Countersink bits

[stummel bum]

This may have been covered somewhere, but what diameter countersink bit is best for the mortise?

[T3pipes]

I've started using a round rotary rasp similar to the one on the right side of This Page. I just press it by hand against the mortise and twist until it is the diameter I want, then place a piece of sand paper under the rasp to smooth it out.

[KurtHuhn]

The diameter will vary depending on the size of the mortis - unless I'm misunderstanding the question.

Beyond that, there's no rules. I think a typical 60-degree countersink would be just fine, though I don't think anyone is going to be measuring your countersink with an angle gauge to determine "correctness".

[stummel bum]

So for a 5/16" mortise, I would get a 5/16" countersink bit?

[SimeonTurner]

No, I think you would want a bigger one.

PIMO, for example, sells a 1/2 inch countersink bit which is perfect for a 5/16th inch mortise. You can vary the depth of the drilling to create a bigger or smaller bevel in the mortise. The deeper you go, the bigger the countersink becomes.

Does that make sense?

[stummel bum]

That's what I was thinking. Just didn't know how much bigger I needed to go. Thanks. I had wondered how big the one from PIMO was.

[Uncle Arthur]

I use the one that I find first. Not professional but then I do this because it's fun and I am still learning.

[RadDavis]

Guys, you can use any size counter sink that will fit in the hole enough that the little cutting edge contacts the wood.

Rad

[Uncle Arthur]

Thanks Rad!

[T3pipes]

practice on a piece of scrap briar first. I was using a drill-press, left the stummel in the vise, switched bits, and had some real bad vibration from the counter-sink and tore up the mortis.

[Uncle Arthur]

I do mine on the lathe . with a VERY gentle feed . Doesn't always work great but I think it's more operator than equipment.

[mredmond]

I've been using a 1 inch countersink made by Beall with some success. It cuts better than the cheaper ones I've picked up at Lowe's and Home Depot. I use it to chamfer mortises, tenons, and tobacco chambers, with success on all fronts. It's not cheap at $19.95 but I use it on every pipe and feel it was a worthwhile purchase. You can find it here: http://www.bealltool.com/products/threa ... ersink.php

- Micah

p.s. I use it on the lathe as well...usually right after facing and drilling, as I find trying to get it centered again after taking it off the chuck is difficult. That might just be me though...I'm pretty new to lathe work.

[RadDavis]

I've been using a 1 inch countersink made by Beall with some success. It cuts better than the cheaper ones I've picked up at Lowe's and Home Depot. I use it to chamfer mortises, tenons, and tobacco chambers, with success on all fronts. It's not cheap at $19.95 but I use it on every pipe and feel it was a worthwhile purchase. You can find it here: http://www.bealltool.com/products/threa ... ersink.php

- Micah

p.s. I use it on the lathe as well...usually right after facing and drilling, as I find trying to get it centered again after taking it off the chuck is difficult. That might just be me though...I'm pretty new to lathe work.

That looks like just the ticket! It'll fit any mortise size you're likely to drill.

You can also put your countersink in the lathe chuck, turning around 250rpm and very gently push the mortise onto it. Touch it to the counter sink, pull it off and turn the stummel 90 dgrees, touch it, turn the stummel 90 degrees, until you get a nice evenly round countersink.

Try it with some scrap. It works just fine. Just don't push hard. Easy does it.

Rad

[KurtHuhn]

And here I was going to suggest a single flute countersink - turns out I didn't need to. That countersink will work great. The single flute versions are designed to prevent the chattering that can happen with 2 and 3 flute countersinks.

[SimeonTurner]

I'm intrigued! I hate it when my 3 flute countersink chatters (even when I advance it sllloooooooowwwwwwwly into the mortise). This looks like it might be a better way to go.

Question: as one uses a countersink like this over time, I assume it will eventually get worn down and need to be re-sharpened. is that even possible, or is it just time to buy a new one at that point?

[caskwith]

I use something very similar to this. I like the design as it acts with a shearing action thats gives a very clean cut and no chatter at all. Can easily be re-sharpened aswell actually though it never cuts quite as good as a new one. When it starts getting dull i buy a new one (tho only on my second in 3 years lol) sharpen up the old one and put it in with my general workshop drills so it gets used when buliding tools etc. Works great on aluminium for countersunk machine screws.