Thursday, July 24, 2014

Bowls & Bowls: when to stop turning

Hi Everyone,

I've been out of the shop for a while and I've just gotten back into the shop this morning. I'm working on two bowls right now-the pecan bowl, which I've blogged about earlier this year, and a laminated bowl out of white oak and jatoba. Both of these bowls are large bowls and I've worked on them several times each. The big question for today is when to stop turning and shaping the bowl and move on to the finishing process.

For me this question revolves around three aspects of the bowl: the volume of the bowl, it's overall appearance and "feel" of the bowl, and it's intended function. Let's take a look at some photos and I'll try to explain.

The Pecan Bowl

It's a nice day for turning and so I decided to take the pecan bowl out of it's paper hideaway and work on it. And I was very happy with the resulting bowl in the photo below. It didn't crack or radically distort while drying and it's very light in weight so it was time to finish it up.

The light weight of the bowl tells me that it's lost a lot of moisture and when a bowl does that it shrinks and it will usually shrink unevenly horizontally and to a lesser extend vertically. While this bowl shrank only a little and looks round, turning on the lathe showed that the dimensions of the bowl are not equal horizontally-ie the diameter is unequal so it's actually slightly oval rather than round in shape.

So what to do about this? I could turn the inside of the bowl but that will result in the thickness of the sides being uneven. I could also re-turn the outside of the bowl (see the next photo) but that would result in the sides being a little too thin. Thin sides can result in the bowl distorting a lot or even cracking. And if the bowl were ever to be dropped, it could break:

So I decided to stop turning the bowl and begin the finishing process on it instead. The sides and bottom are even in thickness so any further drying of the wood should happen more or less evenly and this in turn will keep the bowl from distorting. Also the bowl's appearance is not adversely affected by this. It looks very nice and it has a nice substantial feel and weight to it. And as the bowl is large the volume is appropriate so it can be used for salads, fruit, or other kitchen/food serving activities. So I think the turning phase can stop and the finishing phase can begin.

So I've begun sanding and smoothing the surface. As the bowl is oval, this means that sanding it on the lathe will result in areas of the bowl being sanded smooth and other areas being left rough so this will require a lot of hand sanding off of the lathe. Don't look for this bowl to be finished quickly but when it is finally done, it will be a really lovely bowl that will serve someone for many years to come:

Laminated white oak and jatoba bowl

Laminated bowls are a different story as they don't have to go through the long drying-turning-drying process that solid block bowls do so the distortion issues don't occur or if they do it's minimal. This is due to the fact that the lumber used for these bowls is kiln dried to begin with so the over all bowl is very stable. But the same set of questions still applies here-when is the turning finished?

For this bowl, the volume is large and will readily hold any kind of food placed in it. And the appearance is fine as well. But it does have thicker than usual sides and bottom and I'm going to leave this as is and not turn it further. It has a nice weight to it and overall I'm pleased with the appearance.

I think another turner might feel differently about this and turn the inside of it more and I agree that the bowl could be hollowed out more but I'm happy with it. It's important to remember that I (and you if you're a turner) is the only person on the planet that knows exactly what the finished bowl is supposed to look like and feel in your hands and when you've reached that point, then it's time to stop. I find that if I try to exceed that point, that's when problems like getting a catch or excessive vibration with resulting tools skipping across the surface begin to happen. So when I feel I'm getting close to that point, I stop, take it off the lathe and cogitate about for a couple of days. Then I make the decision whether to go on or not:

So all in all, I'm happy with the way these two bowls are coming out.

And Angus the shop squirrel paid a visit so this has to be a good sign!

I have a whole bunch of jar lids to finish and then I'll do a brief posting about those. See you soon.


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