Saturday, September 20, 2014

A Palm Tree Sculpture

This has been a really busy summer.  I have had little time to think about writing.  When I haven’t been in the studio working on sculpture construction I have been working on design for other projects.  I just finished a couple of projects and felt I should get some notes written about them before the details slipped away.

I finished a coconut palm tree sculpture which was to fit in a space about seven feet tall and thirty inches wide.  The client sent me several images of the space in their gulf coast residence.  Living in Kansas, I don’t encounter coconut palms on any regular basis, so I had to do some research to see how I might interpret that botanical motif.

Since this was to be mounted on a wall and could not really project out into the room and obstruct traffic, I needed to work out a rather flat presentation.  Also, I decided, early on, that it would involve hollow forming to reduce weight.  I decided to make the trunk a half-round form so the back would be flat on the wall with a keyhole slot for hanging on a lag screw.   At the bottom would be another hidden screw hole so a long utility screw could be inserted to prevent the piece from rotating around the hanging point.

Another interesting challenge was my decision to make the piece a modular construction so it could be disassembled for shipment and reassembled by the client with little effort and no confusion.

The finish was to be “black iron” so I decided to work with the materials I use the most - 10 to14 gauge HRS and hot rolled bar stock.

I first made my drawings and worked out the proportions and dimensions for each part.  The next step involved deciding how the main components, trunk, fronds and coconuts would be rendered.  I try to design as much as I can to utilize the power hammer and hydraulic forging press as much as possible to avoid physical wear and tear on my body.  The hammer and anvil work is the most pleasurable but takes it’s toll.

I began by working on the trunk and calculated what width of flat 14 gauge sheet I needed to end up with a half-round form of proper width.  I found that width would be 4-6” depending on the section of the trunk.  I could comfortably work a length of sheet up to about 30”.  I wanted the trunk to have a slight taper and a slight undulation.  I ended up with three sections to work with; a short wide section for the base flare, the lower trunk and the upper trunk leading into the terminal bud where the fronds emerge and the coconuts form.

Each piece of sheet was vertically textured with coal fire heat and a bottom texture die in the power hammer.  To create the irregular transverse raised lines of the frond scars I made a set of dies for the press.  The third step was to produce the cupped volume.  I used one of my cupping dies in the power hammer for that.  Finally, I joined the three half-round trunk pieces by MIG welding.

I had the back face outline cut by water jet from 10 gauge HRS and added the keyhole slot by drilling torch cutting.  The touch marks were added at this stage on the back.

The, potentially, most difficult job is to get the cupped face welded to the flat back without adding twist to the back.  In retrospect I probably should have provided more internal bracing to the back plate.  I did end up with a little twist.

With the trunk completed I turned to the coconuts.  I made them using three different methods before choosing the easiest.  That involved forging one solid steel coconut and getting that form just as I wanted it.  From that master I made a coconut top-half die and a coconut bottom-half die for the forging press.  The dies have to be relieved to accommodate the thickness of stock which will be formed.  That stock turned out to be stamped pipe caps from a ranch store.  They are probably made from a deep draw steel and were easy to work.  

Each coconut was constructed by MIG welding together the top and bottom pressed pieces which had been torch trimmed to remove excess material at the cap rim.  Three coconut groups of 4-5 nuts were made each with a stem.

The frond ribs were formed by making long round tapers in round stock.  The fronds were water jet cut from a single pattern.  I would consider using straight, left-curved and right-curved frond patterns.  The round tapered ribs were sunk and plug welded.  The surface texture was added with the press and the edge slits were made with a throatless shear.

Each frond and coconut bunch was stamp numbered to index it to the modular assembly.  The final step was to group those pieces to the trunk.  Each piece fitted into a socket made from a short piece of 1/4” tube.  I built that step by step keeping in mind the idea of the terminal bud of the palm plant.

The palm frond ribs, intentionally left too long initially, were shortened and the male end forged to fit it’s socket as the final position for each was determined.

The finish was applied and the clients came and picked it up and got the instruction about disassembly/assembly and it left for a new home.  I’ll look forward to seeing a picture of it there.
Trunk texture test

Assembled coconut palm

Coconut bunch detail

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