# My build of Stew's Overcrank engine



## Lesmo (Jun 20, 2012)

Well I finished most of the 3d drawings and now have a better understanding of what makes this overcrank engine tick, so I made a start on the main bit, the engine block assembly. 

I was uncertain whether to post this build so soon after Stew's own excellent build, but thought that it may appeal to anyone like myself who is short on experience and unsure whether to tackle something like this, having only one engine under his belt, or have been put off by having to silver solder such big lumps of brass together. Here goes. 

During the drawing phase I decided to depart from Stews design and make the block from aluminium but keep the brass cylinders. My reasoning being, with brass costing an arm and a leg, one machining screwup could be expensive, more so,if I screwed up twice. So I bought a chunk of 75x75mm ally enough for several attempts if necessary, for the same money as one lump of brass.

I was a little uncertain given the nature of ally whether it would bond with the brass cylinders so I did an experiment using araldite two part epoxy, I bonded a half circle of scrap ally to a 16mm brass dowel and left it overnight to cure. The next day I put the ally in the vice and was surprised at how little force was required to break the joint. I suppose there must be ally etching adhesives out there as Lotus use epoxy for bonding ally on their sports cars, but I could not find anything on the net, so it was back to the drawing board to re-design the block so that I would not have to rely on bonding alone but use a clamping action to hold the cylinders in place.

I made the block a little wider than the half circle shown on the plans, then it was out to the shop to make a start. First I carved a chunk of 75x75 ally and faced the ends square







Marked up the orientation of the clamp bolts and cylinders






then split it across the cylinder centerline with my band-saw and faced both halves






 which were were then drilled and tapped for 4mm cap heads.
















 After assembly it was all faced up square and the centers marked for the cyl positions.






They were center drilled 






Then drilled through with an 8mm drill followed by 12mm 16mm and 20mm endmills






and finally bored out to 20mm using a gauge plug to ensure the correct final size











Without moving the piece, the 5mm counter bore was carried out, using a dial indicator for cutter adjustment and a hole gauge and micrometer as a double check.











The piece was then moved to the other cylinder position and the same operation repeated until I had this.






So far so good. Next up were the brass cylinders which were a fairly straightforward turning job, creeping up very gently on size and making good use of the dial indicators on both X & Y feeds and using the split ally block as a further check.





















With the material leftover from the cylinders I made 2 backplates for the cylinders and put them to one side for a little decorative work later.

Next I turned the cylinder heads.






The heads call for a ME 5/16 32 tpi 6mm deep threaded blind hole and I only have metric taps & dies, and 60 deg thread cutters, also my 8mm shank internal cutter will only thread a 10/11mm hole, so the hunt was on for a cutter that could cut a thread in a 7mm ish hole.

After searching the net I eventually found what I was looking for here http://madmodder.net/index.php?topic=3523.0 so taking a length of 8mm silversteel/drill rod I was able to produce a cutter that would cut inside a 7mm hole and hardened it. 

First set up the lathe to cut 32 tpi, fitted one of the cyl heads into a collett chuck and bored the hole part way through the head to accommodate the gland nut, the hole is as mentioned, 7mm diameter and 6mm deep. the the cyl head being 10mm deep. I wanted a full depth thread but had to find a way of stopping the tool crashing at the end of travel and wrecking the part and the tool. You will gather that I am still a newbie. 

I wound in the tool until it bottomed out and set the dial indicator that sits in my adjustable table stop to a reading of plus 0.35 mm. This is just over the distance the table travels whilst cutting, from the time the Di needle moves off zero, to my releasing the clasp nut. It is my reaction time plus a bit. As you can guess I had practised this with a few dry runs to see what my worst time was, and when I had a consistent time, I went for it. Success, the male thread fitted spot on with no sign of play.






 I had cut my first blind full depth thread without wrecking the piece or the tool. There are probably far better and less nerve racking ways to do this I am sure, but it was a case of needs must, and I must admit, I do like threading on the lathe so it was quite satisfying.





















I certainly look forward to any helpful comments as to how it should be done.

Back at the engine block I dry assembled the cylinders and nipped up the clamp bolts then lightly faced the block and cyl's both back and front.











I put the block aside to do the decorative work on the cyl back plates. I had the previous evening been playing with the 3d cad to see what the cutting patterns would be like for a given radius of cutter, depth of cut and the offset from the disc center. They were all based on an 8 point star. I had previously seen a small star on one of Stew's other builds, I think it was the popcorn engine, but wanted something larger.

I set up the rotab with 3 jaw chuck fitted and a collett chuck in the three jaw chuck chuck, you get the idea. The cutter set at 35mm rad & 2mm off centre and the cut 1mm deep.











Worked like a dream and came out exactly as the cad model predicted.












Playtime over, that's me up to date with the story so far.


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## vcutajar (Jun 20, 2012)

Hi Lesmo

I do not think I know the engine you are building but will follow your progress and see it take shape as you go along.

I got lost a bit with the internal thread you made. Is it a metric 7mm thread?

Vince


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## Lesmo (Jun 20, 2012)

Hi Vince

Thanks for looking in. Here is a link to Stews build showing pics of the original engine which inspired his build. You can read the whole thing rather than waiting for my installments 

http://www.homemodelenginemachinist.com/index.php?topic=12367.0

The thread is a bit of a hybrid, its essentially a 5/16 ME thread but with a 60 degree included angle, instead of 55 deg, it is a nice fine thread ideal I guess for the purpose intended, and as I said I only have 60* cutters. 

Cheers Les


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## SBWHART (Jun 20, 2012)

Hi Les

That's a great start and I must say that's a very cleaver way to fabricate the cylinder. 

Now why didn't i think of that ;D ;D

When you get the cylinder done that's the worst part over.

Hers my engine running

[ame]http://youtu.be/FBEsz7imfh8[/ame]

so newcomers can see what its about.

