# Double Acting, Twin Cylinder, Oscillator



## doubletop (May 16, 2010)

During my building of my 3 vertical boiler John Bogstandard pointed me at two examples of a model marine engine (see his post #73) http://www.homemodelenginemachinist.com/index.php?topic=8687.73

Bogs also provided me a link to the French plans here http://jpduval.free.fr/Moteurs_vapeur_simples/MV%20deo%2010x20.pdf Id post the copies of the photos of his version of the engine he had sent me in the PM but they dont have the Bogs Wallace and Grommet watermark so Ill leave that to him.

This was just what I needed as my next project and something I could try out my new mill on. I decided to save any posting to near then end rather than subject you lot to every cock up I was guaranteed to make. So here it is, a retrospective on a my twin cylinder double acting oscillating engine. Unfortunately I don't have a whole lot of pictures but those I do have I'll share with you as I go.

First up was my first ever milling job for the vertical pillar that forms the frame for the engine. I decided to do it in ally as I thought it would be easy to work and I have a very helpful supplier 10mins from the house. 







This taught me a few things but I wasnt that happy with the result so it was eventually scrapped and started again. 

Call me old fashioned but to me cylinders have to be round and anyway I cant find a source of square section brass so I decided to fabricate the cylinders from a block of brass form steam ports and round stock for the cylinder, both being silver soldered together 

Steam port cradles (with the old pillar)






Milling the steam port block from brass and using a 5/8 ball end cutter produces a cradle of 15.88mm diameter in which a 16mm cylinder sits nicely centrally for the soldering.

Rather than flux up both parts and heat them up as a pair and feed in solder, which I felt would create a messy joint I took the approach of tinning the steam port block first, by fluxing it, heating it up and applying silver solder along the base of the cradle. It then went back into the pickle to clean it up . Then both the steam block and cylinder were fluxed up put together and heated up. At the point the pre-applied solder stated to flow I removed the heat and made sure the cylinder was fully seated by pressing down on it until it cooled below the melting point of the silver solder. A neat solder line could be seen between the edge of the cylinder and the steam block.

Once cooled and cleaned I chucked up the cylinder assemblies in the 4 jaw and finished off each end and made the length the 34mm on the drawing.






Pivot points, steam ports and cylinder ends were all done on the mill.

That's all folks, crankshaft and flywheel in the next installment.

Pete


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## tel (May 16, 2010)

Shaping up nicely so far


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## John Rudd (May 16, 2010)

Looking good.....

Following this with great interest...


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## cfellows (May 16, 2010)

That's going to be a nice looking little engine. As a side note, I wonder how Bogs finds all that neat stuff!

Chuck


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## Blogwitch (May 16, 2010)

Chuck,

Bogs finds all that neat stuff by being an insomniac.

Hours and hours of sleepless nights searching thru obscure links that lead to another, and then another, then BINGO. Something worth saving to my ever growing favourites file, just so I can pass it on when someone asks.

I have found that French and German sites are much freer in sharing good quality plans for nothing. When I see US and English sites selling junk rip off plans for wobblers etc, it makes my blood boil, where with a little work, you can get much better plans for nothing.

The only problems are that they are usually in metric, and in a foreign language. Both of those can usually be solved very easily.

I have shown this many times before. Just click on the one you want to make, and save the PDF plans.

http://jpduval.free.fr/Plans_moteurs_vapeur_p1.htm

You will see the plans for this build on there, bottom left.

For others from this site, go here

http://jpduval.free.fr/

There are some free loco and rolling stock plans on this bit, but also there are some plans that he does sell, and I purchased them a while back, and I can tell you now, they are worth every penny. Look on the left hand side for Bibliotheque de plans, click it, then click on the picture of the plan. I bought the whole set of plans, and I think they came to about 6 bucks each as digital PDF downloads.

This is a video of one of them, I made the flywheel on it for John Somers, showing how to make the flywheel and put a tapered fitting into the centre to hold it on the shaft. Can't quite remember where I put that post.

[ame]http://www.youtube.com/watch?v=YxzFddeph7k[/ame]


John


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## cfellows (May 16, 2010)

Good stuff, John. I always enjoy pouring through the materials you provide us. 

By the way Pete, here is a project you might want to find plans for so you have a vehicle to put you steam engine in...

[ame=http://www.youtube.com/watch?v=1s9vQx7OvB4&feature=related]http://www.youtube.com/watch?v=1s9vQx7OvB4&feature=related[/ame] Some of these guys make some darn nice models.

