Coring system candidate...

[Brent Grooms]

I took some time today to get into a chunk of oak log that I was given a year or two ago and to my surprise... all of the sapwood had spalted!

Now, my idea is to get 2-3 natural edge bowls out of these blanks so that they have a ring of spalt around the tops. How big does a blank need to be to get some use out of coring?

I did do a search and see some of the differences between a Oneway and A McNaughton... but nothing seemed to address the blanksize.

Any advice?

[Jack Mincey]

The depth of your blank is very important when coring. I can get 4 bowls out of a 12" blank if it is deep enough. I usually cut the blank 2 or 3 inches deeper than needed just to make sure I don't make a funnel. You can always get a nice finished edge bowl from the bottom if you have the depth to work with. I use the Oneway system to core with. If you have a round burl to work with you can get another bowl or two from the same diameter blank since the round bark edge gives you more surface on the top of the blank to work with.
Jack

[Reed Gray]

Brent,
Sorry, but I was out of town for a week. Both systems will remove cores as big as you want up to about 18 inch wide blanks and 8 or more inches deep. The biggest difference, as far as shapes go, is the Oneway is set up more for standard bowl shapes, while the McNaughton will do them as well, and is more adept at coring cone shaped pieces, or more flat forms. The McNaughton has a learning curve, while the Oneway is pretty simple to use.

robo hippy

[David Foshee]

I have the Oneway system and like it. simple to use like others have said.
Each knife has a range of diameters that it will cut. I think the ranges are listed on the oneway site.

[Brent Grooms]

The blanks in question are ~13in dia and about 6in +/- thick at the moment. Right now I am planning on attaching a glueblock to save as much depth as possible. When I have time, A local club member has offered to help me with his McNaughton. It winds up being a really good offer as he has a PM lathe as well.

Any tips or other advise in dealing with this. My initial thought is to core the center first and go from there. Good idea/ or bad? Any suggestions on setting up the core cuts /suggested core thicknesses?

[Ryan Baker]

Everybody has a little different method they prefer for making such cuts. The problem with going from inside to outside (when you are trying to maximize the number of cores, and especially if you want to end up with a nested set instead of individual bowls) is that you will probably not end up where you want to be for the last bowl. You can maintain the size steps better if you work from outside in. There are advantages and disadvantages to both methods. You can even use the Mike Mahoney trick of cutting the grooves from outside in to get the spacing you want, but only cut about 2/3 of the way down. Then come back and finish the cuts from the inside out. That may save some rechucking.

If you are working from outside in, it helps a lot to start by making a small tenon (or recess) in the top center to make it easy to rechuck that center "core" to turn its bottom. If working from the inside out, a vacuum chuck can be really handy.

Thickness is mostly a question of your skill level with the coring tool in question as well as whether you plan to turn to final thickness or dry and return later. Turning to final thickness is often the best path in cases like this. Obviously, the cores will have to be considerably thicker if you plan to change the shape any from the simple radius of the coring tool.

I usually find that it is the thickness of the blank that will limit the number of cores more than the diameter. You will usually run out of thickness and the center cores will start turning into saucers. Especially if you decide to cut your cores from center outward, make sure before you start that you aren't going to run out of depth before you get to the large cores.

[Bernie Weishapl]

I have the oneway system and love it. I watched Dave Lancaster do a demo on coring with it. I core from inside out as he suggested. That way everytime I core I don't have to make a tenon on the next bowl down. I make one tenon on the big bowl and the rest I make the tenons after they have dried and returned to the lathe. Haven't had a problem so far.