1867 Otto Langen Engine

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It has been an interesting read of the engine build. I finished mine two years ago and adopted a some what different approach to the build. The problem for me was always going to be the cylinder bore. I did purchase a suitable reamer and after a trial run put it to one side. My lathe just wasn't ridged enough to give a good finish. A friend of mine was building the Henry Ford Sink Engine and was using a length of Molly Tube as used in building racing cars and similar. The internal finish of the tube was mirror smooth and accurate. So while expensive compared to other material types, it would do the job nicely.

I made the base, the column and the top as seperate sections bored out to fit the Molly tube. I then used Loctite to put the pieces together and then finish the column off using a suitable mandrel. I have included a photo of the brass work which I had lazer cut which worked out well. The slide valve I ground on my surface grinder to give it a good finish and I machined all of the gears on the mill which worked out well.

I have attached some photos for any one interested. The build took me two months as we were down sizing and I had pre sold my workshop so I was on a short time schedule to when we moved.

Your build looks great and I am sure that it will run and be exceptional.

Bruce Weir-Smith
Western Australia
Very nice finishing work Bruce,

Yes the bore was difficult and I'm amazed it worked out as well as it did on my equipment. I have heard others mention recycled hydraulic cylinders as a building block for their engines. Thank you for sharing your story and photos.

Two months must have entailed some long days in the shop! Love the wooden base with the brass plate
Oh, yes; ignition. I had no end of problems with conventional points and coil. I kept getting sparks from contact bounce at bad times and got very erratic firing. I ended up with an extension of the slide valve underneath the base with a hall sensor and a "buzz coil" CDI. It fires while the slide valve it near the top of its travel.
Hi DKGrimm,

Interesting to hear how we all solve problems/opportunities differently. I didn't cut my own rack and drilled and tapped the end to receive studs for the piston attachment. I remember destroying a piston and stud and top brace when attempting first fires. It loaded up on acetylene after a few misfires and blasted skyward. Very loud😳😳😳 but all fingers were still there so just parts to replace. Don't remember the piston cocking but I think I put a generous chamfer on the leading and trailing edges.

I used a buzzbox made from a car relay with a 6V coil. It triggered off a simple limit switch in the base. Confusing because I thought it should have sparked when the switch closed as the slide valve descended, but I ended up reversing the wiring schematic and triggered it after it lifted.

Thank you for sharing your experience. This build log is retroactive for me /us but hopefully will encourage others to build a model. Sure is more interesting to watch this miniature power source than it is to watch a solar panel.☀️
Shaft Gearing

The gears were purchased online and only the faces and bores needed machining. The drive pulley is crowned to keep the leather belt centered. I never noticed that on scale models and wanted to try to duplicate it. Saw a neat trick where one attached a profile of the curve to a stationary part of the lathe and set up a dial indicator mounted to the cross-slide. Maintain the indicator at zero as the carriage travels and the contour is replicated. I think it was a chair maker on a wood working lathe that used this method. Worked nicely after some filing and sanding to remove tool marks.

14- crowned pulley.jpg16 - gear shafts.jpg

Another feature that I focused on was the gear shaft trunnions. J De Waal had plans on his site that had some photos of different models and full scale survivors. There was this image of what I thought were very cool and unique trunnions. So I made a drawing and started with the side curve using a boring head on the mill.

16A -J DE WAAL Trunions.png17-trunion plan.jpg

a considerable amount of work and multiple setups to arrive at the desired shapes using a manual machine. The recesses needed to be done on a rotary table to follow the swept curve on the side.
I used aluminum so bronze bearings had to be made. The bearing centers are different heights also which affects other dimensions. I really like them though so I spent the necessary hours.

19-shaft assembly.jpg
one of the hardest parts was the slide body that serves as a combination intake and valve timing assembly. Some seriously small 0.032" holes and weird shapes. Several faces need to be stoned flat, smooth and coplanar. Mine is messy looking because I broke a bit in one of the holes and relocated it slightly. I epoxied it closed later on. The slide part also has the trigger for ignition inside it.

slide plate drawing.png21-slide assembly.jpg

20-slide plate parts.jpg

The intake is both square and hemispherical but you cannot use a ball turning tool because of the threaded tip for the exhaust valve. I used a method seen on this site where you index the carriage over while taking deeper cuts using the mathematical circle equation. Then you use Dykem and file while in the lathe until the blue lines disappear.

