Hi there,
Pretty simple really, the cross bar is carried on two carriages that are adjusted for a snug fit on this old table. The carriage has small ball races on both the top and side of the table. The intention was to build a metal frame for it to run on but the table is OK, meantime. The cross bar is fixed to the carriages by clamps until I decide about the metal frame.The two angled pieces are pivoted to the ends of a piece that is hinged to the cross bar and a tie bar keeps these angled pieces parallel.Despite the apparently crude construction of this device I have taken pains to ensure there is no slop in any of the joins and pivots. Except for the two door hinges that attach the short piece to the cross bar every other pivot point is a pair of ball races that I have loaded by one means or another.
The old drill chuck holds a pin or 'feeler' that has to be the same diameter as the router bit in use. The chuck can be screwed up and down and locked in position.The way it works is a full size model is clamped to the table in a position so that the feeler can be passed over every point of it, which is done by swinging the arms across the table and by rolling the carriage back and forth.The work is placed under the router which moves in X,Y and Z directions as the feeler follows the surface of the model.The accuracy of the process depends almost entirely upon the rigidity of the machine and the elimination play in every joint. I used fairly thin gauge rectangular hollow steel.
So far I have only used it for two demensional tasks cutting shapes for cable connectors in thin panels etc which it does very well.
It should be able to be used for any length of work, width about half the width of the machine and thickness whatever will fit under the cross bar, i.e. propellor blades for any size up to about those they had on the Hindenberg.Cutting a blade from a piece of 8x4 would be a SLOW process but if you roughed the blades out by the highly respected chainsaw method a system like this would make it quite easy to put a nice aerofoil shape on them with some degree of confidence that they would be all the same.Thisi is my trial DIY copy router with an assitance from copy router machine supplier.