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The more of Elmer’s Engines I build the move I love ‘em. This time I chose his #3 engine - an Open Column which describes the appearance. The engine employs porting on the crankshaft in the same way as his ‘Standy’ engine.

My first posting on this build covers what Elmer calls the bearing which in reality is also the main frame of the engine. I had a chunk of hexagon brass bar which was machined to shape on the mill. Here’s how I did it. (Click on pics if you want to see a larger image).

One or two points that may give a better appreciation of my approach to building the frame.

The plan for this engine is available for you to download, free of charge at http://www.john-tom.com/html/ElmersEngines.html I always convert plan dimensions into metric using a simple chart from my Model Engineers Handbook.

Whilst the plan showed the making of the frame in two pieces the ‘chunk’ of brass bar I found in my materials stash enabled me to make it in one piece therby avoiding the need to solder. Soldering will be required later in the build and I will try to guide you through the art of hard or silver soldering when I reach that stage.

I regard my bandsaw as a vital piece of kit in the workshop. I no longer have the stamina to hack through  great chunks of metal. You may notice the steps I have taken to hold short lengths of stock in the saw vice. The long screw keeps the vice jaws parallel whilst I have ‘extended’ the movable jaw with a piece of bar. Sometimes a little ingenuity is called for.

I appreciate that some of you may not have a milling facility. You can get round this to a large degree by buying brass stock closer to the finished shape and dimensions.

In shaping up the frame in the mill I usually take 0.5mm cuts when flycutting brass. With the end mill I probably advance the cutter something like 0.75mm at a time. I reckon more workpieces finish up in the scrap bin through overly optimistic depths of cut. It is sometimes tempting to take deeper cuts to speed the job along. My advice (learnt the hard way) is resist and avoid wasting hours of work.

You will see in the last picture that I have already drilled the hole for the crankshaft. I wanted to do this before milling the gap between the two bearing ends. It is particularly important on this engine to have a good, almost tight fit of the crankshaft through the bearings to prevent pressure loss. Running in will soon ease any tightness. I decided to use 5mm steel for my crankshaft which on the vernier measured 4.9mm. I selected a 4.7mm drill in the knowledge that the drilling action always produces a slightly larger hole than you might be expecting. Drill a fraction oversize can reduce all your hard work to scrap. Better to be undersize - its much easier to remove metal than put it back.

We all make mistokes - well I do anyway, quite a lot.

Just when the first stage of my build of Elmer’s #3 appeared to be going to plan I messed up bigtime.  Simple little job. I decided I would solder  the air (steam) inlet pipe into the engine main frame. It went badly wrong. Basically I didn’t get the frame hot enough and the inlet pipe was close to meltdown. The solder didn’t run so I applied more heat and eventually it did run but made a real old mess. I tried to clean it up with needle files but I wasn’t happy so I abandoned it for the day.

When things do go wrong I usually avoid taking any immediate action. Take a break, mull it over and eventually the best course of action will present itself. The next day I cut off the offending pipe, skimmed the top surface in the mill and turned a threaded inlet pipe - job done. I then continued drilling and tapping M3 fixing wholes in the frame then made up the base out of a handy piece of aluminium. This was cut close to finished size in the bandsaw then into the mill for final sizing and hole drilling.

Having completed the engine frame and base my next job was to machine the cylinder. The cylinder bore on the plan is given as 3/8″ - 9.5mm. As I have a 10mm reamer  I upped my bore size to suit. This I have done a few times with Elmer’s engines and it has never given me a problem. The depth of bore is critical and I stuck with the plan dimensions and finished off my bore with a 10mm end mill to give a nice square cut to the bottom of the hole. I took great care to ensure that the depth of hole was spot on or as near as I could get it.

I decided to add a bit of interest to the outside appearance of the cylinder by adding fins. I seem to have a thing about fins on engine cylinders. I guess it’s because ultimately I would like to build a model of an internal combustion engine. However, here are some pics of this next stage. Click on image for larger pic. By the way I have used a new edge finder on this project. My pal Bogs alerted me to this little gem, available at a very reasonable price from Arc Euro Trade - usual disclaimer.

The next stage was to produce the four pillars supporting the cylinder.  What might appear to be a relatively simple job can in fact be something of a nightmare if you don’t work to the right system. Fortunately Bogs showed me how to produce a backstop for the lathe sometime ago and it really does save a lot of time and anguish if you have to produce a number of identical turned parts. What you need is to aquire a ’soft’ arbor to suit your headstock taper. The likely chances are that it will be an MT3 but check with your machine specification before ordering. I think Bogs will be running a post shortly to explain how to make your lathe backstop but meanwhile my pics will give you some idea how it works. Remember, if you want to see a larger image just click on the pic.

Well today I managed to devote my attention to sorting out my non-running Open Column engine. The problem was resolved by remaking the main bearing block and the crankshaft, aiming for a very close fit. As the porting on this engine is by way of flats on the crankshaft a close fit is essential, almost to the point of tightness. This is to minimise  loss of pressure along the bearing bore. I am pleased, and relieved, to say the engine did run but required something like 40 p.s.i. to overcome the initial stiffness but after half an hour or so the engine was running fine on less than 10 p.s.i. and I think this will continue to reduce as the engine is run in.

You’ve read the book now see the video !

The finished engine showing the forward/reverse control lever.

The finished engine sporting its replacement main bearing block and crankshaft.

A pleasing little engine from Elmer's prolific drawing board well worth adding to your 'to do' list.

A reader’s interest in Elmer’s #3 Open Column engine prompted me to check through my postings on this engine and discovered that I had not added the final chapter and had left readers in the air with a non running project.

I eventually resolved the problem by making a further chassis to slightly tighter tolerances, which reduced the amount of air escaping from the wrong places - i.e. along the crankshaft. This is a lovely little engine which now runs well but it does require more care in construction than say, Elmer’s ‘Wobbler’.