steam engine with 40 mm bore

[Michael S.]

Hello everyone,

I want to start a new build report.
A short time ago I was able to buy cast parts for two steam engines. There are parts for a single cylinder and a 2 cylinder machine. Both with a piston of 40.00 mm diameter. and 44.00mm stroke.
I have a blueprint for the one-cylinder machine, but there is no blueprint for the two-cylinder machine.
The design dates back to the 1930s and was offered in a small series by a small machine factory for model builders. I got the castings from a guy who owns the original wooden models and had some cast iron parts made.
I'll start with the single cylinder engine.

Unfortunately, I could not find out much information about the original manufacturer of the castings. His name was Max Dörfel from the Thuringian Forest and he had a mechanical workshop and was perhaps also a dealer for tools and lathes.

Michael

[Dave Otto]

Looking forward to following along!

Dave

[crueby]

Looking forward to this build!   

[Michael S.]

The first thing I wanted to do was work on the faces of the base. Unfortunately, my milling machine is too small for the part.
I filed the four feet. But previously prepared with the grinder. There were spots as hard as glass on the little feet that had to be removed first.
The top of the base is already quite flat. There is only a small dent in the middle.
Now the only thing that helps is file, file and file.
(The first year of my apprenticeship also consisted of a lot of filing.)
I don't need a 100% straight surface and by constantly checking with the straight edge I have achieved a good surface.
Including a slowly blackening workshop.

Michael

[simplyloco]

Very nice Michael.
One of our later apprentice jobs was to make a surface plate about that big. There were three of us. The instructor removed three completed plates from his cupboard, and smashed a 1/4" chisel into each of them, and said "Now get on with that, and I want them all to stick together like slip gauges!".
It took a while with chisels, files and scrapers, but we made it in the end...

[Kim]

A new project!  How exciting!  I'll be following along Michael 

Kim

[john mills]

I will be following 
John

[Grateful Ted]

Very interesting model, love the crankshaft.
Count me in!

[Jasonb]

It's an unusual design having the two separate extensions to the legs of the "A" frame and I don't think I have ever seen that on a model or full size before and can't see a specific reason why it would have been done that way unless they also offered a different base casting more suited to use in a boat hull that had the bearing housings cast integral to it and the lower height would have been an advantage and then used the same "A" frame for all versions.

The amount of work levelling the top of the box bed casting is a good example of why many full size and model castings have raised areas where any part swill attach. This greatly reduces the amount of machining needed to get a level surface for all the parts to fit to be it back in the day with what they had and now for us.

I will follow along and see how things progress

[Chipswitheverything]

Very interesting to see your excellent pictures and, as it comes together, a build write up,  of engines that are entirely different to the familiar ones that we usually see.  Looks like being a nice project.  Dave

[Michael S.]

I also suspect the "A" stand is intended for a marine steam engine. Just as intended for the two-cylinder machine. For the stationary variant, the extension is an emergency solution.
In the blueprint for the single-cylinder machine, the description at the top also says "ship steam engine"!? But that fits better with two-cylinder machines. But there is no blueprint for this. But the "A" stand is the same and perhaps the one-sided step on the stand is intended for a shaft of rotation reversal. An oil pump could be mounted on it for the single-cylinder machine. I will do that there. I think the original design plan was the marine steam engine.

Michael

[Jasonb]

Certainly an unusual base if it was intended for use in a ship as the propshaft would be very high and the spoked flywheel is not right either.

I suspect that they may have originally done it as one for a boat and then just used the same castings for this model, they would better suit a base like I have shown below. Having said that I had not seen the style beforeI remembered the model "Anna" does actually have a short A frame much like yours http://www.ateliermb.ch/shops/gussteile/ch/contents/de/d37.html

Yes I think that block on the leg would have been used to mount a pivot for a shaft that activated reversing valve gear at each end of the engine, a boiler feed pump would have been a more usual fitment for use in a boat than a mechanical oiler.

[Michael S.]

