David H. Neumann has brought this to us :
Harry: Now that you described the design details, if we combine the
torsional shear stress on the threaded rod (due to repeated
torquing) with the tensile stress, and look at fatigue strength of
the threaded rod at the thread root (instead of static strength), my
current calculations in this scenario indicate an M14 x 2.0 mild
steel threaded rod (property class 4.6) can withstand an allowable,
applied tensile load of 2570 N for a long lifespan. An M12 x 1.75
might also work, if well greased, but the M14 gives you extra
margin

Thanks, but I managed to get hold of a threaded rod of about 20mm OD
complete with nuts. Obviously well over the top for the load, but found
in a scrap yard so quite cheap. The same place had one of those manual
type hydraulic fork lift trucks to dispose of really cheap (£100). Had
I known about it before I started on this it would have saved me a lot
of effort. All it would need is a 'spectacle' frame added to the forks
to lift a bike with ease.

I have made a start now on the base and the vertical post, but I have
had concede defeat on cutting out the sliding part which fits around
the post and onto the 'spectacle' part to actually lift the bike - I
asked a steel fabricator to cut these for me.



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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk