'Debbie' despite international efforts still refuses to run unaided and is now sadly destined to the 'non-runners' shelf until a solution can be found.
Well, sadly, I feel as though I have come to the end of the road with ‘Debbie’. Not only have I spent two months of workshop time but minds with far more knowledge than mine have applied both theoretical brain power and practical skills in what has turned out to be an international effort to resolve this frustrating issue.
‘Aussie’ Jim who has also built a ‘Debbie’ has encountered the same problem as myself in that the engine will fire when aided by the electric starter but simply won’t run under it’s own power. Jim has been to extraordinary lengths to get to the route of the problem using such fault seeking devices as a colourtune plug to view and video the action of the spark plug plus oscilloscope, stroboscope and as far as I know even a kaleidoscope but all to no avail. Jim also tried a bigger flywheel to increase momentum between power strokes and even a smaller flywheel in case the standard flywheel was just too much.
Once or twice I have succeeded in getting my engine to run for maybe 15 or 20 seconds unaided then it simply fades away as it misfires and fourstrokes. I have tried both mechanical coil and contact breaker and more lately an electronic CDI ignition system but with no apparent difference between the two.
I have made a compression seal for the piston rod to minimise any leakage of compressed vapour during the transfer process.
Many hours have been spent perfecting the action of the non-return valve which according to Jan is the most likely cause of poor and non-running engines.
I have made a modified version of the vacuum carb incorporating throttle control. I have also made a revised cylinder head to provide better gas flow and place the spark into that flow.
Jim and I are not the first to encounter difficulties with this engine as last year there was a thread on Model Engineer forum where two or three builders of this engine came up against identical problems.
So, sadly, ‘Debbie’ will be put on a shelf and before starting my next project I shall attend to a number of pressing service issues in the workshop including an overhaul of my DRO system on the mill and a general tidy up after weeks of neglect.
With thanks to all those who expressed an interest in this project and those who took the time and trouble to offer advice. I know of at least one undaunted visitor to my site who is bravely midway through his build of ‘Debbie’ and I am just hoping and praying that he may come up with the answer – good luck Dan !
The basic frame for Elmers #32 vertical engine now completed and awaiting a visit to the paint shop.
I am the first to admit that of late activity in the workshop has been almost non existent apart from a brief excursion into making acrylic torches and pens which some might argue is not proper model engineering.
My last major project was the Opus Proximus vertical engine the plans for which appeared in Model Engineer. Despite considerable effort on my part it still doesn’t run and has been deposited in my non-runner gallery which fortunately doesn’t include too many abandoned projects.
Anyway, onwards and upwards and after lengthy procrastination I have started building Elmer’s #32 Open Column vertical engine which is a similar engine to the Opus Proximus but one which I feel more confident will perform as Elmer planned. I have decided to build this 50% larger than plan. I made a similar decision when I built Elmer’s #33 Mill Engine and that turned out to be one of the best running engines I have ever built. It is no more difficult to build than building to size but it does allow you to add extra detail such as split bearing holders and more bolts in the steam chest – looks so much more authentic. It clearly costs more for materials but compared with the number of hours involved this is fairly insignificant.
I ordered the basic materials from M-Machine in Darlington, you will find a link to their website under Resources on this site. As I find cutting thick plate metals an irksome task M-Machine cut the baseplate and platform to finished size.
Incidentally they cut rather than guillotine which can leave a slightly deformed or rounded edge.
Before machining commenced the plans were converted from imperial to metric and all dimensions increased by 50%. This should provide a good ‘meaty’ model for little extra work.
The main pieces of brass and aluminium required for the build. M-Machine of Darlington cut the aluminium plate to size and required minimal finishing.
With a dial test indicator (DTI) it is important to make sure that the base plate is squared up and level on the mill table before machining the concave profile around the edge.
Note the two 12mm dia. stops on the milling table to ensure the base plate is squared up correctly. It only takes a few minutes to make these stops but it simplifies the setting up of workpieces on the table.
Machining of baseplate completed. The next stage will be to drill and tap the holes for the pillars and cylinder base plate and prepare the top platform which has cut-outs to be dealt with.
A quick coat of etching primer is one way of providing a good surface for your marking out and unlike felt tip pen, which I often use, won’t be washed away with WD40 during machining.
All edges are squared up and cleaned off holding the workpiece in a machine vice clamped on its side. This ensures nice square edges.
To speed up the removal of metal I resort to chain drilling and then finish off with a milling cutter to smooth edges up to the edge of the scribed area.
The base plate and platform have been drilled, tapped and cleaned up and are ready for assembly into the engine frame.
The pillars are tapped M6 at the base and threaded M6 to hold the platform. Domed nuts will be sourced for the final assembly.
The bearing blocks are machined, drilled and tapped as an identical pair to ensure correct alignment and smooth running.