Stew


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## mzetati (Jun 20, 2012)

Hi Les,

definitely another build worth keeping an eye on.
Thank You for posting the link to Stew's thread, too.
Marcello


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## doubletop (Jun 20, 2012)

I've seen enough so far to lock myself in. I'm here for the ride

Pete


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## vcutajar (Jun 20, 2012)

Thanks Les and Stew for showing the engine.

Definetely will be following your journey Les and admiring your work.

Vince


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## steamer (Jun 20, 2012)

Nice job Les!

Dave


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## rebush (Jun 20, 2012)

Les: What a wonderful looking engine. Will be here for the duration. I'm sure I'll learn volumes.

Stew: Thanks for the post of the engine running. As always a beautiful piece of work. You really set the bar high.

Roger


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## danstir (Jun 20, 2012)

A really nice build thread. Thanks for sharing!


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## bearcar1 (Jun 20, 2012)

I'll be tagging along on this journey into the depths. ;D Some very careful and thought out work you are showing us Les, thank you. It's fun to see a tried and true design such as Stew's come to life using different methods. Same destination only a different road so to speak.


BC1
Jim


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## Don1966 (Jun 20, 2012)

Hi Les I will be tagging along also. I like the way you go about your work very interesting and I can learn something here.

Thanks Don


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## Lesmo (Jun 21, 2012)

Thank you for your very kind comments guys, it always warms the heart to know that you are out there taking the time out to write a few words of encouragement, or advice if the need arises. 

I will do my best to have this build measure up to the extremely high standard set by Stew, whos video I have just watched again Thanks for posting that Stew, it is all the inspiration I need for the task that lies ahead, and is just great for visitors who can see what I am trying to achieve. 

I have in fact just emailed the video link to a friend who dropped in last night to see how I was getting on, and present his finally completed project. A pristine 1936 Ford V8 3.6 litre complete with white wall tyres. I thought it was Al Capone turning up on my driveway. 

Cheers Les


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## dsquire (Jun 21, 2012)

Lesmo

You know that you should have had the camera at the ready. We want to see some pictures of your friends pristine 1936 Ford V8 3.6 litre complete with white wall tyres. :bow:

Cheers 

Don


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## Lesmo (Jun 22, 2012)

Hi Don

It will be done, as it happens my pal Steve tells me the car was manufactured in Canada, it is a RHD version. I will post some pictures shortly, Oh and I was adrift on the year, it is in fact a 1934 model

Cheers Les


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## Lesmo (Jun 25, 2012)

Here we are guys as requested, some pictures of Steve's baby. 



























That's it for now, work on the project has been interrupted because I am fitting a DRO to the mill before I go any further.

Les

For some odd reason the pictures have appeared severely cropped, although they are my usual size ???.


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## clivel (Jun 25, 2012)

Lesmo  said:
			
		

> It will be done, as it happens my pal Steve tells me the car was manufactured in Canada, it is a RHD version. I will post some pictures shortly, Oh and I was adrift on the year, it is in fact a 1934 model


Oh I didn't realise that Canada drove on the left until so recently, not recent enough for me though 
My first week after moving to Canada I looked right (as I had done my whole life) to cross the road and stepped directly in front of a bus. I was fortunate; I don't know why, maybe the angle of the blow, but apart from a few cracked ribs, a lump on the head and a bruise that covered every inch of my body the biggest damage was to my pride. This happened during peak hour traffic on one of Vancouver's busiest roads. So not only did I have to contend with the attentions of a bus full of concerned passengers, I also had to suffer the embarrassment of being responsible for a major traffic jam.

I am really enjoying following your build Les, and the pictures of the car are a nice bonus


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## dsquire (Jun 25, 2012)

Les

Thanks for the photo's Les. That sure is a beautiful car and looks to have been very carefully restored. The fact that it was made in Canada is just icing on the cake. In the last photo of the engine you can see "Made In Canada" cast into the cylinder head.






Cheers 

Don


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## Lesmo (Jun 26, 2012)

That was a narrow escape Clive, there arent too many people walk away after being hit by a bus, much less feel embarrassed about it. I had a close shave myself years ago. I spent three years in Germany when I was in the RAF and driving on thr right became the norm. 
When I was demobbed and drove my old (Rommel style) Mercedes home, I arrived in the UK at two in the morning with almost no traffic about. I came out of a junction and strayed over to the right then at the first roundabout I went around it the wrong way and just after the exit from it, I encountered a nutter (so I thought) in a big lorry on my side of the road. Fortunately I escaped but embarrassed doesnt even begin to describe how I felt. :-[ :-[

Glad you liked the pictures Don, she is a beaut and no mistake. Shes four years older than me but has certainly weathered the time a lot better. Maybe I should get a restoration job. :big:


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## Lesmo (Oct 8, 2012)

After fitting the Dro to the mill, I modified the lathe by fitting a limit/cutout switch into the electrical circuit, specifically for use when internal threading blind holes. It saves the fear of crashing the tool into the work if my reaction time is not quick enough. I wont go into detail but here are a couple of pictures which explain how it works.











The thread in the second cyl head was done using this mod, and it was a breeze compared to the first one.

***

Now back to the job in hand.

Armed with my new Dro the next task was to drill/mill the valve steam ports into the block. I started by removing the brass cylinders from the block so that it would fit into the vice when I came to mill 15* taper on the top of the block as I do not possess a tilt table.  First I drilled the side ports and counter-bored the outer ones to accept the brass sealing plugs which would be made later. 
















Next I set the block to a 15* angle in the vice using a digital angle finder, and milled it flat (No pic).  I then drilled the top steam passage to join up with those in the the sides, and using a 3mm endmill, started to mill out the required slots. I then realised that I was milling in the wrong plane as you can see in the picture. Next  I compounded the cockup by milling it in the correct plane, but not engaging the brain before doing . Consequently I over-shot the slot limit by 1.5mm.  I had not taken the cutter radius into account, in my calculations. 






Fortunately I had only taken a 2mm deep bite, so having cooled down, I could see that a rescue was possible by reverting to my original plan of covering the area of the steamchest with a 2mm thick brass plate that would provide a better wearing surface. I just needed to mill out a 2mm recess in the top of the block, then bond and screw it in.  Not having any brass plate in stock I decided to continue to mill out the slots and drill the steam chest stud holes, so that I didn't waste the day.  