Yes, a feed pump is also possible.
Nice that you found the website of the Swiss manufacturer of these machines. I've seen the smaller model in bronze at an exhibition before. I didn't know there were cast parts for it. On the website they write that the model was built after a German model. This machine was also available from Max Dörfel in a different version with a bore of about 25 mm.
Thanks for the hint.
Since the machine will definitely be operated with steam when it is finished, I am thinking about a feed pump.

Michael

[Michael S.]

The first thing I did was the crankshaft bearings. The lower parts were milled in parallel and brought to the same length. The caps were also milled and soldered with soft solder.
The hole for the bronze bearings was then drilled in the milling machine.
The outer contours were machined on the lathe.
The rest was again a job for the file.
I am very satisfied and am waiting for material for the crankshaft and bronze for the bearings. Then I can align and attach both bearings to the base.

Greetings Michael

[crueby]

Great progress!   

[Michael S.]

Yes Chris, I think I don't need a crane eyelet. 😁

[Admiral_dk]

Looks like you are off to a good start on this buil Michael   


Per

[Michael S.]

Bronze and iron came in the mail yesterday. That's when I started with the bronze bearings. It's a shame that so much of the expensive stuff turns into chips again.
I thought Chris' idea was great and finally separated the bearings. The compensation comes later with 0.40 mm brass strips.
The final measurement was made with the adjustable reamer. That smoothes out the hole. The crankshaft is made of 17.00 mm silver steel.

Greetings Michael

[crueby]

Beautiful bearings!   
How did you cut the diagonal oil channels on the inside?
 

[Michael S.]

The bearings got screws. These are M 5 bolts and fortunately I had nuts that are not galvanized. The crank is a cast part and was machined in the lathe and milling machine.
I was able to make the fit so I could press the crank onto the shaft.
Tomorrow the flywheel will be on and I noticed while cleaning with the file that there were hard spots.
Since no big noise is allowed to be made tomorrow on Sunday, I went over it with the Flex today.
Let's see how it turns out tomorrow.

Michael

[Michael S.]

Hi Chris, I did that with the Proxxon (Dremel) and a small diamond disc. It fit well in the bowl.

Michael

[Kim]

Great work on the bearings and crank, Michael! 
Kim

[Zephyrin]

These are M 5 bolts and fortunately I had nuts that are not galvanized.

a short stay in dilute hydrochloric acid will remove this ugly Zn coating...but nuts easily rust after that!
no simple ways to remove the stamped marks of the classe grade on the head of bolts !

very nice thread, thanks to share!

[fumopuc]

Hi Michael,
I do like your outdoor bench with vice very much.
Very useful.
My neighbors here would kill me.
I have a bench in my car port too and during the last 20 years I haven seen 2 times the cops visiting me, after 5 minutes working with a grinder.
So, it is a very special neighborhood.

[Michael S.]

Incidentally, Jasonb has a very good archive and found a report in a German magazine "Das Dampfmodell" from 1990 about a Max Dörfel steam engine. At that time the author bought the inheritance of a mechanical workshop and there were castings, drawings and a finished machine.
He finds it amazing that round head screws and some inch threads are used here. But that was still common in Germany for a long time. (And that's still the case with plumbers today)
Only the 25 mm machine is mentioned in the report.
With around 40 issues, the magazine "Das Dampfmodell" was the best magazine on the subject of model steam engines. Unfortunately, there hasn't been for a long time.

Michael

[Michael S.]

Machining the flywheel on the lathe went better than I thought. First drilled the hole and machined two sides and flipped and realigned the flywheel. That's it.
The crankshaft got a groove for a wedge and I made the groove in the flywheel with 4 saw blades tied together and adjusted it with a file. The flywheel must be brought into position with light blows of the plastic hammer. A worm screw secures the wheel.

Greetings Michael

[Kim]

Flywheel looks great, Michael! 
Kim

[crueby]

That came out great!   

[vtsteam]

Nicely worked! 

[Michael S.]

Thanks Kim, Chris and Steve   

[Djangodog]

Looking great.

[Michael S.]

