My take on Jurgen Galba's beam engine

[Kaleb]

Although Jurgen's designs have been used many times as an exercise in CAD modelling, I haven't actually heard of that many people actually building them, so I decided to have a go. After looking closely at the plans, I decided that my first choice was his beam engine.



Here's a rendering of a CAD model of this engine made by a man named Jerry Koontz. I included it here to give an idea of what the finished engine should look like.

I am making some slight changes here and there to suit how I would do things.



I decided to start with the eccentric. In the original plans Jurgen has specified white acetal resin for this part, but I decided to make it from this piece of steel since I believe it will wear better, will not be affected by heat when the engine is run on steam, and besides, I have more mild steel kicking about than I know what to do with!





With the steady rest used to provide adequate support the work is faced and center drilled.



The stock was turned down to the diameter required to accommodate the machining of the eccentric itself plus a little extra for good measure.



Temporary witness marks were made to indicate the lengths of the various features.



At this point the stock was parted off.



Facing the parted end.



I also took another facing cut on the other end to get a better finish.





The eccentric, which also has a concentric section where the flywheel/pulley mounts, requires a 6mm hole all the way through. However the tolerance for this hole is plus 0.02, minus nothing, which means that it had to be drilled undersize and reamed.







Turning the two concentric diameters, 20mm and 14mm.



Parting off the part-finished eccentric.



Facing to length.



To turn the actual eccentric in the strict sense, the job was set up offset in the 4-jaw chuck. The way I typically do this is to make a center punch mark where I want the axis of rotation to be, and then dial this in using a dead center held against it by a live center in the tailstock.



The first attempt at this literally went pear-shaped since I didn't leake enough stock on it. The circular scratch shows what I wanted to end up with. :fan:



Fortunately, everything went to plan the second time around.



One key change I made on this part was to drill and tap a hole for a grubscrew, which will allow me to adjust the timing, and will also reduce the risk of the eccentric slipping out of time when the engine is running. The plans also called for the flywheel to be keyed in place, which I don't think is really necessary on an engine this size, a grubscrew or two will do nicely.



Finish facing.



The finished part.

 

[Herbiev]

Looking good. Will be following with great interest.

 

[kquiggle]

Well done on the build log - I appreciate all the details, including the minor boo-boo on the eccentric (although it's not clear to me how you initially went wrong).

By the way, where did you get the plans for this build?

 

[jimjam66]

By the way, where did you get the plans for this build?

Here's the link.

 

[kquiggle]

David - many thanks for the link to the plans; quite a few interesting plans at that link.

 

[Jmccrack]

How are you going to do the impeller

 

[Kaleb]

About time I posted an update on this build. Things have been slow lately, but I have made progress.



The next part I turned my attention to was the cylinder. The plans call for stainless steel, which although not the best material to machine, is in my opinion an excellent choice because it wears very well and resists corrosion excellently.





The stock was faced and center drilled while supported in the steady rest.



Machining it down to 30mm. This photo shows one of the problems of working with stainless, which is its tendency to produce very stringy swarf, exacerbated in this case by the lack of a chip breaker on the insert. I should also point out that this swarf is particularly good at cutting your fingers, so pulling it out while running with bare hands is not a good idea.



A 12mm OD boss was machined which will fit into a matching hole in the base or bedplate when it is made.



I couldn't help but notice this rather interesting looking swarf that came off during this operation. It looked almost like miniature slinky's rather than the "steel wool" that I'm used to seeing when machining something stringy like this. I wonder if anyone else recalls getting swarf like this?



Anyway, this is what it looked like after the boss was machined.





The job was then turned around to machine the other end to size after facing it, again supported by the steady rest since I couldn't really have a center drilled hole in the top.



My quick and dirty flycutter that I needed for the next operation.



Flycutting a flat on the side.



The boss also had a flat milled on it, actually two in my case because I forgot that it had to be perpendicular to the first one, so I simply repeated the process. This doesn't really matter though because the boss will be hidden when the engine is finished.



The flycutter left the first flat quite messy, so I faced it in the 4-jaw chuck to clean it up.



This is what it looked like just after cleaning up the large flat. Sorry about the blurry photo.



The bore was then pre-drilled to 10.5mm at that point.

Now for a small change to the design. The plans called for the steam ports to be drilled 2mm and for plugs to be pressed in on the flat side. The inlet connector was much the same story. Now this might work if you soldered them in, but since we're working with stainless, this is not really an option. Press fitting could work but it can be difficult to do successfully and there would have been a risk of the parts coming out. What I decided to do instead was to tap the holes and thread both the plugs and the steam inlet connector. This way they shouldn't be going anywhere.



So the ports were drilled as called for.





Then the upper section of each hole was opened out to 2.5mm and tapped with an M3 thread for a brass plug.





The hole for the steam inlet was then drilled and tapped M6



The next task at hand was to make the steam inlet connection. So I went over to the little Sieg lathe to start by facing off a piece of brass.





Turning the OD and a shoulder for the thread





Drilling out the centre



https://flic.kr/p/BndaL2

After parting off, the part was flipped around in the chuck, faced again and part of the hole opened out to 4mm to allow a piece of K&S brass tube to be soldered in as an inlet pipe.



Then it was over to the Hercus lathe to cut the thread using a die in my homemade die holder held in a tailstock chuck.



Finally, it was back to the Sieg to face the thread off to length.



And here is the finished part installed on the cylinder. The holes located above where the steam ports are were plugged by threading some 3mm brass rod, screwing it in, then cutting it off with a junior hacksaw and filing the top flush.





Back to the cylinder itself, and the next area of attention was the valve chest. So after dialling in a centre punch mark in the required location, the part was centre drilled and drilled 5.5mm.



Then with the lathe in its slowest back gear and plenty of oil, a reamer was used to bring the valve chest to the required size of 6mm.





After setting this part aside for quite a while, I continued since I now have a 12mm reamer to finish the cylinder bore itself. So the pre-drilled hole was opened up to 7/16" which works out to be about 11.5mm. I seem to remember it being 11.54mm, just not sure what that second decimal place is.



The new reamer's first task was to bring the cylinder bore out to 12mm, again with plenty of oil and the lathe in its slowest back gear.





A couple of holes were drilled and tapped M4 to take the cylinder cover screws.



Finally, the cylinder was chucked up to take a slight facing cut to clean up the top surface.



And here is the finished cylinder. Next I will cover the valve and the piston.

 

[Kaleb]

How are you going to do the impeller

To be honest, I'm not sure on that one since I don't have a mill with a rotary table. I might change the design so the blades are straight, and only have four of them.