Read, do, re-read, do…

“The lesson will be repeated until learned.”  That’s the theme of my recent foray into segmented bowl turning. I just had my third disaster at the lathe (for those that are counting, that’s 3 of the most recent 3 bowl projects) making exactly the same mistake as I’d made the first and second time. Does this qualify me as learning disabled?

I posted a short video in my last blog entry illustrating the problem – I made a heavy cut using a chuck (a device for holding the workpiece on the lathe) intended for light finishing passes. The wood is held on largely by friction against rubber stoppers, and any significant shock will tear the workpiece from the chuck. The first time I made this mistake, the bowl shattered. Episode #2 (in the video) resulted in a gluable crack, but the bowl was saved. Episode #3 (yesterday) was only on a ring segment to a bowl, but the ring was large and thick, spun off directly into my face (yes, I wear a face shield for a reason) before hitting the floor and shattering into 3 pieces. I’m pretty sure I can re-glue the segments without obvious flaws, but that’s yet another side-track on this project.

So why do I keep making the same mistake?  Obviously, the lesson hasn’t sunk in, although I’m hoping the 3rd time is the charm. What has struck me, though, is that all of the bowl turning guides essentially warn against this, and I’ve read them all diligently. Book learning was clearly insufficient to prevent this error, and even repeated experience required, well, repetition.  But now when I go back and re-read the wood turning books, the wisdom in their recommendations makes sense in a way it couldn’t have without these disasters under my belt.

My bible for this project (The Art of Segmented Wood Turning by Malcolm Tibbetts) suggests building up projects from bottom up – true the bottom, glue on a ring, true the ring, repeat.  This keeps the working surface co-planar with the bottom and other rings (as opposed to the method where all the rings are flattened on a sander and glued up in a bunch, as I’ve previously done). I fully intended to use that method on this bowl, but somewhere in my excitement to “keep moving” I decided to flatten the main middle ring separately, and that’s when disaster struck.  Using Tibbetts process, the bowl is very securely chucked with proper fastening – using my “modification”, the ring is only attached with a friction fit, and as I realized in the post-mortem, wouldn’t necessarily be flush against the plane of the chuck, anyway.

Enough of the wood turning technicalities. I’m starting to think about instructional guides and their proper use. I have a colleague who is taking an advanced statistical methods class at Stanford, that on the one hand should be “review” for techniques we’ve all been practicing for years, and on the other is intended to revisit them at a deeper level and highlight some of the essential errors and misconceptions we may be unconsciously carrying forward.  I studied under the same professor and encountered many of the same ideas in my first or second year of graduate school, before I had any real-world experience in statistical modeling. While I could follow his reasoning and nod my head, I didn’t have any context for understanding why these were so important (or just not patently obvious). It wasn’t until I’d been practicing in the field for several years that I saw the seduction of statistical shortcuts or the social pressure to use methods that “everyone else thinks are valid.”  Now I can look over my colleague’s shoulder and have a renewed appreciation for what the professor was trying to impart. This wisdom went over the heads of most of his students, not for lack of ability on the part of student or teacher, but because the students simply hadn’t had the years of experience to deeply appreciate why these concepts were so important.

Experts who write textbooks and instructional manuals have the benefit of hindsight – having traversed the ground and scouted out the best routes, they are ready to provide a trail map to the uninitiated. And this is a reasonable approach based in a desire to be efficient – a student should not have to repeat years and years of trial-and-error that the original researchers encountered on the way to enlightenment. My experience as both a self-taught and instructor-taught guitarist has confirmed what a friend once remarked: you can teach yourself the guitar, but you’ll progress 10 times faster if you have a good teacher.  I’m not dismissing the value of instruction.

However, there is an issue of timeliness – when is a student ready to benefit from instruction? I don’t believe this is a linear sequence – my experience with the bowls shows that reading, practicing, re-reading, practicing, etc., seems to be a proper rhythm. This is the basis of what educators call the spiral curriculum – ideas are re-presented cyclically in a deeper and more integrated fashion as the student progresses in his or her learning. So I first learn about chucking wood on the lathe by reading about devices – screw chucks, face plates, 4-jaw chucks, and the like.  I also learn some basic safety rules for using them. Then I go off and work, and eventually violate one of the rules.  Wham!  Wham! Wham! Three disasters later, I’m ready to go back and re-read what each of these chucks can be used for, and in particular I’m highly motivated to understand their limitations.

