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.
Three flywheels to make: brass, aluminium and stainless. It’s a simple task so I didn’t take too many photos.
And lastly, a note on the springs
You can forget all the fancy stuff, I ended up manually rotating the chuck and advancing the slide. The springs were actually quite tricky.
I made the first ones to minimise the pressure (and thus friction) between cylinder and body. But I found that the cylinder lifted off at angle, jamming the pivot pin. They were alright at 5psi but not at 20psi. So I had to experiment to get a spring that worked at 20 psi and still allowed the engine to run at 5 psi. Anyone got a use for a small box of springs?
Jim Greethead from New South Wales enjoying a pint of amber nectar at the Bristol Model Eng Exhibition during a recent visit to the UK.
Jim's trio of beautifully built 'Tinys' each fed with air from a neat three way manifold. I think Elmer Verburg would have been well pleased.
As soon as I heard that ‘Aussie Jim’ was building Elmer Verburg’s #23 ‘Tiny’ I asked Jim if he would consider taking some step by step photographs and prepare write up notes on his build procedure. The following is the result.
Jim was recently over here from his home in Bywong, NSW, Australia and made a point of visiting the 2009 Model Engineering Exhibition in Bristol.
Thanks Jim, this is a first class article and introduces a number of innovative solutions to problem solving from which we can all learn – so over to you Jim for the full story……….
Building Elmer’s ‘Tiny’ Engine
When I saw the Elmer’s Tiny that John Somers built, I knew that I just had to have one. This story is not a tutorial or an instructional article, it is just a few photos and a couple of things I learnt on the way.
The first task was to convert Elmer’s drawings to metric to suit my workshop. This involved DesignCAD and quite a bit of learning. It would have been faster on the back of an envelope but I need to learn DesignCAD anyway. You can see a couple of pencil changes to the drawing as it appears in the photos but it was good enough to work with.
The next decision was whether to make it in aluminium (my favourite material – easy to work and it is clean), or brass (looks good but is expensive and the finished engine needs polishing ) or stainless (hard to work and the only available piece of unknown origin). It seemed easier to make three then to decide between them and, as everyone knows, it is just as quick because the setup time is shared. Mind you, I think “everyone” knows this from theory not from experience.
Not having a form tool or ball turning tool….
…I used a chainsaw file to form the grooves.
Elmer’s drawing shows the bit where the crankshaft goes as being spherical so on the aluminium engine, I rounded it off with a flat file.
But on the others, I just left it cylindrical and I am happy with the result.
Then I buffed them so the buffing would not round off the edges of the subsequent machining. Buffing can hide a multitude of sins (and tool marks).
So now I had three bodies ready for the next step.I actually left them on the stick until they were finished and running. They are easier to handle like that.
For machining convenience, I dimensioned the body from the top end , set an x axis stop and then established both x and y zeros.
A handy bar of 38mm brass was sufficiently accurate for finding the y axis zero.
The 19mm bar fitted nicely in the slots, needing only a couple of clamps to hold it.
After that, the flat was machined and the holes spotted and drilled (and deburred) for the cylinder pivot and the crankshaft bearing.
Then came the ports. Elmer’s drawing shows the ports being #57 drill which equates to about 1mm. After a couple of calculations, I increased this to 1.2mm and then to 1.5 when my last 1.2mm drill broke (in the hole).
The 1.5 gives some overlap but that doesn’t matter-it just wastes a bit of air (and that’s free until they find a way to charge for it).
I also calculated the position of the ports instead of using Elmer’s gizmo.
The next bit was interesting! Leaving the x axis lined up with the ports, I rotated the body left and right and drilled the inlet and exhaust connections (I made them symmetrical).
I found that I needed to set a stop where the drill just breaks through into the port hole because the drill tends to grab and wind itself right through to the other side and then it is back to square one and start all over again.
One more rotation to relieve the pivot hole for the spring. I used a drill in the pivot hole to line it up.Once the crankshaft bearing hole is deburred, the body of the engine is finished.
The choice of your first engine build project is critical and should follow the ‘KISS’ principle.
Keep It Simple and Straightforward!
