Having A Ball With Volcanoes

[joe greiner]

Back in September '07, Claude (laTruciolara) presented a whimsical piece turned by Alain Mailland, with several convex "volcanoes" placed somewhat at random. See http://www.woodworkforums.ubeaut.com.au/showthread.php?t=56108 I used a more formal layout, and made the volcanoes with concave sides. Thanks for the inspiration, Claude and Alain.

This hollow podocarpus (yew) ball is 6 inches (152mm) in outside diameter. It has 12 volcanoes placed at the vertexes of an inscribed icosahedron. The valleys between the volcanoes are on a concentric sphere of 5 inches (127mm) diameter. Early on, I turned a slightly smaller piece of magnolia. Its simpler curved valley design produced small pyramids at the valley intersections. For the final version, I widened the valleys so that their far sides would intersect on the valley floor. Hollowing the practise piece also illuminated an intermediate imbalance problem. To address that, I modified the donut chuck to ride on a new steady rest. Anticipating a great number of re-mountings, I rebuilt the donut chuck to use over-center latches on pillars instead of threaded rods. I also used latches to secure the upper and lower elements of the steady rest. This was the "shakedown cruise" for the steady rest, and I'm currently making some modifications. Including drilling the initial 12 holes in the ball, I estimate the piece was mounted over 100 times. This could have been reduced by combining operations for each mounting, but processing each operation separately helps to attain consistency.

I used a 5.5 rpm rotisserie motor for finishing, with 6 coats of semi-gloss polyurethane (one coat for each separate mounting). The driveshaft is a piece of small threaded rod, with two small rubber bumpers mounted so as to ride on the sloping interior at two holes. Thus, the piece is self-centering and there is virtually no evidence of support. The rotisserie drive practically eliminates any possibility of runs or drips. The "tailstock" is just a lump of wood with a divot to engage the driveshaft.

Part 2 follows.

[joe greiner]

Icosahedron Ball, continued.

Basic turning operations were as follows:
-- Shape the valley floors. I used a parting tool as a scraper, with a cardboard template.
-- Shape the volcano sides. Because the grain direction varied every which way, I used a bowl gouge, with another cardboard template.
-- Sand the valleys to remove slight ridges and whispers of pyramids at the intersections. Grits were 60, 80, 100, 150, 220, 400, & 600. (At the time, I didn't realise I had some 320 on hand.)
-- Sand the volcano sides.
-- Cut the insides with an Oland-style boring bar with 45-degree cutter. To resist torque from the offset cutter, I attach a vise-grip pliers to the shank. The cutter hit 5 neighbouring holes in each revolution, and I had to resharpen it frequently. By the time I was done, the cutter was too short to reach the planned interior surface, so there are interior ridges under the valleys, and pyramids under the valley intersections.
-- Sand the volcano rims.
-- Sand the inside of the holes and partway into the interior. I attached strips of sandpaper to short lengths of tubing, and inserted a screwdriver to stiffen it. Better to beat up some cheap tubing than risk losing a finger.
+++ I repeated some of the operations for refinement of the surface. Also, I numbered each of the holes, and made checklists for the operations; this is the only way I could have made orderly progress.

The rubber bumpers on the donut chuck oriented parallel to the faceplate didn't work as well as expected. Although they provide reasonably good purchase and alignment (with some persuasion), they allow only one design. If I'm ever possessed by demons urging me to do something like this again, the first order of business will be to toss down a strong drink. If the fever persists, I'll remake the donut chuck into something more like a cup chuck, with some variability for mounting the ball.

Joe

[arose62]

Not sure that it reminds me of volcanoes or valleys, or icosahedrons.

Looks pretty organic to me - some complex joining of blood vessels, or an alien life form perhaps?

Very impressive! (with a spoonful of "why???")

Cheers,
Andrew

[Gra]

woah... Man

My first thought was.. you have too much time on your hands...:D

Second thought. Ouch can you imagine trying to sanding that:oo:..n My fingers hurt just thinking about it

to me it looks like a buckyball..absolutly amazing work I am gobsmacked at the talent that comes out here.. greenie fired in your direction

[artme]

is bloody amazing!!:clap::clap::trumpet::trumpet::thewave:

[Hardenfast]

Wow!! springs to mind. Talk about a little bit of every turning technique in one project!

Most impressive Joe - nice photo series. As you and Gra have said, the sanding process is somewhat daunting. Makes my segmented bowl work look easy.

