From Tree to Table, Part 4: Turning a "Green Wood" Bowl

In the preceding parts of this series, we talked about bowl turning techniques that result in the perfectly round  wooden bowls most favored by woodturners today and, perhaps more importantly, by those who purchase their wares(!).  We talked about identifying downed trees most likely to yield usable bowl blanks, how we go about extracting those blanks from the tree, rough-turning and drying our bowls, and finally finish-turning.

But today we are going to talk about turning a bowl from the blank just as it comes from the tree all the way to completion in one fell swoop!  Although we will go into the history of bowl turning in Part 5, it is interesting to note that until the last 50 years or so, wooden bowls were almost always turned to completion from "green" wood.  So, in a way, we're going back in time....

Turning green wood uses almost exactly the same techniques (and safety precautions!) we employed previously. But this time, we will try to anticipate how our bowl will warp and twist as it dries - and adjust our design and embellishment approaches to make that warping and twisting work to our advantage.  We hope (!)

Our first decision is to decide whether we want a "cut-rim" bowl, as described earlier and shown at the top of this page, or a "natural-edge" vessel like the red oak piece on the right, where the bark - or the wood immediately below the bark - forms the rim.  Intended use is our primary consideration, because if we plan to leave the bark in place, the finished bowl almost automatically becomes decorative "art" rather than a utilitarian vessel. (Bark being very fragile.)

That decision made and because our bowl will start to dry while it's being turned, we need to be sure we have enough time to complete our bowl in one session.

Just as described in Part 2, we fix our blank to the lathe and rough-shape the exterior.  (Note that we have not yet completed the exterior shaping.  That comes next.)

At this point, we reverse our blank in the lathe so that the top of our bowl faces away from the headstock. (Several techniques can be employed here.  Each has advantages and nuances that are beyond the scope of this post.  As before, I refer you to the many books on the subject of bowl turning, if you would like further information.)

With the tailstock still in place for safety, we refine the exterior.  We wait until now to refine our exterior for two reasons: first, because of almost certain miss-alignment when we reverse the bowl and secondly, because our bowl has started to dry and is no longer perfectly round.  We expect our bowl to warp and twist over the coming weeks as it dries, but we do need a round exterior at this point so as to be able to apply whatever decoration (beads or coves) we might wish to use(see footnote.)  Once our bowl is again running "true," we take a fresh (read very sharp) bowl gouge and make a series of light cuts to remove any remaining tool marks, along with any grain that might have "torn-out" during the roughing process.  Once the surface is as "clean" as we can get it, we now sand our exterior very lightly with a foam- or sponge-backed sanding pad (or power sander.)  The key at this point is to minimize pressure, friction and the accompanying build-up of heat, which will only hasten the drying process and give us a less-than-satisfactory result.

We next re-sharpen our bowl gouge and hollow-out our interior.  Timing is now especially critical, because our bowl is drying very fast and starting to warp.  Again, I will refer you to the above-mentioned books for specific techniques, but our objective is to hollow-out our bowl as quickly - and SAFELY(!) - as we are comfortable doing.

Once we have the interior shape and wall thickness to our liking, we again take a freshly sharpened bowl gouge (or specially designed bowl scraper) and clean-up any interior tool marks or torn grain. (We can now apply any desired interior decoration as well.)

As a next-to-final step, we finish-off our base using an appropriate technique (see reference books for ideas - of which there are many.)

Lastly, we apply a liberal coating of pure walnut oil and wrap our new bowl in a paper bag for a week or two to control the initial drying.  At the end of that time, we set our new masterpiece in a reasonably controlled environment to enjoy as it completes the drying process.

Again, I thank you for your attention.  Woodturning techniques are not "etched in stone."  Each craftsman (or -woman) varies these techniques to suit individual style or preference.  And so I invite you to post any questions, comments or suggestions.

Next time: A Brief History of Woodturning.

Until then....

Footnote(1): Depending on wood species, the amount of moisture in the wood, and how we oriented our blank on the lathe, our bowl can be expected to warp in either a nice symmetrical pattern - or a wavy asymmetrical manner.  Both can be quite beautiful.  So we want whatever decoration we apply to accentuate or compliment the final shape.  (For example, the red oak bowl shown above was formed with two fairly dramatic exterior coves, which accentuate its now mildly oval shape.) 

Sometimes you Win, Sometimes....

