·:[ Darryl's Coot Building Journal ]:·
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[4 hrs] The nosebox is nearly complete. I drilled and glued on the bearing stiffeners. Each bearings on the right side required a 0.032 shim to sit flat on the vertical spruce support, so I cut and glued on a spruce shim. Finally, I drilled all the bearing mounting holes. Here is the final assembly:

Yes…there are two bolts not installed on the lower bearing. The temporary assembly was done with the old bolts, washers and nuts, which will be replaced later. The previous builder had used the wrong length bolts where the bearings are bolted into the plywood sides. AN3-10A bolts are required there.

In the previous post I mentioned modifying a drill bit to fit into a Dremel tool collet. This was in order to use a Dremel 90 degree adapter to drill between stations 7 and 14 into in the vertical spruce support. I wanted to use a drill—not a Dremel tool—with the 90 degree adapter because a Dremel tool is too low torque and too high an RPM. (The 90 degree adaptor doesn’t fit my Craftsman rotary tool anyway.) So, I cut away the plastic where it mounts to the Dremel tool (at the bottom of the photo). There is a square drive that fits a square-hole chuck on the Dremel tool.

I simply inserted that square-hole chuck into the chuck of an ordinary drill, and used it to drive the right-angle adapter. The drill bit was ground down in a lathe to fit the Dremel collet. It worked great, and I am sure this tool will save me from much aggravation elsewhere on the Coot.

[2 hrs] This weekend I prepared surfaces, did a little trimming and then glued up the nosewheel support bearing and gear retraction bearing stiffiners.

One of the problems I also dealt with is finding a way to drill the holes through the vertical spruce stiffeners for mounting the two bearings. The chuck on an 90 degree drill attachment was too wide. However, a dremel 90 degree attachment just fits. So, I spent some additional time mounting a Dremel tool to my lathe tool post, and used a small diamond grinding wheel to grind the shaft of a 0.1900 drill bit (I have many of these thanks to Boeing Surplus) to fit the Dremel collet.

The work that is still needed for this assembly includes:

• Drill holes for bearings
• Glue in a few horizontal spruce stiffiners along top of nosewheel box (I’ve left them out for drilling access)
• Sandblast and paint bearings
• Cut Teflon inserts for the nosewheel support bearing (I have the material already)
• Order and install O-rings (AN6227B-25) in nosewheel bearing
• Install bearing assemblies

[0.5 hrs] If you look carefully at the top photo in the previous post, the nosewheel retraction arm bearing (#618) hangs over the edge of the vertical support (horizontal in the photo). It hangs over because it is spec’ed at 3/4″ wide on a 3/4 wide piece of wood, but there is a 1/8″ stiffener in there, too. Yesterday I trimmed the excess off in a milling machine. (Yes…using a milling machine is overkill, but I needed to repair the motor variable speed control on my milling machine and tram the head, so this gave a reason to do it.)

While I was at it, I added corner radii on the #618 bearing and the #616 nosewheel support bearing. My Coot will be a few grams lighter as a result.