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.
Woodworking and Pianos Table saw sled cutting grooves Wood clamp