|Steam Dome: The steam dome was tackled first
because it rests on the straight part of the boiler making
than the sand dome which sets on the sloped part of the boiler.
The first step was to chuck the dome and rough bore the
inside so that it would fit over a wood mandrel. The underside of the top lip was also
The lathe in the photo is a 12"X36" unit that
replaced my old Maximat V10P.
|Ken said he used a large washer inside the dome and bolted the
dome to an angle to hold the dome on the mill table.
He then used a fly cutter to machine the radius to
fit over the boiler.
A scrap piece of aluminum served as a washer inside the dome.
|This shows how the dome was bolted to an angle plate that was in turn bolted to
the mill/drill bed. That's a new mill/drill too.
(Both the mill and drill are Chinese and were on sale at Harbor
|The fly cutter previously used to machine the radius on the
smokestack base was used
to mill the bottom of the dome. (The fly cutter proved too
much for the Maximat milling head resulting in toothless
gears. The belt drive on this 700 pound mill/drill
absorbs the impulses without damaging anything.) A
of 200 rpm was used and fine cuts (~0.01") were taken with a
very slow feed. It took about 3 hours. Not a pleasant
task but better than mowing the lawn.
|The base fit nicely on the boiler --- a just reward for the
|The square hole for the steam pipe was cut next. The only way I
could figure to cut the hole was to drill a bunch of small holes, then enlarge the holes and then finish with a
file. That took another hour or two.
|A mandrel was made from a piece of 4X4. It was turned
to be a force fit inside the dome. (Hope she doesn't miss
her landscaping timber.)
|The dome was forced on the mandrel and then the inside of the
top finished with a boring bar. That boring bar is the same
one used to finish the inside of the dome and is clearly
overkill for this job ---- but it was already in the tool holder.
|The outside was smoothed with a course file and then 50 grit
sandpaper. This is the partially smoothed dome.
There were quite a few pits from air bubbles. Most the pits were
removed and then the dome was powder coated.
|Ken said he used a couple studs to hold the dome down.
The studs were threaded LH on one end and RH on the other so
that they could be tightened from inside the dome.
I choose a less sophisticated approach to retain the dome.
A pair of plates were secured under the screws that hold the top
on the steam chamber. The long screws go through
holes in the top of the dome to hold it in place.
The dust specs in the photo came from the inside of the dome
when it was test fitted.
|This shows the finished dome. The heads of the two screws
securing the dome are clearly visible. They will be painted
black to make them less noticeable.
The light colored specks are dust. There are
however numerous small pits still visible. Some are
visible in the photo on the top near the rear screw hole. If one is using
regular paint, the pits can be filled with auto body filler before
priming or auto body putty after priming.
Neither the body filler nor the putty is compatible with powder
coating. I've since learned that there is a metallic
filler that will work with powder coating. I'll order a
can and if the pits still bother me in a few weeks I'll strip
the dome, fill the pits and then powder coat it again. (The
pits became less noticeable after thinking about all that