Finally I milled the 2mm recess to accept the brass plate which I had on order, and that is when I discovered yet another major cockup. All the slots were offset by 1.25mm, which is evident in the next picture.






That makes three cock ups one after another.  I can only put it down to the fact that I was trying to get to grips with the new DRO and not paying enough attention to what I was doing.  I would certainly advise anyone fitteing a Dro, to get a little practice in first, on something unimportant, not something into which a lot of time and effort has already been invested.  

No excuses, but if anyone knows of a chimpanzee willing to do a brain swap, in exchange for a years supply lovely of ripe bananas, get in touch please 

While ordering the brass I also ordered a tilt table which would enable me to keep the workpeice in the plane I was used to seeing it on the drawing, and not confuse my poor old brain as it had in the first of the  *^&>"   moments when the x and y planes were reversed in the vice.

This is the block set up on the T/T on the workbench prior to transfer to the mill, which was being used for milling the brass plate to the correct width, leaving just a couple of mm extra on the length







and the T/T setup on the mill, aligned, and tilted to 15 degrees ready for fitting the brass plate. It will be fitted using two 3mm countersunk brass screws, coated on both surfaces with a thin layer of Araldite steel epoxy before tightening down and leaving overnight to cure 






This time around, I made sure that all the hole coordinates including the two holding down ones, were correctly programmed into the dro and each one manually checked in turn using a length of 2.5mm rod in the chuck. I also double checked the slot co-ord limits again.  

Both retaining holes were drilled and tapped 3mm.  Araldite was then applied to both surfaces and two temporary screws inserted to hold it whilst it set.






Here you can see the setup I used which included my small laptop so that I could transfer co-ords from the drawing to the dro reducing the error potential. (I hope) and If you look closely you can see the brass plate bonded in, and with temporary screws in place ready for machining.





The brass plate was milled down to just above the ally surface, all the 3mm stud holes drilled and tapped, and the 6 slots milled in the correct place, I then turned the two countersunk 3mm screws on the lathe to replace the temporary ones presently holding the plate.
















The screws were cut flush to the surface using a fine hacksaw, and the whole surface was then fly-cut to a smooth finish


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## canadianhorsepower (Oct 8, 2012)

Very nice work, what brand of DRO do you have


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## Lesmo (Oct 9, 2012)

Hi Canadianhorsepower

Thank's your for your interest and your kind words. The DRo is a SDS6-2V Universal Display Console - 2 Axis Display made by SINO and supplied by Machine-DRO.co.uk.  While I was fitting it their stick on badge came off and I discovered who it was actually made by.

Here's a link if you want to see what they do.

http://www.machine-dro.co.uk/digita...play-consoles/universal-display-consoles.html

Cheers Les


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## Lesmo (Oct 10, 2012)

The tilt table was then brought to the upright position and thebrass plate edges milled flush with the block (See previous pic)

Next I re-assembled the block with the brass cylinders, coating both mating surfaces with Epoxy adhesive and then clamped the four clamping screws down tight, in preparation for boring out the cylinders. I setup the assembly on the T/T for the first bore leaving room for the drill to break through clear of the table and started the bore off with drills, 6.5mm - 8mm and 10mm

This was followed by a series of end-mills, 12mm -16mm and 18mm. I then changed over to a boring bar and took it out to the finished size of20mm, using a dial gauge to set the cutter and an internal gauge and micrometer to get the size spot on. As a final check I used one of the cylinder heads to check for a perfect fit. The process wasrepeatedfor the second cylinder.
-
The last couple of bores on each cylinder were done with an extremely fine and constant quill feed.
Time consuming but worth it for the fine bore finish evident in the second picture.

















The next job was to drill and tap for the six 2.5mm studs required in the end of each cylinder, having received 2 x 1m lengths of2.5 and 3mmstainless all-thread this morning.

I used the PCD function on the dro for this, and after a trial on a piece of scrap to check for repeatability, which turned out perfectly, I centre drilled the first six holes in each cylinder and one only in each of the cylinder heads










Next I threaded all the holes using the dro and mill chuck with a brass bearing insert, to guide small chuck holding the 2.5mm tap, which worked extremely well. (Not sure the explanation is clear, but if anyone wants more details on this device please ask) although the second picture gives more clarity.











The studs were cut using my small lathe and a (dremmel type tool) fitted into the tool post and paper covering the ways. This gives a nice clean accurate cut. Spin the lathe on slow speed and the whizzer on mid range. I finished each cut end in the chuck with a fine file before cutting the next stud.

Because tiny studs are a pain to handle I took a piece of brass bolt, drilled and threaded the end and used this first to file the other ends of the studs and then to insert them. It makes the job so much easier.





















The cylinder heads were already centre drilled in one spot, so one of them was drilled out to 3mm, fitted over a stud, secured, and the rest of the holes drilled using the PCD function on the dro. The quill depth being set so that drill went through the head and gave a slight countersink to the tapped hole below it.











I then removed all the studs, reversed the block and repeated the process for the fancy cylinder covers on the back of the engine block. This one differs from the front because I decorated the back covers with an 8 point star so I now needed 8 studs per cylinder to match the star pattern






Next, it was time to join up the steam ports to each end of the cylinders and as I had already worked out the required angle of tilt for each end using the 3d drawing, it should have been fairly easy to accomplish, and it was, until the last one.

That is when I broke the only 3mm slot-mill I had and instead of being patient and waiting for the new ones to arrive, I ventured out again and tried a centre drill followed by a 3mm drill which promptly wandered off and screwed up the cylinder.