Chuck


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## doubletop (May 16, 2010)

Chuck

How did you find that? Its basically the same engine. 

I will search for the plans though as a fully enclosed boiler that can be lit from the flue is appealing.

nice one thanks

Pete


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## doubletop (May 17, 2010)

*Part 2*

The flywheel is pretty basic so Ill skip that bit.

Although the drawings only require two crank counter balance weights I need three as I plan to provide an output shaft much in the way John Bogstandard has done on his versions. These needed to be matched so I took this approach (sorry no photos of progress).


Turned down a brass bar to 28 mm enough for three counter balance weights plus cutoff allowance and drilled centre hole for main shaft

Mounted vertically in the mill in a V block and drilled the holes for the crank pins and the clamp along the X axis


With an end mill, milled the relief to form the counterbalance weights 

.







Mounted the job in a V block horizontally along Y axis and Swung the milling head through 90 degrees and mounted the slitting saw blade. Aligned it all (or thought I did) and cut the clamp slots. _(this may not be the way to do it but my mill head can be rotated so I had to try it)_

Cocked it up and started again.






The second time I scrapped the idea of the slitting saw to make the clamps for the counterbalance weights I decide to go the easier route and use grub screws and flats on the main shaft.

My little Lorch cant part off so once I had a stack of counterbalance weights all machined I went to my mechanical hacksaw and cut off the three weights. 

These then were put into the stepped collet and the hack sawed faces cleaned up.






The main shaft was pretty easy to do and a 1/16 end mill was used for the flats for the main shaft.






The output shaft was a simpler repeat of the main shaft.






Next is the cylinder ends, pistons and other bits and bobs

Pete


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## Blogwitch (May 17, 2010)

Many of you have seen these before, but for those that haven't, this is what Pete is aiming for, the vertical one.






This shows that you don't have to stick religiously to plans, as long as you leave the basic running dimensions in there, you can make them whatever shape and style that takes your fancy. The horizontal one was made for going into a paddle boat, but could be converted back to a vertical one in about half an hour.


Bogs


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## doubletop (May 18, 2010)

cfellows  said:
			
		

> By the way Pete, here is a project you might want to find plans for so you have a vehicle to put you steam engine in...
> 
> Some of these guys make some darn nice models.
> 
> Chuck



Chuck et al

I asked the guy, who posted the video, where he got the bolier plans from as the engne looks like the one I'm doing. Its a Regner off the shelf item "Midi" http://www.traindept.com/bengmidi.html they originate from Germany.

If you look up Regner Midi there are a mumber of land based vehicles using this plant. One based on a Tamiya tank kit.

Pete


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## doubletop (May 18, 2010)

*Part 3*

Im going to cut to the chase as I got this finished and running today but Ill save the video until the end.

This is my second engine and served to give me something basic to try out my new mill which was only delivered on 23rd April. Its gone pretty well, a few of the inevitable cock ups here and there along with my first ever use of a milling machine, a few other firsts and lessons learnt.


Worked out how a wiggler works and now use it all the time.
Worked out how to use slip gauges, surface table and vertical caliper for accurate marking out.
First use of fly cutter, and T slot cutter. (previously having tried end mills and slot drills in the lathe)
Tried out the slitting saw it worked better than I expected. But would work better still if you spend the time setting the job up properly.
Realised that the 1/32 and 1/16 slot drills actually work and with care dont break as soon as the mill is switched on.
Learnt that cutting fluid is to be used on all occasions. This after the end mill I was using to cut out the base stopped cutting, to find the flutes of the end mill full of welded ally that had to be removed with a pin punch. 
Learnt that have TV in the workshop is probably not a good idea as you can get distracted. One brief distraction and a 10BA tap broken in millisecs.
Learnt I now need DROs on the mill cos mis-counting revs can result in having to start the whole datum set up all over again.

Anyway pictures of all the other parts.

Pistons, cylinder ends, gland clamps etc






Cylinders and pistons assembled






Regulator/reversing assembly and inlet/exhaust ports.






Chassis/Frames bearings etc






All parts before assembly






Milling the base runners. Using a T slot cutter to provide a relief which is just cosmetic. Happened to read a book that suggested that T slot cutters were frequently used by modelers for milling the relief in engine con rods.






All done and tidied up following the running in period shown in the following video. You'll also see it now has one of Bogs displacement oilers.











*Video*

Shows the regulator and reversing valve in operation. The pressure on the gauge is 20psi but later in the video it is reduced to around an indicated 2psi. 