Get it right and you will get a huge buzz and a big smile on your face when your creation leaps into life!
* Go for a simple oscillator design.
* There are fewer moving parts.
* It will not require sophisticated tooling.
* It can be built in a matter of days.
* The forgiving design improves your chance of success.
Free Plans !
In my view you can not make a better choice than one of Elmer Verburg’s classic designs. His ‘Wobbler’ #25, for example is well worth a look at and the plans are free – available for you to download complete with build notes from
This was the choice of Tim Evans of Northern Ireland – a professional photographer (which becomes apparent when you view the superb quality photographs of his build sequence which Tim has kindly agreed to share with us). Click on each thumbnail for a larger image.
Tim had the benefit of owning a milling machine but this is not strictly essential. Providing you have a lathe for all the round bits you can get by with hacksaw and files for the flat bits. Similarly for holding smaller parts in the lathe a collet system is useful for achieving a higher level of accuracy (reduced run out). This could result in improved running of the finished engine but Elmers #25 is a very forgiving design and tolerances are fairly accommodating – anyway over to Tim………..
Well after being advised to try a simple wobbler engine as my 1st project I’ve decided on Elmers #25. The fun part has been converting the imperial to metric measurements.
So I dug up a little slab of 6mm ali plate and hacked off a piece approx the size I needed. Then came the 1st issue to overcome, as the biggest milling cutter I have at present is 6mm I felt it was unwise to size the frame piece in one pass. So I took off my milling vice and decided to clamp the frame to the top of a 3-2-1 block that was squared up to the table, and use the side of my 4 flute mill to size.
Once sized up I then marked up for drilling,
After boring all the holes I tapped the intake M4, I meant to tap it M3 but messed up the drilling :doh: so I had to enlarge to M4 as I dont have a M3.5 tap.
So after drilling and tapping all the relevent holes the frame was done, or at least it was machined, I have to clean it up and polish it up a bit.
I then moved on to the cylinder. I had a piece of 19mm square brass bar. This presented a new challenge, I dont have a fly cutter or a milling cutter over 6mm. So how can I machine this 19mm square bar to 17mm x 15mm, and get a reasonable finish?
Up steps the 4 jaw chuck.
I remember reading somewhere about how to turn a cube using a lathe, and I just borrowed the idea, and what do you know, it worked!!
So I now have the cylinder blank sized and ready to bore, and that’s as far as I got.
However, in the process of sizing on the lathe I found out that getting a nice finish relies on smooth advancement of the cross-slide. ( yea, I know that you all know this, but it was new to me ) I found a bit of a cheats way of taking the monotony out of winding it back and forth, and getting a better finish. I just attached my cordless drill to the capscrew holding the handle on the cross-slide and just ran it on a low speed. Got a far better finish than I could’ve got otherwise. You just have to be careful to keep the drill in line as best as poss.
Here’s a pic of the completed (but desperately needing cleaning up) frame and the prepared cylinder blank.
I spent a total of 3 hours to mark out and bore just 1 hole The marking out went easy enough, and I even managed to center punch on the “x” :headbang: I even got it mounted in the 4 jaw and centered up within a gnats whisker.
The center drilling went well, and even the drilling with progressively larger drills until the bore was 3/8″ ( this time I had an imperial drill set, so no metric convertion needed ) It was at this point I realised that the 9.5mm and 10mm reamers I thought I had as a part of a set were not there, the set only went up to 8mm and all are hand reamers, not machine reamers, and so even if the set went up to the needed size they would be useless as the bore is blind and only just over 1″ deep.
So this is where the newbie-ness gets a little more obvious, instead of thinking that I could get a correctly sized and type (machine) reamer in a few days time, this numpty decided to spend 2.5 hrs trying to make one.
Sense has finally prevailed after making the bore look rather rougher than when I had just drilled it, and so I called it a day before I totally wrecked the cylinder blank.
So a total of 3hrs to bore one hole, and even that’s gonna need reaming out.
