"Notes
from the Unit Shop"
Kevin
O'Connor's advice for the beginning small scale live steamer
Putting the Spark in Old Faithful: Improving a Classic
In 1976 the Aster Hobby
Company of Yokohama, Japan released their sort of scale rendition of a 0-4-0
tank locomotive called Old Faithful. It was based on a style of Japanese
logging locomotive found operating in the Kiso forest in the northern part of
Japan, near to where the 1998 Olympic Games were held.
The original locomotive was wood fired, and so was fitted with a spark
arresting diamond stack as well as an impressive “cow catcher” out front.
The kit box for this locomotive has a top cover illustration showing an
alternate outline that features a shotgun type stack and a front drag beam with
a link and pin coupler.
I called Toyoki Inoue of
Aster to inquire more about the model and its origins.
Toyoki told me of the Kiso Forest, and that Aster produced 1200 of the
little locomotives, more or less split evenly between the two outlines.
During the last few years I
was lucky enough to purchase two excellent examples of this locomotive.
One was a factory built unit while the other was kit built: both were the
diamond stack variant. I ordered the spare parts need to turn one of the locomotives
into the straight stack version, and while I was waiting for the conversion
parts to arrive I decided to steam up the kit built version for the first time.
The locomotive’s wheels had no sign of wear and there were no wicks in
the burner, though there was evidence of some soot in the boiler flues.
Down to the shop we went
and out came the steam up kit. I
packed the wicks (more later) and checked the tightness of all the fasteners.
Then I headed to the track for a test run.
I will not bore you with all the frustrating details.
Suffice it to say that my exasperation index was topped out in less than
an hour and I repaired to the house to spend some quality time with a Wild
Turkey.
As I pondered the problem I
came to the conclusion that biggest issue besetting me was excessive condensate
upon start-up. Clearing the
condensate caused the locomotive to jerk its way down the track, with the result
that the condensate trapped in the smoke box sloshed down the two lower fire
tubes, thus extinguishing the front wick. Prior
to retiring for the night, I jotted down all my thoughts concerning the
locomotive. When I wakened the next
morning I had a plan of action. After
breakfast I headed for the shop and disassembled the cab, boiler, and firebox
from the chassis and set to work.
To fix the excessive
condensate in the smokebox problem I did two things. First, I drilled the hole in the base of the smokebox that
the exhaust tube passed through oversize to 9/64” dia. This enlarged hole now acts as a condensate drain.
It does not degrade the performance of the exhaust jet in producing
sufficient vacuum to draw the fire up the fire tubes.
I know that sounds like heresy to the Al Cohols of the hobby, but it does
work. My theory is that the departing condensate, following the
call of gravity, seals off the annulus just enough to maintain a vacuum.
Secondly I opted to shield
the fire tubes from the spray produced by the exhaust jet as it vented up
through the petticoat. To do this I
fitted a short piece of 3/8” dia. K&S brass tubing up into the stack’s
threaded extent ion into the smokebox. The
3/8” dia. tube is just a light press fit into this extension; no machining is
required. I set the brass tube’s
lower length at 1/8” below, and overlapping, the nozzle of the exhaust jet.
This may be all that is required, but not having done anything like this
before, I decided to file away the FRONT of the brass tube to half way through
the tube’s diameter, from where the brass tube enters the threaded extension
down to 1/8” from the end of the tube. A
5/32’ chain saw file was used to remove this material.
I finished up this part of the job by reinstalling the stack and the
smokebox cover.
Paste pipe dope from a tube
was used for a sealant for the smokebox doors.
The newer stuff contains Teflon, but any kind will due.
I like the pipe dope approach because I don’t like cleaning up after
silicone goo. The goo gets all over
and subsequent wipings only serve to thin out the unwanted coating, but never
really remove it. And beside, the
stuff irritates the eyes. Pipe dope cleans up on the first swipe and it doesn’t feel
icky.
The steam regulator
assembly was removed from the boiler’s backhead.
I found that the long copper tube that fits into the boiler was straight
as a die. The meant that if the
boiler was more than half full that the pickup end of the regular was in the
water. I had noticed that, when the
locomotive was assembled, the regulator gland nut was positioned right against
the rear cab bulkhead; actually contacting it, and that the nut was screwed down
all the way on the regulator body. Even
so, the gland nut was leaking ever so slightly, but would not pull up; more
packing was needed. A problem …
if more packing was added, the glad nut would no longer fit within the cab.
I hack sawed 1/8” off the threaded end of the regulator and ran the M 7
x .50 thread further down the regulator’s diameter to allow the gland nut to
move out of the way of the bulkhead. Aster’s
graphite yarn was removed from the glad nut and replaced with three turns of
Teflon coated valve packing.
