Bending Iron: Redux

Commercially available bending irons are acceptable but leave plenty of room for improvement.  After having the heating element fail in my unit, I decided to give the whole unit an upgrade to produce more consistent bending with less chances of burning ribs.

I kept the aluminum ‘iron’ and discarded the rest.  I rebuilt the base from maple in a similar fashion to the original.  The cartridge heater was replaced with a 250 Watt unit.   A PID controller and thermocouple replaced the old-fashioned stove element controller.  This allows for accurate temperature setting, with a clear digital display.  The PID controller keeps the temperature on target.

The aluminum ‘iron’ was hollow, meaning that the outer surface of the ‘iron’ would cool if it was bending wood, particularly when using a wet cloth for steam.  By filling the head with lead free solder, the amount of heat held by the head increased significantly.  The temperature stability improves but the initial time to heat-up to bending temperature is increased.

I’ve very happy with the performance of the rebuilt bending iron.  I’ve found bending temperatures of 160ºC (320ºF) to 170ºC (340ºF) sufficient.

Violin Science (?)

“Science is the capability to predict the outcome of a specific situation…

It is only science when it is applied to the measurable, when it is accurate, consistently predictive, and when the limitations are well understood.

Science, does not explain what we experience, it only interprets and predicts.”

Check out the new Science section.  This section will be both an on-going repository of my own research, and a set of reference material for other makers and those curious about the application of science in stringed instrument making.

The cradle jig

A cradle jig comes in handy during hollowing and base-bar fitting.  I managed without one up until now, but decided it was time.  I based this one on pictures from Courtnall.  Its made to accommodate deep (high) arching, adjustable length (up to large violas), and interchangeable blocks.  The wood is poplar, the adjustment knob is an old piece of ebony, all unfinished at this point.

One jar of spool clamps please…

These are some spool clamps I made on  my lathe early on in violin making.  These are maple and roughly follow the specifications laid out in Courtnall.  I made 32 of them.  I modified the design to include a raised area so that the stainless steel threaded rod does not come in contact with the edge of the plates.  The rod is fixed on one end to ease installation.  They are lined with cork with a diameter of about 25mm and have a capacity of 47mm.  The finish is two coats of tung oil.  This jar exactly fits the 32 of them, so that’s where I keep them.  They work well!

The tool cabinet

I was inspired by Olivia Pelling’s tool cabinet in her workshop – she got the idea from Merton College where she studied.  It’s a large two-door, very shallow cabinet.  I decided to make mine out of pine, with a clear satin water-based finish.  This will be the centre piece of my new workshop, and will help to keep me organized.  It’s about 150cm high x 120 cm wide x 14cm deep (59’x48’x5.5″).  The cabinet isn’t full yet, but that problem will solve itself with time….

Where to put my f-hole cutter…

An f-hole cutter is used to cut the circular holes at the top and bottom of the f-holes.  This is the first step in cutting out the f-hole.  Commonly an f-hole cutter is used to prevent grain tear-out.  A pilot hole is drilled and the f-hole cutter is used to make the final cut, a bit from both sides.

My issue was that my f-hole cutter came in a bag.  After honing the cutters, I had nowhere to put them neatly, so they wouldn’t get damaged.  I solved this by building a small box.  The box is maple with paduke top and bottom, finished with tung nut oil.