Planned to come home with a truckload of bowl blanks today.  At least that was the plan.  As it turned-out, most of the wood was either too small  to make salable bowls (i.e., less than 12 - 14" diameter) or too far gone to be of use.  In any event, Quiet Valley Living Historical Farm got a nice load of firewood for their summer educational programs. So the day turned out well, even if not completely as planned.

The Culture of "Cheap"

Every so often I run across a piece so timely and  brilliantly written that I'm just blown away.  Megan of CraftMBA.com writes a blog that carries not one, but several such pieces.  I would urge you to check out her blog - and particularly her post on "Etsy and the Culture of Cheap" at http://bit.ly/7U0WcO.  Let me hasten to add that I do like Etsy and maintain a shop there.  (Full disclosure: Etsy is my e-commerce portal - so....)  A great read - Enjoy! 

From Tree to Table Part 3, Finish turning

Having spent the last week building and publishing my new website, which I hope you've had a chance to look at, I'm running a bit late on this series.  With that said: let's fast-forward 6 - 12 months from where we left off in Part 2.  Our rough-turned bowl is now dry and ready for finish-turning to complete our project.

But first let's look at our rough bowl.  It's certainly very different from when it came off the lathe so many months ago!  In fact it's barely recognizable!  It's warped, twisted, gone oval and done other weird things - all of which need to be fixed before our bowl can be used or sold.

Our first task is to re-mount the bowl on the lathe.  We also bring-up the tailstock to ensure that our bowl doesn't become an "unguided missile" as soon as we make the first cut. (Which can be a little hard on the bowl - not to mention anything (or anyone) that/who happens to be in its path!)

As before, we rotate the bowl through a full 360 degrees to make sure everything is clear- and that nothing untoward will happen when we start turning. We can now power-up the lathe and adjust the speed so that everything's running smoothly.

Using our bowl gouge, our first cuts true-up the rim.  Next, we true-up the exterior and establish its final shape. Then starting at the top/rim, we work our bowl gouge down toward the base.  It takes several passes, but the outside is now round and we're happy with it.   A couple more light scraping passes and the outside is smooth and ready for sanding.  This we do starting with 150 - 180 grit and proceed through 400 grit sandpaper.

We next re-sharpen our bowl gouge to ensure clean cuts, remove the tailstock and start our "inside" work.

As before, we work our bowl gouge from top to bottom to establish a clean, round surface.  With that done, we cut a slight bevel into the rim and then slightly undercut the rim.  This gives a good firm place to grip and makes carrying the bowl much easier - especially when it's full!  Continuing our undercut, we want the thinest point of the bowl about 1/4 - 1/3 of the way down, then gradually increase the wall thickness so as to lower the center of gravity ensuring a stable vessel. Again, we sand down through 400 grit and create a smooth interior surface.

Now, borrowing technique from old-time gunsmiths who needed a glass-smooth finish on their gunstocks, we spray the entire bowl with a light coating of water to raise the grain.  We sand off the raised grain with 400-grit paper and repeat the process 2 - 3 times - or until the grain no longer raises when wet.  We can now move on to 3 grades of non-woven abrasive pads (think nylon scouring pads on steroids!), which remove the last of the micro-scratches and burnish the wood to a soft satin luster.

We now reverse the bowl on the lathe and finish the foot/base. Our bowl is ALMOST done!  We can now sign and date the finished bowl and note the wood specie for posterity.  The final step is to soak our finished bowl in pure walnut oil, which penetrates the wood, then hardens (polymerizes) to form a durable, food-safe finish.

After soaking for a couple hours (or overnight), we remove it from its walnut oil bath, wipe off the excess, and set it aside in a warm space for a few days to allow the oil to polymerize.  At the end, we have a piece that, with reasonable care will last for generations! (Good thing given the amount of time and effort we've invested!)

I hope you've enjoyed this series so far.  Please feel free to add any comments.

Next time, we'll look at turning a "green" bowl to completion and finally delve into the history of bowl turning.   Until then...

P.S. Blatant Commercial Plug: You can easily get past all the work described above by buying a finely crafted bowl from me.  Check out my website link on this post!

Woodturning Demo on 1/26

A quick note to all N.E. PA woodturners:  I'll be demonstrating creating my "Acorn Series" lidded boxes at the next meeting of the Lehigh Valley Woodturners on Tuesday, 1/26 at the Allentown Woodcrafter's Store. A great group of folks, as well!  Come on out if you're in the area....

