New to cutting bowl blanks - could use some advice

[Matt Day]

A neighbor of ours recently had an Elm cut down (they were told the tree had Dutch Elm Disease) and I got a chunk of it to play with. I've done a number of projects with my lathe (Jet 1442) but never green bowl blanks so I could use some help cutting this into blanks.

The log is about 18" diameter and 24" tall, and as you can see in the attached pictures, the pith is off center (it's probably 3" off center or so). I'm not sure how to cut the log with the pith like this, so I've posted a couple thoughts. In the first picture (blue lines) I'm showing what it would be if I tried to get two equal sections. I think the problem with this would be the grain would be way off center in the bowls, but is that really a huge problem? The next picture (red lines) is if I try to keep the grain centered in the cut, which would yield a smaller and a larger cut. Which would you all recommend?

Also, with a 24" deep log (mind you the arborist cut it to this length, I would have gone more like 18" to match the diameter), and if I cut to the red lines should I cut the smaller section into 2 bowl blanks? I think that would yield 2 10" bowls or so.

Sorry for the newb questions, but I know you guys can straighten me out! (no pun intended ;-) )

Thanks,
Matt

[Gary Herrmann]

Grain won't be a problem. Cut the log according to what you want to wind up with. Consider cutting more pith out than what you've identified there. Maybe add an inch or two to the width of what you remove.

[Bernie Weishapl]

Matt if it were me I would cut with the blue line. I would then cut the log into two 12" lengths which should give you 4 bowls. I don't know what lathe you have so that makes a difference two. My lathe will turn about 15 1/2" so 18" for me would be to big so would rather get 4 medium bowls. If you have a bigger lathe such as a 3520B or a big oneway I probably would cut it like in picture two to maximize the bigger bowl blank. I also agree with cutting at least 3/4" on either side of the pith.

[John Waver]

I'm a newbie so take it for what it's worth, prolly not much. The books and videos I've seen say you should try and have equal amounts of wood on either side of the center to minimize warpage and such. So I'd go with the red or second pic.

[Terry Vaughan]

As Gary said, cut for what you want, either will work. If it was mine (I wish it was, you can't get elm here any more), I would cut the red lines and add a third cut to make the right hand block thinner, then cut the two outer blocks in half, making 5 bowls. If you are new at this, you may do better to keep away from large bowls for a bit. Until you see them spinning on the lathe you may not realise just how big and heavy the blanks are, specially if deep. The smaller blanks will seem big enough! Learn from making them then do bigger ones when you are ready.

Terry

[Faust M. Ruggiero]

Because of the pieces I like to make I would cut the red line version. I like the grain lines centered on bowls. Blue lines will force the grain pattern off center. I like the deep pieces so I have the option of coring, making deep calabash bowls, or more importantly, hollow forms. Instead of drawing straight cut lines, take a chalk and draw in bowl shapes. Then mark cutting lines to match the bowls you want. This log, obviously a huge branch, will allow you to make bowls facing either direction.
A word about summer cut elm. You will get a bath if you turn it too soon. I have left American Elm outside covered in shavings for months with no ill effects. Once the wood loses some moisture, it will turn cleaner, and smell less like a wet dog.
faust

[Brian Tymchak]

I've watched Bill Gumbine's first CD, Turned Bowls Made Easy, and he goes through this very case of cutting blanks from off-centered logs. I believe he would go with the red-lines, or at least close to those. It's been a while since I watched that video but if memory serves, as Faust mentions, this centers the grain in the resulting piece and also should help the piece dry more evenly. I believe that Bill talks about how the compression of the growth rings on the narrow and wide sides of the tree is different and will dry at different rates, inducing warp and possibly splits on blanks with a mix of the more-compressed and less-compressed rings. If you cut the blank so that the rings are most evenly "compressed" through out the blank, it should dry more evenly, since the density of the wood is more even through the piece.

I've not personally cut blanks so I can't vouch for the logic, but Bill has been doing this a long time and is well-known for the quality of his bowls, so I'm willing to give him a lot of credibilty in what he advocates. At my local Woodcraft, you can borrow DVDs, so if you have one nearby, you may be able to borrow Bill's DVD from them.

[Bob Bergstrom]

No doubt about it go with the red lines. It would be reactionary wood if cut on the blue lines and would warp to one side or crack with the uneven tension. The second piece of advice concerns the depth of the deeper blank. The deeper the bowl the more difficult it will be to cut cleanly. the gouge will have to hang over the tool rest father and be more likely to vibrate or catch. Beginning turners should not turn bowls that exceed about three inches in depth. When roughing out the deeper one just make it shallower or rip it again into two blanks.

[Marc Himes]

I like the red lines and agree with Terry that you have plenty of room for more than two bowls. 5-6 inch thick blanks can make very nice bowls. If you cut the pith out giving your self a pith containing slab 3" thick, you can cut the pith out of the center of that slab and have two smaller 24" long slabs for small bowls, pepper grinders. (to match a salad bowl out of the same wood) or other projects and still have enough wood for a very large platter 2" thick along with the bowl blanks. You have a great piece of wood with lots of possibilities. Have FUN!

[Thomas Canfield]

My rule of thunb is to remove pith slab at least 15% of diameter or here about 3", and also agree with the red line orientation for pith removal. You can then remove the pith from the pith slab and have some quarter sawn material about 6 to 7" wide x 24" long, or make the pith slab a little thicker to have more material that could be used for boxes, hollow form, or other. It looks like the bigger side could easily loose some thickness and still yield a nice bowl.

The size of the blanks depend some on what you can turn or want to turn. A 17" D bowl is big and not for everyone to use, display or store. 11 or 12" bowls are a lot more practical for most folks. I also think that depth about 1/3 of diameter works well for beginning turners to avoid what would be a deep bowl. There would be enough depth for a foot in addition to any tenon. Just remember to keep the wood sealed at all the stages to prevent checking on the end grain. You do have alot of nice wood to work with.

[Michael Mills]

Another + for the red line; both in balance of grain and in warping.
I have never cut elm quartersawn as others mentioned but I did just cut some sycamore quartersawn. About 1.5” each side of the pith will give some very nice 3" slabs of QS. A google pic search for Elm QS showed some nice patterns on some.
The large section will still be very deep and I think I would slab off another 2” for a platter (after the QS cut).
In general with an 18” diameter I would cut it 21-22” anyway to allow for cracking while awaiting turning. IF I did cut it to 18” length I would have a nice 6” section to bust out for boxes, etc.
Others asked about you lathe so it would be resized to match. You may come out with at least eight and possible more with a 12” lathe.
I have a 16” lathe but very very seldom turn anything over 12”.