This is what it looks like,
You wouldn’t believe how much of a numpty I feel. When I read your post Bogs it hit me like a ton of bricks, “I have a boring bar set for my mill” :bang: (looks around for the hole in the ground to appear ) But I will file your C-o-C for future reference thankyou very much
Anyway, when I finally got over my numptyness this is what I got done today. I mounted the cylinder blank into the 4jaw, centered it and then took a couple of light skimming cuts and then about 4 repeated cuts to eliminate any springing of the boring bar.
I then remounted the cylinder the other way and bored out the pivot pin socket being careful not to break through into the piston bore.
Onto making the pivot pin. I didn’t have any small diameter brass bar and I didnt fancy wasting some 3/4″ square bar. I thought I’d try and be clever and use a little piece of 19mm x 3.5mm flat stock and turn it down. So I cut some off and chucked it in the 4 jaw.
Then to turn down the other end I wanted to chuck it in a ER32 collet to not leave markings on the pin, but I dont yet have a ER32 chuck for my lathe, but I do have a MT3 ER32 chuck for the mill, and the headstock on the lathe is also MT3. Not having a long enough drawbar I brought up the tailstock to ensure that I wasn’t chased around the workshop.
The crankshaft bearing was completed before moving on to the cylinders.
Having completed the three engine bodies Jim’s build moves on to making the crankshaft bearing before tackling the cylinders
Machining the body was a bit traumatic; three broken drills and three restarts from scratch so for a bit of light relief I made the crankshaft bearing next.
Almost nothing can go wrong with this job, and nothing did. The bearing hole doesn’t need to be reamed, I just drilled it , 2.5mm and then 3mm. I then turned the outside to size, checked that it fitted in the hole in the body and parted it off. After it had been reversed in the chuck and cleaned up, the job was done.
And now the cylinders
All this messing around with the angle plate was a pain so when I did the replacements, I cut the cylinders off first and used a couple of parallels to set them up in the vice. With a depth stop set so the bore went just down to the port, the whole job was completed in a fraction of the time and without constantly swapping from Jacobs chuck to slitting saw. This is called experience.
Cutting points were spotted between each of the cylinders. In a later attempt, I just dropped the centre drill onto the work without it rotating. This gave a point mark that improved the accuracy of the subsequent cutting. The y axis stops were just pushed up against a piece of silver steel in the chuck to align the work parallel to the y axis.
I needed to make 3 cylinders, each 8mm x 8.5mm from 3/8 inch square brass bar so the first steps were to machine the bar to size, spot and drill holes for the port and the cylinder pivot. Once again, the dimensions were taken from one end .
I used this Heath-Robinson arrangement to drill each cylinder in turn and then cut it off the stick. I think I was influenced by some articles on workholding in Model Engineers Workshop. If you look carefully, you can see that the hole in the cylinder has been drilled off-centre. And if I had looked carefully, I would not have had to make another set of cylinders.
The pistons and crank disc came next
This was my only piece of stainless steel , so everything had to be made from it. I turned each one down to match a cylinder. The small diameter was carefully chewed out with the parting tool and then filleted in with a round file. Blessed be the buffing wheel.
Looking at the photos, I have no idea why I chose this method of holding the work to mill the flats and drill the hole instead of putting it in one of the slots. And using an end stop would have been a good idea. Hindsight!
These are the first lot of cylinders (before I noticed that the holes were off-centre). You can see the remains of the spots with which I marked the cuts between cylinders. That is why I just dropped the centre drill onto the work for the next lot.
Had I studied the plans more carefully I would have seen that the holes were off-centre.
The crank disk was turned with a bit of relief to minimise friction, and then attached to the crankshaft with Loctite before being rechucked for truing and cleaning up.
Set up in the milling machine for drilling. It is easier to measure in from the circumference than to find a centre from which to offset the hole. Once setup, each of the cranks were drilled in turn.
This time, I checked with a dti that the work did not move under pressure from the drill but still, the points were not square
It has been my practice to Loctite the crank pins in the holes. But no matter how carefully I drill, the pins never end up square.
Incidentally I noticed that in one of his other designs Elmer uses a press fit for the pin. Despite the difficulties of getting the tolerances right at this size, I might try that next time. This time, I cheated and increased the size of the hole in the piston.
