Improving pendula swing times.
  • OK I get both of my Pendulums to swing for 20+ seconds The bearings have been aligned and the arbors polished to a brilliant shine sliding through the bearings with great ease but still nothing better than 25 seconds! any ideas
    Thanks Andy
  • One of the factors that can slow the pendula down is less to do with the arbors/bearings
    but more to do with the frame alignment.

    If the horizontal frame members are not 90 DEG. to the vertical members, but rather, for arguments sake, back member 88 DEG. front member 94 DEG. then the arbor will be easily "squeezed" by the ball bearings, this effect will increase as the frame sags.

    But there is a solution, the rear ball bearing is basically just for holding the arbor position as the pendulum load is carried by the frontal bearing, so to minimise the "squeeze" the arbor end should be cut/filed as can be seen below
    image

    The arbor should sit about 3mm into the bearing and be slightly conical, so that irrespective of what the frame does or is, then "squeezing" is as good as impossible.

    A big word of warning, you should be certain that the pendula are in their correct position before you trim the arbor. Also both ring stops should be so positioned that the arbor has a max. of 1mm back and forth movement.

    To see whether this could work for you, first just try with the arbors at their correct length, with the pendula protruding further than they should.

    This is a solution to a problem, so if your Pendula achieve similar or better times than mentioned in the Sextus tutorial then leave well alone.
    PENDULUMARBOR.jpg
    386 x 484 - 31K
  • Thank you Dave
    Swinging nicely no around 50 seconds. when the pendulum touches the frame But when the drive cog is added the pendulum touches the end of the line bobbin so reducing the amount the pendulum can swing and the swing time I have also added weight to the pallet on the left side to help it releasing
    Getting close to the Elusive Tick
  • Hi Andrew,I had the same problem.Best I had was 35-45 seconds.I followed Daves advice and the left pendula improved to 60 sec.The right pendula remained the same.I could not find the problem,there seemed no reason for it,eventually I stripped the Sextus right down and examined it very carefully.I found that the right bearing housing on the front of the frame was very slightly out of line allowing the arbor to foul the wood of the frame at the rear end of the bearing,Less than 1ml. I carefully cleared the wood and reassembled not really believing this was the fault. Immediately had 65 seconds. Not sure if I had hit the bearing a little to hard when fitting the bearing originally,but all working now.