Quarter Scale Merlin V-12

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Herman staal

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Good evening.

I have a big intrest in the quartelscale merlin engine. But found out the castings are not avalible anymore.

I had contact with a danish builder who built on of this engines and got it running.

He told me that from what he have heard about 50 of those casting sets were sold. Only few of them completed them.

Is there or does somebody on this forum knows who has a set of castings and would like to sell them.

Hope i could get a set of this.

Best regards
Herman staal
 

gdrhbb

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I came across two online references to help me with machining the Merlin crankshaft. The first is a thread by a Belgium builder 'Zapjack' who fabricated this exact part with some 200 hours of work over a period of two months nearly three years ago. It's located at
http://www.homemodelenginemachinist.com/showthread.php?t=18747
He first published his build on a French forum and then cross-posted its highlights on HMEM in 2012. The original non-English forum where he posted his realtime build as well as an additional two year's work on his Merlin is located at:
http://www.usinages.com/threads/rolls-royce-merlin-v12-echelle-1-4.42350/
Unfortunately, his posts faded away in 2014 after completing the crankshaft, prop shaft, and cylinder liners as well as the crankcase and some of the cylinder block machining.
The second reference is George Brittnel's crankshaft tutorial inside his V-8 flathead build thread starting at:
http://www.modelenginemaker.com/index.php?topic=3846.210
Since I have some limited four axis CNC capability, my hope is to combine the information in the two threads and take advantage of my Tormach's fourth axis. I don't if my particular CAM software can be convinced to continuously machine the offset throws from billet, but it's worth several days of experimenting to see just what it can do. Hopefully, I can at least come up with g-code for some of the tedious roughing.
Work started on the crankshaft by sawing off a 10-1/2" length of 2-3/4" diameter 1144 steel. I've not used this particular alloy before, but it comes highly recommended for crankshafts by George. I bought a piece long enough for two parts just in case my learning curve takes an ugly turn. I purchased the metal from an online supplier who advertises it as 1144 Stressproof or 'equivalent'. The 'equivalent' sounded ominous, but their price was nearly half that of the other online supplier that I've used used in the past for material not available in my scrap collection. Since Stressproof is a brand name, I'm not sure it's legal to use it to advertise a generic equivalent.
Anyway, after facing and center drilling one end, I turned the o.d. down to 2-1/2" over as much of the length as I could before flipping it around, facing and center-drilling the opposite end and then turning the rest of the o.d. After cutting through the black outside layer I was relieved to find the material turns pretty similarly to mild steel. The chips resemble those from free machining steel, and the surface finish is similar. An amazing thing I noticed was the material's consistent o.d.. The run-out at the end of the 10.5" long un-machined round was only .002" after being chucked in my lathe's 3-jaw without tailstock support. The material I purchased was their low-end cold-roll, but it is also available as precision ground and polished.
After studying the crankshaft drawing I realized just how complex this part is. The webs are not identical, and there are many machining features associated with them. Another wrinkle is that each bearing and crank pin is bored-through in order to reduce weight. In addition, both ends of each of these bores must be counterbored for end plugs since internal oil passages supply pressurized oil from the mains to the crank pins. The workpiece I'm starting with weighs 18 pounds, and the weight of the finished part will be only 1-1/2 pounds. A lot of metal has to be removed from some very difficult to reach locations.
The first and probably most important decision to make is how the workpiece will be held for offset turning. George's offset end blocks looked good to me as they positively grip both ends of the heavy eccentrically rotating load. When I tried to adapt his technique to my crank I realized the four-sided headstock block he used for his 90 degree throws would not work with my crank and its 120 degree throws. I looked at using a hexagonal end block but I wasn't happy with two of the four jaws gripping on the corners of the block. A 12-sided polygon would work, but it wouldn't have long enough sides to handle the crank's 1-1/2" stroke in my 4-jaw.
Zapjack center-drilled the ends of his workpiece for center-turning on each of the three offset axes. I don't have much experience with center-turning, but supporting the weight of this workpiece between two centers concerned me. None of Zapjack's photos showed his headstock drive, but I can't imagine it was merely a conventional drive dog.
I decided to both center-drill and mill reference flats on both ends of the workpiece. Currently my plan is to use the center-spots to locate the workpiece between centers while finish turning the crankshaft. However, I will also add a head support block similar to George's to secure the crankshaft to my lathe's faceplate. The tailstock end will just be supported in an offset center-drilled spot by either a live or dead center. Most of the material will be initially roughed out on the mill and probably with the workpiece held horizontally in a vise. If I run into problems and have to come up with a plan B, at least I'll still have the flats and center-drill references to work with.
A first pair of reference flats was milled into each end of the workpiece while it was held horizontally in a vise. The workpiece was then stood vertically in the mill and clamped against an indicated reference plate using a ground block between the flat and the plate. I was relieved that this rather dicey set-up was actually able to hold the workpiece truly vertical and was rigid enough to mill the additional flats. Zapjack actually removed the table from his mill so he could perform a similar operation. The 120 degree center-drills were then drilled, and the remaining two flats were milled on the perimeter. Both ends of the workpiece were similarly machined but an additional nine holes were added to the front-end. These will eventually be tapped and used to secure a driveshaft to the front of the finished crankshaft.
Because of its complexity and the need to modify its dimensions to fit my 'short' crankcase, I modeled the crankshaft in SolidWorks so I could better understand what I will be up against. This crankshaft looks like a part that can be easily ruined by lapse of attention. It also looks like it will be the most complex part I've ever attempted to machine. It wasn't too long ago, when I was intimidated by what now looks like a pretty simple crankshaft in my 18 cylinder radial. - Terry

