Weldon Countersink.

[Chris DentonParticipant @chrisdenton53037]

How do these work?

Tried to countersink a 12.5mm hole with a large one today and it just sat spinning in the hole, with no cutting happening? Hole was already countersunk a bit, does that matter?

[Chris DentonParticipant @chrisdenton53037]

[jason udallParticipant @jasonudall57142]

If its not mullered..
If pilot hole too small…such that the ” cross hole” doesn’t touch…
If pilot hole too large and all of cross hole in pilot. ..
Either will lead to in effect a plain cone rubbing on the hole and getting nowhere..

[Chris DentonParticipant @chrisdenton53037]

The bottom of the hole is in the pilot hole. Is that enough?

[Neil WyattModerator @neilwyatt]

i have some cheap copies of these. I think the answer is one one of the suppliers' websites:

 

Best Countersink Available for Aluminum Single Cutting Edge for Fast Removal of Stock

 

CRL Weldon Countersinks are known for their high quality unique designs and outstanding performance. They cut chatterless finished holes in aluminum every time. Smooth drilling action from a single cutting edge no matter what angle you cut at. The 1/4" (6.3 mm) shank diameter fits any 1/4" or 3/8" drill chuck.

 

In other words, don't expect them to do much in steel. My impression is that, for steel at least, they are OK to deburr or even chamfer a hole, but not countersink it. The geometry changes drastically as the tool enters the hole and you rapidly get to a point where it won't cut, and it just spins.

I get better results with a cone on the end of a bit of silver steel, ground away to half the thickness, like a D-bit.

Neil

<edit> I love the marketing speak: 'single cutting edge for fast removal of stock' – it's like saying a Reliant Robin is faster because it only has three wheels.

Edited By Neil Wyatt on 07/08/2014 20:14:35

[Chris DentonParticipant @chrisdenton53037]

I was using it on aluminum!

This is the one:

http://www.rdgtools.co.uk/acatalog/HSS-COUNTERSINK-ZERO-FLUTE-25MM-30MM-HEAD-9457569.html#SID=39

As it says 25-30mm I would expect it to manage an M12 countersink at 26.9mm?

[Neil WyattModerator @neilwyatt]

Hmm, my countersink marked 10-15mm is for holes in that size range, not that size of finished countersink. It is about 20mm diameter. I consider them as deburring tools and they are often sold as such.

The tool has to enter a few mm up from the start of the hole or it won't cut Is yours for countersinking 25-30mm holes?

Neil

[Chris DentonParticipant @chrisdenton53037]

Possibly it is then.

I will send them an email.

[Neil WyattModerator @neilwyatt]

Wikipedia seems to agree with me:

**LINK**

Perhaps it isn't the best choice of tool for the task.

Neil

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