Author Topic: 3rd Generation Otto Langen  (Read 4765 times)

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #30 on: September 02, 2020, 09:04:29 PM »
Thanks for stopping by.

Over the last few days Iíve finished up the clutch.

Once I got the hard parts completed (the clutch body and the gear) it was smooth sailing.  Here is a photo of the outboard clutch plate;  the side of the clutch that is against the left pedestal upright.   (whooops- looks like the drawing got labeled wrong)


And next, the inboard clutch side, the side that fits up against the governor gear (to be made yet).


Next, a family shot of all the clutch parts, prior to assembly.



And lastly, a mock-up of the shaft with attached clutch, sitting atop the column and platform.


Hey!, with a little imagination you might guess itís gonnía be an Otto Langen engine !
« Last Edit: September 02, 2020, 09:09:38 PM by Craig DeShong »
Craig

Offline Admiral_dk

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Re: 3rd Generation Otto Langen
« Reply #31 on: September 02, 2020, 09:33:02 PM »
Great progress so far and the parts look good too  :ThumbsUp:

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #32 on: September 04, 2020, 09:53:41 PM »
Thanks for the encouragement Per.  Thanks also for those just stopping by.

While I was in a gear making mood; I thought Iíd get the rack out of the way.  I wasnít pleased with the way I made the racks for the previous Otto Langen models.  Milling the racks on my mill certainly worked, but the turntable I was using as an index-able table was prone to rotation so I needed to watch it Ēlike a hawkĒ and it was hard to maintain a consistent depth of cut as I proceeded down the stock and the rack gear teeth were cut.

This go-round, I thought Iíd use my lathe.  Iíll admit that Iíve been working metal for over twenty years and Iíve never had occasion to mount the work to the crosshead of the lathe and mount tooling in the headstock.  Thereís always a first time.

Below is the setup Iím using to cut the gear teeth in the stock that will become the rack.


And below Iím about halfway down the stock.  Iím getting some chatter and each tooth, though formed uniformly, doesnít have the nice smooth sides of the previous gear I cut.  The rack, when completed, is going to be very serviceable.  If I spend a little time with a file itís going to look a lot more presentable. 


This is another task that's taking a L...O..N..G.. time !!
Craig

Offline steam guy willy

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Re: 3rd Generation Otto Langen
« Reply #33 on: September 04, 2020, 10:29:16 PM »
Hi Craig  Looking good  and was wondering about using ready made spur racks..?? In the HPC cat they are available in lengths up to 1828 mm

Willy

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #34 on: September 06, 2020, 11:02:57 PM »
Thanks for stopping.

Willy; Iíd thought about purchasing a rack but hereís the thingÖ
Like many here that build models; for me itís about what Mike says in his signature, ďItís the journey that matters, not the destinationĒ.  Back twenty five years ago, when I started working metal; just turning a rod to the correct diameter was exciting.  Now, twenty five years later, it takes a bit more to give me that real feeling of accomplishment.  When I contemplated the rack I thoughtÖĒI ought to be able to make one of them myselfĒ and after some though Iíd devised a plan that I thought would work, and it has.  Itís a task that was fun and itís an accomplishment that Iím pretty satisfied with.  Yea, I could have bought it but I realized that I could make one too.

On with the buildÖ

In the following photo Iíve just completed cutting the teeth on the rack.  It took a while but the results are superior to the other two racks Iíve cut using the mill.



Now, a little milling.  The full size Otto Langen uses a dovetail to mate the rack to the rack guide.  I suspect that I could have bought some expensive tooling and replicated this, (Geez, George would have made his own :facepalm:) but, I just couldnít see the outlay of funds; I mean, common, this thing isnít going to be THAT much true scale.

So Iíve cheated and decided to just use something like a ďtongue and grove jointĒ which is what I used on the Crossley Otto Langen.  Here Iím cutting the grove in the rack.     



And after a little clean up and drilling the hole to accept the shoulder bolt to fasten the piston to the rack I show the completed rack.  ďAlmost as good as store boughtĒ, as my Mom used to say; though I believe you would have needed to grow up in the great depression (as Mom did) to fully understand the significance of that statement.


Iím following a build thread Bill Hazzard is posting on Smokstak where he documents his build of his full size 3rd Generation Otto Langen I showed in the opening post of this thread.  You can see it here https://www.smokstak.com/forum/threads/one-more-otto-langen-replica-engine.208344/  if you like.