There was no other option but to sleeve it and wait for the right tool to arrive, so I bored the cylinder out to 22mm






Turned a chunk of brass to fit, drilled it and did the preliminary boring on the lathe






Then fitted the liner into the bored cylinder with locktite left it to cure then flycut it flush both ends










The following day the endmills arrived and I was able to complete the connections to the steam galleries without further mishaps


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## Lesmo (Oct 18, 2012)

Having sorted that blunder out, I made a start on the steam chest which would be made from four sections pinned and soft soldered together here are two of the sections being milled to just oversize leaving enough metal to finally flycut to size when assembled.






Here are the four sections ready fot the next step, which will be to drill 2 x 2mm holes in each corner






First they were clamped up square then taken to the mill where the 2mm holes were drilled. the piece was flipped in the clamp and the other holes drilled.






and here it is with the turned pins in place. The pins as you can see, were turned from a large assortment  of old brass screws which I inherited some years ago.






I then applied flux to all the mating surfaces even though I was using multi core solder,  placed it on a fly-ash insulating block and soldered it.






It was then flycut to size and fettled a little to remove the excess solder











and using the same coordinates as for the block, all the holding down holes were drilled.






Checked for alignment using s/s pan heads and then the stainless steel studs were cut from threaded rod on the lathe.











here they are screwed in place and the chest test fitted.











I drilled the holes for the valve guide bit's, and made the parts and gland nuts but became so involved in what I was doing that only one picture was taken. Suffice to say that it went without incident which was a bonus.



























Next the valves, or maybe the base to attach everything to.


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## Brian Rupnow (Oct 18, 2012)

Very nice, well documented build, with great camera work. I built my "Canadian version" of Stews overcrank engine almost simultaneously with Stews build. Stew had posted his plans which I scooped up and changed from metric to British Imperial and changed to a single cylinder engine. I started after Stew, and due to the fact that stew decided to go away on a 3 week holiday in the middle of his build, I ended up finishing about the same time he did. Stew is a very talented guy, and a very nice fellow to "talk" with via the internet. I just read through your entire post, and was very impressed. One note about your 3 "mess-ups" in a row. Whenever I make parts on the mill, I use a lot of layout dye, and lay out all my cuts and hole centers first right on the part. I don't have a DRO on my mill, and its too easy to lose count of how many times I turned a positioning dial. The layout on the actual part gives me a very good reference, and if I turn the positioning dial the required number of times and the cutter is going to cut in a different spot than the layout shows, I can check BEFORE I cut.This has saved me a few times on my builds. I keep a small can of automotive laquer thinners in my shop, which very quickly gets rid of the remaining layout dye with a couple of wipes from a rag dampened with the thinners. ----Brian


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## Lesmo (Jan 1, 2013)

Thanks for your comments Brian, sorry for the delayed reply, I thought I had already replied, grey matter must be getting befuddled.

Have since bought a decent digital height gauge so I am following your example, A double check is always better than cussing afterwards.

Regards Les


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## Lesmo (Jan 1, 2013)

decided to get the base done next so that the other bits would have somewhere to live, so I took a plank of ally and hacked of a suitable sized chunk on the saw






Next I squared up each end






Resetting the base square on the table I set ALE for the DRO at the top left hand corner of the workpiece using an edge finder and zeroed both X & Y settings.
I prefer to work direct from a drawing on the laptop rather than printing out drawings, as I usually find I have missed a dim, something stupid so it saves time doing it this way.

I had marked all of the hole and pocket coordinates on the drawing, so it was just a case of dialing in the correct coords, centre drilling, and finally drilling all the holes to size.






I left the pockets until last as I was going to use the pocket function on the DRO for the first time, which in retrospect was just a bit risky. I should really have proved it first on a bit scrap. However I was lucky, it worked perfectly first time, although I'm not sure it is as quick as drilling the four corners, milling slots to join em up and taking out the centre portion freehand. Maybe it's just a question of use.






Next I milled each end, to expose the holding down tabs, then abandoned the freezing workshop, took the base inside and with a set of needle files and magnifier rounded and smoothed each tab in turn whilst thawing out.






Using a 6mm ball nosed endmill I removed the sharp edge around the base then decided to go deeper and pretty it up a bit.






Finally I flycut the whole surface.

Having finished the base plate I needed some bits to attach to it, so while I was in an aluminium frame of mind I went for the crankshaft bearing walls, and set to and cut some more ally off the plank to make the three units. These are critical components as if the are not spot on and perfectly in line the crank will not turn, so I had better get it right. Having cut the three plates roughly to size I squared them up and taking the datum from the base and back edge, marked out the position 16mm radius on each, and finished by removing the unwanted portions on the bandsaw.






I then flycut the plates both sides to bring them down from 12.7mm to the reqiured 10mm (No pic). Drilled & bored the 16mm radius's and milled to them within 0.2mmof the final size as after the next step it would be time to join them together with a couple of 3mm dowels and then machine them as one.
















First I cut the bearing caps from the portions I had previously cut off the plates, then mill them to size (no pic) then drill and tap the holes for the cap retaining screws, drilling the caps to match.






Here they are with the caps individually marked to match their respective plates, and fitted.  I then removed the caps to counter bore the screw holes.  Which gave me a good excuse to get out of the fridge and back inside for a bit fettling.  I had picked up a small multi position vice with a rubber vacuum base and hard rubber jaw covers, a couple of weeks ago, so the breakfast bar in the nice warm kitchen was a very inviting place to carry out this fairly clean operation











The three bearing plates were joined with snug fitting 3mm dowels, then clamped and milled down to size and the hole for the crankshaft drilled Cent, 4mm,6mm, 10mm 12mm and then I started boring but it was not going at all well, and close examination of the bar revealed it was dull, so I went out and bought a long series 16mm endmill and the completed the hole with that. It was a perfect fit for a piece of 16mm stainless bar left over from another job.











I then drilled and tapped the retaining holes for the bearing plates, I also decided to use 2 No 3mm dowels in each plate to locate them fore and aft rather than just relying on the retaining screws, and did the same on the baseplate using the DRO for both. Because the crankshaft ends were overhanging the vice, I used a shop made jacking device underneath for support whilst drilling


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## Brian Rupnow (Jan 1, 2013)

Excellent work!!! Happy New year!!!---Brian


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## Lesmo (Jan 1, 2013)

Thank's Brian, and a Happy new year to you too.