From Tree to Table, Part 2 - Rough-Turning

In our last post, we went through the initial steps of creating a wooden bowl that, with proper care, will last for generations.  We selected the parts of the tree most likely to yield the best bowl "blanks" and cut those blanks to maximize both beauty and longevity. 

In this post, we explore final blank preparation, mounting the blank on the lathe, rough-turning it into basic "cut-rimmed" bowl and setting it aside to dry before re-mounting on the lathe and turning it to its final dimensions.

But before we continue, a word from my legal advisor: As discussed previously, lathe-turning is inherently dangerous and should be NOT undertaken without proper instruction, experience (i.e., knowing your limitations(!), and adherence to the rules of lathe safety.  (The American Association of Woodturners provides a practical set of lathe safety guidelines at http://www.woodturner.org/resources/safety.cfm.  A good read!)  That said: the following is provided for your information only.  Because of the many variables involved, I assume no responsibility for any incidental or consequential damages that might be suffered as a result of your attempting to duplicate these steps.

Now on with the post....

Our first objective - and one of the most important - is align the blank so that the wood grain is centered in the bowl.  We accomplish that by laying the blank on our bench with what used to be the center of the log facing up.  We then use a compass to draw a circle around the most interesting part of the blank, which describes the basic bowl.  We want the circle as large as possible while staying within the boundaries of solid wood.  (Depending on the species, we may - or may not - include sapwood in our bowl.  For lighter woods like ash and maple, I like to include sapwood, but for dark woods like walnut, I stay within the heartwood. The white ash bowl on the right is a good example of what we're looking to achieve.)

We next round off the portions of the blank that fall outside our circle. (Note: this is another "do not attempt without proper training, experience and following appropriate safety rules!" Cutting green wood - and especially THICK green wood like a bowl blank - requires a somewhat different set of skills and precautions.  Be safe....)

We now mount our rounded blank on the lathe and bring up the tailstock to ensure maximum support. (We use a threaded cast iron fitting called a "faceplate" to affix our workpiece to the lathe because it provides the most secure means of affixing large and/or out of balance workpieces.  Other woodturners, whose opinions I respect, use different techniques, but we will stick with this approach.)  With the workpiece mounted on the lathe, we rotate the workpiece by hand to make sure it clears the toolrest, toolrest holder, lathe bed - and double-check that there are no loose objects that will go flying around when we power on the lathe.  (Don't laugh - it's happened!)  We start the lathe at its lowest speed setting and adjust the speed to the point where the lathe is running smoothly.   

Using our bowl gouge, we turn the exterior of the bowl into the approximate shape of our finished bowl.  Because in this example, we are only want a rough-turned bowl that will warp and distort as it dries, we aren't too concerned about achieving a perfect shape or finish.  We will address final finishing in our next post.  (There are several techniques that can be employed here - all are beyond the scope of this post.  Distinguished turners like Richard Raffan, David Ellsworth, Mike Mahoney (and others) have books and videos that drill down on these techniques, if you have an interest in pursuing.  Full disclosure: I have no commercial interest in any of them.)

Once the exterior is done, we reverse the bowl on the lathe and proceed to hollow out the interior.  Our objective at this point is to achieve a uniform wall thickness that is approximately 10% of the total bowl diameter.  (For example: a 12" bowl will have about a 1-1/4" wall thickness.) That leaves enough material to allow for final turning while providing a consistent surface area that minimizes the risk of cracking during the drying process.  (Again, there are several ways of hollowing-out a bowl - see Raffan, Ellsworth, at al. for further information.)

As final steps, we write the wood specie and today's date on the bottom of our bowl, apply a liberal coating of "Anchorseal(r)" or an equivalent coating to control the drying process and set the piece in a climate-controlled space for 6 - 12 months to dry. (Again, there are innumerable techniques - and variation of same(!) - for drying rough-turned bowls.  The above folks discuss at length.  Enough said....)

Well, if you've stayed with me this long - congratulations!  I hope you have found this informative and at least mildly entertaining!

Next time: Finish Turning.

Until then....

From Tree to Table, Part 1 - How it Begins

A well-designed, superbly-turned wooden bowl - be it a large salad bowl or a small candy dish - is a unique and often treasured possession.  But what went into its creation?  How did it get "from tree to table?"

