© 2000  rev.2019    


    JRBentley.com

the Engineman's



Beneath this photo of the cylinder block from a model tugboat engine is a gallery of color photographs of various miniature engines that I have made in the early part of the past 30 years.

Most of the pictures presented here were taken with film before digital cameras were common and still in their infancy. The prints were scanned at 300 dots per inch. Most were 4 x 6 inch prints, processed at one-hour supermarket photofinishers. They have been in my album for years and carried all over the country. I am amazed by the quality of these images on the computer monitor - it provides near perfect lighting which is seldom found when viewing the originals.

Many of these photographs were taken with a Fujica ST-901 automatic 35mm SLR and a 24mm Pentax lens. On occasion I used a Pentax Spotmatic manual camera body. Film ranged from Kodak to K-Mart (Focal).







Birmingham Dribbler



This is a Carpet Engine - a model of a model. These were the toy trains of the mid-Nineteenth century. They loosely resembled the locomotives of the day and were constructed entirely of brass. This one is called the Birmingham Dribbler. It was made from a package of castings and materials that I purchased from Maxwell Hemmens in Thorganby, England. Mr. Hemmens told me that they were dubbed "dribblers" or "piddlers" because of the wet trails left behind as they lumbered across the living room carpet under steam.







A model mill engine steam plant with dynamo



This engine was made from a set of Stuart Turner S50 castings.
The flywheel is 3 3/4 inches in diameter. 5/8" bore x 1 1/4" stroke



The mill engine is coupled to a Cornish boiler fashioned from silver brazed copper. It is 2 1/2 inches in diameter and the flue contains 16 Galloway tubes. The riveted exterior is only a decorative cover not attached to the pressure vessel. There are six miniature incandescent lamps on the model, as well as a working voltmeter and pilot light. The control panel houses a voltage regulator to supply a precise 3-volt output. The plant is capable of powering a radio at room filling volume at a fairly slow shaft speed.


ALCOHOL POWERED ENGINE


Here's an internal combustion engine that was made from a few pennies worth of leftover materials from my workshop. It's an experimental unit that I made to test my skill on several machining operations and to try out a homemade threading attachment on the Taig micro lathe.

The displacement is approximately .05 cu. in. and the base is about two inches square. The throttle return spring is actually the fuel line. It is made from silicone rubber and just pushed on with a little bit of a counterclockwise twist.....it works like a charm.

No, I didn't make that glow plug - I bought it at the local hobby shop!






A MODEL FIRETUBE BOILER IN THE MAKING



A four-pass unit modeled after a present-day prototype - Cleaver-Brooks CBH-70



The boiler is three-inches in diameter and designed to operate at 50 P.S.I. The prototype is fired with heavy oil, but I chose to burn propane gas in the model.



Resting on a coffee mug in my workshop
during maintenance



I was fortunate in having a good friend who was installing a real one of these units in his family's laundry business. I was able to get dimensions and other important information from him at the end of each day over lots of cups of coffee and tea.

Many thanks Bruce!    


Here is the finished model boiler






A GRASSHOPPER ENGINE


The original design of using a swinging link to achieve straight line motion in the piston rod is usually credited to Oliver Evans.

This model was made from odds and ends and operates quite smartly at a steam pressure of only four pounds per square inch. The engine itself is about five inches long and the boiler is one and three-quarters inches in diameter. This was an early project for me, constructed before I bought my first lathe. Any turning was done in the chuck of a hand drill with a file ...not a practice that I recommend!

That's my Dad standing in the background - he passed away in 1993. He was always interested in planes, boats and engines.






THE AEOLIPILE
The world's first rotating steam engine



Actually a steam reaction turbine, the Aeolipile was invented by Heron of Alexandria in the first century A.D. It was described in detail in his book Pneumatica.

A fire beneath the cauldron boils water, producing steam which is conducted through one of the copper elbows to the pivoted brass sphere. This steam issues from nozzles at the ends of the two small opposing arms on the sphere causing it to spin.

This little replica spins practically silently at 1500 RPM with a steam pressure of only 1.8 pounds per square inch.



T. A. MacLEAN ENGINE



The prototype of this steam sawmill engine was designed and built in my hometown circa 1890 by T.A. MacLean, successors to MacKinnon and MacLean. It now stands at the entrance to the home of a well-respected local antique engine collector.

Seated on a wooden platform to allow clearance under the five-inch flywheels, this replica has been fabricated in one-twelfth scale. No castings were used in the construction of this model. All the parts (including the flywheels) were made from flat metal sheets and bars, silver brazed together. Much of the finish work was done by hand with a file and sandpaper.

