Monday, June 15, 2015

Small hygometer

                                         I made a large wooden hygrometer a while ago and now
                                         wanted to try make a smaller hygrometer. I use it to measure  
                                         the relative humidity in my shop and to show customers
                                         how humidity makes changes in wood. 

                               Since the gauge will be used for my work and my shop I made a 
                               slot the size  of a business card so I can record the humidity cycles
                               throughout the year.

                                I wanted to change the wood from my last one so I found this piece 
                               of  Cherry in my scrap pile, it was some leftovers from a hardwood 

                              Here are the pieces laid out, they are the same size as the one I made
                              a few weeks earlier. The first one I made was my prototype and it
                              turned out very nice so did not have to modify anything.

        Size of the box - L 166 mm. W 58 mm. H 25 mm. Arm L 135mm.

                              Glueing the sides and one end only. I did not glue one of the ends 
                              since this piece will hold the arm and will be glued when the arm is 
                              ready. The other end will be raised to make a slot for a business card.

                               Here are the two pieces to be glued together. I used some mahogany 
                               veneer and some Sitka Spruce. The Spruce will be the driver so the 
                               grain must run against each other. But first they need to be dried.

                              To dry them I made this hot box,  I  used a plastic box, trouble
                              light 60W. and a board for a  lid. I left this overnight to let out as much
                              moisture as it could. I checked it with a gauge and the temperature 
                              was at 45 degrees and the humidity was under 20%.

                               Next morning I glued it and  put it back in the hot box for an hour
                               to let the glue set. I did not want to introduce any new humidity
                               to upset the glue joint.

                              Easy way to trim the veneer is with a pair of scissors, then use 
                              a belt sander to clean it up. The arm is now hydrating and you can 
                              see it slowly changing.

                                A small notch was cut in the end block and the arm was glued in. 
                                Now this can be glued to the box. When you stain it leave the arm out 
                                and glue it later. I gave mine a coat of Varathane.

                              The arm is attached and it is slowly moving. In my shop the humidity
                              is at 45%.  Last month it was at 75% . Humidity changes day to day
                              and with the business card slot it is interesting to record and see the 


                             Here are some of my other related videos on how to make panels
                             used to make the hygrometers, hot box and glueing etc.

See also:
Woodworking and Pianos             Table saw sled cutting grooves             Wood clamp


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