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## Lesmo (Jan 15, 2013)

The next move was to fit two of the bearing plates with dowels and check for alignment using a 16mm piece of stock. It was spot, on giving a nice sliding fit with no play and no tight spots.











I then cut 4 pieces of brass for the "return con rod"  guides, squared them up and marked them to keep track of their positions.






They then had the slots milled leaving 1mm top and bottom for final milling once attached to their respective bearing plates. The reason for this was that I was going to retain their alignment by means of 2 hidden 3mm dowels, then do the final milling using the base of the bearing plates as the datum point. 
















I then fitted them all to their plates ready for the next stage, which would be carried out in the warmth of the kitchen. 











And after a few hours of patient fettling I had this, all ready for the crank, which was next on the list, and my first attempt at making one. Fingers crossed



























Unfortunately I was unable to get 20x8mm flat strip for the crank webs from my local supplier so had to make do with 25x12mm, I cut two lengths off the stock, milled them down to size, and marked them up.





Starting with a center drill and then a series of larger drills 4mm to 11.5mm I drilled the holes, completing the final ones using a new 12mm endmill.
















I then marked them as pairs and cut them into individual webs. Next I made a mandrel using a 16mm bolt and mounted each one in turn to radius the ends.











Having done that, I thought they looked a bit unfinished so I remounted each one and added a chamfer to each side. It was a little time consuming but I thought they looked better for it.











I then cut the two big end journals and faced them to the exact size needed, as the next operation was going to be, first a degrease, then bond them into the big end webs using red locktite and leave them overnight to cure.  To keep the alignment perfect, I first slid both units onto some 12mm stock which would later become the main bearing shaft. 






The following morning they were both drilled and pinned with 2.5mm pins. At this point I almost carried on and completed the crank, but fortunately during my break for lunch I remembered that I needed to make, and fit the two eccentrics, and the center main bearing before doing so. Its so easy to get carried away when thing are going well and screw up the correct sequence.  






I found a small length of 30mm steel from which to turn the eccentrics, then reduced it to 28mm, changed to a parting tool, and made a cut 1.5mm deep x 4mm wide, leaving 1mm each side of each recess, then partially parted it off, then repeated the step for the second one.  I then polished up the edges and the eccentric surfaces with 400 paper and a thin strip of ally.











I then removed it from the chuck, and sawed off the two parts by hand, remounting each for a final facing cut











Now just a couple of 12mm offset holes and grub screw inserts and they are done


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## Brian Rupnow (Jan 15, 2013)

Excellent work!!! Stu would be proud of you!!!---Brian


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## don-tucker (Jan 15, 2013)

Are there any drawings available for this engine les?an interesting engine to have ago at after my clock is finished
Don


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## Lesmo (Jan 15, 2013)

Thanks Brian

Stew has set the bar high so I am taking my time and doing the best I can, thanks for looking in

Regards Les


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## Lesmo (Jan 15, 2013)

Hi Don

There are a full set of Stew's drawings available in PDF format, but I am not sure which forum I got them from. Probably this one I guess, before the fall out last year. I am not sure if they are still here.  I think Stew now uses Mad Modder. I know his build is on there.

If you have a problem finding them, I have copies of three different versions of them, I think Stew altered things whilst the build progressed, As you do. 

I also have my own 3d drawings to supplement them if you need any more details, and would be only too happy to pass them on to you, although mine were not intended for publication but they contain all the necessary dims.     

Cheers Les


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## Brian Rupnow (Jan 15, 2013)

I have a complete set of plans in British Imperial, not metric, for the single cylinder version of this that I built.---Brian


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## don-tucker (Jan 15, 2013)

I shall have a good look around ,see what I can find,have you got a pic of the single cyl engine that you built Brian?
Don


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## Brian Rupnow (Jan 15, 2013)

Here is a link to the single cylinder version I built. It runs very well. A download link is embedded in post #200. Let me know if the link works okay for you, please.----Brian
http://www.homemodelenginemachinist.com/f31/overcrank-single-cylinder-engine-14770/


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## don-tucker (Jan 16, 2013)

Brian,yep the link is fine Thank you,I think i shall go for the twin if I can get a set of drawings,help!
Don


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## Lesmo (Mar 27, 2013)

Next I set up the rotary table with a chuck to hold the eccentric located the centre mark and offset the Y by 4.3 mm centre drilled it then gradually took it out at 1 mm increments from 3 mm to 11.5 mm and finished off with a 12 mm end mill. 
















The reason for the small increments was the fact that it was only held by a small surface area and I did not want to disturb it in the chuck. 

The eccentric was next placed in the mill Vice with the offset hole at the bottom and a 2.5 mm hole was drilled through the thickest part of the eccentric which I then tapped to 3 mm.  I then turned two small dowels in brass about 2.4 mm x 6 mm long to act as a cushion for the grub screws as I did not want bearing directly onto the shaft and scratching it, because I would probably have to make several adjustments to the eccentrics and I didn't want to mark up the shaft with the grub screws.











Now before finishing the crank, Im going to make the big end, and main bearings. I sorted a short length of brass and fly cut one surface then cut it in half.






I then tinned both faces and soldered them together, 






after which all faces were fly cut.












The assembly was then placed in the 4 jaw and 30mm was gradually turned down to just over 16mm. At this point I thought I would take a shortcut and use the 3 jaw, with the piece reversed in the jaws to turn down the remainder of the square section. 







All was going well until I started to centre drill the first section when the solder gave way and I ended up with two halves lying in the swarf. 






I tried to rescue at least some of the brass so swapping the three jaw for a collet chuck I inserted the two halves which I had turned down to 16mm into the chuck and parted it off leaving 15 mm. I then bored at the centre using a series of drills and finished off with a 12 mm end mill.












Unfortunately the hole was slightly larger than the 12 mm stock from which I made crankshaft. I knew I should've bored the last bit to size.






