Zhivago Balance Page 3 (continued)
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There needs to be a thread in the crotch of the slot, to engage the threaded rod and prevent the weight from sliding out of position when the balance tips. There are a number of ways to create this thread, all a little fussy and none of them clearly superior. Here are my two favorites.
You can drill a hole where the end of the slot will be, using an undersized drill bit, then tap the thread using threaded rod in a drill, and lastly cut the slot (Figure 23). The transition from the saw-cut slot to the thread will need to be cleaned up so that the remaining half of the thread will drop easily onto the rod. This method will work better for hardwood than for softwood.

Or, you can coat a piece of threaded rod with some kind of mold release (I brushed on paste wax with an acid brush), let it dry, put the rod in place, then create the thread using thickened epoxy. Make sure the epoxy contact is limited to the upper half of the rod, extending the radius at the end of the slot, or the rod won’t come out. It is easier to apply the epoxy accurately just outside both ends of the slot (Figure 24), rather than inside it. The rod can be held in place with a rubber band (Figure 25) for the epoxying, and a light tap with a hammer will remove it after the epoxy cures.

If you decide to experiment with another method of thread fabrication, bear in mind that the thread needs to be simultaneously engaged at both ends of the slot because the weight will shift its load to the uphill end of the slot when the balance tips. If there is only one point of engagement, the weight will disengage and slide down the threaded rod.

Fine-Tuning the Weights
To fine-tune the weights, I used a balance made from a 3-foot-long 10-24 threaded rod and sewing thread (Figure 26). The rod was suspended from a clamp by a piece of thread, at eye level, with a shelf serving as a horizontal reference in the background. I tied the thread in a figure-eight knot around itself to form a loop that tightened like a noose around the rod and clamp. Then it was easy to adjust the rod into balance by screwing the rod in the right direction through the noose, until the rod was parallel with the horizontal reference.
To suspend the smaller catalyst weights, I hung threads from the rod at 7 and 10 inches from the cen-ter, on the opposite side from the resin weight’s thread, providing the correct arm lengths for the weight pro-portions (Figure 26). The accurately spaced grooves in the rod made it easy to place the threads at precise distances. I doubled these threads and tied figure-eight knots to make 1-inch loops, then pushed the threads through the loops to form nooses that were easily released. These held the catalyst weights nicely.


To suspend the large resin weight from the rod, I hung a thread from the rod at 2 inches from the center thread, using a noose. At the bottom, I doubled the thread and tied a figure-eight knot to form an open loop, large enough to hang the weight in it
Once all the thread hangers were added, the rod was a little bit out of balance, so I added a piece of string to the light end and adjusted it in and out until the rod balanced again

Because I had hung my balance from a clamp on a shelf, it was convenient to hook the light end under the shelf—or the heavy end over the shelf—when a weight was removed for lightening.
Zhivago Balance (continued)
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Epoxyworks 20 / Fall 2002

Copyright © 2002, Gougeon Brothers, Inc. All rights reserved.
This page is maintained by Gougeon Brothers, Inc. Last Modified on 10/28/02.
Reproduction in any form, in whole or in part, is expressly forbidden without the consent of the publisher. EPOXYWORKS, Gougeon Brothers, WEST SYSTEM, Episize, Scarffer and Microlight as used throughout this publication, are trademarks of Gougeon Brothers, Inc., Bay City, Michigan, USA.