Help: cherry sphere needs balancing

[Mac]

Hi all, I'm working on a piece of sculpture based on a floor globe. I built a 22.5 inch diameter hollow cherry sphere and carved in the oceans, leaving the major land masses in relief. After carving the oceans I discovered the sphere is very unbalanced and swings in the meridian ring so that the oceans (light side) always remain in the up position. This link may help:

the globe has two openings at the poles (for the axles), I was thinking I might be able to pour something into one of the holes and let it set-up inside the lighter hemisphere (after careful measurements of course). Possibly a two-part epoxy, like the stuff they use to pour countertops and such. However, I've never used this stuff and don't know if it will make a sufficient bond with the wood. I would hate for it to break loose inside the globe! Anyone have experience with two-part epoxies or know of another liquid medium that would bond with the raw wood and be heavy enough to balance the globe? Any suggestions welcome. Thanks,

-Mac

[bob.kirkpatrick]

Try

for an example of epoxies designed for woodworking. As long as the interior is unfinished the epoxy will form a very strong bond with the wood. You should tie weights on the outside to balance it to get a feel for the weight and location needed. I would mix the epoxy with metal balls like airgun BBs or birdshot (from any gunshop that sells reloading supplies) so as large a volume of epoxy wasn't needed.

[Mac]

Hey Bob, Thanks for the link, I've been working with wood for years but never got into the epoxies. I planned to use lead sinkers taped to the outside to get the right weight. I like the idea of adding shot but my access hole is only an inch in diameter and need the epoxy to flow, possible through a long tube and funnel. Time to start the experiments :-)

-Mac

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[Lew Hodgett]

An old trick.

Mix sand with epoxy to get added weight.

Mix epoxy in small batches, then add sand, mix and pour.

Max amount poured should not exceed 1/2" thick dollop at one time.

If it helps, use some rigid tubing like a soda straw to locate mixed epoxy in the correct place, then discard.

Have fun.

Lew

[Tom Banes]

As others have suggested, mix some lead shot (# 9 shot is ~.08" in diameter and weighs ~.75 grains per piece of shot, #8 shot is ~.09" dia and weighs ~ 1.1 grains per piece (1 oz = 437.5 grain)) in with the epoxy. Do a small bit at a time and use a hunk of 1/2" plastic pipe as a guide to get the mix in the correct spot. For real tiny adjustments, substitute sand for the lead and ease up on the balance spot.

It's probably cheaper to just buy a box of 12 gauge target loads (~$3.50) in #8 or #9 shot size and cut some open to get the shot as raw lead shot is sold in 25 lb bags (~$20.00) - course, if you have a bud who's a shotshell reloader he'll be glad to take any leftovers off your hands.

[Mac]

Thanks for all the suggestions folks. I now have the epoxy and I have some shot so it's time to get to work. Thanks again,

-Mac

[Edwin Pawlowski]

Before you get started, one word of caution. Using epoxy, the weight is going to be permanent. With global warming and the polar ice melting, you may have to recarve the oceans and the balance will be off. Allow some access for future adjustments.

[bf]

I just want to say: that's great work.. Let us know how the epoxy works out.