Akihiro Danjo’s VP Mechanism for F1M and F1D
Click here to download a PDF of the plan.
Construction Photo Essay:

Drive arms and stop arm are made from a single piece of 0.011” music wire for F1M and .008” for F1D.

The shaft is inserted though the arms. The shaft diameter is 0.013” to .015” for F1M and .012” for F1D.

The main body is 2mm thick #10-12 balsa, 3mm tapered to 2mm for F1M. Lighter wood and 2x2mm for F1D. I use total eight figure ‘8’ hinges for F1M and four figure ‘8’ hinges for F1D.

The Drive pin is 0.011” wire for F1M and .008” wire for F1D.
Drive pin for F1M is short and straight. It is inserted (pushed) into the socket tube and the filler and then CyA glued.
Drive pin for F1D is ‘?’shape and is glued to outside of the socket tube (therefore there is no filler for F1D).

Spring supports are 2x2mm #10 balsa for F1M and a little lighter balsa for F1D.
This is an extra short spring, so the supports are not a triangle but just a small block.

Stopper screws are nylon #0-80 x1/8” for F1M and 00-90 for F1D.
Screw holders are #10-12 balsa. I don’t use a tap for threading. Just only screw a nylon screw into the prepared hole. Sometimes very thin glue is used to harden the thread.

If you need softer, thinner, spring for F1D, it will be better to join thinner, i.e .010”, wire together than using thinner than .012” wire for the shaft.
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