After a 3 month haul making my Beam engine I wanted something less demanding and finally chose Elmers #19 Standby engine which is an interesting variation on the ‘wobbler’ engine in that the cylinder doesn’t wobble ! (although it may on mine !).
Bogsie introduced me to the concept that if you are making one engine you may as well make two, three or even half a dozen as most of the time is spent on setting up and once you have done one its only a moments job to make another one (or two). Yeah, right Bogsie.
I started by cutting three ‘blanks’ of 1″ x 2″ chassis plates from 1/4″ thick aluminium and bonded them together with superglue before milling them as one down to final size.
Incidentally I found my Black and Decker jig saw ideal for hacking through aluminium plate – change blades frequently and lubricate with lashings of WD40 and save yourself the effort of using the hacksaw. I then machined down to final size on my milling machine
Three rough cut aluminium engine frames are superglued together for machining to overall size then to finished ‘L’ shaped profile.
It is as easy to cut three frames as one with the workpieces bonded together. WD40 helps to achieve a mirror finish.
The three blocks are now trimmed to the final size and can eventually be separated with heat from a gas blowlamp.
The engine frame ‘L’ shape is machined with an end mill and bearing holes drilled as one. Mounting holes and airways need to be drilled individually.
Completed frames milled to final shape and drilled for bearing holes, cylinder mount points and airways shown with two brass cylinders.
After using the flycutter to trim the block of three chassis plates down to size the next job was to drill the various holes. Everything was going well until I had to drill along the arm of the chassis with a 2mm airway aprox 1 1/2″ long. With care I managed the first two then on the third I snapped a drill leaving the broken bit embedded in the chassis. So, I now have to remake a third chassis plate. It was at this stage that I abandoned the workshop and sought solice in a cool beer in the warm sunshine.
More next time
Sooooo, I set to and made a third chassis plate then went and messed that up. It was at this point that I decided to cut my production run from three down to two.
Once the pivot pin was turned down to the right size to be tapped M3, I then cut the M3 thread. You probably noticed that the tailstock is removed for this, I ran the lathe at the lowest speed ( I thread at the lowest speed so I dont run into the chuck ) and as I found out when trying to remove the ER32 chuck it was well stuck in there.
Once that was done, I removed the pin and then loctited it into the cylinder. (it was a pretty good press fit)
And that’s as far as I got today. Thanks to Bog’s for reminding me of what I actually had sitting in the corner of the workshop.
I managed to sneak a couple more hours in the workshop this afternoon. I started off by hacking off a little lump of brass for the piston and chucking in the 4jaw, turned down half to diameter.
I then chucked it the other way round in the ER32 collet but made the error of not tightening it enough and it came loose just as I was parting it off to length so I added to my collection of spare “smaller than I wanted” pieces and hacked off another lump of brass, chucked it and turned it down as before. This time I also drilled and tapped M3
I find this to be a good method of tapping on the lathe, to explain; The drill chuck is not jammed in the MT of the tailstock, it has some grip but is free to turn with light pressure. Also the tailstock is also free to move on the ways, and the tap in the chuck is also loose enough to turn if the tap jams in the work. I then run the lathe at a very low speed.
So that’s all I got done today, just 2 pistons made, 1 junked and one that fits ok. If I put a M3 screw in the piston and slide it into the cylinder and turn it upside down the piston gently slides down and stops at the entrance of the cylinder, with out the screw it just falls out. I dont know if it’s too loose, if I pull the piston out rapidly I get a satisfying “pop”.
Things I’ve learnt today;
I learnt that my ER32 chuck has a runout of 0.02mm,
Always start off with a piece of metal that is longer than you need as it makes life easier.
I also tried making a con-rod out of 303 stainless, it didnt go quite as planned but I learnt that it really helps to use sharp carbide tooling and that it doesn’t like my Hss threading tool.(prob was a bit dull, I must resharpen it) I’ll try again the next time with some brass as per the plans.
Also learnt to think a few steps ahead to see what I can do while workpiece is still chucked and true before taking the piece out and then spending 15mins truing it up with the trusty dial indicator.