I noticed that on the full size, the rack is attached to the piston with a morse taper plug.  I hadnít thought of that but makes sense.  Oh well, too late to change the design now.  What Iím using worked on the first two Otto Langen models Iíve built and there is no reason to think it wonít work on this one too. 
« Last Edit: September 07, 2020, 01:00:15 AM by Craig DeShong »
Craig

Offline crueby

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Re: 3rd Generation Otto Langen
« Reply #35 on: September 06, 2020, 11:30:08 PM »
More wonderful work, I'm off for another bag of popcorn so I can keep up!   :popcorn: :popcorn: :popcorn:

Offline kvom

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Re: 3rd Generation Otto Langen
« Reply #36 on: September 07, 2020, 11:49:08 AM »
Nifty setups.  I imagine getting the rack aligned took some care.

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #37 on: September 07, 2020, 08:46:56 PM »
Chris and Kirk; thanks for your comments.  Thanks also for those that just stop by to see the latest ďhappeningsĒ.

Chris: You must be out of chocolate chip cookies already! :thinking:  None left over after the show ?

Kirk: not as difficult as youíd think.  When I cut the piece of aluminum that mounted on the lathe cross slide, I made a recess in it so it fit down snugly over the cross slide platform.  This not only prevented rotation, but also assured me it's edge was perpendicular to the cross feed.  It was then a simple matter to get the rack material aligned with the edge of the piece of aluminum and I was assured that the teeth I cut would be perpendicular in the rack material.

It was a beautiful day here in North Carolina; almost to pretty to spend in the shop. :naughty:  I did spend part of the day there and made the piston.  I had slated this to be steel, but after searching my inventory, I only came up with a suitable chunk of cast iron.  There are lots of cast iron pistons out there, so cast iron it is.  The finished piston you can see below.


Next Iíll be looking toward fastening the piston to the rack, and then making the rack guide.
Craig

Offline crueby

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Re: 3rd Generation Otto Langen
« Reply #38 on: September 07, 2020, 09:00:14 PM »
Still a couple of bags of cookies stashed in the freezer, I make big batches!

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #39 on: September 10, 2020, 01:08:05 AM »
Thanks for stopping by to see the latest.

A landmark event; getting the piston, rack, and rack guide installed and have everything work smoothly without binding.


Next Iíll address the piston rings.  You would think I might just purchase these but in reality, Otto Langen rings are different from normal piston rings.  Here Iíve cut out the ring blanks.



If youíve built models for a while youíll know that everything doesnít scale linearly with the reduced size of the model, and the ability of the piston to traverse the length of the cylinder in an Otto Langen engine is a typical example of this.

The full size Otto Langen has a combined piston and rack weight that is probably close to 100 lbs.  A little resistance of the rings sliding along the bore isnít going to matter much with this amount of weight forcing the piston to the bottom of the cylinder.

This Otto Langen model has a combined piston and rack weight of a little under 1 Ĺ lbs.  You want the ring to seal but you just canít afford any appreciable frictional resistance between the rings and the cylinder wall.  This results in piston rings that are considerably thinner than standard piston rings.  Itís a tightrope walk between a ring thick enough to seal the cylinder but not too stiff to cause enough resistance that the piston will not drop to the bottom of the cylinder.   
In addition, the Otto Langen ring has the ring gap cut on a diagonal.  I suspect this is due to the high demands for a ring that seals well.  On the model, it helps create a better sealing ring, where the ring just canít press that firmly against the cylinder wall.

Iíll be taking all these issues into consideration as I make the single piston ring for this model.
Craig

Offline crueby

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Re: 3rd Generation Otto Langen
« Reply #40 on: September 10, 2020, 01:10:05 AM »
Slick! Very impressive machine.

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #41 on: September 12, 2020, 12:08:10 AM »
Chris: Thanks for your comment.  Thanks also for those stopping by to see the progress.

Over the last few days Iíve been continuing work on the piston ring.  Making these things is quite an ordeal since with the method Iím using, the work is quite labor intensive.  I do keep my fixtures, so if Iíll need to make another ring out there in the future, I already have the fixtures made, which will cut down appreciably on the work involved.

This is the same procedure Iíve used before; so if things seem dťjŗ vu, itís not you.

The first task is to turn an arbor on which to mount the ring blank in order to turn its outside diameter to size.  Here you see the arbor, with the ring blank attached.  Iíve used a radiator hose clamp to compress the ring blank onto the arbor.  Then Iíve pulled a retainer down on the ring blank to hold it in its compressed state.



With the ring blank held on the arbor, Iíve removed the radiator hose clamp.


In this view Iíve turned the outside diameter of the ring blank down to the required 2 inch diameter of the engine bore.  (The retainer is a bit off center, so it looks like the ring blank OD isnít circular, but it is.)



Next I made a fixture used to turn the inside diameter of the ring blank to true size.  The ring blank fits in this fixture, and then the cap is screwed down onto the ring blank to firmly hold it in place.



Here you see the fixture mounted on the lathe, ready to accept the ring blank.



And in this photo Iíve inserted the ring blank.



