Homemade Screened Bottom Board Construction Technique

[Lesgold]

Hi Folks,

With the arrival of Varroa, our beekeeping methods are about to change forever. Many of our techniques and the equipment that we use will have to be modified to a certain extent to give us the edge over this pest. A lot of people on the forum from other parts of the world have been dealing with this issue for many years and they have developed some great ideas in their approach to managing varroa. One area that I have been looking into over the past couple of years is screened bottom boards. The experts in Australia are telling us that they play a minor role in keeping varroa levels down by allowing phoretic mites that fall from bees to pass through a screen and be collected in a tray. If these bottom boards were able to play a major part in the control of varroa, I?m sure that everyone would be using them. In reality, many beekeepers do a great job with solid boards and don?t feel there is any reason to head down that path. I get that and have no argument with what they are saying.

I?m changing to screened bottom boards because of a number of reasons that apply to the situation in my area. Varroa is getting close now and may arrive at any time. I want to be able to check hives regularly to see if mites are present but don?t want to open the hives until the weather warms up a bit. A sticky mat under a screened bottom board will be a good way to show the presence of mites and from that, alcohol wash tests could be performed. When mites hit, hive strength will be impacted significantly and this will give small hive beetles a huge advantage. The SBB tray will be used to help control beetles with either oil or diatomaceous earth. Finally, during summer months, the tray position could be changed to modify air flow into the hive.

Why make bottom boards when you can buy them already assembled? There are many reasons for this. The first reason is ?because I can?. I have a bit of workshop equipment, the time to dedicate to the task and always enjoy building stuff. The second reason is cost.  Quite a bit of money can be saved by constructing them at home. The time used to make them is not an issue as I?m retired. Next on the list is painting. I hate painting with a passion. It bores me to tears. Painting assembled bottom boards with screens in place would be a nightmare. The other issue is that you are not going to be able to get paint under the risers which will cause rot issues down the track. Store purchased BB?s are made from pine and are not going to last long in coastal areas. I have been told a couple of years is what you would expect to get. That?s just not good enough. The last reason is in relation to the trays. They are constructed from galvanised sheet. If acidic mite treatments are to be used, rust will be a real issue.

I designed and made a few variations of a SBB that have been in use for about 12 months now. They seem to be working well but there was too much time allocated to making them. The design has been simplified to make assembly easier and I plan to run you through the construction process as 10 of them are made. Hopefully it will give some of you some ideas and hopefully you can improve upon what is presented. Timber will be purchased tomorrow and we can make a start. Major dimensions, material costs and suppliers will be provided as well as a stack of photos.

[Michael Bush]

Many of us went to screened bottom boards only to go back to solid.  It didn't really help with the Varroa.  In fact there is some research that it made things worse.  The Varroa reproduce better if it's slightly cooler...

[Lesgold]

Interesting comment Michael. The bottom board that I will be making doesn?t increase ventilation unless you want it to so it will be good to find out. As I said earlier, there are other reasons for using the SBB as well. It would be nice to know some detail on how they perform in different climates. I know you are a fan of solid BB?s because of how they work for you in your environment and how you manage your bees. I would love to be in your position to be treatment free but unfortunately the information coming through about hives in my temperate climate is devastating.

[Lesgold]

The main materials for the bottom board are shown below. The tray was purchased from Kmart. They are 450x350mm and fit quite well into the internal space of the bottom board. There is a gap of approximately 10mm on each side so it will cover the brood area quite well. Cost is very good at $3.50 per unit. Being plastic, it won?t react with any acidic varroa treatments and will be able to hold vegetable oil or diatomaceous earth for beetle control.

I was able to find a supplier of woven stainless steel mesh. It is pre cut to 495x 400mm which works quite well for a 10 frame box. The wire is .99mm in diameter with an opening of 3.5mm which will prevent bee entry but allow varroa and beetles to fall through. I purchased a pack of 5 about a month ago to see what the quality was like and was very happy with how sturdy the mesh looked. It would have been better if it was a few mm wider but it still works. A pack of 5 cost $40 + postage. They ended up costing about $12 ea. delivered. A larger order was placed a couple of days ago and the unit price dropped to below $7 (including delivery). This item was purchased from The Bee Store in Melbourne.

The timber I decided to use was cypress pine. It has a high, natural oil content and will outlast most other timbers in an external environment. The only issue with it is that it doesn?t nail well and will crack if pilot holes aren?t used. I will drill and screw all major components together which removes this problem. The timber also tends to contain quite a few knots so there is time needed to select individual pieces. 65x20mm pine pickets are available from Bunnings. The timber is dressed but is not seasoned. This is not an issue as it is quite stable and when assembled and does not move. 900mm pickets are a convenient size and offer the best value for money. 3 pickets will be needed for each bottom board. Cost per item is $3.80.