There is a degree of knocking in one direction but that reduced/cleared after about 10 mins of running

[ame=http://www.youtube.com/watch?v=vW-cKh8jIM0]http://www.youtube.com/watch?v=vW-cKh8jIM0[/ame]

That's about it for now folks. Now all I need is another boiler...................

Pete


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## Blogwitch (May 18, 2010)

Very nice indeed Pete.

I see you went for the easy way of mounting the springs, just as I did. To me, the way the plans show them how to be mounted is just too finicky.

When I built my first batch, I also got 'knocking' in one direction. It was eventually traced to the big end. The piston rod screw was not perfectly square with the big end bore. Yours has most probably worn itself right by now.

Well done.

Bogs


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## arnoldb (May 18, 2010)

Pete, well done indeed :bow:

Regards, Arnold


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## mklotz (May 18, 2010)

Very well done. That should drive a model boat at a fair clip. 

I was pleased to see that you wrote...



> Learnt that have TV in the workshop is probably not a good idea as you can get distracted. One brief distraction and a 10BA tap broken in millisecs.



Ever since a friend severed three fingers trying to use a radial arm saw while watching football, I've been on a campaign to get hobbyists to understand the danger of having a TV in the shop. Amazingly, many people who are otherwise quite sensible about safety can't seem to understand the risk this practice represents.


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## SBWHART (May 18, 2010)

Very well done Pete those two cylinder wobblers make up into a real powerful engine I've had my eye on building one of those for a while.



			
				mklotz  said:
			
		

> Ever since a friend severed three fingers trying to use a radial arm saw while watching football, I've been on a campaign to get hobbyists to understand the danger of having a TV in the shop. Amazingly, many people who are otherwise quite sensible about safety can't seem to understand the risk this practice represents.



A few years back I was in charge of a machine shop, for a while I had a battle with the machinists listening to Walkmen, whist operating the machines, I thought it was dangerous, in the end I had to discipline a couple of them to get it stopped,:- Yes its true Foremen don't know who their father's are. :big:

Stew


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## Deanofid (May 18, 2010)

That's a really nice runner, Pete. Good job!

Dean


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## rake60 (May 18, 2010)

Nice runner Pete! :bow:

Rick


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## Blogwitch (May 18, 2010)

Marv,

This little engine, due to it being a long stroke double acting (10mm bore x 20mm stroke) will easily power a nice Windermere type hull of at least 4ft long on 25psi.

http://www.visitcumbria.com/amb/winsteam.htm

They really are wonderfull little engines that can be put to use. Maybe even the next step up from a small wobbler.


John


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## mklotz (May 18, 2010)

John,

There's just nothing quite so elegant as the classic British steam launch. There's a lot to be said for centuries of naval expertise (and the cultural good sense to preserve these examples of a more refined age).


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## fcheslop (May 18, 2010)

Sorry to intrude on this build thread.What a nice performing engine I really likes these in model boats and believe when well made and designed there simplicity and performance is difficult to better. Bogs do you by any chance know the weight of this engine in brass as I've been looking to build a scale model of BAT the drawings are nearly complete and not sure wether to go for a wobbler or a piston valve . Thank you, just for info the Windermere Steam Boat Museum has been closed for a few years due to some wrangling or other and some of the exhibits have been out of the water for some time sadly 
regards Frazer


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## tel (May 18, 2010)

Beautiful Pete - just the ticket for a 1 to 1.2m steam launch.


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## doubletop (May 18, 2010)

Once again thanks for your kind words and support. Its the knowledge that you are there looking over my shoulder, a bit like a virtual shop foreman, that ensures progress and of course quality of workmanship is maintained.

On the boat; I'm looking for the plans for a suitable gas fired Scott/Inglis type boiler, or at least it has to be horizontal and out of 3"tube 'cos that's what I've got. Those plans I've seen are for 5 or 6" tube which I'm never going to find in NZ. Any ideas on plans?

Other than that the next engine is going to have a valve chest and eccentric setup. Something like Touts POM winner or I've also seen Bogs plans for one that may suit as some of the parts bear a resemblance to this model (are they the same?). However, I do plan to slow down a bit as two engines and a boiler since I started in February is burning up valuable 'house points'

Thanks guys

Pete


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## 4156df (May 18, 2010)

Pete,

Very nice engine and a smooth runner. I really like the red accent paint.

Dennis


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## Blogwitch (May 18, 2010)

Pete,

Really, it isn't worth you building the Paddleducks engine, as it was designed really to get someone with very little experience to produce a fairly complicated engine, more a 'learn as you go' exercise. The bore and stroke is exactly the same as the one you have just made, but it is much larger and a lot heavier, it could have been made a lot lighter and trimmer, but then I thought that doing so would really be pushing what a novice could achieve. 
It can be used to power a boat, but it would have to have a lot more room in it for it to fit.