Wayne

[DJ’s Timber]

Fantastic work Joe, lots a thought and planning evidently went into this. How long did it take you?

Greenie fired

[OGYT]

Joe, Just lookin' at that, I got sick, my head hurt, my eyes blurred, and my toenails curled up. Even after all that, it's still amazin'! That's some fine work, even down to the photography! I could watch you make that, and still couldn't do it. And, like DJ, I'm curious how long it took. Great stuff!

[WOODbTURNER]

Love it Joe. Great to be different. http://www.woodworkforums.com/images/icons/icon14.gif
Jeff

[Gil Jones]

Joe, it is a curious piece, and it looks very complicated.
Having held it in my hand, I am seriously impressed with your imagination and talent!! :2tsup::2tsup:

[Harry72]

Yep... Wow!
Looks like a microscopic spore of some sort.

[hughie]

Hmmm dunno how your gonna play that one :?





seriously, that is a great piece of turning, well done :2tsup:

[ss_11000]

whoa:clap:.

looks like a great science model:2tsup:

[dai sensei]

is bloody amazing!!:clap::clap::trumpet::trumpet::thewave:

:whs: I am amazed you still have all your fingers after sanding that beast.

[Skew ChiDAMN!!]

Bicarb and vinegar, anyone? :U

[joe greiner]

G'day mates. WOW! What a response! Your kind assessments exceed my wildest dreams. Thanks for all.

Hmmm. Why indeed? Mostly to convince myself I could do it. But for the past 30-40 years I've had an abiding interest in "mathematical sculptures," starting with Martin Gardner's Recreational Mathematics columns in Scientific American (Google for many of his books still in print). Currently, there's a web site named something like "Geometry Junkyard" with megatonnes of ideas.

The sanding wasn't all that scary. In pic 5 of the second post, note that my left hand is on the toolrest with all but the left index finger in safe territority. My right arm is resting on the tailstock. I pressed ever so slightly on the back of the sandpaper, and dithered the sandpaper under it to reduce extra scratches - worked a little like a belt sander. Yeah, I got bumped a few times, but nothing serious. And as I said, I improvised the tool for sanding the hole interiors. Also note that I re-mounted the piece for each operation in the pix - never sanded the whole thing at once. BTW, the latches were quite the brainstorm; if I had to do it with threaded rods I would have abandoned the project.

So, how long did it take? I didn't keep precise records. I turned the blanks (the magnolia and the podocarpus) in late October '07. By 4 November, I'd turned the spheres and drilled both, and completed the magnolia practise piece (hollowed only three holes - the imbalance was too severe to proceed further). I reckon I had about 12 hours invested by then. Between then and late January '08, I modified the donut chuck and built the steady rest. The steady rest is general purpose, so that shouldn't count. I reconstructed the time line between 27 Jan '08 and 3 Feb (USEST times and dates) by examining my diary and the dates of some more WIP pix. Looks like about 24 hours for that interval; the finishing was only a few minutes every half-hour or so - the rotisserie did the rest of the work. All told, about 40 hours I guess, although I've probably underestimated.

Some details I omitted: The thickness is about 1/4 inch (6mm). The layout itself was a bit of an adventure. There are formulas relating the centre distances to the radius of the circumscribed sphere, for all sorts of polyhedra. Basically, you select a starting point, and swing arcs to create a triangular array on the surface. With luck, the final swings will land at a single spot on the far side - Nope; ain't gonna happen; so you fudge some of the points as needed. Try laying out a large triangular array with compass alone on flatwork if you believe otherwise. A few more oopses came from breakouts. On the hollowing work, there was a faint amount of wobble and I allowed the shank to touch the back side of the hole. Luckily, the breakouts were in one piece each and they weren't too hard to find for gluing back in. Example pic attached.

Thanks again for your generous comments. Now to turn a few Q&D weed pots for therapy.

Joe

[TTIT]

Wow - that's dedication Joe! Very impressive bit of work :2tsup:

[ticklingmedusa]

Very impressive Joe.
Reminds me of some organic form... larval sea urchins maybe.
Well done.
John

[wheelinround]

:hooray::wave::way2go:

One should bow in the presence of greatness well done Joe

[joe greiner]

Thanks, Vern, John & wheelin. A high-res pic has just been posted at http://n-fl-woodturners.org/images/2008-02/2008-02-08.jpg

Joe