Risers will be made from Weathertex. It lasts extremely well and is easy to machine and paint. Many hardware stores sell this material as do beekeeping suppliers. I was able to pick up a packing sheet that was damaged for $2 from a hardware store.

Most components will be held in place with galvanised screws. Stainless would be a better option but I decided to keep costs down. Most screws will be covered in paint or concealed from the environment so they should last quite well. 8-10# countersunk 25mm and 40mm screws will be used for the project. They were purchased from Bunnings at around $10 per pack of 100. A few other minor components will be needed for the project and will be spoken about at the appropriate time.

The equipment used for construction of these bottom boards include a drop saw, saw bench, portable power saw, drill press, cordless drill and a narrow crown stapler. Many people won?t have access to much of this equipment and I will describe alternatives as the construction phase takes place. It is possible to make this project using just a cordless or even a corded driver drill and a portable power saw. For those people who don?t feel comfortable using a power saw, a jig saw could be used in its place. These options would just slow the process as a few jigs would be needed to safely hold material during the cutting process.

[Lesgold]

The first step is to mark out and cut the long sides of the bottom board. In this design, I won?t be including a landing board as I don?t believe it is essential. I have a number of bottom boards that finish flush with the end of the brood box and the bees don?t have any issues with it. For those who want one, you can add it after the BB is assembled. It just makes extra work and increases the cost slightly. Australian 10 frame boxes are 508mm long so a stop is set exactly to that distance and multiple cuts are made while the drop saw is set up. If you are using a jig saw or a portable power saw, individual pieces could be marked out and cut or a simple jig could be made to ensure each piece is cut square and exactly to length.

Standard 10 frame boxes are 406mm wide so the length required is calculated and one piece is prepared and the width dimension is checked before the drop saw is set to cut remaining pieces. Please remember that dimensions given when purchasing timber are rarely accurate and adjustments will have to be made.
 
The last photograph shows the material cut for 10 bottom boards and the small amount of waste produced. This should take about 15 minutes if you take your time and double check measurements. Using a jig saw or portable power saw will just increase the time. It?s better to be accurate than to rush.

[Lesgold]

2x cleats per board are then cut to 406mm in length using the same method as mentioned above.

The Weathertex cladding board has a piece docked to 508mm and then strips are cut on the saw bench to a width of 20mm.

The end riser length is calculated and they are then cut using the same process. If using a jigsaw or portable power saw, a fence would be added to the saw to enable risers to be ripped.

[Lesgold]

The mesh does not cover the full width or length of the bottom board so a shallow rebate is cut in the top surfaces of the sides and the back of the BB. This could be done with a router or even a portable power saw. (A jig would need to be made to cradle the pieces of timber to perform this operation safely). I used the saw bench as it was quicker. A piece of wood was cramped to the fence of the table saw after the blade was dropped below the table surface. The machine was turned on and the blade was slowly raised to make a cut like what you see in the first photograph. I could them adjust the size of the rebate to be cut so that the mesh would sit flush with the top surface of the timber. The second photo shows what I was after.

After recessing the sides and back of the BB, the width of the front piece had to be reduced by about 2mm to allow the mesh to sit over the front side at the correct level. The whole process looks a bit complex but only took about 20 minutes to complete for all 10 BB?s.

The rear side of the BB was then ripped into two halves. This would create an opening for the tray to slide in. The bottom half would be used as a sliding door to seal the tray in position. A jigsaw or power saw could perform this task but another jig would be needed to support the work. I used the bandsaw for this task as my table saw as a very thick blade.

[Lesgold]

Now that all material is cut to size, the next step is to drill clearance holes for the cleats, risers and sides of the BB. If you were only making one or two units, you could mark them out all out and drill the holes. As I am making 10 at a time, I will construct simple jigs to improve accuracy and speed up time. The cleats will have a hole drilled in each end to secure them to the BB. One hole is marked out to help align the jig. It is constructed from waste material and holds each component in place while the hole is drilled. The holes will be 9mm in from the edge as the material I am using is 18mm thick. A 4.5mm drill will be used for all clearance holes. The first photo is self explanatory. The jig and drill bit are aligned to the mark on the cleat and it is cramped in place for the holes to be drilled.