Although I plan to add some detail to the bearing blocks it is reassuring to find that the crankshaft runs freely in the bearings – so far so good !
Time and care spent on setting up the bearing blocks on the rotary table for the machining of the arched profile is well rewarded.
Temporary location marks on the edge of the rotary table is a great aid to accuracy whilst machining of the arch. Remember to avoid climb milling.
A small diamond cutting disc was used to create the illusion of split bearing holders. M6 domed cap nuts provide a neat finishing touch.
The frame or chassis for Elmer’s Open Column engine was whisked away for a professional paint job at a nearby paint shop. It was powder coated in satin black to provide a good durable finish and care was taken to mask off threaded holes and ball race holders. It cost less and gave a much better finish than if I had done it myself with car spray enamels.
Whilst it was away I fabricated the eccentric strap and the two movement support arms. I became so immersed in machining that progress photographs were forgotten – sorry about that. My first attempt at making the eccentric strap was consigned to the scrap box but I was reasonably satisfied with my second effort.
Today I have made a start on the heart of the engine – the cylinder block. There is a big investment in both material and time so I am proceeding with extreme caution. Here is how this mornings workshop activity has proceeded.
Radiusing the arm ends using a simple jig set up on the milling machine.
Milling the arms as a matched pair ensures identical dimensions for both components.
After a quick polish the finished arms will be ready for assembly onto the engine chassis.
The tape measure provides an indication of the size of Elmer’s enlarged engine. Note that the chassis has been powder coated for a good durable finish.
The eccentric strap with added detailing provides the illusion of a split bearing.
The lump of brass for the cylinder block is brought effortlessly down to size in the bandsaw whilst I have my morning coffee. A temporary jig using an old machine vice was required.
After facing each end in the 4 jaw chuck the block is transferred to the mill for drilling and milling operations. My DRO system removes the need for marking out though I employ both methods as a belt and braces precaution.
As I am building 50% up on plan size I am increasing the number of steam chest holding down studs from four to six for appearances sake. Here I am starting the threads by hand to ensure correct vertical alignment.
The block is offset in the independant 4 jaw chuck using a dial test indicator (DTI) and the bore drilled in stages up to 10mm
I then switched to the boring bar to increase the bore up to 12mm to provide the necessary clearance to attack the hole with my new indexable internal lathe cutting tool.
I reckon that the indexable tool is more rigid than the boring bar and produces a more accurate and smooth finish throughout the length of the bore.
Before removing the cylinder block from the four jaw chuck the outer edge is turned to plan as it shares the same centre as the bore.
The 'heart' of Elmers vertical open column engine is nearing completion. Note the addition of bolt-on inlet and exhaust manifolds and additional bolts on steam chest cover.
This stage is concerned with the fabrication of the steam chest and air control valve. Built according to plan (enlarged by 50% from Elmer’s original). The only deviations relate to added detail in the form of six, in place of four, hold down bolts on the steam chest. The two additional bolts are dummies simply attached to the cover but, in my view, improves the overall appearance. The other modification is the addition of inlet and exhaust manifolds which again add a little authentic detail.
A further point worth commenting on is the fabrication of the valve rod which was made in two pieces – rod and attachment clevis. Easier to produce in two pieces and also provides some adjustment should this be required during the final setting up.
Now that the ‘heart’ of the engine has been completed the remaining work concerns the fabrication of the running gear – linkages, crank and flywheel. Doesn’t sound too much but will inevitably take longer than I think. Domestic issues will mean there will be a break of several days before production re-commences.
A brass blank is carefully set up in the independant 4 jaw chuck with the aid of the DTI (dial test indicator). This is a procedure that does become a little easier with practice.
The end sections of the steam chest are turned down to size. A central hole is then drilled for the valve rod and the entry end drilled and tapped for the gland nut.
After marking out the cut-away area for the steam chest four corner holes are drilled just within the scribed lines. Clearance holes for the hold down bolts are also drilled at this stage.
Working in a clockwise direction to avoid climb milling the bulk of the material is removed and light final cuts are taken up to the scribed line.
A suitable piece of brass flat was flycut down to the required thickness for the valve plate. A mirror finish on this piece is highly desirable.
A good level of precision should be aimed for when drilling the air (steam) holes on the valve plate. The plate will be cut from the main piece of stock when machining is completed.
I like the appearance of inlet and exhaust manifolds and these are turned from round stock.
Manifold clearance bolt holes are drilled then surplus material is removed using an end mill cutter.
The valve rod was made in two pieces (clevis and rod) for ease of construction and is shown here with valve attached.
Shaping the underside of the valve with a 2mm slot drill. I made three before I was satisfied – hopefully my care will be rewarded !
