Bowl Turning - Recess in the bottom to fit over Nova chuck

[ron david]

A skew does work, but I want the angles to match as perfectly as possible for the best grip possible. Specialized tool makes that a lot easier. The burr on a skew won't hold up very well either.

robo hippy

well if you cut a few you get an eye for the bevel. if the skew needs sharpening , just sharpen it and get on with it. only if I ever need an exceptional cut would i hone a turning chisel and especially on a dovetail mount as I would remove the dovetail at the conclusion if finishing of the bottom. the dovetails only function for me is to hold it in a chuck
ron

[Reed Gray]

I don't hone them, I take them to the grinder, a well broken in 180 grit CBN wheel, 6+ years old, but can't remember. So, scrapers cut with a burr, unless you are cutting really hard woods or some of the acrylics. Best burrs come from the CBN wheel, far better than the standard white, pink or blue wheels. You can burnish a burr as well, which I do by hand. Still experimenting with that one, but easier to do a quick touch up with it, and like a card scraper, you can turn the old one down, then turn it back up a couple of times. You can also hone a burr on. Talking to Kel McNaughton (maker of the coring system) some years back, he suggests to hone the burr on his coring knives. He said, 'the coarser the honing card, the better the burr.' I experimented, and did like the 220 grit burr better than the finer cards. The coarser cards leave a stronger burr. Depending on the wood I am turning, some times the burr is good for several bowls, some times good for only one or two. Haven't tried the 600 grit wheel yet, which has round edges, or the 1000 grit which has square edges. Dang, more experimenting ahead... I think the idea with a finer grit is that it is almost like burnishing if you push it enough...

robo hippy

[John K Jordan]

well if you cut a few you get an eye for the bevel. if the skew needs sharpening , just sharpen it and get on with it. only if I ever need an exceptional cut would i hone a turning chisel and especially on a dovetail mount as I would remove the dovetail at the conclusion if finishing of the bottom. the dovetails only function for me is to hold it in a chuck
ron

I mentioned earlier that Mark St Leger is a proponent of using a 1/4" round skew to shape and enlarge inside diameters of recesses including shaping dovetails. Another turner (can't remember) advised using a diamond profile parting tool ground at the dovetail angle for both recesses and tenons. I've been using this for years (and also a small scraper I ground with dovetail angles) but I was surprised at how well the small round skew worked. I think it's better than the scraper and the parting tool and I'm using it often now (and it's also perfect for cutting small beads, of course!)

As for cutting the recess I usually use a parting tool ground straight on the ends, although where appropriate a 2-1/4" Forstner bit is a lot faster, either in the drill press on in the tailstock. I just cut about a dozen recesses this way in round blanks I flattened first on the drum sander (for Beads of Courage boxes). As someone else mentioned dovetail jaws hold fine in most woods without actually cutting a dovetail since the wood can deform. The Forstner bit does make a hole a tiny bit too big - a 2-1/16" bit would be better or maybe a 52mm.

BTW, when the mood strikes I occasionally make the recess part of my base design:
bottom_IMG_4687.jpg bottom_IMG_4749.jpg

JKJ

[John Keeton]

Like JKJ, I use a decorative base to incorporate the chuck recess. Nearly all of my platters are done this way, though I rarely use it for bowls or smaller turnings because of the lack of sufficient surrounding material to support the stress on the recess.

[John K Jordan]

Like JKJ, I use a decorative base to incorporate the chuck recess. Nearly all of my platters are done this way, though I rarely use it for bowls or smaller turnings because of the lack of sufficient surrounding material to support the stress on the recess.

I agree, the design and wood and strength must be taken into consideration. For non-platters I generally use it where my base is thicker on purpose. I'm making Beads of Courage bowls/boxes this week and for those I like to design a thicker base to lower the center of gravity.

JKJ

[Reed Gray]

My daily use 'utility' bowls have a finished recess for the bottom. The dove tail scraper does a fair job of cutting, but to clean it up for a 220 sanding, I use one of Doug Thompson's small flutelss gouges for going across the bottom, and another one of them ground to a detail gouge profile to make a cut down the edge of the recess. It leaves every thing slick, and pretty much tear out free..

I don't like the idea of trying to cut come what close, and then having the wood deformed by the chuck jaws. That puts uneven pressure on parts of the recess, which, if you have a catch, can cause failure. If the angles are very close, most of the time it will survive the catch without having to make a whole different recess.

A skew can be used, which is pretty much a negative rake scraper. While that can work okay, the burr has no durability compared to a grinder burr, or a burnished burr. I do sharpen when dull, but prefer a 'production' edge to a finish cut edge for most uses.

robo hippy

[ron david]

do you also have different tools for different days?
ron

[Reed Gray]

Well, not really..... It still confuses me when one gouge will work fine on one bowl, but not the next. Even on bowls from the same tree...

robo hippy

[John K Jordan]

do you also have different tools for different days?
ron

Well, not really..... It still confuses me when one gouge will work fine on one bowl, but not the next. Even on bowls from the same tree...
robo hippy

Sometimes I use a different tool for different minutes. Yesterday I tried five different tools to find the one that worked best for that situation - hollowing mixed hard and soft layers through an opening wide enough to feel the inside so it needs to be perfect.

JKJ