The one drawback to these additions is that the vanes of the
turbine may strike them. As an alternative, patches may be soldered to the
under side of the plate (Fig. 76, b) before it is joined to the barrel;
this will give longer holes and a truer direction to the steam ports.
[Illustration: FIG. 76. Steam port details.]
Note that it is important that the ports should be all of the same diameter
and tangential to the circle on which they are placed, and all equally
inclined to the plate. Differences in size or direction affect the running
of the top.
Solder the spindle to the wheel in such a position that the vanes clear the
boiler by an eighth of an inch or so. If tests show that the top runs quite
vertically, the distance might be reduced to half, as the smaller it is the
more effect will the steam jets have.
A small brass filler should be affixed to the boiler halfway up. A filler
with ground joints costs about 6d.
A wick spirit lamp will serve to raise steam. Solder to the boiler three
legs of such a length as to give an inch clearance between the lamp wick
and the boiler.
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