Having obtained some 3/4 x 3/8 brass section and a length of 18mm brass round I started over. First using 18mm round, I turned down the two outer main bearings which were just round, not split.  I first drilled, but this time bored the centres to final size. This worked much better and fitted perfectly.
















I decided this time not to solder the two sections together but and simply rely on the jaws to hold them together and do the bearings individually. I fitted the two sections inside the jaws and centralised them, then machined them down to 16mm over a length of 15 mm plus sufficient to part them off. 






I then parted them almost through leaving about 3 or 4 mm, clamped the end into a collet chuck and using a hacksaw parted the remainder off.
















 Having done two 15 mm big end and one 10 mm main bearing,






 I then used the collet chuck to bore out the centres finishing with a small boring tool. Success thats all the bearings done.

At this point I turned a 180mm ( the only size I could get) backplate down to 125 for my newly acquired collet chuck, which was a messy operation. Cast sure is a dirty material to work with.

Right back to the crankshaft. I then took the 12mm stock for the crankshaft and put it into the collet chuck and turned down both ends to a shade over 8mm for the flywheels






And threaded both ends 8mm






I setup the first crank on the shaft using red locktite and left it to cure overnight, rather than doing two at once. 






The following day I set it up in the mill vice on parallels and used a square to get the  second crank at 90 to the other, again leaving overnight to cure.  Meanwhile I started on the oilers.






Taking a piece of M16 brass stock I thought I would turn the three oiler caps first, machine thread them with a  0.75mm pitch thread, and then do the bodies, threading them internally using the same threading tool that I made to do the cylinder heads. and then knurl the tops. 


The thing I like about threading on the lathe is that, as in this case, the drawing called for ME 3/8 x 32 tpi,  but not having an ME Tap/Die set, and as I like to keep to metric sizes, I choose the closest metric pitch draw it out and make the parts to suit each other.  If I can find out how to include a PDF of the thread drawing in my post, I will do so, as I remember last time with the heads my explanation caused a bit of confusion. A picture is worth a thousand words. (particularly mine)

View attachment OC_oiler.pdf


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## SBWHART (Mar 27, 2013)

Hi Les

Just caught up on you're progress (where have all the smilies gone) ) 

Great work its looking really good

Stew


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## Lesmo (Mar 29, 2013)

Next the oiler bodies. M16 brass stock turned down to 14mm for the length of the body including the thread. Bored out 8mm dia to a depth of 16mm, then internally threaded to a depth of 8mm with the homemade threading tool.  At this point it occurred to me that it would be a good time to use the first body to face off the three caps, which had parting off nibs.






This was then parted off reversed in the chuck and the diameters reduced to 8 and 4mm respectively.






The drawing calls for a chamfer between the 14 and 8mm diameters but I wanted a nice smooth radius and realized that my plan of using the ball turning device would not be viable as it would not be able to approach close enough to the chuck to do the job. so had to resort to using the file, which turned out ok.











For the next couple I reversed the process so that I could use the ball turner for the radius.






And could also drill the 1.5 mm oil hole part way through and join it up to the oil reservoir later.






This was also a good point to tap the 4mm thread using a piece of flat brass stock in the chuck to keep the die square.

I also ground a tiny 1mm wide parting tool to relieve the unthreaded part adjacent to the shoulder. No pic.






Three oilers complete.






Next step was to drill and tap the crankshaft bearing housings to accept the oilers. First they were drilled 2mm with the bearings in place for the oil hole. Then the bearing was removed for drilling & tapping to M4.  The cap was then recessed with a 4mm endmill to allow 1mm of the oiler to protrude through to act as a bearing retainer. 













The bearings were then set up as pictured and a 4mm slot milled in the top of each across the oil hole.











Assembly ready for the oiler to screw in.






Having found a 150mm length of 78mm dia bronze tube I bought some years ago to make a primary shaft bearing for my old Mini Marcos, I decided to make the small flywheel outer ring from it using the same method as Stew. 

Starting on the centre I took a short 25mm piece of brass, faced one end, put it in the Hex collet chuck and into the mill vice using the backstop for depth control. I then setup the Dro for length & depth of cut and put a homemade jack under the work for additional support, then started milling the hex.











I then took it to the lathe and put it in the chuck, checked if it was running square, centre drilled and drilled it out to 7mm. It would later be bored & reamed to 8mm











It was then back to the mill to drill & tap the 5mm holes, giving each a slight countersink to ensure good contact with the spoke shoulders.






Now for the six spokes, so back to the lathe, a length of 8mm stock in the collet chuck and turn down each one for a 5mm thread using a supported die.





Using the tool I ground earlier I relieved the area where the thread met the shoulder to ensure full contact.






Each one was then polished with 1000 W&D and parted off to length allowing a few mm for turning, and this is the finished assy.






This seemed like a good time to polish the centre while it was still held in the collet chuck and while I was at it I found a chunk of ally, tapered the end and tapped it to hold the spokes whilst being polished, otherwise they would end up in some dark corner never to be found again.






Polishing done. 






All spokes locktited in place







Now for the outer rim. I took my dirty old chunk of bronze and put it in the three jaw, and selected a low speed to check it turned without a wobble, increased the speed and faced it off in small increments. I was prepared to make something to support it with the tailstock but it was not necessary and it turned beautifully






I then cleaned up the outside face for a distance of just over the required 20mm





Changing to a boring tool, I bored the inside to 56mm for the same distance as the outside. I then took another 1mm out a distance of 14mm to give an inside dia of 58mm The 8mm spokes sit against the 56mm face and are held in place with locktite. Finally the edges were given a small 45 deg chamfer. 












The outer ring was then parted off and reversed in the chuck to face up the parted side and the edges given the same chamfer.






Turning my attention back to the spokes, I set it up in the 3 jaw and turned the spokes down to within 2mm of final dia and at the same time bored the centre out to 7.25mm.






It would have been nice to part it off at this stage, but the spokes wont allow that, so I reversed it, centre drilled and used the tailstock to support most of the parting cut and finished with a hacksaw. Then faced it.






