We did not finish this series of posts before building a second hive and modifying our first, so it might be more accurately titled but we will claim some authorial license and carry on with the original series name.
An observation window is an optional but very popular feature of top bar hives as it allows a look, albeit limited, into the hive without the need to open it. Although it may lose value as the beekeeper becomes confident in the ability to read a hive by merely watching the entrances, it is useful (and fun!) for a novice (like us) to be able to take a quick peek within the hive without opening it. And even if the utility declines, we can not imagine the fun ever going away.
Since transparent wood is unobtainable, some other material must be used to make the window (typically glass or plexiglass) and that introduces two problems:
- keeping the window flush with the wall so the follower board can move against it freely without leaving gaps
- allowing for differences between the expansion/contraction of the window and the surrounding wood with changing temperatures
There is also the need to provide a shutter or cover of some sort to keep the hive’s interior dark but satisfying that requirement is not really difficult. And, of course, one must decide how much of the wall (the one without any entrances) will be occupied by the window. Annabelle’s runs roughly half her length from one end. By installing packages at that end we can observe the brood chamber. It is less crucial to observe the other end but we do find ourselves wishing we had opted for a full length window when we commissioned her construction. We have no such regrets with Beatrix, which we built with two windows, allowing us to peer into her entire length. Hives are available with a single wide window but two smaller panes struck us as easier to handle.
Instructions for providing a window commonly begin with cutting a window hole into one side with some sort of saw. If one is a particularly neat worker and did not have to make an overlarge starter hole for the blade then the cutout may be useful for part of the shutter but it is more likely to become one of those stray bits of lumber that accumulate in wood shops. For Beatrix we instead framed the two holes by dowel joining three short vertical lengths of wood between top and bottom long pieces. Sadly we do not have any pictures of this stage of construction. Shutters were later made separately.
The usual method of flush mounting the pane is to rout a recess around the inside window hole perimeter with a depth equal to the pane thickness and a width sufficient for the pane (necessarily larger than the hole) to drop in with a little extra space to allow for expansion of the pane material. Then some means of holding the pane in place is required. Trusting souls have used adhesives with mixed success. Others drill holes in the pane (Glass and plexiglass each pose different challenges to this.) and screw it in place with washers or other hardware. Finally others use some sort of flattish mounts such as glazier points, thumbtacks, or similar hardware attached outside the pane and reaching in to press it in place.
Annabelle’s first window was one-eighth inch thick plexiglass, loosely fixed at the corners. The hardware slightly spoiled the flushness but not significantly. Unfortunately she was constructed in an unheated workshop during some very cold winter days. As she sat in our warmer basement the window bowed sufficiently to make gaps that a bee could pass through. We removed the plexiglass, redrilled the screw-holes to be a bit larger, and re-installed it in the hive flush and flat. But it was to no avail. When the hot days of summer arrived the window once again bowed and we hastily covered the gap with some painter’s blue tape. This improvised solution held for as long as we had bees.
This year for both hives we switched to glass, which is more fragile but expands and contracts with changing temperature much less than does plexiglass. We mounted a metal corner bracket on each side of each window so that the corner projected just a bit over the opening to simply hold the pane against the recess but let it float within it. (As always, clicking the picture will display a larger version of the image.) These brackets are a bit of a problem for flush fit but the follower board will never be positioned that close to an end of the hive so we only need to be careful in one short span to lift the follower high enough before moving it back.
On the other side of the window the shutter needs to be somewhat larger than the window hole and attached in a way that it can be hinged or slid out of the way or, like ours, removed entirely. To do a better job of light-tightness our shutters are rabbetted around their perimeters to fit into the window hole without quite touching the pane. (Please do click on the pictures near this paragraph for a larger view. It will make the text clearer.) The left and right rabbet cheeks have holes to fit corresponding hanger bolts protruding from the hive exterior on either side of the window hole. The shutter is affixed by sliding it onto the hanger bolts, seating it in the window hole, applying washers, and tightening down with wing nuts. Making the holes slightly larger than the hanger bolt diameter makes removal and replacement much easier. We keep intending to epoxy the washers onto the shutters to have fewer bits to drop when opening and closing the shutter but have yet to do so.
And so we finally near the conclusion of this lengthy post. If you are building a horizontal hive we definitely recommend the additional bother of installing a full-length observation window. Besides the practical utility of being able to take a quick peek within the hive without suiting up and disturbing the bees, it is a simple pleasure to watch them bustling.
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