Motorcycle Tyre Balancer
Find some odd bits of stainless steel lying around and use them to make a shaft and centring cones:
Glue the frame bits together with a MIG welder (this was my Romarc 200 getting some exercise):
A couple of offcuts of aluminium angle...
were used to make mounting brackets for some old bearings...
on which the shaft can turn (reducing friction which should make it more sensitive, oo-er missus):
Simply remove one of the centring cones, slip the shaft through the wheel, refit the cone and secure with its grub screws. Then rest the spindle on the bearings and give the wheel a gentle spin (having removed any old wheel weights first). A properly-balanced wheel will stop at a different point every time. If it stops in the same place then the lowest point is obviously the heaviest and self-adhesive weights can be stuck to the rim at a point diametrically opposite the heavy spot. Repeat until the wheel stops randomly and that's it balanced:
It turns out that the centring cones are not actually required; the wheel will rotate just as happily with the shaft finding its own position. The balancing weights can be had very cheaply; so cheaply in fact that mine were free - from the place that fits tyres to our numerous company vehicles!