Author Topic: Lehmann Stirling Engine (Read 10357 times)

yogi · « **on:** December 20, 2018, 10:20:20 PM »

In this series I will be documenting the build of a Lehmann Stirling engine from plans by Ernst Vogt.

The project was started 20 years ago. But as so many things in life, priorities change, and so this project ended up being mothballed shortly after I started building it. It was safely stored away all this time in my brother’s workshop.
During a recent visit to my brother and family, I decided to resurrect this engine and take it home with me to continue and finish the engine.

I’ll start this build log with an overview of the parts that I have so far.

The main cylinder housing is made from 100mm square tubing, and is mostly completed. What’s missing is the cylinder tube. I had one made, but for some reason it ended up being not round and needs to be remade.

The hot end:

For the flywheel, I got some help from my other brother (I have two). At the time, he was working on a large multi task machine, and he machined the flywheel for me. It is not completely finished yet, as it needs to be bored out and the outside diameter finished up.

The big pieces together gives an idea of the size of the engine.

The two part cast iron piston:

Bearing blocks:

Some brass parts. The oil cups are not finished and I might remake them anyway. Not decided yet.

The coolant reservoir:

I’ll be spending some time to work myself back into the project. I’ll also be inspecting the parts and start to plan how to proceed with the build.

I hope you’ll be along for the journey and stay tuned for more.

Yogi

tvoght · « **Reply #1 on:** December 20, 2018, 10:33:03 PM »

A very interesting project. I will be watching.
--Tim

Ye-Ole Steam Dude · « **Reply #2 on:** December 20, 2018, 10:41:01 PM »

Hello yogi,

That is a great looking engine and will be following your build.

Have a great day,
Thomas

10KPete · « **Reply #3 on:** December 20, 2018, 11:27:07 PM »

Pete

Dave Otto · « **Reply #4 on:** December 20, 2018, 11:37:37 PM »

Cool project Yogi, I'm looking forward to following along.

Dave

crueby · « **Reply #5 on:** December 21, 2018, 12:18:18 AM »

Thats quite an impressive engine, looking forward to seeing you finish it up.

b.lindsey · « **Reply #6 on:** December 21, 2018, 12:52:31 AM »

Looks like you got more than a good start on it, however long ago it was. Nice looking project!!

Bill

Dave Otto · « **Reply #7 on:** December 21, 2018, 01:20:27 AM »

I remember from one of the GEARS shows a a few years back one of the guys displayed a similar engine, maybe it's the same engine that you are building?

Dave

PJPickard · « **Reply #8 on:** December 21, 2018, 02:28:01 AM »

I will be following for sure...where can one get the plans?? I've been interested in this engine for a while.

Paul

Ian S C · « **Reply #9 on:** December 21, 2018, 02:31:35 AM »

Looks interesting Yogi, I'll be watching this one.
ian S C

yogi · « **Reply #10 on:** December 21, 2018, 02:13:55 PM »

Thank you guys for the kind comments, and following along.

Dave, that engine seems very similar as it's a Lehmann type stirling, and about the same size. I see enough difference though, that I can tell it's not the exact same version.

Paul, it looks like the plans are still available: http://dampfmodellbauer.de/webshop/product_info.php?products_id=39

Yogi

Roger B · « **Reply #11 on:** December 21, 2018, 05:36:03 PM »

That's quite a size

I will be following along

fumopuc · « **Reply #12 on:** December 21, 2018, 08:22:58 PM »

Hi Yogi, what is the future job of this engine ? To open and close your garage door ?

PJPickard · « **Reply #13 on:** December 21, 2018, 09:44:06 PM »

Yogi,

Thanks, it's funny I spent a LOT of time looking for plans for Lehmann and never found that link. Now to see if I can figure out how to order from there.

Thanks for the help!
Paul

tvoght · « **Reply #14 on:** December 21, 2018, 10:51:19 PM »

I don't think anyone has posted a link to this video yet:

<a href="https://www.youtube.com/watch?v=mgIkP0eCKlo" target="_blank">http://www.youtube.com/watch?v=mgIkP0eCKlo</a>

--Tim

yogi · « **Reply #15 on:** December 21, 2018, 11:17:12 PM »

Thanks guys!

Achim, that or maybe power the shop...

Tim, thank for posting the video. That an exquisite model. Here another video of a beautifully completed engine:

<a href="https://www.youtube.com/watch?v=Ncw0VwS7AtE" target="_blank">http://www.youtube.com/watch?v=Ncw0VwS7AtE</a>

Yogi

toolznthings · « **Reply #16 on:** December 22, 2018, 01:41:25 AM »

Busy

Nice project !

PJPickard · « **Reply #17 on:** December 22, 2018, 02:27:25 AM »

If you search youtube for "Lehmann Stirling engine" you will find a bunch of nice models. The Lehmann is one of my favorite hot air engines. I look forward to seeing this model develop!

steamer · « **Reply #18 on:** December 22, 2018, 02:30:01 AM »

Nice looking project Yogi, Propane fired?

