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I have a customer who needs a half sphere sign made from HDU. Basically like a basketball cut in half. I will add a border and paint. I figure i can glue up a few pieces, cut it in a circle, and sand for a week. I dont have a lathe, which would be the easiest and best way to achieve a smooth uniform sphere. Any suggestions on this one? I think it would be a cool job, if i can figure out how to do it. Thanks for any help!
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Gemini makes half spheres in various sizes of formed plastic up to 30". Seems it would look the same after painting. I don't know if they advertise here or not. Edit: Yes, apparently they do, good.
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Thanks Chuck! I should have mentioned there needs to be several 1/4 inch wide lines cut vertically and horizontally. Like latitude/longitude lines. Thanks for the info on the plastic. May need these in the future.
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why, here in redneckville we'd just jack up the truck, remove a wheel, then bolt on a piece of plywood. then we'd screw through the back of the plywood into the foam and put the truck in low gear. (disclaimer) this is for professionals only. don't try this at home.
------------------ Dave Utter D-utterguy on chat Sign Designs Beardstown, Il. utter@casscomm.com
Posts: 777 | From: beardstown, illinois, usa | Registered: Mar 1999
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First, cut circles of HDU, each one a little smaller diameter and stack them up (with glue). 1/2 inch pieces might work better for this than 1.5 inch. 1/4 inch pieces would work better than 1/2 inch pieces. 1/8 inch pieces stacked up would work better than 1/4....you get the idea. The thinner the pieces stacked up would be better.
Next, make a circle templet. Take a piece of Kometex and draw a radius arc on piece. Cut the Komatex. Secure a pin in the Kometex so that it will attach the to top of the HDU circle stack and curve over the edge. Carefully notch a groove in the stack until the Kometex templet fits. If you gouge to deep, you can fill with putty later. Just get the templet to fit in one groove.
Last, start sculpting next to the edge of the Kometex templet to bring the next "groove" into shape.
Move the templet, and sculpt a new groove. Slowly work your way all around the stack,
Refine the sphere with sanding and putty, sanding and putty, sanding and more putty and sanding.
Its a lot of work, so make sure you customer knows this is going to be expensive.
This is how I would do the process, which is just "A" way, not necessarily "THE" way.
While working with the wood craftsmen doing the Cathedral renovation at St. Patrick Church in Decatur, Illinois (see Sign Builder Illustrated December issue) They would sometimes spend an entire day to make a templet to cut a few pieces of wood which took 20 minutes! Among other things, they made wood cylinders about 14" in diameter and 18 inches high, and hollow on the inside. The vertical individual boards were notched so they would be interlocking with each other. Then they formed a circle with these individual boards and somehow fitted the last piece in so that it stood on its own without glue ( they added glue later after they made sure it would work.) Next they had to work the surface so that it was perfect, and I did not see a lathe in the shop....they did it by hand!
------------------ Draper The Signmaker Bloomington Illinois USA My Next Article In The April Issue of Sign Builder Illustrated covers step by steps on "digital airbrushing" YOU CAN DO! 309-828-7110 drapersigns@hotmail.com Draper_Dave on mIRC chat
Posts: 2883 | From: Bloomington Illinois USA | Registered: Nov 1998
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