Have a look at this one. Just down the road from you. I think perfect for what you want.

http://www.steamech.com/marine-engine-model.htm

But read this first.

http://www.homemodelenginemachinist.com/index.php?topic=3925.0

I am just about to start the second phase. Personal things have held it up for a while.

John


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## Maryak (May 18, 2010)

Pete,

Very Nice. :bow: :bow:

Best Regards
Bob


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## cfellows (May 18, 2010)

doubletop  said:
			
		

> Chuck et al
> 
> I asked the guy, who posted the video, where he got the bolier plans from as the engne looks like the one I'm doing. Its a Regner off the shelf item "Midi" http://www.traindept.com/bengmidi.html they originate from Germany.
> 
> ...



Thanks, Pete, the detail that goes into some of these RC models fascinates me. And, I have to guess, there's a fair amount of capital involved as well.

Bogs, I've always loved those two oscillators of yours. They are both very classy engines. Have often thought about putting together a pair to match yours! I'm actually toying with the idea of a steam powered RC boat using the vertical engine version. By the way, would you mind sharing the bore and stroke of those two engines?

Chuck


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## Blogwitch (May 19, 2010)

Chuck,

They are both exactly the same engine, but by making a few extra exchange parts, they can easily become either horizontal or vertical.

They are both based on the plans that Peter did his build off, just a few cosmetic, material and engineering changes to make them more robust and long lived. Both are 10mm (3/8") bore X 20mm (3/4") stroke.

Some of the ones I have made must now have hundreds, if not thousands of running hours on them, and I have only ever had one negative feedback, if you could call it that. It was a couple of months ago, a chappie had lost a part somewhere in his shop during his annual strip down and service, getting it ready for the new sailing season, and asked if I could make a replacement part. It just so happens, I had some bits already stored away, and just as I was about to send it, he found the missing part. They really are the sort of engine that will go on forever if made from the right materials.


John


BTW, I only have the horizontal one now, I gave the other one away to a friend who wanted it.


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## doubletop (May 19, 2010)

Bogs

See other post regarding Steamech model. It looks interesting but I'll give the guy a call to see if we can get to the bottom of the issues.

Thanks again everybody.

Pete


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## fcheslop (May 19, 2010)

Hi Pete, what about the double concentric boiler on the John Tom site.The original drawing was by Basil Harley for his steam launch Miranda its a very simple design and when gas fired with a poker burner quite effective.Don't know who posted those drawing on J T site as they are a mix of designs and the boiler fittings seem to be Peter Arnot or Malcom Beak apologise if I've spelt the gentleman's names wrong.The original boiler and engine drawings and launch drawings are still available from My Hobby Store and anybody looking for a simple steam launch model cant go wrong as even I managed to build it 20 years ago and she still sails well although a little rattly. That is a beautiful engine you have made and is crying out to go into an open launch as you can tell I am a fan of these boats :big:.
regards and best wishes


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## doubletop (May 19, 2010)

fcheslop  said:
			
		

> Hi Pete, what about the double concentric boiler on the John Tom site.The original drawing was by Basil Harley for his steam launch Miranda its a very simple design and when gas fired with a poker burner quite effective.Don't know who posted those drawing on J T site as they are a mix of designs and the boiler fittings seem to be Peter Arnot or Malcom Beak apologise if I've spelt the gentleman's names wrong.The original boiler and engine drawings and launch drawings are still available from My Hobby Store and anybody looking for a simple steam launch model cant go wrong as even I managed to build it 20 years ago and she still sails well although a little rattly. That is a beautiful engine you have made and is crying out to go into an open launch as you can tell I am a fan of these boats :big:.
> regards and best wishes



Thanks for the pointer it took a bit of searching but found the dual concentric plans on the John Tom site. http://www.john-tom.com/MyPlans/SteamPlans3/Steam%20Boiler/DualConcentricBoiler.pdf  

It looks interesting and worth consideration. At first my attention went straight to the 15mm cross tubes, which would be under compression. However, if its a myhobbystore plan its no doubt fine. I'm a member of their site so I'll have a dig around there.

Thanks for the heads up

regards

Pete


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## doubletop (May 30, 2010)

Steam engines need boilers, so work has started on one for this http://www.homemodelenginemachinist.com/index.php?topic=9553.0

Pete


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