I then made a mandrel creeping up very carefully to 7.25mm dia.  I was able to use the as yet unthreaded portion to check for fit as I progressed.  Finally I threaded the end, and fitted the hub, and it ran true.











The spokes were then turned with the utmost care until the outer ring fitted perfectly.  I had not used any lube during the operations but cleaned the mating surfaces with thinners just to be sure the bond would be good. Applied locktite and left it overnight to cook.







The following day I removed it from the mandrel reversed it and set it in the 4 jaw, using parallels and a centre cone to get it roughly positioned.





I then cut a ring of ally from a beer can, wrapped it around the work and let each jaw kiss the ally. (No pics too involved) removed the tailstock cone, and then spent some time making sure it was dead on centre. I then bored the centre to just under 8mm then reamed the remainder. Next the conrods.


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## SBWHART (Mar 29, 2013)

My word Les you've made a cracking job of that flywheel 

Stew


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## Lesmo (Apr 1, 2013)

*Hi Stew

Thanks for looking in and again for your kind remark, although all the credit must go to you for the methodology, it certainly worked a treat.

Regards Les ;D *


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## canadianhorsepower (Apr 1, 2013)

awesome work unbeilevable


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## Lesmo (Apr 4, 2014)

Having taken a long break from the workshop, which amounts to most of 2013, to do various jobs on the domestic front, I am now getting around to catching up on the parts I had completed and not written up, and continuing with the parts that are as yet still living inside the bits of metal still lying around gathering dust.

Two lengths of 10 x 34mm plate were cut squared and pinned together using 3 roll pins. The holes were countersunk so that the pins were below each plate surface. 





The pair of plates were then blued,  marked up, and placed in the mill vice to be coordinate drilled using the mill dro, starting at the small end, as the big end has to be split faced and screwed together before boring out to size. As you can see holes were drilled at the radius points each end, so that the scrap could be milled out ready for final finishing.










(Img 







Next I set the pair vertically in the vice for drilling the big end bolt holes, and splitting the big end caps from the rods. 
Before doing so they were all marked so that they could be relocated in the same place from which they were cut.  

















After cutting,   the rods and caps were lightly faced and the rods drilled out for clearance.  (The thread being in the caps)











The pair were then transferred to the saw for cutting, as the next step before returning them to the vice for milling out the bulk of the waste.












And this is what they look like, pins removed, and then paired up again for the next operation.











Placing them back in the vice again, this time in the other plane, the waist and inside ends of each rod are milled to the finished size.










Because the big end bolts go in from the rod end, it is necessary to cut a flat surface into each big end radius, and for this a special tool has to be made to cut them from the underside, whilst applying the drive from the cap side. Unfortunately I missed the pictures from this operation, but did get some of making the tool for the purpose, one of which is scrap.

As it is many months since I made this tool the size details are a bit sketchy in my mind. But here goes.

I used a length of 10mm silversteel (drillrod) and turned a 4mm shaft with a 8mm portion on the end, then milled and fettled a cutter shape on the shaft end of the 8mm portion, keeping in mind, the direction of cut.    Then hardened it.























I then placed the rods, big ends upwards into the mill vice, inserted the cutter from underneath through the 4mm hole and into the mill chuck and applied reverse pressure on the quill to make each cut, and this is the result of all the above blather.








And here they are assembled and awaiting the next step, which is to bore the big end at the correct Centre to Centre distance from the small end, which should coincide with the split line.






Back into the mill vice they go and the datum point for the DRO is double checked with a gauge







The big end is first milled out to 10mm, then 12mm, and bored out to the finished size of 16mm.  







You will notice that both ends of the rod have remained the same width throughout and will continue to do so for as long as possible to facilitate holding.

The unit was then transferred to the rotary table to give a 30mm radius to the big end caps. Unfortunately I only have one setup shot of this operation and none at all of the radiusing as when I get involved in a complicated setup, my brain overloads and I forget to get the pictures.  Poor old sod 







After the big end cap radiusing it was back to the vice to thin down the rods to 6mm except that is for the big end portion,which remains at 10mm, then mill a decorative recess into both sides of each rod using a 10mm ball nosed mill. Finally separating the rods and cutting off the small end ears, reducing the big end width, hand fettling to the final shape and polishing.  It doesnt take long to write, but it was a very slow and time consuming operation. I then lay down for a while to recover. 


























I am considering re-making the conrods again in Brass or stainless, but will leave that thought on the back burner to cook for a while.

 Now its on to the return rods of which there are four. So I cut 4 strips 175mm long, off a bright stock length of 30mm x 3mm and cleaned up the ends with a file.  I then placed them in the mill vice, drilled them for roll pins, and squared both ends. I then coordinate drilled all the holes required and removed them to mark up the areas from which I needed to remove metal.      

















They were then setup on the Rotab to make three radius cuts and the unwanted metal was milled away back in the vice, forming the narrow section














Next the holes in the thick section were enlarged and the scrap milled away with a slot mill. 











They were then taken to the belt sander and the other small radii made by hand. Next came the labor intensive bit, hand filing, fettling and polishing. 





















I next made, the piston assembly connecting beams, which join the return rods directly to the piston via an 87mm x 5mm silver steel shaft. They are made from 10mm Sq section and are each 32mm long.
First I took a length of 10mm sq brass and set it up in the 4 jaw chuck
then centre drilled it.




















I marked it up in situ then using the tailstock for support and a fine hss cutter, turned the parts to the shape shown in the drawings. These will be fettled and polished later before assembly.

















The pistons were made from some 25mm ally round. The pistons are 20mm dia, and each 5mm thick with a 2mm groove in the centre. They were tapped 5mm in situ to maintain concentricity, and parted off.







And here is the complete assembly ready for fitting






While I had the 10mm sq in the chuck I made the beams for the opposite end of the return rods. These were made in the same way as the other ones but turned barrel shaped instead. 













It was now time for a bit of trial assembly, which was followed  by a few choice anglo saxon expletives.  As you can see from the picture below, the piston centres do not match up to the return rod centres.







