Author Topic: Oscillating Engine Pivot Speculation  (Read 2509 times)

Offline Jasonb

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Oscillating Engine Pivot Speculation
« on: December 18, 2017, 04:12:18 PM »
Would anyone care to speculate how the cylinder pivot in the foreground is constructed on this engine?

As I see it there is a finger screw which allows  adjustment of the friction/fit of the opposite port face. This screw is locked by a collar which has its lever hanging vertically. Assume the screw has a point to it that mates with a conical hole in the stub on the side of the cylinder. I don't think there is any spring in the pivot which would allow the port face to lift off in condensate built up.
 
Thanks, J.

Offline pgp001

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Re: Oscillating Engine Pivot Speculation
« Reply #1 on: December 18, 2017, 04:27:49 PM »
Jason

I think your description sounds to be pretty good. Its hard to see how else it could work.

Phil

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #2 on: December 18, 2017, 04:35:42 PM »
Given that the supports look reasonably robust I'd have thought if the taper screw is properly adjusted the port face wont lift at realistic operating pressures.

Is it possible there may have been a small spring on the port side pivot ?

What is the engine ? I saw something similar a week or 2 back on ebay - if I can find it I'll post a pic.

Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #3 on: December 18, 2017, 05:31:29 PM »
Thanks Phil, that is what I have gone for.

Peter, sometimes it is desirable for the port and cylinder to be able to separate as it will let out condensate much like a slide valve lifting of the port face. A parallel screw into a hole and a spring would have been another option but would have thought a less easily adjusted lock nut would have been used in that case.

The engine is one that Jo took a couple of pics of at the Midlands show, I had fancied doing an oscilator for a while and it court my eye so have drawn it out to use up another of those 24mm O rings that I have, flywheels suit a pair of Stuart No10 size. I had sketched out the rough sizes and being stuck home with a sore back decided to draw it up this afternoon as provided I can stand up it will make a nice little project fir the Christmas hols to run along side the more involved projects. All seems to move as it should on the screen so hopefully it might run.

J

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #4 on: December 18, 2017, 05:38:26 PM »
Ah ok I see what you mean.

Heres the ebay engine I mentioned, its a bit different to how I remembered it so I don't think it will be of much use but it does have a few similarities.

https://www.ebay.co.uk/itm/EARLY-ANTIQUE-VINTAGE-CAST-METAL-STATIONARY-STEAM-ENGINE-WHEEL-PISTON-PUMP-MODEL/222757108955?hash=item33dd5bbcdb:g:f9oAAOSwke9aM9lS

Online b.lindsey

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Re: Oscillating Engine Pivot Speculation
« Reply #5 on: December 18, 2017, 05:41:21 PM »
Interesting design Jason, and what you are describing sure sounds like it will work. One to follow through the holidays if you decide to go for it.

Bill

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #6 on: December 18, 2017, 05:46:36 PM »
How about making one like this :-


I think it's a great looking engine and has great chuffabilty  :)

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #7 on: December 18, 2017, 06:05:34 PM »
If you had asked I would have shown you the other side  ::)

Jo
« Last Edit: December 18, 2017, 06:08:53 PM by Jo »
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Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #8 on: December 18, 2017, 06:11:05 PM »
The E-bay one is not unlike one designed by Muncaster which in his book also uses a pointed screw. Julius has drawn up a version that uses a ball into two connes and a spring but I can't see how the spring would compress to let water out if the ball is making good contact with the cones to keep the cylinder in line.

http://modelengineeringwebsite.com/Muncaster_double_oscillator.html

The one in the video link is not unlike the Coventry that a couple of members have posted about on here.

About the time Jo posted the photo there were a nice pair of cylinders on e-bay that I was tempted to buy that look like they would have suited this design well

https://www.ebay.co.uk/itm/OLD-VTG-Brass-OAK-BOUND-Piston-Cylinder-Spare-Part-for-Toy-Steam-Engine-MODEL/222699211159?hash=item33d9e84997:g:CxEAAOSweM1Z90rn

Thanks for the interest Bill, will see what comes of it.

J

PS Please Miss can I see your the back side ;)

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #9 on: December 18, 2017, 06:15:06 PM »
PS Please Miss can I see your the back side ;)

 :hellno: This is all I will let you see.

Jo
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Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #10 on: December 18, 2017, 06:18:34 PM »
Thanks Jo

May have another think about how I did the passages for the steam, I kept them under the cleading but having that larger block would be easier and also give somewhere for the banding to fit, I was going to join it underneath.

The one in the Photo sits a bit lower than mine, I went with a thicker base and slightly taller pivots so heh flywheels clear without having to use the wooden plinth but anyone building could reduce these and use a plinth if they wanted.

Not quite decided on all the materials but will probably go for a built up bronze/brass cylinder and iron pivots despite them showing bronze on the rendering. Bed will be aluminium for ease of machining but could be done in steel or iron.

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #11 on: December 18, 2017, 06:21:43 PM »
I do rather like oscillators despite their simplicity.

Sometime ago I posted a few questions in forums and asked the youtube member about the brass engine in the video but cold find nothing about it. I'd quite like to make one sometime in the future if I could find the plans.