The engine was constructed from photographs, measurements and drawings which I made in the summer of 1996 from the original antique engine. Practically completed, this miniature steam engine was designed to be operated on 60 - 75 P.S.I. at 100 RPM.



In this front view of the same engine you will notice the boiler in the background with the adjustable-weight, lever- type safety valve on top of the steam dome.

If you look closely, you can see the difference between the two pulleys: the left one has a wider rim, while the other is out farther from the crankshaft bearing to accommodate the eccentric and governor belt pulley. In practice the larger wheel was used for the main drive, and the smaller one for the auxiliaries.

Here is a view of the boiler front


It is a wood-burning HRT (horizontal return tube) unit three inches in diameter. Heat from burning tiny Manitoba Maple "logs" on a stainless steel grate first heats the bottom of the boiler shell, then passes through fifteen flue tubes toward the front, boiling the water. An induced draft from a steam blower in the smokestack keeps the fire burning fiercely.



Note: These shots were taken prior to much of the pipefitting that went into the final plant.


This back view shows the angled blowdown valve and spring safety valve (top at back).



This photograph was also taken before the boiler installation. The boiler shell is eight inches in length.





A STEAM POWERED HYDRAULIC ELEVATOR


Scale: 1/24


THE ELEVATOR OF CHOICE IN 1900

While the electric elevator of the day was merely considered "simple and cheap" to install, hydraulic elevators were "intrinsically safe, reliable, smooth-acting and under perfect control."  These words were from The International Textbook Company in 1902.  In Britain they were referred to as "hydraulic suspension lifts" and the system of wire ropes and pulleys was termed a "jigger."  This kind of elevator is still produced today and usually marketed on this continent as a "roped holeless hydraulic elevator".  However in current versions the steam pump is replaced by an electric one.



The best hydraulic elevators were said to be the vertical tension elevators, the type chosen for this 1/24 size replica.  Like the originals, I selected water as the hydraulic medium.  A steam-powered water pump provides the pressure to operate the system.

Steam for the pump is produced by an alcohol-fired boiler of the Babcock-Wilcox pattern.  The boiler and water tubes are suspended by straps from an "exoskeleton-type" I-beam framework, barely visible in the background of these photographs.  A 70-tube economizer extracts more heat from the boiler flue gasses before leaving via the stack.

Economizer (the raised box between boiler and stack)


For a sense of scale: the large vertical stack on the left of this picture is 1.5 inches diameter


The photos were taken prior to the threading of the ropes. Only a single line was attached at this point.
That is really too bad... as quadruple lines through the pulleys make quite a sight!










A PRETTY SMALL LATHE !



This is a large view of the top banner image on the Engineman homepage.

This little project was an early one for me. The spindle turns in ball bearings and the headstock can be swiveled to allow it to be used as a grinder. It was made from aluminum and stainless steel. It is powered by a small 6-volt motor coupled to a three-speed pulley system. The capacity is a one-inch swing and the distance between centers is about two-and-a-half inches. It is a semi-scale model of the well-known Austrian Unimat (an early blue SL MK.4).




A model builder's
3-INCH SLIDING COMPOUND MITER SAW



Although this thing is tiny it can sever a wooden clothespin in half a second.

It would be a great tool for building model boats. The green metal base contains nickel cadmium cells to supply electricity to the motor, making it cordless. The motor is no wimp...in its former life it powered a cordless grass string trimmer.

I designed it originally to use an abrasive cut-off wheel to cut the very thin brass tubing and channel stock that is sold in hobby shops everywhere. The performance really shines with a woodcutting blade installed. The cuts are extremely fast and clean. I made the table portion of this tool entirely from sheet metal - including the base and lugs. Fabrication was by silver brazing.




LARRY'S LAMP


This four-inch high kerosene lamp was constructed from an old engraving in an encyclopedia. The shade is copper and brass, the body is brass and the base is aluminum. The glass chimney functions well, noticeably increasing the whiteness of the flame. It will run for a considerable time from the kerosene contained within the urn-shaped reservoir.

I made it as a Christmas gift for Larry, our good friend who has provided me with wise counsel and support on numerous occasions over the years.

It is burning atop the 1937 Coronation Edition of the Encyclopedia Britannica in which I found the original outline.




BOOMERS



Barrel length: four inches

Six of these guard our city from attack by sea. As far as I know, on the only occasion we could have used them we threw up our hands and gave all our riches, and the Town Seal, to privateers. In more recent times a procession of cruise ships comes from over the horizon and now the flow of Gold is most happily reversed !

