This page documents Steve building this engine
and taking it to NAMES and getting a award and cash prize for his
craftsmanship. This is truly a major accomplishment. David.
The engine and work in progress pictures.
I needed a break from the "Hurricane" So I
decided to build a nice "Little" "Simple" project to release some of the
stress from racking my brains to complete the "Hurricane"
So, I decided to build another "Flame Eater" engine as these are nice simple
engines that require little more then an alcohol lamp to operate. No complex
calculations on Dwell time, or intake and exhaust valve spring tension. No
Piston rings or tricky mechanisms to fool with, just simple function. A
wonderful stress free quick project.
And So............................ The "Husky"
The "Husky" is an air cooled, center crank vacuum
engine. Based on Jerry Howell's "Side shaft Vacuum Engine" with a few
modifications. Some out of personal preference and some out of necessity!
Pictured here with my new Company Salesman "Uncle Jack", is the start of the
cylinder, frame and Crank Discs.
Once I had the Basic Frame and Cylinder done I
started on the Belt Driven Cooling fan. I made several fan blades as wasn't
sure how they would work out and I wanted a few on the side just in case.
Next I went ahead and machined the piston
connecting rod and started working more of the final frame shape. The
original plan was to press fit the Crank Shaft together in a solid frame
with Precision Ball Bearings, but was later changed to a more interesting
idea. I didn't take any pictures of Lapping the cylinder and really should
have! I have never lapped a brass cylinder before and My "Mule" Side shaft
Vacuum engine runs very well with out being lapped. I decided when it came
time to start the engine the first time I would need to lap the cylinder,
but how to do it was a question. I didn't have stock and tooling to make a
lap for a cylinder of this size and at a last minute decided to try
something different. I took a piece of brass thin wall tubing a little
larger then the bore and cut an 1/8 inch slot from end to end and squeezed
it down into the cylinder with a mixture of Grease, Oil, and Brass-O.
Since I had no way of holding a lap of this type in a chuck I chucked the
cylinder in the lathe and did it that way. It worked out very nicely! If
anyone knows of a reason this is not a good idea, or it is a good idea, I
would love to hear comments.
I decided on Delrin for the crank bushing
and the Wrist pin bushing, Although I had not thought far enough ahead to
the heat the wrist pin would be taking. After several hour now of heat the
wrist pin bushing has had no visible signs of damage.
In the picture below you can see the Valve
workings and the interesting idea for the Crank I mentioned earlier.
Instead of the crank being assembled in the frame. I decided to press
fit bronze bushings over the bearings, assemble the crank, bore the
frame holes to the exact size of the bearing bushings and mill .100
short of half way off the frame. This idea was also a smashing success !
any comments welcome ! This makes for a tight snap fit, much like a toy
truck axle and so far with being snapped in and out several 100 times
during engine testing has held up very well and if need be the bushings
could be locktighted or soldered with low temp solder.
I decided to go a little different route
on the valve mechanism and eliminate the need for a small spring and a
small piece of steel shim stock was used instead to maintain pressure on
the valve plunger. All of the 11 parts of the completed crank are press
fit together. Why 11 parts. well the bearings I salvaged out of a
computer cooling fan were metric and the steel brazing rod axle was
standard, so a brass tube was press fit over the axle to bring the size
up to meet the bearing ID. The connecting rod journal is hardened drill
rod salvaged from the computer's hard drive , plus the bearings and
bushings. A Lot of parts for a crank I know !
Next we see "Uncle Jack" with the engine a
little farther along. I am really beginning to like doing my flywheels
of different materials, I think it's becoming my trade mark!
The Flywheels were made from bronze rings press fit over aluminum
centers to add centrifugal force and momentum with out the full weight
of Solid Bronze .
Here we see once again that we at the
"Maxum Motor Company, Stand Behind Everything We Build" and after many
days of trial and error testing, re-engineering, repairing , fool
proofing, and just plain dealing with the "Temperamental Nature" of
small engines. The engine has several "Short" Minutes of run time! I
had a great deal of trouble with the valve arm flipper breaking loose
and loosing the timing of the valve, and some trouble with heat
expansion causing the valve arm to loosen and drop off the front of
the engine as well. But, after grinding a small flat on the valve rod
for the set screw on the Hub to grip the arm stopped falling off.
Another flat on the other end and some soft solder so far has ended
the flipper problem as well. and when she feels like running , she
really runs! During the first few runs she has maintained a good 1200
RPM and sounds something like a small Chainsaw. She really screams!
This next picture is of the "Maxum Mule"
side shaft Vacuum engine and "Husky" together give you a better idea
of what it looks like !
The glass cylinder oiler and small
grease cups for the crank are done but not on and my camera will not
focus on them despite many attempts and the engine is now
disassembled and being painted. The cylinder and head are being
blacked with Brass Black and I will post more progress when I get to
Steve P. Uniontown, Ohio
Since I couldn't find a
saw blade commercially made. I Made myself a Saw Blade from Aluminum.
Since it will not be doing any real cutting, I preferred it not be very
I started out with a
.025 thick disc . Set it up in my turn table and cut the teeth in two
passes at different angles. A slight mis-calculation made the teeth a bit
meaner then I had planed, but they look very efficient!
I decided on a Belly Tank and Burner for the Fuel System. After Many, Many
Hours of bouncing ideas around I finally decided this was the best way to
go. The Burner sits down in a ring
on the top of the Tank sealed with a rubber "O"
Ring. The handle on the burner allows the distance from the flame and head
to have some adjustment as it will travel on an arc in front of the valve.
Once in place only the burner and fill tube will
be visible. A small wooden handle will be added to the burner arm and a nice
polished brass fuel cap will be added.
Next it's back to finishing up the Saw and with
any luck will be completed in time to show at NAMES.
Test burn completed. I was a little worried , due to size, that the
burner might get warm and Vaporize the fuel. After the initial 10 minute
burn, with the flame at max height the burner was less then warm to the
touch. Everything works as it should , so far . Heat is On with only a
week until NAMES Chips are Really Flying NOW!
Last update before Names.
Saw table is almost finished, just needs paint
and the springs installed. The table is spring loaded so when it is pushed
in to the blade it will spring back out. The belt is on and made from a
piece of cassette tape. X-mas music I believe. All that is left is the saw
blade safety guard.
Unfortunately it is not running at this point.
I spent a good 4 hours trying to get it started today, but when I brass
blacked the cylinder it formed some scale on the fins that flaked off and as
I feared it also scaled a small portion of the cylinder wall. I just don't
have time before NAMES to lap the cylinder, make a new piston and get it
painted and polished in time, so it will have to wait until I get back.
After many hours of playing I did have it running very well and as usual
paint and polish always seems to effect these engines. Even my "Mule" is a
pain to get tuned in after I polish it up for a show.
Completed the Husky This morning !
Copyright 2003, Florida Association of Model Engineers
and engine builder as noted above,
All rights reserved.