This project was born from research into bird houses.

When I saw the Rocket Bat House I couldn't wait to make this a CNC project.

When considering the re-design it was presented with a number of problems. Schools would probably not have easy access to posts and if they did the costs would be prohibitive and finally it would not be possible to then machine the post on conventional schools CNC machinery. They don't like things sticking out of the door.

So the whole center of the post and the casing would need to be re-engineering.

The thought then occurred that if the center column had the right internal dimensions it could then drop on an existing post. Something which most schools would have as part of some fencing, alternatively the post could be placed in the grounds to accommodate the new Bat House.

Then I realised the flaw in the original design i.e. If you cut your post add the outer box etc. When you come to bang the post in you will probably damage the outer casing with the post hammer. Scenario 2. You cut the post with a view to assembling the casing after the post is banged in, but then you would be hammering on the thin point at the top. So if the Bat Box in the original design is made prior to siteing, the installers will need to dig a hole and then back fill with either cement or packed gravel, this may result in a loose post if the installation is not done well.

So on to designing the BatHouse, the internal dimension of the center column needs to be 75mm or above and the gap between the inner and outer shell needs to be 18mm to allow the bats to craw into the roosting stations.

Having established these limits the rest of the design was a matter of matching finger joints and producing the angles roost stations.

The project was cut in 6mm plywood, in the prototype stage it became very obvious that the smooth nature of the plywood surface may cause it to be difficult for the bats to climb.

So 1mm deep grooves were cut at 12mm spacing on all the surfaces of the center column.

Machining :-

It is very important when machining these boards that you control the order in which pieces are machined. The final cut being the outline that will release the unit from the board. Using 6mm ply or MDF the green items will be machines at 1mm depth using a drill setting. The blue items will be machined at 7.4 millimeters depth using an inside setting and the red items will be machined at 7.5mm depth using an outside setting. If you are having problems with the items moving then adding tabs for a trigger depth of 7.5mm will only produce tabs in the perimeters of the red items leaving blue and green untabbed.

Finally assembly Tips:-

You will notice my style of manufacture throughout many of the Boxford projects this includes:- Size for thickness machining of all holes in wood and fiberboard and size for thickness finger joints with no allowance for cutter diameter. This means that if a piece is to be inserted into a hole the tang will be exactly the same size as the hole and the hole will have radii at the corners. This causes the corners to bind up on the board as it is inserted creating an interference fit that will hold the work whilst the glue dries. Some projects are serviceable on assembly with the glue serving to make the joint permanent.

The must buy tool you will need to assemble these plans easily is a rubber hammer, they are available from most woodworking suppliers for less then £5.

The hammer will allow you to hit directly on the edge of the board without damaging it as you bang pieces into holes and hammer finger joints together. You may need some cramps to hold some joints but most will hold just on hammering together.

Try to work on opposing sides so that the hammering keeps joints from springing apart the more you do you will find this method of assembly remarkably easy.

Bathouse Inner Column

Cutting Details - All cuts are made with a 3.2 or 4mm tool.

Green is 1mm deep and intended to make climbing holds for the bats.

Red and Black is set to outside 7mm deep.

Blue is set to inside 7mm Deep.

Bathouse Outer Wall

Cutting Details - All cuts except green are made with a 3.2 or 4mm tool.

Green is 1mm deep using the VGroove Cutter

Brown is set to 2mm Deep.

Red is set to outside 7mm deep.

Blue is set to inside 7mm Deep.

Have fun.

Centre Column 2D Draw Files -Download

Outer Casing 2D Draw Files - Download

Centre Column MillDesign Files -Download

Outer Casing MillDesign Files - Download