Bernays 1878 running Air Engine.

[propclock]

I saw this engine first on HMEM, there was a wonderful l post on the build of one ,and there are several beautiful, beyond perfect examples
of this engine on HMEM and on the web.
I run my "steam" engines on air at shows and at home . So my approach to this build was biased by my
desire to run on low pressure air. A good tip was also mentioned on HMEM that said " don't even try to build out of anything but cast iron "
because it is so out of balance that the mass is needed.
Sorry I am not going to look up the contributors names. But thank you.
Well with this in mind I made the crankshaft 2 piece, with a 2 ball bearing main block , and an outer BB bearing for a power take off and flywheel support.
I counter balanced the crankshaft as much as possible. This required some changes to the valve links, minor.
I also lightened all the above crank weight by making the parts out aluminum not steel.
I also found that air consumption can be an issue for my air pump, so I reduced the cylinder bore to .75" .
Because is it just an air demonstration engine I made all the wear components out of Delrin with Teflon packing.
So the pictures/ video are of my completed but not polished or painted engine. runs great IMO. 4psi aquarium - large volume air pump.
One more comment, almost all the metal used were gifts from friends,
enough bla bla bla. Here is the tube link

 

[GreenTwin]

Beautiful build !
I like that crankshaft balance.

I have seen various builds of this engine around the world, and there are some variations between builders, depending on exactly where they got their Bernay information.

My dad saw a print about the Bernay engine in a book that Tom Lindsay (Lindsay Books guy) sent him, and dad decided to try his hand at building one of these engines.

Dad's engine ran prefectly, which is impressive to me given that dad created some fairly crude (but geometically correct) drawings for his Bernay.

After dad built his Bernay, a model engine builder named Jesse Livingston (of Troy TN) created his own original drawings for a Bernay, and had that engine build published in Live Steam Magazine.
I was a bit disappointed in Jesse's build in that it was smaller than my dad's engine, and also the design varied quite a bit from my dad's engine.

I ended up taking my dad's engine apart, measuring every piece, and creating drawings for this engine.
I have heard from several folks who used my drawings that they are accurate, and engines produced from them do run well, so that is good to hear.

Here is the post I made about my dad's Bernay build, and the drawings I created for my dad's engine.

I am more than delighted to see this engine design flourish, from wherever it originated.

https://www.homemodelenginemachinist.com/threads/bob-js-bernay-steam-engine.34339/

Edit:
I guess I need to make castings in gray iron for this engine, given how unique and popular it seems to be.
It does lend itself to barstock construction though given that flat rectangular crankcase/cylinder housing.

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[propclock]

Yes I am sorry I didn't credit your fathers build and your creation of the drawings. I used them to
extent that I could. Other than my mentioned changes to run more balanced on air they are
in fact 90+% based on your Father's build/your plans. Thank you very much.

 

[GreenTwin]

No problem.

Beautiful build; most impressive.

I never gave a thought to the credit thing until I posted a photo of my dad's Bernay engine here years ago, and someone said "You are a bit late, someone has already designed and built that engine", referring to Jesse Livingston's design, which occurred after Jesse saw my dad's engine design.

Same thing happened with my Dake drawings, and a knock-off of that got published with no mention that my drawings were the go-by.
I was asked if my Dake drawings could be used to create a new design, to be published, and I did say "Go for it", but some sort of reference would have been nice, since the comments said things like "What a genius to figure this out by yourself".

And then I went to Grabcad, and looked at a large number of 3D models made from my drawings, including the Bernay engine, and all the credits go back to Julius De Waal.

So it is unfortunate that things get muddied over time, but such is life.

I do spend a lot of time and effort creating accurate drawings, and so of course I don't want to see credit for those go to someone who did not create them. I think everyone can understand this issue and the need for clarity with respect to the original creator of drawing sets.

I did contact Julius De Waal, and to his credit he and the website where he publishes did make some changes to note exactly where they were getting the material for the drawings I created, so hats off to De Wall on that.

And there are quite a few other Bernay drawings and designs out there that I have seen, that are unique, and those are quite interesting too, and differ significantly from the Bernay print shown above.

Its all good.

Keep up the fantastic work !

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[GreenTwin]

Here is an example of a Bernay variant, published perhaps in Belgium.

These are not my photos, but I am posting them under the "fair use" doctrine, which is a partial sample of a larger work.

There are some good drawings for this engine out there somewhere in the world.
I have seen a sample of them.

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[propclock]

As far as grey iron castings go , I know of at least 2 possible customers . They don't do "air" they are full time steamers.
I am a member of BAEM but we use the hospitality of
Golden Gate Live Steamers for our meetings and there are some active steam engine builders . I know selling castings is a total loss issue but ???

 

[GreenTwin]

I found this print online, and it originally appeared in the May 3rd issue of "Engineering" magazine.

I did not find this in my dad's material, so it would be interesting to compare the geometry of this print with my dad's geometry, and see how close they are.

I distinclty remember my dad complaining about how difficult it was to figure out the geometry on this engine.

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[GreenTwin]

As far as grey iron castings go , I know of at least 2 possible customers . They don't do "air" they are full time steamers.
I am a member of BAEM but we use the hospitality of
Golden Gate Live Steamers for our meetings and there are some active steam engine builders . I know selling castings is a total loss issue but ???