Assembly of the steam chest and valve components. PTFE gaskets are fitted to all joint surfaces. Note four hold down bolts – the other two are dummies fixed to the cover only.
Detail view of linkage showing connection of piston rod, connecting rod to guide arms. A touch of Loctite on the screw threads should hold everything nicely in place on assembly.
With the cylinder and steam chest completed the next stage was the fabrication of linkages, eccentric and flywheel. Most of these items are relatively straightforward though it pays dividends to take your time and make each component as precise as possible. It’s tempting to rush the final stages but to me this is a mistake. Hurried workmanship now can so easily result in hours of frustration when your engine refuses to run.
One problem with Elmer’s plans is the quality, or lack of, of the pictures featured in the build notes. At first I had a struggle trying to sort out the detail of the linkage relating to the connection of piston rod and connecting rod. I think I have resolved the dilemma and the picture on the right shows my final result. I hope this is of some help to those of you following this build. I was also unsure on Elmers method of retaining the connecting links to the arms and you will see my solution in the gallery of build pictures.
By the way, with building my engine 50% up on Elmer’s plans I had to source a 4.5″ flywheel. Surfing the net took me to martins models I can highly recommend these top quality flywheels, beautifully cast with an excellent selection of styles and sizes. At the moment the $20 flywheels come into the country without attracting customs and excise duty which currently applies on items exceeding £18.00 in value.
So with a glimmer of light at the end of the tunnel I set about the final stages of completing Elmers #32
Studs were made for both guide arms from 3mm stainless and threaded M3 at both ends. After silver soldering the centre piece was cut away.
As I din’t have a convenient piece of 50mm dia. brass the crank wheel was fabricated from aluminium plate and rough cut by hacksaw.
The ‘Flinstone’ styled wheel was clamped up in an arbour and turned down to size. Note ‘rough cut’ index cutter in toolholder.
Over to the mill for shaping the crankwheel. A large diameter end mill provided the profile I needed.
Switching from horizontal to vertical was the best way of arriving at the final shape for the crankwheel.
After cleaning up the spokes with a hand file the flywheel was set up in the three jaw for final finishing.
A drill bit holds everything in place during trial assembly of linkage. This is the pic that is hard to decipher from Elmer’s build notes.
Trial set up of crankwheel and flywheel on crankshaft. Everything checked for smooth free running.
Testing the motion of the running gear. Care and accurate maching will have paid you dividends when you arrive at this stage.
Any slight stiffness in the running gear will disappear during the running in process. More serious binding needs to be sorted before proceeding.
My final machining job was the eccentric. You need a 4 jaw independant chuck for this – simply follow Elmer’s build notes.
The completed eccentric turned from mild steel bar – the final piece in the jigsaw.
An overhead view of the crankshaft, flywheel and linkage down to the cylinder and steam chest.
It was at this stage in the proceedings that I couldn’t resist putting some air through the engine to see if there were any signs of life and I am pleased to report that after just a few minor adjustments my new creation burst into life !
So here we are, another model to add to my small collection. For visual effect I have added insulation lagging to the engine cylinder in the form of strip hardwood procured from my local model shop. The engine runs well on very little air supplied in this case by my ‘fridge pump based silent compressor. As with all new engines both the volume and pressure of air or steam drops significantly with an hour or so of running in.
All in all a very satisfying engine, particularly so at the increased size. Elmer’s original plans are available here for download free of charge. Unless you fancy having a go at making your own, attractive top quality cast flywheels are available from Martin Models.
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).
With metric conversion calculator on hand I measured up for the bearing/engine frame.
The chunk of hexagon bar was cut overlength by 3 or 4 mm in around 30 seconds on my bandsaw
An indexable cutter was used in the first stage of squaring up my hexagon bar.
This is one occassion where protection against flying swarf is essential.
As my indexable cutter was not wide enough to pass in one sweep I switched to a fly cutter for the removal of the last few mm.
Using my edge finder I locate the precise edge of the workpiece. Zero my DRO, move in half the width of the edgefinder (2.5mm) zero again and that positions the centre line of the chuck exactly on the edge.
An end mill cutter in my mill was used to carefully shape the block to plan dimensions.
A satisfying afternoons work, the frame now ready to receive the drilling of airways and fixing holes.
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.
Near disaster through poor soldering – stop work and reflect on your options.
Inlet pipe was cut off then the surface skimmed flat in the mill taking just a minimum of cut.
The chuck on the lathe was replaced with an ER32 collet from my mill. The MT3 arbour fits into the lathe headstock.
The M3 die was held in the lathe tailstock to ensure squareness of cut.
The replacement inlet pipe screws into position and the job is back on track.
Quite a number of precisely positioned holes are required on the frame. Treble check each one, including the depth before drilling.
After drilling the holes that require tapping I start the tap off by hand using the mill chuck. This ensures the tap is running square. Cut to full depth in the vice later.
