Rocking Engines

[sbwhart]

When I was skiming through the John Tom drawings I saw the rocking engine  and thought it was a osilating engine and passed it by, the name intreged me so a few days later I went back for another look, that,s when I got another dose of  its small size suites the type of work I like doing and it looked like It could be a weekend project, and as I'm going to retire in two weeks I thought it would make a nice presents for couple of work friends.

It's also a good delaying tactic to avoid assembling the loco, perhaps it would boost my enthuseasm.

These are the drawings
http://www.john-tom.com/MyPlans/SteamPlans3/RockingSteamEngine/ROCKING%20STEAM%20ENGINEs.pdf

Any of you chaps made this engine ?

I'm a great beliver that its just as easy to make two of something

First job do all the turning bits.



I made the two cylinders together to speed up the work, turned the OD of the cylinders to the size of the square diagonal, put a groove to show where the join would be, and used a 3/8" end mill to finish off the flat bottom hole.



To mill the square set up in vice touch down on the job set DRO to zero mill off 1/2 the difference of the diameter and across flat size you want zero DRO, flip it over 90 deg with the flat against the vice jaw mill down to zero flip it over 90, mill off the remaining difference zero dro, flip it over finish off other side you've got a square.




To mill out the pocket for the crank I used a long reach 1/8 slot drill set the job up in the mill with the vice stop, milled the first pocket out zeroing everything up, turned it round and making sure it was up against the stop and milled the seconf pocket working up to the zeros, the same routine was done for the crank and stand holes.





For the flywheel turned down the bar to size then transfered them over to the RT in the mill and drilled the spoke holes deep enough to make two fly wheels.



This is one engine finished off with the second waiting for the flywheel



Does it work

NO 

If you look at the photo showing the finished engine it sitting on a pad with a lot of figures on it, what this is about is for some reason the piston was bottoming in the cylinder, a quick measure and a calculation and yes I'd drilled them wrong    I'll just have to make again.

Slightly frustrated

Stew

[bogstandard]

Stew,

Does measure twice, cut once spring to mind.

A real bummer, but actually I wasted some time today, making a couple of bits. But it wasn't my fault. You will need to read the post on the little engine I am restoring, when eventually it is posted.

So you are not alone.

HEADLINES

The sky falls on Crewe, two machinists in a bad mood and brassed off.

Bogs

[sbwhart]

Hi John

It must be something in the water.


            

You've got to laugh.

Stew

[raynerd]

Looks like a nice little engine and not all the parts are wasted right? Post us some pictures when you re-do it and get it running.... 

Chris

[Stilldrillin]

Oh, BUGGA!!!   

But, they do look really nice & purposeful...... 

David D

[NickG]

Oh dear! How does it work Stew? Don't understand it! 

[sbwhart]

Oh dear! How does it work Stew? Don't understand it! 

Neather do I thats why I've made one 

The crank shaft centre line is set above the cylinder centre line, so that when its on the return stroke the piston rocks back and acts like a clack valve when it reaches bottom dead centre the crank pin lines up with cylinder centre line and the piston seals the bore and you get a power stroke, hope this makes sence, havn't got one working yet:- it looks an improbable system doesn't it

Stew

[raynerd]

Nice little animation of how it should work here:

[Stilldrillin]

Is it me? 

It`s running backwards.......
That`s a pump, innit? 

David D

[raynerd]

Yea, I see what you mean. If it was to be correct then the piston is going to be moving into the cylinder when it is sealed  Should the piston be moving into the cylinder at an angle so that any pressure is released around the sides? I`m just trying to get my head around how that works. There must still be a fair force acting against the piston through its return stroke even if air/steam is escaping around its sides.

Hope you get it working Stew, then we can see how it runs for real.

Chris

[sbwhart]

Hi Chaps

It is a bit of a quere beast init,  now you can see why I got  just to see if it would work, it'l be a couple of days before I get any quality shop time before I can have a go at fixing it. 


 I've asked on another forum if anyones made one, as yet its been a negitive.

Stew

[NickG]

Sounds weird but innovative. I kind of get it, can't see the animation here though! Might have to draw it up on CAD to see!

Nick

[bogstandard]

Dave is quite right, he has got the animation upside down on the piston movement.

It should be tilted as it goes into the cylinder and square on as it is coming out.


Bogs

[rleete]

I was just now given some brass screws (1/4-20 pan head) which are a perfect size to turn down for the piston.  I think I'll have a go at this, just for grins.

[Stilldrillin]

This took some finding!

I`m sure Indiana Rog won`t mind sharing with us..... 

He has 3 of them! 

http://www.indianarog.com/lineymachineengines.htm#255440530

David D

[raynerd]

Nice find and nice engine - good luck Stew. The plans for this one have been filed away!.

Chris

[sbwhart]

Chris and David D

Thanks for taking the trouble to find the animation and video and sharing, at least we know that they run all we've got to do is prove it to ourselves. 

Have fun

Stew

[DavesWimshurst]

Stew,
Here is a video I found a while ago on some engines and compressors using the same type piston:

&feature=poptnjrf4a

It took me a while to find it again but your build reminded me I'd seen it somewhere.
The exaggerated claims sound flaky of course

Dave

[NickG]

Just had a closer look at the drawings - I like it! Will give this one a go when get my workshop sorted.

You got one working yet Stew?

[bogstandard]

I think you have hit it on the head Dave,

That chappie is a bit full of it for his own good, and is talking out of the wrong end most of the time.

Within a minute of starting, he is giving out false information about steam engine design, and he has no grasp of efficiencies, power input and output, etc. at all.

I could get a cruise liner generator to light up a small bulb, but try doing the same thing with two burning blades of grass.


John

[sbwhart]

Just had a closer look at the drawings - I like it! Will give this one a go when get my workshop sorted.

You got one working yet Stew?

Hi Nick

Been up at Ridsdale saying my good buys to the chaps, so not had any shop time, tomorrow night I'm going to give it a good go.

Stew

[Divided he ad]

Ok.... So this is just annoying!!


I'm going to have to add this little beauty to my to do list!    



After seeing all of those videos thanks to David D I'm really going to have to have a go at at least one!!!  




 


Looking good Stew...... Drilling to the wrong depth..... What'd be easier..... re-making the piston/con rod or the cylinder?

I'm sure it'd work with a shorter stroke?



Now sitting here re-designing the exterior of the engine I haven't yet seen the plans for  ..... BLING!





Ralph.

[John Hill]

OK, colour me dumb!!! 

I can see how the piston 'opens' and closes to get the required exhaust valve effect but what happens on the inlet?  Is all just being wasted while the piston is on the way 'up'?

[bogstandard]

You got it in one John, unless there is a poppet valve arrangement in the head to only allow it to 'fire' when the piston reaches TDC. That was what the goon was showing in the little plastic engine in the vid that Dave provided. Otherwise it is a continuous pressure feed that the engine only uses when on the power stroke. Half used, half wasted.

John

[John Hill]

Ah, thanks John,  still it is a neat enough little engine in a tiny size and one that runs so fast you would not notice air escaping 'tween strokes.