A Good Plan Goes Astray . . .

I hate it when a good plan goes astray.

Set up the machines to make 11 of these little shafts.

(I know I have to fix that lens distortion - they are actually straight!)






















Only 25mm diam. and 265mm long.
They go in a high-speed fan in a harvester.
No problems. Done them before.
They take about 20mins. each so I can
work on the camper while they are being done.
Only really need to pay attention every 20 mins.

OK.

Finally rig up the pulleys in the bed frame lifter.
Give it a test.
(ie Yank on the rope!!)
Hmmm.
Feels a lot harder than I thought it would be. . .
Damn . . .

Fit a spring in temporarily to see how that goes.
Doesn't seem to want to work at all.
Damn . . .

Rearrange the pulleys (trickier than it sounds)
to give a 2 x 1 advantage
(ie reduce the pull required by 50%)
Feels a little lighter but not 50% !!
It must be losing about 20% mechanical advantage
for each pulley it goes around.
Better but not "YeeHaa" better.
Damn . . .

Now of course the rope requires twice as much movement
at the pulling end to get the bed fully up.
That means the spring idea is out the window!!
Damn . . .

So now I'm going to have to resort to some complicated winching system which will require all the ropes to be brought to one central position to wrap around a drum.
Damn . . .

That means each rope will be a different length.
And while the rope didn't stretch under test at the shop
it sure as hell is stretching now.
Different lengths, different amounts of stretch, different amounts of lift . . .
Each corner moves differently and the bed not level.
Damn . . .

Will have to try a different rope "guaranteed" not to stretch.
If that doesn't work will have to resort to wire.
Wire rope however will cut the nylon pulleys, so
will have to change the nylon pulleys to steel.
Damn . . .

Oh well.
So much for that plan.
Time for a new plan.
Damn . . .