At the weekend it was the A stand's turn.
A part that is a bit too big for my lathe. The center hole was very precise in the casting and I was able to make a rod to press into the hole. Now the upper edge could be turned to size. But unfortunately I could not edit the lower surface. The Support is in the way. I'm missing more peak height.
I was able to do the job on the old "LOEWE" lathe. But only in very small steps. There were very hard spots around the edges. It worked. When working on the small board, I got to the stand with the lathe tool. It's annoying but I was able to fix it with soft solder.

Michael

[Michael S.]

The old lathe was my salvation. I couldn't drill the hole for the crosshead with the old dinosaurs. The bed has been sanded.


<a href="https://www.youtube.com/watch?v=36CKZnlBA9s" target="_blank">http://www.youtube.com/watch?v=36CKZnlBA9s</a>

[crueby]

Clever setup!   

[Kim]

Wow!  That was quite the setup, with the whirling legs of death and all!  Looks like it worked well for you! 

Kim

[Michael S.]

The bore for the crosshead is 35.00mm and I finished at 34.90 on the lathe. The lathe tool has to be very long and therefore swings a little. I was able to smooth the rest out with the adjustable reamer. With the two-cylinder machine I have to work with a boring bar.
The large slot was drilled out and then milled.
The two foot parts were milled at an angle at the bottom and then brought together to a uniform height and drilled for threads.
It fits together.

Michael

[crueby]

Great progress!   

[Michael S.]

Yes Chris, I hope to get the machine ready in the spring. If not, it doesn't matter.
When the weather gets better soon, there will be a lot to do around the house and in the yard. The tree is already blooming but it snowed again today 😒

Michael

[Michael S.]

Today the first work on the cylinder began. The outside diameter at the flange is quite good for clamping.
The run is good enough.
So I machined the sides and then made the hole. The side where you drilled is then at the bottom of the cylinder. I milled a U for bottom and an O for top. Then I can no longer interchange it.
the holes for the drainage go into the casting attachments provided for this purpose. Unfortunately, they are far too far away from the edge and I drilled at an angle with the cordless screwdriver and a long 2 mm drill at the bottom of the 6 mm hole. as best it could and actually got closer to the edge.

Greetings Michael

[crueby]

Excellent start on the cylinder!  Watching along...

[Kim]

The cylinder is coming along nicely, Michael! 

You did a great job on that free-hand drilling too.  That can be a scary operation 

Kim

[Michael S.]

drilling was a small risk. Do I get too close to the edge or does the drill break off. But the material of the cylinder is very soft, good cast iron with graphite. It would have been better to get even closer to the edge. I didn't know how to do it any other way.

Michael

[Michael S.]

I continued to work on the cylinder. The outer edge still has to be brought to the required diameter.
Milled the openings for steam inlet and outlet and drilled the bore to the cylinder.
I always stick millimeter paper where the channel is marked. Worked very well again.
The steam box is riddled with extremely hard spots in the cast iron. I almost threw it in the trash but it worked in the end. I often had to grind the milling cutter.
Should I have put the part in the oven again to remove the hardness? Or is it no longer possible to get rid of it?

Michael

[Michael S.]

The lid of the steam box was a bit softer and could be worked on well. The top cylinder cover had a hole in the cast iron. I soldered it with soft solder and turned it again in the lathe.
Now the main parts are almost done and the black dust in the workshop will stop.

I wish you a happy Easter

Michael

[crueby]

Looking great!   

[scc]

Lovely work  Michael        Terry

[Kim]

Looks great, Michael!   

Sorry the cast iron was giving you grief there.  I can't really help you with the solution there.  I've heard other smart people on the forum saying that you can anneal the casting.  The recommendation seems to be to embed it in the coals in a fire pit. Then it should heat up in the fire and cool slowly overnight and be more workable when it cools.  But I've no experience at that.  I'll have to let others provide more meaningful input.

Kim

[Admiral_dk]

Good progress - though I do understand your fustrations 

Kim is right - the problem is how to ensure that the cooling down take hours ...!
An Electric Oven/Kiln that can be programmed to have a Temperature Profile, is by far the easiest way of doing it .... but only a few have one. So if you stumble across on for firing Clay/Ceramics @ a cheap price .... (you might need to add the sensor and controller - but they are cheap in China).