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #12 on: December 19, 2017, 08:55:06 AM »
We might have found the original build details  :whoohoo:   

:-X

Jo
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Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #13 on: December 19, 2017, 09:22:22 AM »
What will it take to unzip you? Maybe an offer of my metric drawings in nice whole millimeters ;)

Jo do you remember if the engine was on a club stand or the SMEE one? SMEE have another more detailed oscilator that is also on my to do list.

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #14 on: December 19, 2017, 09:54:18 AM »
What will it take to unzip you? Maybe an offer of my metric drawings in nice whole millimeters ;)

The model engine drawing hoarder is still looking for the book it is in  :Doh: but I will (and he might once I have PDF'd them) accept a set of Alibre drawing files then it could be made to look more like the original engine design. I have found the vertical version so it is looking likely to be the right engine ::)

Quote
Jo do you remember if the engine was on a club stand or the SMEE one? SMEE have another more detailed oscillator that is also on my to do list.

It is not a SMEE engine  :hellno: It was exhibited at the Midlands on the Tee publishing stand  :headscratch:

Jo
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Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #15 on: December 19, 2017, 10:19:12 AM »
Could it be in a Tee book?

They would have to be drawing files, as I think we now have the problem that you won't be able to open my part files as I have taken advantage of the reduced rate to upgrade to the latest Alibre Pro from the new owners.  However 2D drawings would likely be more use to the hoarder I should think.

There are not that many parts to it so should be easy enough to draw and mine would be for fabrication rather than the original which looks like castings were used. Would be interesting to see the details though and I may well tweak mine a bit more.

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #16 on: December 19, 2017, 10:21:49 AM »
No the book predates Tee.

You will have to send me a file so that I can see if I can open it.

Jo
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Offline Zephyrin

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Re: Oscillating Engine Pivot Speculation
« Reply #17 on: December 19, 2017, 02:55:32 PM »

Wobblers are not "bona fide" steam engines, with expansion and compression issues...
there is never condensing or water lock problem with well made oscillating engines, even without springs !

in fact a wobbler will run with a stream of water or other incompressible fluid. 

In some oscillating engine, ports are greatly modified and/or an intermediary steam distributing plate is added, for resembling to a real steam distribution with lap and lead and so on...

 

Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #18 on: December 19, 2017, 03:38:19 PM »
SMEE have another more detailed oscilator that is also on my to do list.

 ::)

Jo
« Last Edit: December 19, 2017, 03:49:25 PM by Jo »
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Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #19 on: December 19, 2017, 03:46:16 PM »
That's the one, you must have been looking at an old post on mine on that forum you don't like to visit ;)

I have several more images of it and think it is based on this old engraving.


Offline Jo

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Re: Oscillating Engine Pivot Speculation
« Reply #20 on: December 19, 2017, 03:53:25 PM »
That's the one, you must have been looking at an old post on mine on that forum you don't like to visit ;)


:lolb: It was not difficult to guess as that is the only oscillator that the SMEE boys normally take to the shows.

I only visit sites where the members actually post about making model engines ::)

Jo
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Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #21 on: December 19, 2017, 04:18:48 PM »
Jo, do you have any idea what engine that SMEE oscillator is ?

I seem to remember seeing a youtube video of a very similar full size engine working in a museum, I can't find the video but knowing something about the model may help  :)

Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #22 on: December 19, 2017, 04:23:56 PM »
Peter, see my post above about what the engine is. that catalogue page is dated 1876

There is also a bit more mentioned about the maker of the SMEE one here

http://myweb.tiscali.co.uk/remark/pages/workshop/projects/models/walleng.html

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #23 on: December 19, 2017, 04:33:56 PM »
Thanks Jason, I didn't see the text in the thumbnail photo.

The engine I seem to remember was used to pump water in a museum (or some preservation), I can't quite recall exactly but I think it was possibly the same engine or something very similar.

It's interesting to see the price list in your post - 50 for a full size 6" bore engine  :pinkelephant:
« Last Edit: December 19, 2017, 04:37:12 PM by Gas_mantle »

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #24 on: December 19, 2017, 04:46:50 PM »
I found the video I was thinking of - but the engine is a lot different that I seemed to remember, its probably 2 yrs since I looked and memory fades.

Nevertheless it's quite an interesting little engine  :)



Offline Jasonb

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Re: Oscillating Engine Pivot Speculation
« Reply #25 on: December 19, 2017, 05:00:34 PM »
I remember watching that one while trying to find some details of teh valve gear on teh SMEE engien as that doe snot use an eccentric.

Have you got those cross head guides done yet? You need to get a move on as this one is ready for you to make ;)

Offline Gas_mantle

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Re: Oscillating Engine Pivot Speculation
« Reply #26 on: December 19, 2017, 05:10:56 PM »
Its funny you mention the guides, I had a little break while feeling a tad under the weather so concentrated on playing around with the boiler that didn't involve machining.

I've now been doing a bit more though - mounting the cylinder, making the piston, I'll update the build in a day or 2.

That base looks to be just the thing :-)