Moisture meter

Wood expands and contracts because of the humidity changes. It shrinks and expands differently along the grain than perpendicular to the grain. With humidity swings there is a continuous expansion and contraction of the wood.

 As a piano technician and woodworker I am always watching this. I built a moisture meter  years ago and it hangs on the wall behind my drill press. I can see the pointer move daily, in the summer when it is humid the pointer moves to the right and the opposite in the winter. 

How to Build

I will build one similar to my original design except this one will be larger. 

  

This is the first one I made and its length is 14" and  the new one will be  L 20" x W 4-1/2" and D 1".  To start I will build the back of the frame and for this I will be using solid oak. Plywood would work as well but I like the solid wood look.  

I used my table saw sled  to cut an oak plank, this will be for the back.  The cross grain strip will run against the back of the frame so it has to run horizontal. 

To cut a thinner board it was resawn with the table saw. This works fine but I would not go over  4 1/2 inches.

Making the channels                                                                

I installed my dado stack and was ready to make one cut on a small piece of scrap. This will later become 2 pieces to make the sides. The height of the blade was 12mm  since the strip will be 10mm thick.  

While the dado blade was in I was able to make several more cuts to the piece. These cuts will make the slots for the sides, and they will be for airflow, plus I think it looks better.  

After the blade was changed back the piece was cut in half. This is an easy way to make 2 exact pieces. 

I did some colourful clamping. These are the sides being glued to the back.

Making the pointer

A small block was screwed onto a board to safely make a tapered cut. The board will ride along the fence and give me a small tapered piece to make the pointer.

 

This is the other part of the pointer, it will have lead weights and 2 screws in it. One screw will be an adjustment screw and the other will hold the pointer to the frame.

The 2 pieces of the pointer are glued together.                    

The lead weights were hammered into the holes I drilled out earlier, and then sanded down. This will make a weighted pointer that will help with its movement. Stain and lacquer were applied on the pointer and frame  except for the spruce strip.

                            
   The   cross grain spruce strip was cut from a panel I made a while back. I cut it to L 14" x W4 ". It was sanded smooth  and no finish was put on this piece.

   The adjustment screw is cut to the right size and then adjusted to the  setting which is best for the pointer to sit in the middle of the gauge. It can be adjusted anytime depending on how much the pointer moves, you don't want it to move out of the frame.

                               

The small stop block was put in the bottom of the frame and secured with 2 small screws. 

The 2 gauges are sitting side by side as well as my hand held hygrometer to give me some readings.  A piece of tape or cardboard can be used to mark the position of the pointer. The new one on the right one has 3 marks from 1 day of moving around the house. 

                                                     Temperature   Humidity

                        Inside house          21  C                64%

                        Workshop              14  C                 67%

                        Outside                   14  C                 74%


Conclusion

I hang this moisture meter in my shop and can see how the humidity is changing throughout the year. The pointer can tell me the moisture content of the wood.  Even though wood moisture is difficult to measure because of grain angles and grain density, this gives me an interesting visual on what's happening. 

Do you measure your shop humidity or check your wood with different types of moisture meters?

     


     New tool cabinet                                                          Wood movement test

Magic Trick Puzzle Box

A wooden puzzle box or mystery box is a lot of fun to play with. And if you are a woodworker this is a very easy build. 

 Great for hiding gifts or treasures and it will keep people guessing. Just watching kids and adults try to open the box is entertaining. Everyone seems to just about get it but will give up!

 The box is made with hardwood maple, some brass rods, screws and glue.

 I like the look of maple and it is durable. It can also be made with other woods such as plywood or finished wood off the shelf at your local building center.

 You don't need a lot of tools to build this box. Having many tools is nice but you can make this box with just a handsaw or jigsaw and some clamps. If you are a beginner woodworker or advanced this is an easy project. If you can build a box you can make this.

                             
                                      

 Here the box sides are being cut. I will use my miter gauge  to cut the pieces the exact length. It is very important and this will ensure a perfect square box.


                                      

Since rough maple was used the pieces  were ripped with the table saw and cut to 17 mm. for 2 sides. The two ends were cut to 24 mm. thick.  The height of the pieces is 70mm. 

The sides are now ready and I wanted an easy way to join them so I will make dado cuts on the end pieces and glue them. This is very easy and does look good.

The ends now have a dado cut on them, this was done using a Sled and a single blade. The sled has a stop on it so you can chip away until you get the exact cut which is the thickness of the side piece. This way is very accurate and saves the time it take to change the blade or if you don't have a dado blade. 

The ends are marked and three cuts are made on each as shown above. The cuts are longer than we need but can be filled with some wood strips later.

 The same technique was use to make the dado cuts. First measure, mark and then set the fence and chip away until they are 1/4" wide. 

                                                   
                    
 The pieces are first dry fit making sure the box was square. It is always a good idea to check with a square. It should not be glued at this time. It is best to make the lid and then test all the pieces together for a nice fit. 

Making the lid


                             

The lid top is 107 mm. x 213 mm. 
The lid is built up, the first layer is solid maple (10mm.) then a piece of plywood (10mm) is glued to it. This piece was traced from the inside of the box then cut out.

Several strips of maple are cut, they will be the guides for the brass rods.

                                       

Now is a good time to make the brass rods. Any metal rod can be used, these were just what I had on hand.

The 7 mm brass rods are cut first using a pair of bolt cutters. They are cut slightly larger, and then they can be ground down to 178 mm in length . 

                                       

Using a belt sander works nicely and you can get very good results.


                                       

                                       

The guides are glued and they are spaced 13mm apart. The brass rods are tested for fit. Everything looks good and now the last piece can be glued on. 

                                   



Glueing the box together

                                     

                       The sides are now glued together and clamped. Again the box is                        checked for squareness. If it is not square apply more or less                            pressure to the clamps until you get it right.

The dado cuts are filled with some dark oak strips. This will add some contrast to the inside of the box.

Small wood screws are added to the middle end of each slot. Depending on how they are set this will make the difference on how the rod moves over the screw tip.

If they are turned clockwise it will be more difficult and counterclockwise will be easier. A small amount of turn will make a large difference. 

                                     


The top fits nice and it is ready to test. I just added a few coats of spray lacquer and it looks great.

Conclusion

Boxes are easy to make and if you can make a puzzle box it will be more fun. I so far asked 24  people to open it and only one could, and that was just lucky because the rods were in place. 

I fixed that......

Adjusting the screws a very small amount it will make the lid more difficult to open since the rods have to move over the screw ends. To open it will need a harder spin to move the rods.

 Without knowing the trick it is a very difficult puzzle. What wooden puzzles have you built? 

                                                                                                       

         Make a Multi Bit Screwdriver        Tool Caddy                        Dowel Stop Gauge