Per       

[ettingtonliam]

I just used to make up the fire or stove before going to bed, bury the nasty casting in the coals (or wood), leave it there overnight. Rake out wth the ash in the moring.

That worked for me several tmes.

[Michael S.]

Now that it's warmer outside again and not so cold in the workshop, I was able to work on the machine after work. All holes were drilled and threads cut.
First rehearsal setup.
The screws are provisional and will be replaced with bolts and nuts.
The last picture shows the Reeves and the Dörfel side by side.

[crueby]

Looks great! 

[Kim]

Just a bit bigger, eh? 

Wonderful work, Michael!

Kim

[Michael S.]

More small steps on the cylinder done.
The steam box has bushes made of bronze. For the valve stem. I also added a socket to the top of the box. Wasn't foreseen in the plan.
The lower cylinder cover also gets a bronze bushing for the piston rod.
The work for the 12 bolts on the cylinder was a bit exhausting. Instead of 4 pieces in M ​​6, I made 6 pieces in M ​​5 thread.
I had a lot of bolts converted to M6 threads and M5s. Wasn't faster than making it straight from the 5 mm rod.
But the material of the bolts was optimal.

Paint was distributed on the machine base.
Fields taped and painted the black color.
A thin orange stripe is added later. But first it has to dry well.

Greetings Michael

[crueby]

Looking great. Not long till it is done!

[Kim]

Lots of nice little pieces! 

The base paint is looking great too! Looking forward to seeing the racing stripe!

Kim

[Dave Otto]

I do like the color!

Dave

[Michael S.]

I've finished the piston. The piston rings are from some small motorcycle. I could buy them exactly in 40.00 mm.
The crosshead only finished on the outside on the piston rod.

Greetings Michael

[Michael S.]

And now the base with rally stripes.

[crueby]

Excellent!   When the piston rings are compressed in the bore, does the gap at the ends close up completely?

[Michael S.]

No, there is a gap of about 0.30 millimeters. I think that's enough for heat expansion. Is there any experience?

[Admiral_dk]

Great Paint job Michael and the rest looks fine too

When the piston rings are compressed in the bore, does the gap at the ends close up completely?

First thing I thought when Michael said small Motorcycle (and 40mm Bore) is a Yamaha FS50 (I know some other brands has the same bore too) and I can see that it is two-stroke rings (in the picture) -> so they DO have a gap when reaching much higher temperatures than in a Steam Engine (if not -> Destroyed Ring, Piston and Cylinder and maybe worse). I believe the 0.3mm is a cold gap - but it is sufficient 

Per       

[Michael S.]

Today, on Labor Day, of course, we worked.
I aligned and fixed the cylinder with stand on the base plate. For this I made a piece of PVC material so that it simulates the connecting rod and I could align it to the crank. That was an easy way and the best orientation. Align the valve body parallel to the flywheel and then transfer the 4 holes to the base. worked fine
The crosshead was also sculpted into its final form.
The whole machine is placed on a wooden panel made of old weathered wood. The wood was once used as a walkway for the chimney sweep on the roof.
I'll probably work a little slower on the machine now. There is still work to be done but now that the weather is getting warmer there are other priorities.

Greetings Michael

[Michael S.]

The stuffing box for the piston rod is made with a packing from still old remnants of this valve packing. I soak the threads in steam oil with graphite grease.

[crueby]

Excellent.   

[Kim]

Beautiful, Michael! 

I really like those pin strips of orange you have on the engine!

Did you 3d print that orange PVC support you made? That's a pretty good idea!
Kim

[Michael S.]

Hi Kim, no not printed. But it's an idea to print something out. But I don't have a 3D printer. The part is made of PVC round material. One 35mm diameter piece for the crosshead guide and one 15mm piece for the width of the big end of the connecting rod.

Michael

[Admiral_dk]

It is already a beauty now - lovely paintjob Michael

So 'just a number of small parts to do' - to make it a runner 

Per