One of the sides of the BB is marked out and the jig is then modified by having an extra guide fence nailed in place. The holes are drilled 15mm in from the top and bottom and 9mm in from the edge. There are two holes drilled at the front and only one at the back. (You will see this in a later photo)

IMPORTANT: each side of the BB will be a mirror image of the other side. Only drill half of the sides and then adjust your process to ensure that you mirror image the other side.  You will see what I mean if you mark out both sides of the BB and position all components onto a bench before drilling any of the pieces.

The risers can then be drilled. The end holes are 25mm in from each end with the long risers having 5 holes and the short risers containing 4. A simple fence is constructed to slide the riser along so that holes will be drilled accurately. Notice the pencil alignment marks on the fence. They were put in place during the drilling of the first set of holes.

[Lesgold]

I should have said that all holes were drilled from the underside of the material. Any chipping out would occur on the outside or top surfaces which would be then cleaned up by countersinking the holes. A countersinkbit is then used to provide the tapered hole for the screw head. A large drill bit can be used for this process but be careful as the bit can pull in very easily and you can end up with a bad result. The pieces are now ready for assembly.

[Ben Framed]

Hi Les,
Being a retired wood shop teacher, I suspect you have had many appreciative students throughout the years! Your work is top notch.

Phillip

[Lesgold]

Thanks Phillip. I decided to put this thread up to give a few people ideas so that they can make improvements and construct their own SBB?s if they have the ability to do so.

[Lesgold]

Assembly of the boards is quite simple. The sides and ends are glued and cramped into position and then a pilot hole (3.5mm) is drilled before the 40mm screw is driven into place for all 6 locations on the BB. The project is tested for twist and the corners are checked for square before creates are glued and screwed in place. The slide in rear door is now cut about 1.5mm shorter in length so that it will slide freely into the rectangular recess at the rear of the BB. The BB and risers are now ready for painting.

[Lesgold]

Paintings done and the next step is to staple the mesh in place. I mentioned earlier that the mesh was 400mm wide but when it was actually measured, it turned out to be 380mm. Was still able to use it but had to make sure that it was stapled on an angle. The mesh was weighted down to hold it in place. If you don?t own a stapler, the mesh could be kept in place with 20mm galvanised clouts. They are 2.8mm in diameter so a 2.5mm pilot hole could be drilled on an angle to prevent splitting. The next job will be to add some tray guides.

[Lesgold]

I decided to use a 25mm angle as a slide for the tray. The angle was cut 20mm less than the internal length of the BB and was stapled into position (the angle was lifted 3mm above the cleats) this would essentially seal the BB and keep pests from entering under the screen. Screws could be used to hold the angle in place if required. The risers ere then screwed into position. A 3.5mm was used to drill pilot holes. The sliding door then had 2.5 mm holes drilled in place for a handle. The holes were positioned 140mm in from each edge. The first pair of holes was marked out and a simple jig was constructed to allow the procedure to be accurately repeated.

[Lesgold]

Some galvanised 2.5mm wire was cut to 240mm in length and bend points were marked out. Some spacers were made from raw plugs which had been drilled out to 2.5mm. Raw plugs were cut as spacers and the handle was bent in the vice. Components were then pushed into place.

[Lesgold]

To finish the BB, 2.5mm holes are drilled into the end of the trays, the wire handle is inserted and then bent to 90 degrees to hold the components together. The bottom board is now ready to be put into service. I normally allow a couple of weeks for paint to cure fully. A bit of wax can be rubbed not the surface of the risers to prevent brood boxes from sticking.

[maxell86]

There are a few reasons to use screened bottom boards. Most of decision reasons are personal to the beekeeper, localisation and situations.

Langstroth, is what, over 175 years old give or take, copied from another guy many years beforehand.
What has been working for the honeybee industry, is not working with the count of twenty or more diseases and pests impacting honeybees in each country.

Considering most of the bottom boards, screened or not are plastic which are available to purchase locally in Brisbane. Gladstone sells wood and metal screened bottom boards. Online is a mix.
We may be forced to invent, innovate, create and connect as beekeepers to rid varroa once and for all.

Much appreciated are the numerous posts from Les.
We all should get out in the shed and create something better than standard hives. Very nice board screen board.

Caution regarding kmart plastics are known as imminent landfill? try some double strength 8% vinegar on it in the sun (when it shines) and see the result?

[Lesgold]

Thanks Maxell86. Will give that a go and see what happens. The trays are not exposed to sunlight but I will see how they perform over time. If there are issues, I will have to try an alternative. Just about to make up some sticky boards to test for varroa. Having the screened bottom boards makes this process easier.