Weighing beehives
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Some years ago I asked an engineering friend how *he* would weigh a
beehive. I expected some sort of tripod lifting arrangement with
scale and lever. Instead, he thought about 10 seconds and said
"Using a plastic wine bag!". Took him the best part of an hour to
explain it to me and convince me it would work.
OK, here goes: cheapish wine in NZ comes in 3 or 4 liter cardboard
'casks', with plastic bag with valve out the side. The bags, once
empty (ahem...) are in fact flat in construction - find one that is
pretty big. Small bag means greater accuracy, but harder to measure
(hence less accurate, if you see what I mean). Best I ever made was
with a commercial sized bag that was almost the same size as the
inside of a bee box.
Build the floor arrangement. Basically, a flat base with a
telescoping lid that fits over it. Hole cut in base to
accommodate the valve arrangement of the bag. Take out the
'guts' of the valve, and glue 10mm diameter plastic tube
about 800mm long into it. I added a 20mm x 50mm piece of
timber, fixed to the telescoping lid thing with a hinge, to
support the plastic tube up the side of where the hive will
sit.
Fit it all together, put it under a hive. Now, here's the part I
couldn't really figure: how much water would you have to pour into
the tube in order to lift the hive off the base? Hardly any! After
only a bit, water starts to 'back up' the tube to a certain height,
then doesn't come up any further! If you keep pouring water, the
hive will lift higher, but the distance from bottom of hive to top of
water in the plastic tube remains constant.
The proper name for this thing is a manometer. If you can't
get it from this description, go to a good engineering book
to get the concept. By pouring only a little bit of water
into the tube, the telescoping lid thing 'lifts' off the
base, and the hive is floating on a waterbed type thing.
The height of the column of water can be converted into the
weight of the hive!
The height of water is the 'head'. Imagine a column of water the
same size as the plastic bag, and as tall as the head. The weight of
that water would be equal to the weight of the hive. So you can
calibrate a scale up beside the plastic tube to give hive weight.
Weight of hive (gm) = Area of bag (cm2) x Height of water in column
(cm) x 1 gm/cm3 (weight of cubic cm of water).
For the bag size I used (the only variable), it worked out that each
kg of hive weight equated to 9.7mm of water height in the column. It
meant you could go some pretty accurate weighing, but the cost of the
thing was just about nothing. You *might* want help drinking all the
wine...
I realise this description is pretty confusing! When I found my file
on this, I found about three starts of articles I began more than a
decade ago, each time giving up when it just didn't sound right! I
guess that is one reason I like BEE-L - it doesn't have to spot on
first time...
I've done a very crude drawing of it that you can get by sending a
message to:
[log in to unmask]
(Don't just reply to this - it would go to the whole list...)
and in the Subject: line, put:
SEND SCALES
That will get you a .GIF format graphic 'attached' to the reply.
You'll have to figure how to extract and view it! That might be
worth more than the nearly thousand words above!
When I got to my files, I also found all the various articles I had
collected over the years. I think I must have some more, as I
remember one in French that I *think* predated this one by about 20
years or so!
If anyone has other hive scale references, I'd appreciate them!
Nick Wallingford
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Busker, L.H. The WATDIT hive stand. Gleanings in Bee Culture. Sept
1970 pp 521-525. Hive stand with built in bathroom scales under back
of hive (WATDIT stands for What Are They Doing In There).
Bryan, Ernie. If there is a will there is a weigh. Gleanings in Bee
Culture (?). April 1977 page 161. Bathroom scales inserted into
frame below hive. Scales not permanently fixed.
Shaw, F.R. An improved device for weighing colonies. American Bee
Journal 96(8):322. 1956. Uses spring scale with two people lifting
hive off the ground using pipe across hive. Hive supported on sides
and back.
Owens, C.D. New hive scale for use by one man. American Bee Journal
98(4):140. 1958. Two wheeled cart with forks. Foot operated pedal
with 4:1 advantage used to lift hive. Commercial
hydraulic-compression unit between lifting lever and moving frame to
read weight.
Harding, J.P. A simple method of weighing a hive. Bee World
43(2):40-41. 1962. Pipe inserted into permanent stand below hive.
Hive lifted from sides using spring balance. Total is sum of two
sides weight times two.
Al-Tikrity, W.S., Hillmann, R.C., Benton, Dr A.W., Clarke, W.W. Jr.
Three methods for weighting honey-bee colonies in the laboratory and
field. American Bee Journal 111(4):143-145. 1971. Modified pickup
truck hive loader method: boom off truck using block and tackle and
hanging spring scale. Lifting method: one person on each end of rod,
lifting hive with hanging spring scale. Leverage-lift method: Wooden
bar is pushed down, pulling wire cable to lift hive in building.
Bell, Roland. My homemade hive scale. American Bee Journal February
1979: 97. Uses screen door spring, piece of baling wire, short chain
and three iron straps. Long bar (beam) suspended at the one foot
mark, weight can be lifted from the short end when long end is
pressed down at 2 to 1, 3 to 1, etc.
Hofmann, Chas. S. Wintering its in's and out's. American Bee
Journal 105(1):6-8. 1965. Telescoping device used to lift back of
hive. Pointer moves up given distance before hive lifts off ground,
indicating weight.
Anonymous. Introducing hive monitor(tm) weighing base, a
revolutionary advance in hive management. Gleanings in Bee Culture
105(4):138. 1977. Base to sit hive on, mirrored scale with pointer.
Claims accurate readings to within 1/2 pound.
Anonymous. Fuers bienenhaus. Chr. Graze catalog 1973-74 (German bee
supply company). "Plastikwaage" DM 21.80 (1982 price). Appears to
be a manometer/hydrolic scale, with water being poured in tube.
Wedmore, E.B. A manual of bee-keeping. (publication details not
available). p 228-229, items 880-883. Describes value of scale
hive, use of spring balance to lift hive.
Reid, G.M. Personal communication. 1974. Describes use of spring
balance with lever arrangement (fits into handhold on bottom box, to
measure 1/2 weight of hive). Commonly used in South Island, NZ.
Gilberd, Darcy J. Make your own bale weigher. NZ Farmer, September
25, 1986, page 57. Uses four car tires with tubes filled with water,
joined by stems with copper tubes, then up to plastic tube against
scale on wall. Will take up to 2 tonnes.
end
(\ Nick Wallingford
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