And finally, always remember to check that whatever chucking device is used it is properly tightened up.
Today’s update.
I started out by sharpening my threading tool and spending 15-20 mins trying to single point 3mm 303 stainless for the con-rod. Deciding that beating my head against that particular spike was not fruitful :bang:, I moved on to machining a new con-rod out of brass. This was much easier.
Then I extended a bit more out of the chuck and turned that down.
Once turned to size it was over onto the mill, I mounted it into the spin indexer thingy, supported the free end with a 3-2-1 block and a little stepped thingy and drilled out the hole for the crank, 2.4mm if I recall correctly.
After a little cleaning up and filing the edges round I have a piston with con-rod
After that I had a little time so I made a start on the crankshaft assembly, specifically on the crank disc which I made out of some unidentified steel, turned some down to 17.5mm, hacksawed it off and remounted it in the ER32 chuck, faced it off and then drilled it 4mm.
Ok, managed to get a couple of hours in the workshop today. Started off by setting up and drilling the offset hole for the crank pin.
The more observant of you will have noticed that the Crank-disc is not properly seated on the 3-2-1 block and so did not drill square. I didnt notice that until I’d finished today and as I’ll explain in a bit I may have to re-bore the pin-hole square. Anyway, after that I found a use for the screwed-up piston, I turned it down to make the crankshaft bush shown below in the middle of the other hacked out bits.
I then chucked up a length of 6mm 303 stainless to turn down for the crankshaft, I turned down to 5mm for the main shaft and a short section 4mm to fit the crank-disc.
Then I did something similar for the Crank-pin, except I started with some 4mm stainless, turned it down to 2.4mm for the press fit into the crankdisc and 2.3mm for the easyfit into the conrod. I also pressed the crankshaft bush into the frame, after I cleaned up the frame,
then did a little assembly just for fun.
Once I did the assembly and tried to turn over the crank I found that it was sticking at TDC and BDC. After a little wondering I checked the squareness of the crank-pin ( it’s amazing how hard it is to use a 4″ engineers square on a part that’s only 17mm wide and the pin’s only 3.5mm high !!) I then realised that the crank-pin is not square and is what is binding up twice per revolution. I’ve not totally decided what to do about this. I could pull the pin out and re-bore the hole wider and square and then make a new pin to fit. Or to just try and bend the pin to square. I’m leaning towards just bending the pin back to square, and that’s what I did.
I managed to make a start on the flywheel, and got one side shaped, to a fashion, and today I bored and reamed the 5mm hole for the crankshaft, then remounted to machine the other side, centred it using the 5mm hole as a reference and then shaped the 2nd side. ( I was so excited about getting so close to completion I forgot to take any pics of these parts )
I then turned a some 6mm brass rod to a close fit for the flywheel, and threaded the end M5, and mounted the flywheel to it to clean up the rim and make sure (hopefully) that I dont have a wobbly flywheel.
After that I drilled and tapped the flywheel for the setscrew I then turned to the air-intake-to-aquarium-type-tubing-adaptor-thingy. I used the same 6mm brass rod and turned some down to 4mm and then threaded it M4 and then bored it through with a 2.2mm bit
Then after some jiggery-pokey with a parting tool,
It was over to the spin-indexer to make a nut-shaped bit.
The next stage was to make the cranks and for these I chose stainless steel. I have never had much success with mild steel but find I can achieve a reasonable finish with free cutting stainless. The piece I had available had to be turned down a considerable amount to arrive at the size required. For this I used an indexable cutting tool which utilises the broad side of the cutting insert for rapid removal allowing fairly heavy cuts.
I used a liberal amount of cutting oil applied by small paint brush to ease the cutting process. I have found that (fine cut) emery backed sponges are ideal for cleaning up workpieces in the lathe. Never be tempted to use a rag as this can so easily wrap itself around the chuck and drag your fingers in before you realise what is happening. Safer to use paper towels but I find the emery sponge ideal.
