon deburring or countersunk bits? Also, how close is the pitch of the jig's infeed to the pitch of the relief on the Weldon bit? ( I'm calling it pitch though there is probably a better term )

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I have a handful of Weldon bits that would benefit from a resharpen and your little jig inspires me to have a go at one of my own.

Bob.

Hi Bob,

This is a difficult question ! The taper on the cone varies depending on the size. I've used an average for 3/8", 1/2", 3/4" which is about
30 thou. Hence the 1.25 mm pitch thread, or you could use 20 tpi, they are both close to 30 thou.

I do have some Weldon countersinks that will countersink or deburr a 1 mm hole, but the taper is so shallow it is very hard to measure.

The way I did it was to put the countersink in the lathe chuck and run a dial gauge on the edge. Of course the problem with this is you are also measuring the chuck runout, which will be added or subtracted from the actual taper value. I tried with a 1/4" countersink and gave up.I just couldn't get a consistent reading.

Using the jig is easy, just set it against the wheel at the correct angle, with the high point, just before the edge of the hole, touching the wheel. Then turning the screw clockwise will move the countersink forward, grinding the taper. I use my Kant clamps to secure the jig to the grinder table.

Let me know what you find.