My idea for writing this series is to explore how that metamorphosis comes about.   This first post talks about what happens when a tree is taken (or comes) down, how wood is selected for bowl turning, and how we go about forming a bowl "blank."

In later posts, we'll talk about rough-turning that blank into a basic bowl form that can be set aside to dry without (hopefully!) cracking or splitting in the process.  We will talk about "cut-rim" versus "natural edge" and "green" v. "twice-turned" bowls.  And we will also delve a little into the history of bowl turning. How bowls were made before 220-volt, 3-phase power became available!  Finally, we'll talk about "finish turning" and my thoughts about proper bowl finishes.

So lets begin.

Bowl turning is a large subject and the techniques I will focus on are the ones that work for me after watching and studying others, applying years of practice (and, in the process, cranking-out literally tons of  sawdust), and making LOTS of mistakes.  Others may do things differently.  That said (and this is where my lawyer starts talking): if you are a bowl turner - or have any ideas of becoming a bowl turner - be aware that wood turning, chain sawing, and all related activities are inherently dangerous!  That danger includes significant risk of injury or even death to the operator and/or bystanders.  The activities described herein should NOT be undertaken without proper instruction by a qualified teacher and appropriate experience.  I assume no liability for incidental or consequential damages or anything else that might occur as a result of anyone's trying to duplicate what I describe in these posts.  (Translation:  I presume you're a competent, responsible adult.  Be safe.  If you're uncomfortable, nervous, tired, taking medication, or in any way impaired or distracted, STOP - go do something else.)

Now back to the story.

Living in the mountains of Northeastern Pennsylvania, I'm fortunate to have an abundant supply of ash, cherry, elm, maple, oak. walnut, and other hardwood trees that is perfect for creating wooden bowls that can last for generations.    Every year, hundreds (if not thousands) of local trees are toppled by forces of nature or cut for urban renewal and other reasons.  So, it's basically a matter of being in the right place at the right time to rescue one of these magnificent creations that would otherwise be left to rot or cut-up for firewood.

So what happens when we find a downed tree?  The first thing is to obtain the landowner's or township's permission to work on it.  (We value the rights of others, and will not trespass on another's property without the owner's consent.  Most of the time, the owner (or township) is delighted to have us haul away the downed leviathan!  But we do need tah ask(sic!))

Next, we examine the main trunk.  We want solid wood at least 14" - 16" in diameter (and larger, if possible) with no visible rot or insect infestation. We also look at crotch pieces where two or more large branches split off at the top of the trunk.  These intersecting pieces are usually incredibly strong and often contain interesting grain patterns that yield spectacular bowls!  Sad experience, however, has taught us to avoid nails, barbed wire and other visible foreign matter that can ruin an expensive chainsaw or lathe tool.  We also stay away from limbs.  Because of the forces exerted on them while the tree was growing, limbs seldom make satisfactory bowls.

We next cut the trunk into pieces that are about as long as the tree is in diameter at the point of each cut.  So if the tree is 20" in diameter where we're cutting, we make that piece 20 - 21" long.  The length of the pieces will naturally decrease with lessening diameter as we work up the trunk.  Thus, the next piece might be 19 - 20" long and so on.... These days, for reasons we'll discuss later, we seldom bother with pieces less than about 12" in diameter.

Now that the tree is "sectioned," our next task is to cut each section in half lengthwise to remove the pith and create the beginning of a bowl blank. (We avoid cracks at all cost and the pith is where 99% of cracks start.)   The pith will often already have a longitudinal crack, so with the piece still on its side, we carefully align our saw with those cracks and execute a longitudinal "rip" cut about an inch outside the pith (or whatever distance safely clears any cracks/checks radiating from it.)

If we did this right, we now have two half logs that are ready to be turned into bowl blanks.  This last step can be accomplished in one of two ways: either by using the chainsaw to round-off the corners or - for smaller pieces - by transporting the half-logs back to the shop/studio and using our bandsaw to create a circular "blank" ready for mounting on the lathe. (In most cases, the larger pieces will also need to be "cleaned-up" on the bandsaw to ensure a reasonably well-balanced blank suitable for turning.)

We repeat these steps for every section of log and haul our blanks back to our shop/studio.  After unloading and setting our bowl blanks in a cool, shaded place - out of the sun and away from any heat source, we take a well-earned rest!  (But not for long.  We've got to rough-turn our blanks before they have a chance to even THINK of cracking!) But that's the subject of our next post.

Until then....