I made this tiny replica for my late friend Gordon who was kind enough to lend me his early Kodak digital one-megapixel camera to get some missing shots which I needed for this page.



I won't forget hearing those first sketchy reports of the loss of the Thresher over WKBW radio in Buffalo.
All hands were lost on April 10, 1963.





A fifty-five-pound model of the nuclear attack submarine Thresher.

Length: 60 inches









MODEL TUGBOAT STEAM PLANT


This marine steam plant uses a twin launch engine made from castings and fitted with a Stephenson Link reverse gear. Powered by a kerosene-fired Yarrow-type boiler, it has two heated stainless steel tanks which together hold a half gallon of water.

The copper boiler has sixty-six watertubes heated by six kerosene wick lamp burners with induced draft. They are are ganged in two banks of three for easy pushrod use with future radio control. The double-walled boiler casing is entirely made of stainless steel.

In addition, there is a feedwater heater, an economizer, superheater, stack dampers, displacement lubricator, stop and throttle valves, manual and engine-driven feed pumps with filter, steam blower, whistle, exhaust steam separator, automatic regulator and safety valve, steam pressure gauge, water level gauge and a stack temperature gauge.

Bore & Stroke: 1" x 7/8" Wt: 28 lbs (wet)



PRESSURIZED KEROSENE TANK


I made this tank to supply fuel to an experimental burner for the tugboat steam plant above. This tank includes a pressure pump and float-type level gauge. The bands and feet are of stainless steel and the brass drum was made from a 5" naval shell casing. The burner provided far more power than required so I continued to use the original six-wick burner unit.





THE IMPERIAL MODEL A



Only about the size of a baseball this is a 1/5 scale model of  "The Imperial" gasoline marine motor.

For many years, Bruce Stewart & Co. produced the full size version of this 5 hp engine and a variety of smaller and larger related types. These two-stroke engines were used in the small boats of the inshore fishery on the Atlantic Coast.

In the first half of the 20th century a great number of small foundries were producing machines of this kind. Early Imperials like this one used a standard "jump-spark" ignition, later going to the more waterproof "make-and-break" system.

The little motor presented in this photo was entirely fabricated without the use of castings. This model sports a working water pump for cooling and a homemade spark plug. For purposes of display, I purchased the unfinished propeller casting from James Bliss Marine in Boston.




ATMOSPHERIC ENGINE



I took this photograph a while after some friends dropped by one evening many years ago.  The couple arrived bearing a carton of old Popular Science magazines from a flea market that they thought I might enjoy - and they were right. There are enough things to construct in those old magazines to do me a lifetime!

The February 1950 issue provided the plans for this little gem.  It's a vacuum or atmospheric engine.  It burns alcohol, makes a nice plopping sound, cost almost nothing to make and I can shut it down simply by blowing out the flame.


Well that was years ago...


Both the engine and my hand are now twenty-nine years older.


HERE IS A PICTURE TAKEN TODAY  (Dec. 8, 2019)
(same place but a different season!)



It is safe to say this engine has weathered those years very well and it still works fine.





A WORKING ORNAMENT


Constructed from scratch in the winter of 1995.

This tiny steam plant has a three-flue dryback Scotch marine boiler with cross water tubes in the furnace.  The boiler is silver-brazed copper with a decorative brass lagging sheet.  It is coupled to a single-acting oscillating engine of brass and stainless steel.  A throttle and a forty-p.s.i. safety valve are included.

The entire plant is approximately three inches square and rests on a four-inch square block of American walnut.






HYDRAULIC RAM



The object above is a two-inch-high hydraulic ram or impulse pump (it is no relation to those long cylinder-piston assemblies filled with oil and now using the same name). These units can pump a small quantity of water higher than their own supply using only gravity and the momentum of the water in the supply pipe to provide the work.

The black PVC parts are only to display it as a working model and are nonexistent in the prototypes. The discharge pipe can be connected to either the brass nipple at the bottom front or the top of the air chamber as seen here.




A MINIATURE GASOLINE BLOWTORCH
overall height 3 inches


A tiny replica of a Butler 100. The tank on this torch was hollowed out from solid brass stock. It has a working air pump and vaporizing burner to produce a hot (and loud) short blue flame. I turned the handle on my Taig microlathe from the trunk of an unfortunate Flowering Crab in our back yard.


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© John R. Bentley 2000.  All rights reserved.