After centre drilling I ran a 2mm pilot hole in the end of the bar before carefully selecting, in this case, a 3.8mm drill to match the actual diameter of my 4mm stainless shaft that I intend to use for the crankshaft. Do check drill and shaft sizes carefully with your vernier to ensure that you finish up with a nice snug fit. I normally drill slightly undersize as the rotation of the drill does produce a slightly larger hole than you might expect.
Although this next stage could have been completed with hand tools (junior hacksaw and files) it is easier to use the mill. Each crank was set up in the vice using a small length of shaft thro the larger hole and an appropriate drill bit for the smaller hole. Use of the ‘X’ and ‘Z’ readouts gave me control of the cutting area. The backstop allowed me to turn the crank ‘upside down’ for identical machining on the other side. It also allowed me to machine the second crank to the same dimensions without the nead to reset machining limits.
Screws with shoulders to provide a bearing surface for the connecting rod were turned up in the lathe and a die held in the tailstock to provide a 3mm thread. A quick polish on the buffing machine finished this stage of the build.
An indexable broad facing tool is used to bring the stainless steel bar rapidly down to size.
Fine cut emery sponge proves ideal for finishing and cleaning up turned bar.
After centre drilling the hole for the crankshaft is drilled whilst on the lathe to ensure alignment.
When parting off rigidity of cutter is important. Use the shortest length of blade possible and lubricate well.
A light skim to the final thickness cleans the crank disc up nicely removing burrs and any uneveness from the parting off operation.
The profile for the crank webs are formed using an end mill with repeat positioning taken care of with the backstop.
Two completed crank webs fitted with shouldered crank pins that were turned on the lathe.
At this point I did a quick mock-up of all the parts and positioned the crank for transferring the hole position from the exhaust of the frame to the cylinder. Then after removing the indexer from the mill and clamping down the vice, I drilled the cylinder with a 1.6mm bit.
I then found a spring that was about the right size and assembled all the bits together, and here’s the result.
( notice the immaculate chatter on the flywheel )
The other side
Imagine my joy, now to get it running. But how? I have a little air compressor, but no way to attach the length of 3mm (id) tubing to it :bang:
So I decided to build an adaptor. I just copied the connector off one of my air-nailer, and bored a 4mm hole up the centre.
I then made another air-intake-to-aquarium-type-tubing-adaptor-thingy as above, except I haven’t milled the nut-shaped-bit on it yet as I had to come in to make me grub, and that’s all I got done.
I started today with the air-hose adaptor that I started last post, I drilled the other end and tapped it M6, and then I milled a flat and then drilled and tapped M4 for the air-hose-barb-thingy.
Then back onto the lathe, I chucked a 6mm brass rod, and turned a 5mm to 3.5mm taper on the end. This is gonna be the inner tapered pin that will block or let a controlled amount of air through to the air outlet.
Then I threaded the rod M6, and then knurled the end
(notice the slight mess-up on the threading, I hadnt got enough of the rod sticking out and didnt match the thread up well enough during the 1st pass on the 2nd section :doh:)
But when put together it fits and works ok. There is a little leak of air from around the knurled/threaded area when the home-brew valve is open, but not so much that would bother me at the moment.
I then made up a round base out of some ali bar I had, drilled it and counterbored for the mounting screws, and also drilled and tapped a center hole M6. The center tapped hole is for mounting the Ali base onto a wider turned wooden base that I plan to make. (if folk are interested I’ll do a project log on that too)
Here’s the little wobbler on its little base.
And then, (drumroll please)
It runs
I finally got round to finishing off this project by turning a wooden base for it. Now this is more familliar territory for me, and while I did this on my woodworking lathe, the techniques are the same on an engineering lathe equipped with a toolrest. 1st of all I got a chunk of oak that happened to be around my dad’s workshop (that’s where my woodturning lathe is residing), and that chunk of oak just happened to be quartersawn ( nice looking grain ).
I then marked it out with lines on the diagonals. This was because I was going to mount it on the faceplate, but then I realised that I had my external jaws on my 4jaw self-centering so I just gripped it with that.
