I purchased this antique analytical balance. An analytical balance is designed to weigh very accurately, usually to 0.0001 grams. It is glass enclosed to prevent air movement from causing errors in measurement. In the old mechanical types,weight can be determined remotely through the use of outside levers and slides. This prevents air movement from effecting the measurement.
This unit appears to be fairly old, I suspect sometime in the 1920’s or 1930’s. It has a beautiful dark wood frame and internal components made of brass.
It was fairly dirty and missing some pieces.
I was able to find a similar scale at Beckort Auctions that was missing fewer parts. It was not the same scale but does have a similar construction and is made by the same manufacturer. The auction piece does show the missing balance piece shown below.
The scale along the top would have a weight resting on it that could be slid back and forth with a remote brass rod that slides in and out above it.
The plan is to restore the pieces I have and then fabricate a balance section from both new and vintage pieces. I plan to make the balance section in a steampunk style.
The first part of the process is to remove the black obsidian base and mechanical’s from the wood frame. The glass was also removed.
Someone had previously stripped the varnish from the wood, but when I took the sections apart there was still some varnish left on the joined surfaces. This I stripped, then sanded all of the wood surfaces.
Some of the wood screws that held the frame together broke off inside the wood when I tried to remove them.
I used a brass tube mounted to my drill to extract the broken screw pieces.
Wood dowels were then placed into the resulting 1/4 inch holes and glued in place.
I then machined the surfaces flush on the milling machine.
The balance is now completely disassembled and the wood sections repaired, stripped and sanded.
In the top of the balance is this slide mechanism. It’s purpose is to allow the movement of a weight across the scale on top of the balance. The slide allows this to be done without opening the front door, eliminating errors caused by air movement.
Above is a closeup of the slide. Below, the brass pieces after stripping, sanding and polishing.
The frame is then reassembled. Some parts of the brass slide are integral to the frame and can be seen in the reconstruction below. The frame for the front door glass piece is not seen, but is designed to slide up and down in the groove on the front of the piece. The top frame has not been replaced in this picture. The top frame was missing the glass pane. Presumably this had broken at some point. I will need to get a new piece cut before my balance can be completed.
All wood surfaces are then re-varnished. The wood is most likely mahogany. It has a very rich dark color after varnishing. No stain was used.
Below are pictures of the bottom of the balance.
This is a lift mechanism. When the knob on the front of the unit (seen in the picture at top right) is turned it lifts the balance and weighing trays. In practice this essentially turns off the balance. This allows the weights and item to be weighed to be placed on the scales trays. Then after the door is closed, the lift can be released to allow the scale to balance free of air movement.
This is a closeup of the cam rod and front rod removed. This is turned to lower the lifts and tray supports when weighing. Note some of the screws that held the frame together. You can see one broken one in this picture.
During the cleanup and painting of the cast iron piece that holds the release mechanism, I dropped the part, braking off a small piece. Since this is required to both hold the cam shaft in place and allow it to be limited to a 180 degree rotation it needed to be repaired.
The first thing I did was to machine a relief for a permanent clamp that would be installed. This clamp will hold the broken piece in place.
A clamp was then machined from 1/4 inch brass square rod.
Finally, I used the clamp to glue the broken piece in place with a military grade epoxy.
In the restored unit I placed the clamp onto the repair permanently. This probably wasn’t necessary as the glue joint is bonded with a 4500psi adhesive, but better safe than sorry.
The obsidian base was then cleaned and prepped for reassembly.
The bottom of the unit has three legs. This one is the back peg leg.
It was wire wheeled, polished and reinstalled.
The two front legs are made from these brackets, with knurled screws. These allow for the leveling of the scale.
The brass nuts and brackets are shown here after cleaning and polishing.
The base and legs are reassembled and attached back to the wood frame.
The cam shaft and lift mechanism is then reattached. You can see the brass clamp I fabricated holding the repaired cast iron in place in the center of thebase.
The front door slides up and down. This small brass handle is used to facilitate this. At right it has been cleaned and polished. Below it is attached to the door frame.
With the outside frame and base completed, it is now time to move on to the mast and lifts that will ultimately support the balance section.
The mast and lifts are made from brass that has been painted black. The small brass point on the base of the mast (left) is a pointer that is used to level the scale. A plumb bob dangled from the top of the mast is lined up with the pointer by adjusting the front leg heights.
After cleaning you can see that the paint is chipping from the brass.
Paint stripper was used to remove the paint from the lifts and mast.
This is a side by side view of the two lifts. The one on the left is just stripped, the one on the right is also cleaned and polished.
This is both lifts ready for assembly. These will lift the missing balance piece when the lift is engaged by rotating the knob at the front of the unit.
Pictured here is the mast after stripping, cleaning and polishing. The center section was re-painted black.
The mast and lifts are then put back together.
Then mounted back into the base and frame.
These wood strips hold the glass panes into the frames. These were sanded and varnished.
The panes are then cleaned and re-installed. I used brass round head screws to hold the mounting strips in place. The top glass pane has not yet been replaced.
Here counter weights have been put back into the unit. The strings are threaded though the pulleys. They will be attached to the bottom of the front slide door.
This is a close up of the metal plate that covers the right side counter weight. It has been re-painted after stripping and sanding. The left looks the same.
The restored unit with the front door closed. The two brass holes on each side are for small posts that will rise up when the lift mechanism is engaged by rotating the knob on the front. This lifts the weighing trays removing tension from the balance.
With the front door open.
Before moving on to the fabrication part I cleaned up the hangers and weighing pans. One hanger was pretty bent and needed to be straightened. These weighing pans are supported, when the lift mechanism is engaged, with brass posts that lift up. These will need to be fabricated.
That’s all for now. The next step will be fabricating the balance and steam-punking it up a bit. Making the lift rods for the pans as well as the plumb bob for leveling are also on the agenda. The glass pane for the top frame needs to be purchased and installed as well.
I will use this picture as a rough guide for the balance.