Monday, February 10, 2014

Wire Tinning Solder Pot

 I need a way to tin the hard wires which brace the internal structure of the wings and fuselage.  When the WACO was built the wire was available already tinned.  Today they only sell it un-tinned.  The wire comes wound as a coil about 2 feet in diameter. The easy way to tin it is to tin it while it's in a loose coil by slowly winding the strand of wire through a long skinny solder pot.  It would also help with soldering the wire wrapped ends of the external brace wires.  To make a long skinny solder pot I bought an 18" piece of zinc plated steel Strut Channel from McMaster-Carr.  The channel is 1-5/8" wide x 1-5/8" deep, perfect for a solder pot.  To close the ends I cut a tab on each end and folded it over.  I cut along the bottom with the band saw and then cut off the tab on one side. To make the tab fit, when bent over, I used the die grinder to cut 45 degree notches.  It's not shown in this picture but I did cut the end of the tab as well.

 To make the bend I fit a block of hard wood in the end and clamped it so it wouldn't move.  Then I just hammered the tab over to fit.  Before I made the bend I sand blasted off the plating where I needed to weld the edges to seal it.  The tab sticking out on the bottom is there to mount the pot to the heating element. I drilled a 1/4" hole in each end to line up with the holes in the heating element.

 I also bent up and welded a support for the pot so it would all set up away from the wooden base I used to mount everything.  The piece setting between the support and the pot is the heating element.  It's a strip heater from McMaster-Carr which is used to heat dies and othe machine tools.  It fits perfect under the pot being 1-1/2" wide.  It's a 400 watt heater which runs on 120volts (3.3 amps).  It heats to a maximum of 1200 degrees F. so I went to Lowes and bought a dimmer designed to handle 600 watts.
 The parts are welded here and the heater is setting on the support.  The white stuff is Heat Sink Compound from Aircraft Spruce.  It helps transfer the heat from the heater to the pot neither of which is perfectly flat.

 All the parts are assembled.  I still plan to pack the box with fiberglass insulation to reduce the heat needed to maintain the temperature.  I also need a thermometer to monitor the temperature in the solder (50/50) so it's just hot enough to flow well.  I may add a light so I can tell if the electricity is on.  The dimmer is designed so you push it in to switch it on and off, but without a light you have to wait for it to get hot to know which way it's switched.
It works!  The solder bar is melting.  I bought 5 lb. bars of 50/50 solder through Amazon.

Now I need to build a stand for the wire coil and work out a method to feed it through the pot.

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