My goal is to set up a non-profit organization in the next few years, so that some castings can be made on a non-profit basis, and in very limited quantities, and donations would go towards "SOMECH".

https://www.homemodelenginemachinis...engine-casting-heritage-project-somech.35550/
I talked to the folks from PM Research at NAMES in 2019, and they said they make their own castings, except for gray iron.
I told them I could show them exactly how to do gray iron themselves, but they did not follow up on it to my knowledge.

I want to preserve the casting knowledge, so that if all the casting kit companies vanish (many of them already have vanished), we can continue this hobby on our own.
I am expecially keen on passing on the knowledge of how to make high quality engine castings in gray iron on a hobby level.

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[GreenTwin]

Looking at the section in post #7, it appears that the original Bernay cast engine may be a headless design on the bottom, perhaps with just a small hole for the boring bar? Can anyone else see that ?

And as was typical of gray iron engine castings, the thickness of any section appears to be uniform, and the same thickness.

The crankcase appears to be hollow.

So a casting would have a cored interior, cores for the cylinder bores, and a cored exhaust passage.
Coring the steam passages may be difficult at that size.

It appears that the steam chests are cast integral to the cylinder/crankcase assembly.

I would have to start over with the 3D model, with the intent that the patterns would be made for casting; ie: with the appropriate draft angle, etc.

I think this engine design would be a perfect candidate for the lost-PLA method, and that would solve the issue of the small passages, etc. You woud have to use a hot iron pour, and use runners and gates to allow a fast fill, else you will get a partial fill in the tight spots.
Probably a vacuum assist would help fill all the mold quickly.

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[GreenTwin]

.double post - deleted - not sure how I did that

 

[Jasonb]

Nice Model, the geometry is similar to the "Non Dead Centre" engine but inverted.

Pat it does look a blind bore but your image is a bit small to be sure

 

[GreenTwin]

Figure 2 in the lower left corner would be a section through the exhaust passage, at least on the left side of figure 2.

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[Jasonb]

Still a bit small but I'd say completely solid. There is a groove for the end of a cutter to run out into

Maybe try the Compound!

 

[Jasonb]

hopefully this is larger and looks completely Solid Some interesting cores if the valve chest arrangement is to be replicated, projecting port face and overhanging flange for the chest cover.

What is the sectioned part on the left of the crankshaft shown on the end elevation?

 

[GreenTwin]

This print is one of those "waste no space" drawings, since it shows an exterior view on one side, and a section on the other side.
Saves paper and drawing time, but makes it a bit more complex to comprehend.

The 1/2 of the engine under the label "Fig.2" is a section cut horizontally through the centerline of the D-valve.

The crankcase is hollow between the two cylinders, as you can see in Fig. 2 and 3.

Fig.2 shows the exhaust passage to the left of the cylinder.

This engine could be cast using cores, but the tiny passages would be very difficult to core.

I think this engine would best be cast using the lost-PLA method.

I think we have highjacked this fellow's thread, perhaps we better break this discussion off into another thread.

Edit: Nothing was solid on the old engines; everything was cored out to give a uniform wall thickness for all the walls of the casting, so that you did not get shrinkage defects caused by the thinner parts solidifying first, and drawing from the thicker parts that were still fluid.
You will get hot tears if you don't maintain uniform wall thickness throughout.

Edit: I am not sure what the bolt is about at the bottom center of Fig.1.
A bolt would seem to indicate that two crankcase/cylinders were cast, and then bolted together.
The top of the crankcase is open.

 

[Jasonb]

Two halve sheld together with 3 bolts.

Even with lost PLA getting the sand/investment into the steam passages won't be easy.

Given the blind bore it may be more practical to use a sleeve that is easy to machine and hone, mill the vertical steam passeages into the outside and ends of the sleeve and then all you have to do on a cast or solid is some horizontal drilled or cored passages to connect port slots to the passages in the liner.

 

[GreenTwin]

I have noticed that some model engine kit companies make the passages more in a square shape, where a full sized steam engine uses a rectangular slot shape for the ports/passages.

Tiny passages and parts is the main reason I don't like to make/cast small engines.

Below is what passages typically look like on the standard D-valve steam engines of old.
There is a passage missing on the left side in one of the screencaps, but there should be passages on both ends of the cylinder.

At some point the passages get very tiny, and the cores get very small.
I have not successfully cast a small passage yet.

.

 

[GreenTwin]

These were some early experiments with sodium silicate cores for passages.
I forgot I had tried this.

The ports on the port face actually turned out very clean; being a nice rectangular shape.

The entry of the port into the cylinder is not so clean, and I think the cement I was using gassed at the inside joint.

And these passages are in gray iron.

So after reviewing these photos, I think I could actually make small ports/passages, since these came extremely close to working.

This was probably the 2nd iron casting I had ever made, and so I really had little idea about exactly how to do things.
If I knew then what I know now................

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[GreenTwin]

So it begs the question, could a 3D printed PLA pattern or corebox be used to make lost wax pieces ?

What is the temperature of hot wax ?

It would probably be worth the effort to at least try the lost PLA method.

I would cast the cylinders and crankase in one piece.
No need for two pieces on a small model.

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[GreenTwin]

I will start a new 3D model for the Bernay.

I may increase the size a bit, to make the casting easier.

This would be a good testbed for using small cores, and for testing the lost PLA method.

From the photos above, I know that non-reinforced sodium silicate passages will withstand iron temperatures.

Casting the engine with removeable lower cylinder heads would make things much easier from a casting and machining standpoint, and would not really be noticeable.

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