I then turned a dovetail recess on what will become the underneath of the base. ( this was to match the dovetail jaws that I then mounted on the 4jaw ) then I removed the oak from the external jaws and bandsawed it into a rough circle. (the only type of circle I can cut on a bandsaw )
Then I mounted the dovetail jaws onto the 4jaw, and mounted the oak base onto them. Then I turned a recess to fit the ali base of my elmers#25.
I then turned a concave section, 2 flat bits and 2 tiny grooves.
Then I sanded it 120,220,230 and then 420grit, burnished it with 0000 wire wool (sourced locally from steel sheep :lol: ) Then I finished it with quick-drying friction polish, then I polished it up with some canuba ( I think that’s how it’s spelt :scratch: ) wax.
These are the tools I used,
I find woodturning a very tactile experience, when I started to turn the base I didnt fully know what shape I was going to make, the wood sometimes just lends itself to a certain shape. The shape just flowed on this one.
The key to getting a good finish off the tool is to let the bevel of the tool rub against the wood as the tip cuts, this gives a clean cut and also burnishes the wood, this is especially true when turning woods that are not close-grained (such as Oak, Pine, Balsa … )
Anyway, I spent some time today doing some final photos of this project, I’ll post up a bit about how I did it in my post about photography.
On to the last lap with this Elmer variation. The cranks were machined out of stainless using plenty of cutting oil. I picked up a litre bottle of cutting oil from Machine Mart and as I work mainly in brass and aluminium the oil is lasting me a long long time. Turned the stainless down to size on the lathe then transferred to the mill for cleaning up. I always seemed to find that when parting off two things happen. The cut veers away from the face of the machined part and there is often a protrusion remaining as the parting tool breaks through. Both these unwanted formations can be cleaned up easily in the mill and then on to forming the web. An M3 screw with a shoulder to act as the bearing surface for the ‘big end’ of the con rod was machined up.
Next on the ‘to do’ list was drilling and tapping the back of the cylinder for attachment to the engine frame taking care not to drill through into the cylinder bore – 4mm seemed about right. Where possible I use a guide block to ensure my tap runs square to the hole. You can also replace your drill bit after preparing the hole to be tapped with the appropriate tap and turn the chuck a few turns by hand to get the thread started and running square. This can then be transferred to the vice for finishing off.
A length of brass bar was centred up in the 4 jaw independant chuck using a DTI (dial test indicator).
The offset hole is started for the cylinder bore with a centre drill then opened up with a succession of drill bits.
The critical depth of drilling the ‘blind’ bore is checked against the vernier scale.
A boring tool makes the final cuts to size and imparts a fine finish to the bore.
A profiling tool provides an attractive curved finish to the cylinder of Elmer’s Standby.
The completed engine mounted on a wooden base runs well on just 5 psi of air.
The next stage I am afraid didn’t get covered photographically. However, the piston was turned from aluminium, cross drilled for the gudgeon pin (or wrist pin as it is called across the pond). The con rod was turned up on the lathe and again transferred to the mill for putting the flats on both small and big ends. The con rod needs to be turned as narrow as reasonable to clear the base of the cylinder.
The crank shaft was machined from stainless rod to produce the flats which cleverly act as inlet and outlet ports. Clearly to be effective your crankshaft needs to be a very snug fit in the bearing to avoid air loss. I am sure it is not aproved engineering practice but as you will see from my picture the crankshaft was overhung from the vice for milling the flats. Very light cuts were taken and a satisfactory result achieved.
Care needs to be taken when drilling the exhaust outlet along the length of the crankshaft – slowly does it with plenty of backing off and cleaning and lubing of the fine drill bit. The crank was ‘loctited’ into position making sure it was set square to the inlet and outlet flats on the crankshaft – refer to your plan.
Now I would like to tell you that I assembled all the components, connected up the air and off she went. Well I found that I couldn’t quite get a full rotation due to the top of the piston making contact when approaching TDC. I used a milling cutter by hand to clean up and ‘bottom out’ the head of the cylinder. The engine now rotated by hand – a spot of oil added to cylinder bore and bearing surfaces, air connected and off she went and after just two or three minutes she was running a treat on around 5 p.s.i.
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.
