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The KR2S Project

Rudder Pedals


My rudder pedals are made from 5/8” 4130 tube with a wall thickness of .049”. I have had to decide on hanging them from the shelf or bolting them to the floor. I have gone the floor option, as I am not sure that I want the brake cylinders on the forward side of the pedals.
 
cutting 4130 Two sets of identical pedals are cut using the mitre saw with a metal cutting blade attached. The sawdust bag was removed, as it is nylon and would surely fail the spark collection test. 41oC (106oF) days led to working without a shirt but I did wear safety glasses. No flying debris would penetrate those “abs of steel” anyway!
debur steel Each piece of cut tubing had to be deburred. A metal file did the job and made the ends smooth and ready for welding.
rudder pedals I lined everything up on some chipboard and used the a few jig blocks to hold it all in place.
 
joint close Here’s a close up of the angled joins, which I was pretty happy with.
tig welding Simon is a LAME (A&P) who spends a lot of his time welding aircraft and boat components. I am amazed at how quiet TIG welding is as I was expecting sparks and noise. It is an almost silent operation. In the interests of safety, I took this photo over my shoulder and just hoped for the best.
welded pedals The welds came up a treat and the rudder pedals fitted back onto the jig board for the trip home meaning there was no noticeable warpage.
wire brush Before spraying with a rust inhibitor, I used a wire brush to remove all surface oxidization that left the pedals very bright and shiny. They were then hung from some screws that were passed through clamps, ready to be painted.
linseed oil Simon was telling me how the tubing on many WW2 aircraft discovered in the jungles, is found to be severely rusted on the outside but in great condition on the inside. This is because heated linseed oil was used as a rust inhibitor by coating the internals. Good enough for them….good enough for me. Heat, pour in, swish around, pour out. A good way to check the welds for leakage too. Mine passed with flying colours.
nylon block The rudder pedals are hinged to the cockpit floor using nylon blocks.  I sourced a 6" piece of 1"x1" nylon and ripped it in half on the table saw.
spade bit The two halves were then clamped together and 5/8" holes drilled with a spade bit.
drilling nylon I then cut each hinge from the piece of nylon with the mitre saw and used the drill press with a 3/16" bit to drill two holes through one side of the hinge.  This is then mated to the other half and used as a drill guide. 
pedal hinges The rudder pedals rest nicely in the hinges and the caps are a perfect match.
two rudder pedals These AN3 bolts are fitted in the holes just for show as the proper ones will be longer and reversed, coming up through the cockpit floor with the washers and nuts visible on top of the hinges.
4130n pedals Couldn't wait for the bolts to arrive so I drilled the holes through the cockpit floor and placed short bolts through the nylon blocks just to see how good the pedals look.
pedal extensions If you look at the photo above, there is a gap of about 2" between the sides of the pedals and the fuselage.  To re-claim the 2" on each side I have had extensions welded onto the pedals.  The rudder cables will then be connected to these giving more leg room.
rudder pedals I decided to give the pedals a few coats of gloss white enamel.  I am no interior decorator but I like the look of the white against the natural timber and the green nylon blocks.
cable to extensions The holes for the AN42B-10A eyebolts have been drilled so that the eyebolt is in line with the AN130 turnbuckle assembly and the rudder cable.  I will safety wire the turnbuckles a little later.
nylon washers As I had envisaged, the cable runs along the fuselage wall without actually touching it, down to the AN219 phenolic pulley.  To protect the paint I have used black nylon washers with the eyebolts.
ready to weld From some 4130N offcuts I start to make the tabs that will support the bottom of the Matco master cylinders to the pedal near floor level.  This improvised welding clamp worked a treat to stop bending as the weld cooled.
red hot weld I bought a Henrob 2000 welding torch and accessories a while ago and have practiced and improved my welding technique to a standard that I am happy to use in the KR.  
cardboard pedal The best way for me to work out how I wanted the brake pedal to fit and look was to fold some cardboard, punch some holes through it and roughly mark out the shape.
bending aluminum I copied the bend lines off the cardboard onto some 1/8" 6061T6 aluminum sheet and then set up my own version of a bending brake in the vice.  The picture shows the setup.  Ally is bent over timber's radiused edge using 4" x 1-1/2" pine as a lever.
matco cylinder Here is how the master cylinder sits in the bottom bracket.  There is enough room in that square tube for the cylinder to move back and forth as the brake is applied and released.
pedal finished The brake pedal is a simple affair that is held in place by an aluminum sleeve with a screw through it.  The action is smooth and I am very happy with the result.
matco brakes Brake pedals finished but for some lightening holes.