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Hello, I really need this drawing very much. I love it. Do you have any plans to sell it?
 

mayhugh1

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gdrhbb,
I'm sorry but it's copyrighted material, and I can't supply it. Others have been down this path trying to purchase the drawings from the original author even though the castings are no longer available, but his position has been firm and he won't allow them to be distributed outside the casting set. Your best bet is to purchase the set of castings and drawings from Randy above. You're going to need the castings to build the engine, they are very rare, and if Randy is willing to sell his you may not have another opportunity.
I don't know what your skill set is, but if you decide to purchase the castings and go on with the project, you should get a few other engines under your belt before attempting the Merlin. It will take only a single slip up to ruin an irreplaceable casting, and many of them will require straightening. Best of luck to you and keep us advised of your progress. Everybody loves a Merlin. - Terry
 

mayhugh1

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Randy?Excuse me, who is it
He's the person you communicated with in post 843 above.

By the way, I happen to remember that there was a change to the crankcase casting that ended up making later versions of the crankcase slightly longer than earlier verdions. There was a warning about this issue on the Dynamotive website when it was still active a few years ago. This casting modification changed some rod locations from what was given in the drawings. Mine happened to be one of the ones that required these changes. In fact these changes rippled on up through the entire engine. So, before you start machining the crankshaft, make sure you have the actual crankcase casting that you'll be using in your hands. - Terry
 

mayhugh1

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Terry-did you end up using glow ignition, or magnetos?
Elliot,
I used a spark ignition with two CDI's. The distributors were disguised to look like magnetos. - Terry
 

CJD

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I realize this is an old thread...but...

I just bought a set of the basic engine castings from an estate sale. It appears to have the castings for the basic engine, groups 1 through 4. I wondered if anyone has a line on the castings listed in groups 5 through 9 that hey would be willing to sell. These include the "bonus" items like the intakes, supercharger, carbs, magnetos, and a few other items. I would even be interested in a complete set of castings that include all the groups.

Thanks,

John
 

goldstar31

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My old Merlin fitter mate- 12" to the foot guy has just passed the Grand Lodge above but his favourite TB-731. ( JM-R) is still airworthy-- from 1949.
So is dear old VP-981, the DH Devon C1 which later became the hack for the Battle of Britain Memorial Flight. Gypsy Queen 71's. I used to joy ride in it instead of playing soccer.
 

CJD

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Well, got the castings. They came with valves, keepers, springs, seats, and rockers. They did not come with the rear gearbox or supercharger. I have a couple projects to finish up, and then I'll get serious about looking the Merlin over and come up with a game plan. This build will be complicated by the fact that Dynamotive is shutdown and does not respond to any attempts to contact Richard. I am missing all the documentation to the rear gearbox, but I actually look at that as a plus, as there are a few things I do not like about the original gearbox and cam drive plan.

Terry, your build documentation here will be invaluable, as the plans leave a lot to be desired. I believe this is a first generation set, as the initial castings are dated 1996, and the final contacts with Richard were in 2000. The original owner was receiving the castings as they first became available.