At a macro-scale, our education system is not well-suited for the read – practice – re-read cycle. Some of this is due to simple age constraints – if we decide that kids can’t do much useful outside of school for their formative years, perhaps we’d better keep them constantly supervised in “productive” learning environments (not that I’m agreeing or disagreeing with this sentiment – just reporting what I observe). But for adolescents and early adults this argument starts to make less sense. Why go through four straight years of undergraduate work when people are still trying to figure out “what works” for them dispositionally, intellectually, and avocationally?  Why not attend, say, a year or two of “foundational” higher education, and then go work for a while, and then come back and continue education when one has proper practical insight and motivation?  Again, I fully understand the practical constraints – it’s hard to interrupt one’s work/career to go back to school full time, there are financial constraints, wouldn’t we just prolong a period of delayed adolescence, etc.  But our current system of 4 continuous years essentially force-feeds a wonderfully rich meal to youth, and hopes that they’ll be able to digest the bulk of it over time, such that years later, they’ll look back and appreciate the value of what they were exposed to, even if they couldn’t fully fathom it at the time.

Just a thought… I wrote a few more paragraphs about the origins of higher education in the US, but then erased them. I was going too far afield for a single posting. For now I’ll just let this basic idea cycle through the back of my mind – the dynamic of reading/doing (and for many, the third leg is “teaching”). Read/do/teach/do/read/do/teach/do….  Time to re-read and repair my bowl and try again.

Happy New Year!

Wow, I’m taking way too long between posts. Just when I think “I should sit down and blog…” something distracts me. Not that I’ve made any “New Year’s Resolutions,” but I’d like to get into more regular writing.

Woodshop news: after winding down from the craft fair I did make a couple of tongue drums, for my nephews and a friend’s child. They were big hits, and I look forward to adding them to my repertoire in the future.

I took some time off over the holidays, and then started tackling the chairs to go with my dining table (yes, there are still touch-ups needed on the table…). Then I had a table saw mis-hap. The table saw is the freakin scariest piece of equipment in the workshop, bar none. It’s not just the blade itself, but it’s the fact that the blade rotates so that the cutting part (top and leading edge) are rotating directly back at the operator. If you drop a block of wood on a spinning naked blade it will shoot back with the force of a cannon shot. When ripping wood (cutting lengthwise) on the tablesaw there’s always the chance that a slight bend or twist will press the wood into the back of the blade, which is on its upward path. This lifts the board up and hurls it back – known as a “kickback.”

Fortunately, this wasn’t so bad. I did violate one cardinal rule, and got what I deserved. When a piece of wood is cut and doesn’t pass completely out the back of the blade (sometimes the offcut just “hangs” there on the back of the table), you should turn the machine off and wait for the blade to come to a complete stop before moving the wood. I didn’t. I know to be careful to not let the wood swerve into the blade, so with the saw still running I stepped in back and gently tugged the 2 foot piece of off-cut through that last couple of inches past the blade. I was never in danger of being cut, and was out of the path of the wood should it go flying. What I didn’t count on, though, was that moving the wood nudged the plexiglass blade guard into the path of the blade, and a tooth caught the guard. What happened next was truly amazing. The guard literally tore in half – the blade didn’t even have time to cut it, it just grabbed the guard and tore it up. This also pulled the splitter (a piece of metal right behind the blade designed to help prevent wood from swerving into the blade in the first place) out of its fastener and right into the blade, stopping the blade instantly. When I realized what had happened I turned off the motor (it was “humming” but not turning) and inspected the damage. Two carbide teeth from the blade had broken clean off, the splitter had a gouge in it, and the guard was a piece of junk. I’ll include photos – maybe – next time just to remind myself not to be an idiot again.

So, lesson learned: safety rules exist for a reason. I thought the only danger was kickback, and yes, I was very careful about how I moved the wood. To be honest I’m not entirely sure how the guard wiggled enough to touch the blade. It may have been loose to start with (in which case I actually did myself a favor by being on the other side of the table when it cut loose). At any rate, from now on I will always turn the machine off before making any move to remove offcuts.

I’ve got an order in for a replacement guard from a guy who’s making them in his own shop – it comes with an easy-to-remove splitter (the OEM version requires using a wrench in a tight space). I’ve had to remove the splitter/guard lately to make some special cuts for my chairs (yes, there are alternative “guards” in place to protect hands), and the problem with the OEM splitter is that most people, after removing it, don’t put it back on because it’s such a pain in the butt. I did some research on alternatives, and hope the Shark Guard pans out. I’ll keep you posted.

Oh, and I needed a new blade, too. I’m trying a Freud general-purpose blade (10″ 50T) and so far it has cut like a dream. Freud blades have a great reputation in the biz.

The chairs! I’m trying a pair from this Popular Mechanics plan. I’ve got the pieces cut out, the mortises drilled, and after a little more cleanup on some of the tenons, I’ll be ready to dry fit one. The anxiety-producing part is that this is my first chair, and I’m cutting pieces in their directions on blind faith it’ll all come together correctly. In a day or two I’ll discover whether I’ve made an error in measurement, or where joints aren’t fitting. The problem is I don’t have enough experience with chairs to know where there can be some wiggle-room with fit, and where perfect fits are required. I strongly suspect there is very little room for error in chairs, because they take such a variety of heavy loads and are moved around a lot. I’m sure there will be lots of lessons learned here. 🙂

That’s it for now. I’ll try to post more regularly in the future!