The tubing arrived that I needed to install the supporting diagonal on the undercarriage mount so first job was to cut and weld this into position - my joints may not be the prettiest but I guarantee that this is not going to come out!
Next job was going to be to make a start on the right horizontal stabiliser but that uses the same tubing as the front spars for the flaps and ailerons (1-1/4" * 0.035"). These require longer pieces so I decided to cut these first to make sure I didn't end up with tubing in the wrong lengths. Having cut them I then set about making the Delrin bearings that support the aileron torque tubes in the flap spars. Four of these were made from 30mm round Delrin bar stock. I used a 3/4" holesaw in the drill press to cut the hole through the bearings and then reamed them out for a loose fit on the torque tube as called for in the plans. The outer 30mm diameter needed just a light sanding with the belt sander to get a tight fit into the spar tubing. For each flap spar there is one Delrin bearing in the middle and one at the outer end. You can just see the installed bearing in the flap spar second from the top in the picture. It is secured with a 4-40 set screw tapped though the spar and into the bearing. The inner end of the flap spar has a metal bearing so I've ordered some 30mm bronze bearings. As these are metal I can heat the spar tube to insert these and get a shrink fit. The inner diameter of these is 15mm so they will need drilling and reaming to fit the 3/4" torque tube. Not surprisingly you can't buy bearings with a 1.18" OD (1.25 - 0.035 - 0.035) and 3/4" ID.
The 1-1/4" diameter aileron spar has to be connected to the 3/4" aileron torque tube so washers with the same 1.18" outer diameter and 3/4" inner diameter are required to centre the 3/4" torque tube in the spar for welding. These were fabricated by cutting out circles of metal plate using a 35mm holesaw which happens to give a disc of metal, normally, discarded ,pretty close to 1.18" in diameter. A 3/4" holesaw was then used on the same centre to create the final shape of the washer. The plans call for just one washer at the joint but I'm going to use two spaced about 3" apart to make sure the aileron spar and torque tube are nicely co-axial.
Next job was going to be to make a start on the right horizontal stabiliser but that uses the same tubing as the front spars for the flaps and ailerons (1-1/4" * 0.035"). These require longer pieces so I decided to cut these first to make sure I didn't end up with tubing in the wrong lengths. Having cut them I then set about making the Delrin bearings that support the aileron torque tubes in the flap spars. Four of these were made from 30mm round Delrin bar stock. I used a 3/4" holesaw in the drill press to cut the hole through the bearings and then reamed them out for a loose fit on the torque tube as called for in the plans. The outer 30mm diameter needed just a light sanding with the belt sander to get a tight fit into the spar tubing. For each flap spar there is one Delrin bearing in the middle and one at the outer end. You can just see the installed bearing in the flap spar second from the top in the picture. It is secured with a 4-40 set screw tapped though the spar and into the bearing. The inner end of the flap spar has a metal bearing so I've ordered some 30mm bronze bearings. As these are metal I can heat the spar tube to insert these and get a shrink fit. The inner diameter of these is 15mm so they will need drilling and reaming to fit the 3/4" torque tube. Not surprisingly you can't buy bearings with a 1.18" OD (1.25 - 0.035 - 0.035) and 3/4" ID.The 1-1/4" diameter aileron spar has to be connected to the 3/4" aileron torque tube so washers with the same 1.18" outer diameter and 3/4" inner diameter are required to centre the 3/4" torque tube in the spar for welding. These were fabricated by cutting out circles of metal plate using a 35mm holesaw which happens to give a disc of metal, normally, discarded ,pretty close to 1.18" in diameter. A 3/4" holesaw was then used on the same centre to create the final shape of the washer. The plans call for just one washer at the joint but I'm going to use two spaced about 3" apart to make sure the aileron spar and torque tube are nicely co-axial.
