Full Steam Ahead!

[sandy_ACS]

Hi PD’s – I have a continuing issue with the mechanical strength of the reversing gear linkage shaft & the securing of it in my JMC 3H engine – the first snap shows my engine linkage with the hex allen key in the 2 mm diameter hollow pointed grub screw that locks the arm to the shaft, but the 2 mm diameter shaft has an unsupported length of 29 mm – when I questioned the shaft deflection & resultant stripped thread with JMC on receipt, the only result was a posted envelope with a new linkage arm & 3 x additional HPGS but not a written word – the engine is superb – it’s just the language bit!!!!!!!!!!!!!  
   
I am now using a servo slowdown set to 5 seconds to actuate the reversing function, but still get shaft deflection which results in incomplete reversing valve movement and after a short number of actuations the HPGS is loose despite Loctite primer & a drop of 243 Stud Lock– interestingly when we view the second snap of a similar JMC sized vertical engine we see the reversing gear shaft supported by a center journal  
   
I have considered mechanically locking by soldering a 5/32 “ square brass tube filled & soldered with a 1/8” diameter brass rod between the two outboard linkages arms and back to the center control linkage arm so that the new cross member would accept the greater portion of the rotary torque movement….. any thoughts appreciated – Derek  
   
Oh PS ………watch out for that Easter bunny……………………  
         
 
 

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Hi PD's....say's a small voice form the distant past....I thought I had better post something, or that DW will start claiming FINE MONEY :roll:  :shock:  


I am in total agrrement with both Eddy and Engineman on this one Derek, and I am somewhat taken aback ny JMC's apparent lack of interest on this.

I would also add, Derek, that there is a third problem....nameley, the shaft (Known as a Weighshaft) is also un-restrained from side ways movement on your engine, unlike the vertical version, which will put a lot of strain on the 'LIFTING LINKS'...the small  arms that connect to the Stephensons link, by allowing them to shift sideways, which in turn can cause these to wear very rapidly.

I attach a rough sketch of a possible solution, which will support the thin shaft along it's length and also prevent any undue sideways movement.
I realise that this may require a bit of modification to the existing 'Weighshaft' supports, but I believe that something along these lines is going to be required.

If I can be of any help in making up these modified bits, then just shout.


Engineman.....You can be justly proud of your latest engine....superb.

Ok...so now I have been demoted to keel barnacle I will sign off.


More soon.

Best Regards.

Sandy

PS....I have spent all day fitting my re-ground lathe spindle and new bearings....you will be pleased to hear that it is now all up and running again....so now I play CATCH UP....      

[Eddy Matthews]

Great to see you back Sandy!

And even better that you agree with my comments - gee a real engineer agreed with me for once! :-) But now I have a slight problem...

My head is now so large that I cannot get through the door to go to bed!

[sandy_ACS]

:twisted:  :twisted:  :twisted:  :  

I suppose you will just have to stay up all night then....    :music  

All the best.

Sandy.

[derekwarner_decoy]

Hey thanks Engineman, Sandy & Eddy - your collective comments gives me food for thought  - so do French bronze bits taste best with Garlic or do you think a dash of Tartare sauce would be OK as all this is smelling a bit FISHY to me  :rant

It is the flexural issue that concerns - I cannot detect any longitudinal 'weighshaft' float [even with a dial indicator] & attribute this to the four sealed ball bearings supporting the crankshaft journals & eccentrics....

I checked the Anton site last night & their verticals appear to have well supported weighshafts but of larger diameter than my JM... ...C - ...... - regards Derek  :?

Oh BTW1 Sandy - nice  : term 'Gallows  Brackets' - did they get their.... you know..name from the supporting structure that supported a piece of rope & a noose :?:

Oh BTW2 Sandy - I am glad the lathe is back in operation, so this means you can get back & do some real work with another stock order of those Black Japaned beauties [ASP] engines  

[Engineman]

Hi gents!

Nice to hear from you again Sandy and thanks for your compliments. Upto my mind it is nothing to be proud about - what you can see is only a set of nice shiny pieces and that's it. It is not an engine as it was never steamed yet  :wink: . For sure I'll do my best to put it in a good shape to make it move'n'puff   .
I have a prob with proper papers for pressure vessels  :cry: So I guess, Sandy we'll have a special talk about a special boiler to fit all the <censored> standards as I have a lot of plans in mind for my boat and my engine. Anyways, looking for an extra discount instead of extra charge  

Cheers,
Engineman

[derekwarner_decoy]

Hi PD's - I spent an hour using an industrial microscope viewing the M2 diameter x 2mm long HPGS that keep failing to lock the weighshaft reversing arm - turns out that the internal 'inhex' 0.9mm AF is collapsed or split open across the six points - so at least I understand the root cause of the weighshaft to lever unlocking   - as I mentioned JMC posted out three replacement HPGS but have decided not to use them

Plan now is to reinforce/reduce the loading to the weighshaft supporting journals in a manner 'similar'     to that recommended [Sandy/Engineman/Eddy] but also to use M2 socket head cap screws to replace the three installed hollow pointed grub screws in the reversing linkages..................