Now Iíve screwed the cap down onto the fixture, securely clamping the ring blank into the ring grove in the fixture.



Then, boring the ID of the ring blank can commence.



With the ring competed, here is a photo of the ring just after removing the fixture cap.



And a photo of the completed ring.



Finally, the ring mounted onto the piston.

Craig

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #42 on: September 12, 2020, 08:32:13 PM »
Thanks for stopping by.

Today I was working on closing the cylinder of this model so I could see how well the cylinder with its new ring seals.  The ring/cylinder fit on these engines needs to be a fairly good fit because any appreciable leakage will just rob the engine of power and these things make such little power that you really canít afford to lose much to leakage.   

Below is a video of a Ďcompression testí.  I have the engine sitting on a rubber pad and as you can see the rack isnít dropping at all, even when I press it down and it bounces back against the cylinder pressure (actually the bit of leakage you see is some air leaking by the rubber pad; with the spark plug in, It wonít leak at all).  Once I tip the engine over to break the seal on the pad, the rack immediately drops to the bottom of the cylinder.  This is exactly what I want in this model.


Now, on to a separate topicÖ one Iíve been contemplating for a while but didnít think I could pull offÖ now Iím encouraged.

The 1st generation Otto Langen engnes that were governed used a different type of governing than the 2nd and 3rd generation engines.  The 2nd and 3rd generation engines use a governor mechanism that directly releases the pawl and allows it to engage in the ratchet- thus starting another cycle.  The 1st generation engines that were governed employed a governor that held the spent exhaust gasses in the cylinder, thus not allowing the piston to settle to the bottom of the cylinder where a mechanism was tripped to start the next cycle. You can see this happening if you watch this video of Wayne Grenningís magnificent 1st generation full size reproduction.  You can even hear the exhaust gasses hiss as the governor finally allows them to escape and the piston is finally allowed to settle to the bottom of the cylinder

With the piston and rack on a model weighing so little, I did not think it was possible (at the size Iím modeling)  to have a good enough seal between the piston/ring/cylinder to trap the exhaust gasses so the piston would not settle to the cylinder bottom on its own accord, but yet have a fit that has so little friction that once the gasses are allowed to escape, the piston would settle.

But it appears that I have managed to do just that with this model.  The point Iím making is that this opens the possibility for me to build a 1st generation, governor controlled model.  Iíll need to think about this for a while.   
Craig

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #43 on: September 17, 2020, 09:45:08 PM »

Thanks for stopping by.  The last few days have occupied me in making the ratchet and pawl parts. 

Below is a close-up view of the ratchet.  It is keyed onto the end ot the mainshaft.



Next is a bracket that holds the pawl.  I might have misled you at the beginning of this build.  The 3rd generation Otto Langen engines do have a secondary shaft; albeit a stub shaft that runs inside the main shaft.  The pawl mechanism attaches to the end of this shaft that protrudes from the main shaft.



This is a little bolt/spindle that screws into the above bracket and holds the pawl.



And here is a photo of the pawl.


Lastly I give you a photo of all the above assembled onto the engine.  In this view, the ratchet and pawl are engaged.



And in this last view Iíve compressed the spring, dis-engaging the pawl from the ratchet.

Craig

Offline Craig DeShong

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Re: 3rd Generation Otto Langen
« Reply #44 on: September 22, 2020, 09:50:19 PM »
Thanks for stopping by.

Iíve been working on the ratchet escape mechanism over the last few days.  This seems to me to be a forest of levers and crank arms; if I didnít know better Iíd have thought I was making baker valve gear for a locomotive. :facepalm:

This is the arm that lifts the piston using a pin on the rack.  I have as yet to install the pin in the rack; its placement is spotted once this lift lever is installed and all the motion is verified.



Iíd spent the entire day Saturday making this bell crank.  I didnít think to look last week to see if I have some hot rolled steel from which to make it and Saturday morning, when I looked, I did not.  I did have some cast iron and I thought, ďcast iron will be okĒ.  A little voice in the back of my mind kept saying, ďcast iron is too brittle for those long thin arms and they will breakĒ. :old:  But I ignored the voice and made the bell crank as you see in the picture below.  While fitting it, one of the arms broke, :hammerbash: I should have known better. :slap:



Anyway, yesterday I purchased some A36 hot rolled steel and today I spent the entire day re-making this bell crank. 

Itís a curious part.  Below Iíve use my rotary milling head to form some of the curves this piece requires.


And in this photo Iím cutting the offset to one of the arms.



I was so excited to see how well it fit I forget to take a completed picture; but here I show it mounted on the engine.  Iíll use a tapered pin to hold it on the shaft and keep it from rotating but itís position is quite critical so Iíve used some red tread locker to ďspotĒ attach it in place.  Once the Locktite dries I can drill, ream, and install the taper pin.

Craig