Dave

ShopShoe · « **Reply #19 on:** December 22, 2018, 01:34:08 PM »

That is a very interesting Engine.

It is pleasing to watch and I am impressed with how quietly it runs.

Thank You for posting.

ShopShoe

bent · « **Reply #20 on:** January 02, 2019, 08:58:57 PM »

Very cool looking engine, and a nice size. Wondering what the purpose of the flyball governor is and what it adjusts (if anything) to regulate speed?

yogi · « **Reply #21 on:** January 03, 2019, 03:09:17 PM »

Thank you guys for the kind comments! It's very much appreciated.

Dave, yes, the plan is to have it propane fired.

Bent, the governor will open a valve into the displacer cylinder and relieve air pressure from the engine, regulating the speed.

Yogi

Craig DeShong · « **Reply #22 on:** January 07, 2019, 09:57:28 PM »

I've sidelined a few projects over the years myself, then returned to them and thought, "Why did I ever put this aside, it's pretty far along and it's going to be really nice to finish it".

I'm thinking this is one of those projects too. I'll be following along.

yogi · « **Reply #23 on:** January 09, 2019, 12:31:30 AM »

Craig, thanks for checking in and yes, it's definitely good to be working on this project again...

To continue, I'll be making the cylinder. I made it out of 1144, and has a 50mm ID, 62mm OD, and is 194mm long when finished.
The challenge on this part, is for the tool not to chatter in the long bore. To rough out the bore, I used a carbide insert boring bar and roughed it out from either side. To finish, I used a HSS boring bar, to be able to take light cuts, and was able to accomplish it without chatter.

Taking a finishing cut, using a 1" boring bar with a HSS bit. The stick out on the bar is 8 inches.

The surface finish from turning alone was really nice already, as shown in the picture below. To make it even better, I used a small break cylinder hone. This took only a few passes to finish.

The cylinder is installed in the cylinder housing with Loctite 609.

The honed cylinder, even though the surface finish isn't showing up well in the picture (in reality it's better than it looks).

Thanks everyone for following along, and stay tuned for more.
Yogi

b.lindsey · « **Reply #24 on:** January 09, 2019, 01:46:32 AM »

Very nice finish on the cylinder. Still watching along even if quietly Yogi.

Bill

yogi · « **Reply #25 on:** March 07, 2019, 07:31:24 PM »

Thanks for following along Bill!

The next parts for the engine are the bearing blocks.

For the tall bearing block, I used hot rolled bar, and milled the profile to full depth on the first op.

Moving on to the second side by milling away the remaining stock and finish to final thickness:

The top is tapped for the mounting of the cap.

The bottom mounting holes are drilled:

Counter bore from the top for the mounting pads. To be able to reach, I used a DA200 collet extension.

The short bearing block was already made, all it needed to be finished, was a small slot as a cosmetic feature.

The bearing caps are installed, and bored out for the bearing.

The caps are then finished up by tapping a hole to mount the oil cups.

And the last part was to drill a hole in the blocks for a pin to prevent the bearing to rotate.

The finished bearing blocks:

Thanks everyone for following along, and stay tuned for more.
Yogi

cnr6400 · « **Reply #26 on:** March 07, 2019, 07:50:30 PM »

Looks great Yogi, well done!

Ye-Ole Steam Dude · « **Reply #27 on:** March 07, 2019, 08:59:27 PM »

Hello Yogi,

Beautiful workmanship.

Have a great day,
Thomas

b.lindsey · « **Reply #28 on:** March 07, 2019, 09:15:42 PM »

A unique but very pleasing shape to the bearing blocks Yogi, especially the caps. Looks very nice.

Bill

Dave Otto · « **Reply #29 on:** March 07, 2019, 09:55:55 PM »

Nice looking parts Yogi!

Dave

toolznthings · « **Reply #30 on:** March 08, 2019, 02:06:41 AM »

Lots of great progress !! Moving along nicely.

scc · « **Reply #31 on:** March 08, 2019, 04:23:52 PM »

Excellent

yogi · « **Reply #32 on:** April 05, 2019, 08:29:08 PM »

Thanks everyone for the kind comments! It's very much appreciated.

Progress is slow, but I do have a part to share with you guys.

The base plate is milled from 3/8" 6061 plate. I divided the milling operation into two, milling two sides at the time.
Carefully placing the plate on 123 blocks, making sure the blocks don't interfere with the tool path. Clamped down, again carefully checking the clamps are not interfering, the right and the left side are milled.

Finish pass:

I moved the claps one at the time to the side of the plate, making sure not to move the part from its position, to mill the remaining two sides. Again, making sure the clamps are clear from the tool path.

In the same set up, I spot drilled the location for the mounting holes. Here the base plate after it came off the mill:

The drilling and tapping was done manually on the Bridgeport.
The finished part:

And the mandatory family shot of the parts so far:

Thanks everyone for following along, and stay tuned for more.
Yogi

yogi · « **Reply #33 on:** April 20, 2019, 01:12:27 AM »

For the split bearings, I first milled the bronze stock into halves.