So the head of a SHCS may not be in visual keeping with a 19 the century steam engine, but neither are the slotted cheese head metric screws holding the engine together....... this plan does make me a little more   - Derek

[Engineman]

At last the TB project got a move  Hopefully there will be more interesting photos soon...

Cheers,
Engineman

[Eddy Matthews]

I'm glad you've got back to the TB Engineman, really looking forward to seeing it progress.....

I was at a model engineering show earlier today, and there was a magnificent model of Turbinia on display, complete with steam turbine! A true work of art, but sadly I didn't have a camera with me!

Regards
Eddy

[Engineman]

I was at a model engineering show earlier today, and there was a magnificent model of Turbinia on display, complete with steam turbine! A true work of art, but sadly I didn't have a camera with me!

Regards
Eddy

Nice to hear from you Eddy!
Is it a Harrogate engineering show or another one? It is really a pity that you did not get your camera with you...

Cheers,
Engineman

[Eddy Matthews]

Yes, at the Harrogate show Engineman - Turbinia has always been one of my favourite ships, aand one day I might just get around to modelling her?

Regards
Eddy

[Engineman]

Yes, at the Harrogate show Engineman - Turbinia has always been one of my favourite ships, aand one day I might just get around to modelling her?

Regards
Eddy

Modelling TURBINIA - that shall be a tricky build I am experiencing a lack of displacement even with my 65 tons to scale 1/24...
Anyways, may be somebody from PD's had a possibility to visit Harrogate Show with camera? TURBINIA model with live steam turbine - that looks pretty intiguing...

Cheers,
Engineman

[Eddy Matthews]

A couple of photos of the turbine unit in Turbinia - I hope to get some more images later today/tomorrow....

Regards
Eddy

[derekwarner_decoy]

Goodness PD's....I had no idea of her chequered build history,........ ...so it looks as though the model @ the Harrogate show is the hybred version ...... single turbine but converted to 3 prop shafts...still an engineering challange by no stretch of the imagination......Derek
..................................................................................................
Designed by Charles Parsons in 1894, TURBINIA was an experimental craft intended to demonstrate the potential of the successful steam turbines already being produced by his company to drive generators for ship propulsion. TURBINIA had a long narrow hull form (100ft x 9ft) and, powered by a single 1000hp steam turbine, was expected to achieve 30 knots or more. TURBINIA was launched on 2 August 1894 and her trials started on 14 November 1894. Initial results were very disappointing as she could only reach 19.75 knots. The problem was traced to the propeller which was not capable of performing efficiently at 2000 rpm. Two years intensive work followed, during which the effects of cavitation on high speed propellers were discovered and eventually overcome.

Rebuilt and now fitted with three steam turbines, each one driving a shaft fitted with three propellers, TURBINIA achieved 29.6 knots in December 1896 and further improvements gave 32.76 knots in April 1897. She was then the fastest vessel in the world.

[bogstandard]

That turbine looks a nice neat conversion of two commercially available 'toy' turbines, put nose to nose with a collector chamber to gather up the exhaust which normally is discharged to atmosphere.

http://www.youtube.com/watch?v=nDfx-Y71_Ik

I would like to see it put thru its paces on the water, as those turbines have very limited power, especially once the exhaust is restricted by the collector.

Maybe he has come up with a great method to achieve what people have been dreaming about for many years, but I very much doubt it.

What is needed is a turbine that will reach full shaft power almost instantly (within say 4 or 5 seconds), and although that one would most probably get there eventually, it won't have the 'guts' to do it straight away.

I have been playing about with turbines for a while now, and have had a certain amount of success, and a lot of information has been gathered from my two prototypes, and if ever I get my final version built, I think I will have cracked it in producing a cheap and easy to make powerful turbine for model boats.

You can build them a lot more complex and get them to work, but making them and keeping the costs down is another thing.

My latest monster cost less than £20 in raw materials, and could easily be knocked up in a week of spare time working. That pair of Jensons have cost him a very lot more than that, maybe up to 10 times that price. I am looking at one about half the size of my latest, and because of the smaller rotor size and mass will reach full speed in just over 3 seconds at 35 to 40 psi. Running at around 40K rpm, that will be reduced down with a 10 to 1 box to give a max shaft speed of 4K rpm. Just got to find some nice reasonably priced stainless bearings that will hold that speed continuously + 100% safety range.

http://www.youtube.com/watch?v=Amm89H65IFo

John

[Eddy Matthews]

A few more photos of Turbinia....

Regards
Eddy