Build a Scale to Weigh Bee Hives

Portable Hive Scale

The goal is to build an accurate, electronic bee hive scale for under $50 that allows anyone to weight 4 hives per minute – up to 250 lbs each – without materially disturbing the colony.

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Problem

In my first year as a beekeeper, I had 2 out of 3 hives swarm. I think. I experienced a Tulip Poplar nectar flow. I think. I saw bees gather nectar – some days more than other days. I think. I say, I think, because I am led to believe that these things happened and I saw evidence that they did occur but I cannot be sure. And if they did occur, I cannot tell you if it was more or less than previous occurrences. But if I could have weighed the hive once or twice a day, I would have known for sure:

    * I would know the population of the runaway swarm …estimated at 3500 bees per pound.
    * I would know the mass of nectar (and pollen) gathered during the day and of water evaporated at night. One pound equals roughly 1.04 US pints.
    * I would know the number of bees foraging by monitoring the loss of weight in bees leaving in the morning.
    * I would know the rate of growth of daily nectar collection as a nectar flow began.
    * I could compare my hives with the hives of others and with my own hives in previous years.

Lord Kelvin said, “To measure is to know.” If I could weigh a hive, I would know a lot more than I do now…

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How Does It Work?

The scale has 3 fingers or tongue that lift one side of the hive. The two outside fingers push down while the center finger lifts the hive. A $16 electronic luggage scale measures the force required to separate the center tongue from the outside tongues. The force to lift up the back of the hive is roughly half the total weight of the hive.
 

This is the luggage scale that I bought off the Internet for $16. You attach your luggage to these hand-held devices and lift them with the luggage attached. The scale beeps or stops changing value and then you read off the weight. Their maximum range is about 125 lbs – less than a lot of bee hives. However, if you measure the hive by only lifting one side - and assume that weight in the hive is more or less centrally distributed - then you are only measuring half the hive's weight. You have a loss in accuracy but your maximum range is now extended to 250 lbs.

You do not need to use exactly the same scale shown here. However, you may need to get creative in attaching the luggage scale to the scale handle.

Assemble all the parts in the photograph. You can find a complete parts list at http://www.beehacker.com/wp/?page_id=55. These are all available from Lowes or Home Depot.

Not listed are bolts, washers, and screws. I used mostly 1/4″ x 1″ rounded headed screws. You need washers to prevent the bolts from sinking into the wood and getting loose. Some of the parts are shown at right.  Moving clockwise, the parts shown are

    * Electronic luggage scale
    * 1-1/2″ corner brace (one of two needed)
    * tee hinge (one of two needed)
    * pulley as purchased. You need to break off the black hanger and drill out the axle.
    * steel mending plate shown in the middle of the picture
    * pulley assembly at top consisting of:
          o two (2) 2-1/2″ corner braces shown prior to bending of bottom flanges
          o 1/4″ clevis pin axle
          o one 1″ nylon spacer with .257” ID, cut in half to get 2 1/2” pieces
          o one nylon pulley

Saw out the outline of the paddle in 3/4" plywood, oak, maple, hickory, or other tough wood. Make a lever that the user will use to pull the luggage scale with. Then drill the holes.  Cut out the center tongue as shown at right. I used a band saw for the two long cuts down the tongue then used a jigsaw to join the two cuts.  Sand and finish with a tough marine varnish.

A note on drilling the holes: the mending plates on the bottom share some of the same holes as the corner braces on the top. I could see no way around it. You just need to be precise in your drilling.

The parts screw together quickly.  Note that the two smaller corner braces hold the luggage scale to the lever. In order to allow the luggage scale to move freely, I had to saw some plastic off of the side of the scale near the attaching screws. You may need a few slightly longer screws to hold the pulley assembly to the paddle and mending plates on the bottom.

The cable is 1/16″ wire rope attaches the lifting tongue to the luggage scale with ferrules on both ends. The ferrule is used as a stop on the lifting tongue.

The photo shows that I added two things:

1. A red plastic level insures that the scale is held consistently each time I weigh the hive.
2. A threaded insert, bolt, and 1/4" screw are shown under the lever. This insures that the tongue is lifted a consistent amount each time.

Both of these improvements will improve the accuracy of your hive scale.

In order to pry up one end of your hive, you need a slot that you can insert your pry scale into. You can either route out a slot on your bottom board or deep body or simply build a stick like the one shown that you will simply leave under the backside of your hive.

There is currently a NASA-sponsored nation-wide research project  (http://honeybeenet.gsfc.nasa.gov) that asks volunteer beekeepers to take daily weight measurements of their bee hives. The data is used to estimate when nectar flows begin in order to answer how changing climate effects honey bees.

For more information on this project and many other projects for beekeepers, hackers, and beehackers, visit http://www.beehacker.com.