A base was made up for the engine from a handy piece of aluminium plate.
The frame and base were given a quick polish before being screwed together.
The frame and base are now completed and await the fitting of the remaining components.
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.
After centre drilling I drilled with a 3mm bit with a brass tube sleeve to ensure correct depth.
I progressively increased drill size up to 9.5mm reducing lathe speed for the larger drill sizes.
Reaming finished bore at 10mm with a very slow speed setting.
The bore of the cylinder was bevelled at the base to provide clearance for the con rod.
A useful, and easy to make, carriage stop enables repeat turning cuts to the same point. Here I set the travel to 4mm using a 4mm drill bit as an accurate measure.
Using my new edge finder I locate the centre distance between the vice jaws which is the same as a centre point of the brass bar. Spot on for locating the inlet hole.
A 1mm rotary saw blade is used to cut dummy cylinder head cooling fins. A little bit of work is needed with the calculator to ensure correct spacing.
Finished cylinder with engine frame mounted on base.
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.
Backstop arbor inserted into headstock spindle taper is the key to turning a number of identical parts.
A simple easily made tapping block will ensure that you tap your holes fair and square.
Columns supporting the cylinder and its base plate are screwed into position.
Today’s job was to produce the inlet pipe from the forward/reverse control to the cylinder head. A simple little part that should only take a few minutes – wrong ! I guess it took me a couple of hours to machine the small connecting manifold requiring both my lathe and mill. The pipe was bent to shape using a handy tool that I made last year and silver soldered to the cylinder at one end and into the new manifold at the other.
I learnt early on that in model engineering time is unimportant – it’s how you spend that time that is crucial. Satisfaction is not gained by how quickly you can make things it is gained by developing and improving your skills. When you take stock after completing a model you most likely have two trains of thought. The first is you may be self critical as you see imperfections in your workmanship but deep down you have the enormous satisfaction of knowing that your skills are gradually improving. The joy of seeing your new creation spring into life makes the effort and time spent seem irrelevant.
The turned manifold was not separated from the bar and was inserted into the mill vice and a centre finder used for positioning.
The readout displays were zeroed then using the ‘x’ travel it was an easy job to locate the correct position for the manifold bolt holes.
Drill bits were used to locate and level the manifold ‘disc’ in the vice.
The manifold was machined to depth, the DRO zeroed, the piece flipped over to machine the other edge.
The inlet pipe positioned prior to silver soldering in place. I intend to cover the art of silver soldering in a future article.
The soldered joint after ‘pickling’ in a jar of citric acid for half an hour.
The finished pipe now bolted to the bearing block with two M2.5 cap screws.
Today I have produced the flywheel – a straightforward turning job on the lathe. Watch out for the thin 1/64″ bosses either side to prevent binding in the engine bearing or frame as I prefer to call it.
Next was the con rod for which I am showing one or two pictures – this was machined out of a length of round bar, drilled for little and big ends then tapered in the lathe and finally tidied up with needle files.
The piston was turned out of a hard plastic – Delrin or something similar. It machines beautifully, turned at a low speed as a precaution against meltdown. A gudgeon pin, or wrist pin as they call it t’other side of the pond, was cut from a 1.5mm drill bit using a small rotary diamond blade in my mini drill.
The final bit of machining was to make a forward and reverse valve as per plan – a delicate bit of milling with a 1.5mm slot drill. Everything was assembled with a touch of oil on each of the bearing surfaces and connected up to the air supply. I would like to say at this stage that it burst into life. It didn’t, I had had enough for one day so scrubbed up with Swarfega and grabbed a beer from the ‘fridge.
The diameter for the crank was turned to size in the lathe then zeroed with the aid of a centre finder.
After the first cut the ‘x’ and ‘y’ reading were noted so I could repeat for the other side.
Cutting the second side repeating the positional data from the first side.
Lineing up for drilling hole for 2.5mm grub screw on the flywheel
Machining flats on the conrod so it would still hold in the three jaw for tapering.
Drilling for ‘big end’ and ‘gudgeon pin’. The DRO propvides the required dimension accurate to 1/1000″ .
Angling the cross slide enables the centre section of the con rod to be tapered.
Machining valve for forward and reverse porting using a 1.5mm slot drill.
Followers of this series of posts are probably wondering what has happened to my build of Elmer’s #3 Open Column Engine. Well, whilst it looks to be ready to run it resolutely refuses to respond to the input of air. The crankshaft with inbuilt porting is clearly a critical item but despite making a replacement with extra care there is still no joy.
I have double checked all the porting and the reversing device but no real clues to its reluctance to perform. So, when time allows it will be a strip down and maybe a new bearing block – I will let you know !
Click on ‘More Posts’ below to see the final nail biting episode !
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.
