Sunday 6 June 2010

6th June 2010 - Propeller crush plate

Over the last few days I have been slowly gluing up the left wing. So far the inner leading edge and the strengthening gussets, the aileron spar and gussets, and the main and rear upper spar caps have all been glued into place. In addition the bushings for the strut attach bracket bbolts have been glued into place and drilled and one of the 1/4" 12-ply plates glued and drilled. Remaining to do are the lower spar caps, the leading edge to the root rib, and the strut attach ply plate. Then it's time to sand......

While waiting for the glue to dry, I've used the CNC router with a special purpose aluminium cutting endmill to cut out a 1/2" thick propellor crush plate to match the SAE#1 propellor drive on the engine . In the bottom picture you can just see the holding tabs that keep the piece together as the mill cuts. The bolt holes are 3/8" diameter and are cut using the 1/4" mill bit using a special spiral descending cutting action. It still seems remarkable that a home made CNC router made out of MDF can cut to this accuracy. Total cost £7.00 for the piece of aluminium stock.

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