Further investigation revealed that all the individual parts matched Stew's drawing exactly. It looks as if somewhere during his build he had may have thought things were a bit tight in the eccentric area and made the crank wider, moving out the outer crank bearing posts to the the edge of the base to suit. This is now evident looking at his General plan view. 

I originally found three sets of drawings for this engine, which came from either HMEM or Madmodder, I cant remember which.   I could see various changes being made from drawing to drawing . But the base and crank drawings looked to remain the same so I assumed them to be OK.

Let me just state that I do not lay any blame at all on Stew.  We all modify things as we go along if we see a better way to do, or improve things, and its so easy to miss the drawing update, particularly when  making a one off.  I am just grateful that he took the trouble to produce the drawings in the first place, as its very time consuming job.  

I hold myself entirely to blame, because I departed from my usual and well tried procedure. Which is to draw out each individual item in 3d  regardless of what it is I am making, and assemble it on the computer, beforehand, this way it shows up any fit problems beforehand, but on this occasion I didnt do it, but you can bet I will stay with the plan in future.

I should be able to salvage the crank webs and big end journals, if I can get it apart without damaging the webs.


Well the Crank came apart without incident, so I cleaned everything up and turned a new shaft between centres then assembled it again using locktite and set it up to cure overnight 
























The following day I pinned it and set it up to cut out the unwanted portions and finished the process by milling flush with the web surfaces.











The cast iron flywheel I bought at the start of this project looked a bit large when it arrived, and I put it to one side meaning to return it for a smaller one, but time went by, I was enjoying the build and I forgot all about it. 

When I dug it out and measured it it was 200mm dia by 50mm wide, but then I got to thinking that the reason I wanted to make this engine in the first place, was that it looked so good running slowly. It reminded me of the huge water pumping beam engines with their enormous flywheels, that we had in this area when I was a lad, so decided to trim it down some and see how it looked in relation to the rest.  I dont have a pic of the start size, but it was meaty. Here are a few pics of the operation


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## Lesmo (Apr 4, 2014)

What a messy material cast is to machine, particularly when ther
e is so much meat to remove, I was glad when it was done.

I followed Stews method of using a tapered bush machined at the same angle as that bored into the flywheel centre, for securing it to the crankshaft.  The bush was made immediately after boring the flywheel so that both angles matched exactly, it was then split in the mill  

















Next task was to remove the two unwanted portions of the crankshaft using the bandsaw. I used the following setup.






















Then milled the ends flush with the crank webs.




With the crank put to bed, I started on the eccentrics and decided to fabricate the basic shape from flat and round brass bar, silver soldering the parts together.












As there was plenty of thickness, I cleaned them up first on the belt sander then superglued each one in turn, to a piece of square section tube, which I had previously milled flat & parallel. Then fly cut them to size 






















I then made a mandrel for the ro/tab to hold the pair while I milled them to the shape and size required












They were then placed in the mill vice and the bolt holes drilled first to the tap size then the top portion to the relief hole size.  Removing the mandrel they were then cut across the centre and faced (no pics).  The lower portions were then tapped to size, assembled and placed in the vice to mill the centre hole.












As I thought there was not enough support to mill out the large centre hole using the present setup, I set them up on the rotary table to carry out that operation. 























I next silver soldered some ears onto the stems, fettled everything up and polished them

















Next, the stainless steel swivels for the eccentrics.





























Almost there, just a few bits to go.

Valves were machined from a single piece of bar and parted to length.





















Next came the cover made from 2mm brass plate cut and machined to size and then coordinate drilled to match the engine.






On to the valve assembly starting with the most difficult bit first. The valve wheel.

Being a bit short of the correct sized brass bar I decided to fabricate the wheel from two sections of round and silver solder them together.
Trouble was I got a bit carried away during the heating process and ended up with a melted mess, which will be shown soon with the finished wheel for comparison.

Meanwhile I sized and parted off another brass disc, then drilled it to fit the bar, and this time soft soldered it together.











It was then placed back into the chuck, turned to size, and the outer rim radiused






It was then transferred to the rotab for drilling and milling to shape

















And here is the finished item

















Next item was the base for the valve body, this has to be fitted at an angle to the valve cover, so after drilling it, parting it off and milling the angle on the bottommaking the I made a small central hole with a small sacrificial brass dowel to hold it in place while it was soft soldered on to the cover.  The angles were setup using a digital angle finder. 

























And so on to the valve body, first it was turned to size and drilled







Then transferred to the mill for pcd drilling and tapping






Stainless studding was cut to size using contra rotating lathe and whizzer.






Now for the assembly for which I would need gaskets. These were printed out on robust photographic paper and cut out with punches and a scalpel knife. No pics of assy unfortunately.






























And I found a solution to fitting those tiny 2.5mm nuts having retrieved several from dark corners which is where the usually
end up, that or lost.

Pencil & Blu tak makes it so easy and they dont drop.







And here it is awaiting its wooden base, a little compressed air and some timing. (Really looking forward to that)  











Well thats it finished. It ran first time and I only had to tweak the timing on the LH eccentric to get it really smooth. It runs nice and slow on minimum air pressure, which is how I like to see these engines run. I will make a video soon.

Meanwhile a few shots of the finished engine mounted on its hardwood plinth.









































And here it is running as I had hoped it would.  At the start I was unsure if I had the ability to complete this project, having only previously made the relatively simple Elmer from Brians drawings, which I altered the design of, as I became more confident. 

My inspiration for getting started on this far more complex engine of Stews, apart that is from admiring Stews engine running so sweetly, is due to something Bogs wrote. I cant recall the words exactly, but it went something like this.  No matter how complex the project, just take it one part at a time and make each part to the best of your ability.  

[ame]http://youtu.be/6imVcygNPfE[/ame]

Lets hope the link works.


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## don-tucker (Apr 5, 2014)

That's a lovely lovely job Les ,and runs beautifully .
What's your next project,I'm looking for inspiration
Don


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