Cabin Heat Controls

Before I can install the fuel tank I need to hook up the controls to the cabin heat box I made.  The problem was I wanted to control it with a Bowden cable and I wanted the valve Pulled closed when the cable was Pushed closed.  I also wanted to keep the controls away from the rudder pedals.  I had made a baffle to go on the inside of the firewall to split the airflow toward each pedal keeping the feet warm.  If I could mount the cable on the baffle so it attached parallel to the firewall I could keep it clear of the pedals.  I thought about some sort of bell-crank attached to the baffle but worried it would stick out far enough to interfere withe the rudder pedals.

 I decided a curved piece of tubing sliding through a hole in the baffle would probably work to Pull the door open and Push it closed. The end of the tube is split and slightly flattened to bolt it to the eye bolt on the door.

I clamped the baffle in place so I could use the edge of it like the edge of the planned hole so I could work out the curve needed in the tube.  There are stacks of washers under the baffle to position it as if it were on the back of the firewall.  It took a couple tries to get a bend which allowed the tube to touch the edge of the baffle and for the free end to stay close to the face of the aft.

 Now I needed the guide hole in the baffle.  The tube is 3/8" aluminum so I drilled a 7/16" hole.

I realized that because of the angle the tube passed through the baffle it would work better if it were oval so I filed it to an oval shape.

 To provide some bearing surface I took a 3/8" rod and twisted the hole.  The tube fits nicely through it.

 To attach the Bowden cable I added a bracket which was riveted on with the inside splitter wall and gets screwed on with the screws holding the baffle to the firewall.

I used 2 clamps so my foot wouldn't accidentally twist the cable to one side.

 The Bowden cable had another problem.  I wanted to install it in a hole in the cockpit front bulkhead where another cable had been installed.  Unfortunately the threaded portion of the cable housing wasn't long enough because the bulkhead is 1" thick.  I decided to make an escutcheon (cover plate) which could be screwed to the bulkhead with the cable attached.

I needed some clearance for the nut to be tightened on the back of the plate with it screwed to the bulkhead.  I decided to put a big dimple in the plate using a hole in a piece of wood and a socket wrench as the punch.

 I put some 1/4" washers in the hole as a stop to pound the aluminum down to and lined them up on a 1/4" drill as a locator for the piece of aluminum.

I punched a 1/4" hole in a piece of 0.040" 3003 aluminum and placed it on the drill.  I used the drill to line up the hole in the clamp plate.

 The socket could now be pounded into the bottom plywood block to create the dimple.

 A nice flat dimple in the aluminum.

The plate was cut to shape, screw holes added, some text added and the I Alodined it for a better look.

 I found a washer to fit in the cap on the Bowden cable so the nut could be tightened properly without bending the escutcheon.

 With the knob pushed in the valve door is pulled closed.

 When the knob is pulled out the valve door is pushed open.

Now we can install the tank.