22- intake rough.jpg23- intake smooth.jpg24- carb assembly closeup.jpg

the studs are adjusted using spring tension to find that right amount of sliding friction to effectively seal the acetylene and air mixture in the combustion area. It also serves as a relief valve when the mixture is wrong and blows outward. There is a small piece of shim stock screwed inside that acts like a reed valve. Its all very genius like whoever figured this out, I just followed the drawings and troubleshot things with a vague concept when it came time to attempt starting this beast.
Back in the far past I had a "carbide cannon" toy that would make a loud bang when the gas produced by some wet powder was ignited by a spark.

In the army when on the rifle team, we used carbide lamps to darken our sights with the smoke.
Back in the far past I had a "carbide cannon" toy that would make a loud bang when the gas produced by some wet powder was ignited by a spark.

In the army when on the rifle team, we used carbide lamps to darken our sights with the smoke.
Hi Kvom,
yes that's probably why they still sell it. It's still used to blacken things. From the maker:

Miners Grade Calcium Carbide for Carbide Miners Lamps as well as many other uses!​

We are the #1 Distributor of Calcium Carbide in the U.S.!!

For use in Carbide lamps, blackening of gun sights for match shooting and much much more. HQ Company has been the primary distributor of small quantities of Calcium Carbide for over 25 yrs.

when I was attempting to tune the engine to run slower, it "misfired". It sounded like a cannon going off and broke the stud that holds the piston on the rack and bent the 1/4 cap nut
I added springs to cushion the top rack in case it happens again.

250-piston and rack.jpg
when I was attempting to tune the engine to run slower, it "misfired". It sounded like a cannon going off and broke the stud that holds the piston on the rack and bent the 1/4 cap nut
I added springs to cushion the top rack in case it happens again.
Never had that happen while running but did several times when starting. My startup routine now is to spin the engine by hand for about 20 cycles with gas on and ignition off, then switch on the ignition while it is still spinning.
several more pictures from the build....

the store bought one way clutch was disguised with end covers. I read that the clutch was a novel idea and that Langdon was given credit in the name for this.
26-clutch assembly.jpg

As parts were added to the top platform things started getting tipsy and the base was made from Walnut and finished with boiled linseed oil and paste wax. A lot of visual interest in the various moving parts here. The ratchet wheel and pawl required a fair bit of fiddling and were case hardened after the final shape. Small springs were wound from music wire and catch levers were silver brazed to the hubs. I recall having to replace both 1/4" pieces of drill rod that guide the vertical rack and piston motion because of very small distortion in them. I verified true by rolling them on a plate of glass and listening for a clicking sound. Something I had learned as a teenager when working on car engine pushrods.

27-walnut base.jpg29-geartrain details.jpg30-ratchet wheel.jpg

A standard weed whacker sized spark plug was used as it is completely hidden below the base.

A one inch cut of 1018 steel 8 inch diameter was bolted to a faceplate and the blank turned with rim recess and hub bore. This "large" diameter pushed the limits of my 9x20 import lathe.

32-flywheel blank.jpg
flywheel and water trap

last few pictures of the build and the video as adjustments were made to operation. Speed control is a combined effort of dialing in acetylene production/flowrate and exhaust valve position.

The "acetylene generator" was made from some chrome-moly pipe using a matching fine thread to join the upper and lower halves. Upper half has a floor and a top shaped like a hemisphere. The top half is filled with water and dripped down onto the bottom that is partially filled with calcium carbide rocks. The rate of water dripping is controlled by a needle and seat arrangement. The two test tubes serve as a water trap and water scrubber. They provide a flashback arrestor so a errant misfire doesn't follow back into the generator, and also a visual measure of flow as the gas bubbles through the water.

I never painted this engine because it came out so nice as is. I polished all the rotating parts in the lathe with Mother's chrome polish and Just used an anti corrosion spray that is based on lambs wool on the rest. It has some very light pitting on the fluted steel column after several years of handling it. The acetylene generator nearly welded itself together after layup, and had to heat it to get it apart. I now use anti-seize on the threads and inert/lubricate both chambers before storage between runs.

33-flywheel spokes.jpg34-flow meter-water trap.jpg