Hi NormK, All arms are 50cm in length with 45cm between pivots. The drawing and calculation shown only on one but the actual design has to be two pares of dual scissors. The length of the arm is calculated based on the maximum height of 90cm and maximum angle of 60 degrees. From base to first mid of scissors at Max height is 23cm and possibly car scissors jack can be used to lift the mid up to 23cm high. The total weight of the frames or platform was taken into account on the design to calculate the initial force to lift the scissors at full load of 30kg. You can use a 50x50 or 65x65mm post for the channels where the bearings goes inside the post with side slot. The arms you can use a 50x25mm fence frame or similar.
