Bearing housings, pipe, shaft, hub, and pulley
Good fittings are required between these components, so
repetitive boring and turning are needed. Most of these components are
made using Aluminium alloy instead of mild steel as it is a lot more easier
to machine. First, the Aluminium bearing housings are bored to press fit
condition. The boring diameter of 16mm is very small but fortunately only
shallow depth is required (5mm), so right hand cutting tool and clockwise
rotation is used in the lathe instead of the standard boring tool. Next,
the mild steel pipe is bored at both sides using standard boring tool
for the pair of bearing housings to press fit in. Then, the Aluminium
hub and pulley are turned and drilled with hole slightly smaller than
bearings bore size. The square groove in hub is turned using cutoff tool
while the pulley round groove using a cutting tool grinded to round shape.
Finally, the Aluminium shaft is turned to fit the bearings bore, hub,
and pulley hole.
Blurred pipe image with shaft
From top left anti-clockwise: Lower housing, upper housing,
hub, band brake pulley, large rotor pulley, small rotor pulley
Tower or frame
The tower consists of a collar for holding the pipe, the
tower, and huge flat plates as the base. Thick mild steel plates are used
for the tower and base so that the welding (SMAW) work to join all this
components together will be a lot easier. The collar is turned, drilled,
and bored from solid mild steel round bar. The flat plates for tower and
base are sheared to length before welded together to form the tower.
Assembled frame, collar, and pipe view
Band brake pulley system
The band brake consists of a pulley at the vertical rotor
shaft, an additional pulley with horizontal shaft and a shaft stand, a
spring scale stand, a rope, and some weights (200g, 100g, 50g, 20g, 10g,
5g). The additional pulley with horizontal shaft will direct the rope
downward so that weights can be attached at this rope end. The pulley
has a small ball bearing directly mounted on its bored hole so that a
low friction pulley can be achieved without much hassle. The stationary
shaft was welded on a flat plate stand. The spring scale stand will hold
the spring scale in horizontal direction. Both the shaft stand and spring
scale stand height were adjusted to match with the height of the pulley
on rotor shaft. A cotton rope is selected as friction material with the
surface of the pulley on rotor shaft. Both ends of the cotton rope are
attached with a fishing line before attached to spring scale and weights.
These fishing lines will minimise the friction at the additional pulley
and reduce the weight of the rope.
Spring scale holder and weights holder (stand) with rope over the rotor
pulley
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