Still interested in any castings still out there...
 

CJD

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I finally got the heads and cylinder blocks. I can see right away that the cylinder spacing is going to be an issue due to differences in the casting shrinkage between the crankcase, cylinder block and heads. The documentation is not what I am used to in technical drawings. I am afraid Richard was intentionally sparse with details about measurements, and he has shut down all contact with the outer world. It appears he sold the castings to help finance his side of the project, and kept the details (and copyright) close to his chest.

I have decided to build the engine virtually in Autodesk Inventor before even thinking about breaking a chip. That will allow me to finalize all the details in cyber world, as I can see immediately that it would be easy to back myself into a hole otherwise. Once I get going I will break my project off into its own thread. Even with the issues ahead, the castings are truly mesmerizing to look at. I can understand the effort that Richard put into them, even though I feel it's a shame he refuses to sell any of the copyrighted documentation. It's it lot of work that will never be put to good use.
 
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skylark

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My old Merlin fitter mate- 12" to the foot guy has just passed the Grand Lodge above but his favourite TB-731. ( JM-R) is still airworthy-- from 1949.
So is dear old VP-981, the DH Devon C1 which later became the hack for the Battle of Britain Memorial Flight. Gypsy Queen 71's. I used to joy ride in it instead of playing soccer.
The Spitfire 16 JMR. was Air Chief Marshal Sir James Robb personal aircraft when it was based at RAF. Northolt ( hence the marking JMR. ) This was fitted with the Packard Merlin 266 1,372 hp. - I last new this to be flying with the Air Gunnery School at Exeter in 1953. - Where is it now?
 

goldstar31

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RAF Northolt at the time pf SL-721 and the other 2 Vip Spitfires was a satellite to Hendon.

I was stationed At Hendon there 1948-1950
 
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goldstar31

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Norman Franks First in the Indian Skies give some aircraft details. It is inaccurate as Franks was going off someone one's recollections. Sadly not very true. Four VIP aircraft - 3 Spits and Devon VP-981 were in the care of my mate in 31 but they were 'not on strength' so to speak. James Marshall Robb's kite was JM-R replicating his intials on SL-721. I'm keeping quiet about one 'jockey; but there is one helluva story about Boothman and the Sneider Trophy. Although Robbs Spit appeared in Warbirds of Canada, his plane never went to war. It hdn't any guns LOL but somewhere and I think Warbirds again and Jimmy ob. there are the lads on B Flight with the Proctors. Tucked away was probably a French Nor1000 or otherwise a ME108 Taifun. My mate helped to put it together.
Devon vp-981 is far more interesting. It was actually DH Dove originally but was sort of a cousin to our Devons whivh were replacing our Anson 19's. It 'beonged' to the Air Officer Commanding in Chief Coastal Command and flew with a bass fiddle across the seats as a liferaft. Well, it was Costal Command.
In early 1950 the message came through "subsmash' A British submarine was in trouble and the dan marker had surfaced off Sheerness on the River Thames. 981 was in for a service in Tech Wing R&I and my phone rang pn 19. I was boss of the Signals billet then. ' Corp, do you kmow what a Danbuoy is because 981 is on the Peri trck across from you. Catch i i was sitting opposite. We flew at f all feet over Buckingham Palace with the Roya Standard flutering and down the docks of the London river.
We got there to find that the sub had been spotted and the lifting gear had come from Portsmouth in the night. We were too late and the deaths on truculent were appalling and it was a wing dip in salute and home for tea. Days later, I'd been jabbed for a trip in an ambulance Anson 12. The RAF Regiment corporal and were the best shots with 9 millie Sten( I'm deaf now) and thing quitetted down and SL-721's engine basher and I were off into Civvy street. Johnny went to BR RAcing and here me-ahem.
VP-981 was then sent as the hack to the Battle of Britain Memorial Flight and was superseded by a proper Wartime Dak. 50 years to the date of the Crash we tool the girl friend and the sistr of the 2 of the 3 crew and we kept in touch until John's death last year.
So the two of us are left- Eddie my top clerk has gone as well.

When this pandemic is over, walk the haunted hallows of Hendon and move up to the National Arboretum to the RF 31 Goldstar memorial . Read the names of the great people of th past.
there is a comfortable garden seat for your convenience. I put it there inmemory of my late father in law by my late wife on behalf of ALL of us.
 

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