I like to have gauges on my
boilers so I drilled out the side of the regulator body between the valve seat
and the backhead flange and soldered in a 1/16” dia. siphon, to which I
attached a 0-50 psi x 3/4 “ dia. pressure gauge. Prior to reinstalling the regulator into the boiler’s
backhead I removed the dummy sand dome (box?) and its stud from the top of the
boiler. I filed the steam end of
the copper pickup tube in a 45 degree angle and then bent the business end of
the copper tube to poke up through the sand dome boss as the regulator was slide
into place and screwed to the backhead.
Since the copper tube now
stuck up into the boss that the sand dome stud screws into, something needed to
be done to make room. I wanted the
tube in this position in order to pick up steam from a point the greatest
distance from the surface of the boiling water.
This was intended to cut down on condensate carryover.
The threaded end of the boss was drilled 5/32’ diaa. x 5/16” deep,
which allowed the copper tube to nestle within the stud at assembly and formed a
tiny, but effective steam dome. The
45 degree angle insured that there was no chance t hat the copper tube would
seal itself off from steam flow.
Modifications were made to
the valve spindle. Its
steam-metering end was drilled and bored out to accept a .065” dia. insert,
which protruded 1/8”. This insert
was turned to .058” dia. with a 45 degree chamber for steam sealing purposes
where it meets the stainless steel spindle.
A 6 degree included (3 degrees per side) angle is machined onto the
.058” dia. right up to the 45-degree chamfer angle.
The addition of this
machined insert “tames” the throttle settings and allows for easily adjusted
prototypical speeds under varying, especially light, load conditions.
I turned the brass valve wheel to 3/8” dia. and chucked up a piece of
½” dia. hard wood dowel, faced it off, and counter bored it was a 3/8” dia.
endmill about 1/16” deep, then parted off the end of dowel about 1/8” thick.
A tiny amount of JB Weld™ was sparingly applied to both the brass valve
wheel and the 3/8” counterbore in the wooden disk.
The brass wheel was inserted into the counterbore and firmly pressed
together. Black Magic Marker was
applied to the wood disk to blend it in with the cab’s interior.
Now there is no chance of burning fingers while fiddling with the
throttle.
The stock steam supply line
runs from the backhead forward to the steam cylinder distribution valve via the
outside of the firebox. This line
is not only very long and in unlagged, but it also runs through a large
displacement-type lubricator that presents ample area to radiate heat into the
atmosphere. Since the
locomotive’s operation suffers from an excess of steam condensate in the
smokebox and exhaust, I decided to reroute the steam line forward through the
firebox. To do this two slots have
to be filed in each of he left hand firebox baffles right at the level that the
steam line passes along. A 5/32”
dia. chain saw file is perfect for this purpose.
The slots are just deep enough to let the steam line snuggle in.
IN rerouting the steamline, some additional heat energy from the firebox
is imparted to the steam passing within, but not enough to be considered
superheat. AT this point the
locomotive was reassembled.
The last thing needed is
wicks in the burner. This
locomotive likes to have both its wicks made from fiberglass and very tightly
packed into the burner’s wick cups. I
don’t think that you can pack them too tight.
Tight wicks use fuel sparingly and promote long runs. Trim both wicks no higher than ¼” above the burner cup
tops and contour both til they resemble the business end of a .45 caliber
dum-dum round. Attention to this
detail will pay dividends later I the proper combustion.
If the wicks are higher, or loose, the flame will burn too hot and the
safety valve will lift and shorten the run.
I have found that this
locomotive likes to be steamed up on blocks.
Any thickness block will work as long as the wheels are above the
track’s surface. Steaming up on
block allows he locomotive to clear its exhaust of condensate (it’s a real
“slobber stack” without jerking its way down the track.
Once the locomotive’s exhaust is running clear at a slow throttle
setting just lift the locomotive off the blocks and send it on its way.
If you are pulling a consist, it is necessary to shut down the throttle
and add the cars/vans prior to moving it off.
One might ask, “Why go to
all the trouble?” To me the
answer is clear. It is because the
locomotive runs so much better after the attention.
This kit built locomotive, depending on temperature (my runs were in the
40F to 50F degree range), runs 30+ minutes pulling two Aster #51 four wheel
gondolas weighted with 4oz. each of fishing sinker, over a distance of 3700’
to 4000’.
This article originally appeared in Issue No.
47 (Vol. 8. No. 5) of Steam in the Garden. appreciation for permission to reproduce it on SouthernSteamTrains.com
is expressed to Kevn O’Connor, author; and to Ron Brown, Publisher / Editor of
Steam in the Garden.
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