Double Acting, Twin Cylinder, Oscillator

[doubletop]

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

 

[tel]

Shaping up nicely so far

 

[John Rudd]

Looking good.....

Following this with great interest...

 

[cfellows]

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

Chuck

 

[Blogwitch]

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

 

[cfellows]

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

 

[doubletop]

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

 

[doubletop]

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

 

[Blogwitch]

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

 

[doubletop]

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

 

[doubletop]

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

 

[Blogwitch]

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

 

[arnoldb]

Pete, well done indeed :bow:

Regards, Arnold

 

[mklotz]

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.

 

[SBWHART]

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.

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

 

[Deanofid]

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

Dean

 

[rake60]

Nice runner Pete! :bow:

Rick

 

[Blogwitch]

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

 

[mklotz]

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).

 

[fcheslop]

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