Chucking the two pieces in the 4 jaw, the bearings are turned and parted off.

Last operation is to drill holes in the bearing half's. In the bottom half the hole is for a pin to prevent the bearing from rotating, in the top it's for the oil passage.

The finished bearings:

And the bearing installed in the bearing blocks.

Thanks everyone for following along, and stay tuned for more.
Yogi

yogi · « **Reply #34 on:** May 10, 2019, 10:13:07 PM »

The next parts for the engine I made are the crank and return crank. They are made from 303 stainless.

The first side is finished to full depth.

The second side is then finished using the trusty soft jaws.

The finished cranks:

Thanks everyone for following along, and stay tuned for more.
Yogi

Plani · « **Reply #35 on:** May 11, 2019, 08:43:53 PM »

Great progress and very nice parts

Looking good!

Plani

Art K · « **Reply #36 on:** May 12, 2019, 02:27:17 AM »

Yogi,
Missed this build I will be following along. I have to admit that it is no fun boring a piece that long on the cylinder 8 inches. that's where you find how good your equipment is. Looks great so far.
Art

b.lindsey · « **Reply #37 on:** May 12, 2019, 02:35:57 PM »

Wonderful family shot yogi. This really is quite a large engine but the motion is fascinating!! Still following along.

Bill

toolznthings · « **Reply #38 on:** May 13, 2019, 01:13:55 AM »

As always, nice looking parts ! Following along

PJPickard · « **Reply #39 on:** May 13, 2019, 11:06:55 AM »

Great work on a fav of mine! I love your Maho!

Dave Otto · « **Reply #40 on:** May 13, 2019, 11:45:56 PM »

Very nice Yogi!

Dave

yogi · « **Reply #41 on:** June 18, 2019, 12:29:44 AM »

Thank you guys for the kind comments and checking in on the project.

The engine has a set of levers for the typical Lehmann motion. My first thought was to bend some flat stock to shape. After an attempt at bending, which didn't turn out well at all, I felt that I have two choices. Either I'll build bending jigs or I'll machine the levers out of the solid. Machining out of the solid might seem a bit overkill, but building a jig is also a lot of work, and still no guarantee that I'll achieve the accuracy I'm looking for. Milling out of the solid will be a challenge and a lot of fun, so out of the solid it is.

The first operation was to drill the holes and mill the radii at each end of the lever. Making sure I have enough stock left to clamp it in the vise for the next operation.

The pieces laid flat in the vise, the contour is milled out.

Using a set of accurate machined spacers, the levers are finished. In this operation the tapper in the lever was added on both sides.

The two finished levers:

Thanks for following along, and stay tuned for more.
Yogi

toolznthings · « **Reply #42 on:** June 18, 2019, 01:35:34 PM »

Levers came out great

Machining was the best way. Hate trying to bend thick parts to size.

b.lindsey · « **Reply #43 on:** June 18, 2019, 02:33:55 PM »

Very nice looking parts yogi!!

Bill

Ye-Ole Steam Dude · « **Reply #44 on:** June 18, 2019, 08:45:51 PM »

Hello Yogi,

Beautiful job on the levers.

Have a great day,
Thomas

PJPickard · « **Reply #45 on:** June 19, 2019, 11:04:45 AM »

Excellent work, I will remember that when I make mine! Thanks!

Roger B · « **Reply #46 on:** July 11, 2019, 06:27:44 PM »

Still following along in the background

Milling the levers from solid was an interesting and successful solution

yogi · « **Reply #47 on:** October 03, 2019, 09:04:16 PM »

Thank you guys for the kind comments. It's very much appreciated.

To continue the work on the lever assemblies, I'll be machining the forks.

The first side is milled out.

The fork is then turned over, and the second side is finished.

To finish the fork with the radius at the top and the holes, I used a set (of well used) soft jaws.

The finished fork:

Thanks for following along, and stay tuned for more.
Yogi

toolznthings · « **Reply #48 on:** October 04, 2019, 01:10:24 AM »

Very nice !

PJPickard · « **Reply #49 on:** October 04, 2019, 01:23:40 AM »

Good to see this still going...I will make one. Someday!

yogi · « **Reply #50 on:** October 07, 2019, 09:24:09 PM »

Thanks guys!

The forks for the second lever assembly are made in a similar way as the first.

Milling the first side.

As usual, the second side is finished up in a set of soft jaws.

The two finished forks:

To silver solder the parts together, I carefully located and clamped the pieces to prevent any movement while heating the parts.

..and the two finished lever assemblies:

Thanks for following along, and stay tuned for more.
Yogi

toolznthings · « **Reply #51 on:** October 08, 2019, 12:59:23 AM »

Following along, nice work for sure !!

Dave Otto · « **Reply #52 on:** October 08, 2019, 01:03:28 AM »

Very nice work Yogi!
Great to see more progress on the Lehmann.

Dave

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Author Topic: Lehmann Stirling Engine (Read 10357 times)

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