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[Patternmaker]

[quote author=gondolier88 link=topic=26776.msg263953#msg263953 date=1287852920

Stuarts are very nice engines- but don't think the design is perfect, it's not. However, also don't think it's hard to improve the design, it isn't, and you can have fun and learn a lot along the way.

Greg
[/quote]

Greg I am surprised you think Stuarts design can be improved considering they have been established since 1898. The sole plate design is used on most of their engines, if  machined correctly with bearings reamed in line I cannot see a better solution, as you have discovered a brass sole plate will distort when heat is applied.

Obviously some aesthetic improvements can be made using brass or bronze, but in my opinion the engine is well designed with very good quality castings.

The only change I will make is to machine the complete crankshaft from EN1A steel.

You say you are discarding the D10 boxbed, to save weight I see from your pictures you have a 3” dia flywheel surely this will increase engine bearer height, and with a 3mm steel sole plate the weight avantage will be negligible.

What Lathe and Mill do you have?
 
Mick

[Patternmaker]

Ian,
I am staying with the 10V and taking George's advice on the reversing gear, when this is completed I would
like to build a Stuart compound launch engine.

Thanks, I will enjoy the experience.

Mick

[gondolier88]

Greg I am surprised you think Stuarts design can be improved considering they have been established since 1898. The sole plate design is used on most of their engines, if  machined correctly with bearings reamed in line I cannot see a better solution, as you have discovered a brass sole plate will distort when heat is applied.

Obviously some aesthetic improvements can be made using brass or bronze, but in my opinion the engine is well designed with very good quality castings.

The only change I will make is to machine the complete crankshaft from EN1A steel.

You say you are discarding the D10 boxbed, to save weight I see from your pictures you have a 3” dia flywheel surely this will increase engine bearer height, and with a 3mm steel sole plate the weight avantage will be negligible.

What Lathe and Mill do you have?
 
Mick

Actually it is not only my opinion, many model and full size stuart engines are modified to make them better- they are as I said good engines, but they can be made better. Across the range they don't have big enough bearing surfaces, the models have brass for the pistons, and I don't agree the castings are all that they used to be- the replacement cylinder casting I have is a much older casting and is a FAR better finish than the one supplied last year.

I am not using the flywheel- it was simply a practice peice on the lathe after I just bought it, I might not have a flywheel at all yet as the model has a hefty bronze proppellor that should easily suffice.

I'm doing all the work on my lathe - an Axminster SIEG C3 7" X 12", currently under modification to take as much of the 'Chinese-ism's' out of it as possible.

People accuse me of masochistic principles- why have you chosen to make the compound launch next and not the twin launch, or is the next one not going into a model boat?

Greg

[Patternmaker]

I must have an old set of castings then, I meant the twin and yes I intend to build a Windermere Launch for it.
 
Mick

[gondolier88]

That's good to hear- which launch are you going to model? The twin is such a pretty engine- I aspire to make one in the future too. Have you got the castings yet?

Greg

[Patternmaker]

Steam launch Bat, I haven't purchased the castings yet,

Mick

[gondolier88]

A beautiful boat- are you scratchbuilding from drawings? If you need any help with details let me know and I can take some photos for you.

Greg

[ooyah/2]

 Greg,Having reread your post on your D10 improvements I must comment on your design
changes.
Firstly you want to discard the base plate and mount new bearing blocks which according to you are better than the brass ones supplied by Stuart and you are to solder brass bearing blocks to a steel plate which will be impossible to line up the shaft, I did advise you that it would be better to bolt the bearing blocks to the plate which will allow the shaft to be lined up, but please don't stick a twist drill through the blocks while soldering as you have already told me, there is nothing wrong with Stuart bearings ,if machined properly give many years of service.
How do you propose to reduce the C.G. when distance from the underside of the standard feet to the center line of the shaft dictates the O/All high of the engine and you will require blocks to sit the standards on which will do nothing to improve the over all design of the D10, so with the standard con/rod and piston rod lengths it will be impossible to reduce the C.G..
In another thread ( soldering a D10 crankshaft ) in which you failed  to get a result, where did the silver steel come from, Stuart don’t supply silver steel, parts 34 crankshaft  & 35 crank web clearly states mild steel, don’t you know the difference, there are reasons for not using silver steel for crankshafts.

You have said on many threads that your knowledge of all things steam related are extensive which is not in doubt and I must praise you on your boat building skills but you have a lot still to learn on engine design and machining.
Maybe you should temper the arrogance in you that you recently confessed to BRYN YOUNG on the postings of his experiences.
You must remember that us old wooly heads have a wealth of engineering experiences and knowledge gained over our working lives and that you are still just a lad but we can still gain valuable information from each other, but I don't think that you have in any way improved the D10 design.

Greg please note that this is a comment not advice as you have said before that you will ignore my advice if given.
George.

[flashtwo]

Hi Mick,

One recent D10 mod that I've made is a two-part piston.

With the original pistons, when I wanted to renew the silicon 'o'-rings, I would have to unscrew the piston from the piston rod  and then screw it back down to its exact previous location and and then tighten a lock-nut (another previous mod), otherwise I would get piston slap. Also, I always had trouble fitting graphited yarn without it jaming or coming loose (hence the 'o'-rings).

The new piston has the lower two-thirds permantly screwed to the rod and the top part is a threaded disk with two counter-sunk 8BA locating screws that holds both parts of the piston together. To change the 'o'-rings now, I just remove the two 8BAs undo the top disk and replace the 'o'-ring.

Last Sunday the engine was a bit difficult to start, but today  they have bedded in and the engine is turning over at about 7psi (forward and reverse).

I tried to get plans for a steam launch from the Windermere museum, but they were no-longer available. I've managed to get plans from a full size boat yard near Bath called Selway-Fisher who also supplied and excellent instruction book on strip planking.

Ian

Ian

[gondolier88]

George,

I didn't mean the CoG in the engine, as I said it regarded the weight of the engine and CoG in the boat- something that is changed by not having the weight of the casting and I can undersling the baseplate under the engine bearers, something that would be impossible with the casting. I also don't think I remember telling you I would not be taking onboard your suggestion to bolt and shim the bearings to the bedplate, as you pointed out it allows full control over positioning unlike soldering, so why you are accusing me of not listening to you I don't know.

I think you may also find that Steamboatphil- someone who has vast experience of D10's and Stuart engines completely agreed with my decision to replace the bearings- as does everyone else who has done the very same thing for the very same reasons- I'm not setting a trend, I am following it!

I must apologise for the use of silver steel in the description- I had mis-read, though I take offence at your blatent attack on my knowlege, everyone mis-reads from time to time, that doesn't make them ignorant. Though I must admit I don't know the reasons for not using silver steel for a crankshaft- perhaps you could enlighten those of us that don't know?

I have not said many times I know all things steam related, I have said a few times that my knowlege on STEAM is extensive, there is a marked difference, and perhaps the fact I post my questions on here regarding the building of steam engines, not the principles behind their operation, is a reflection of this difference, and an attempt at trying not to be so arrogant.

Greg please note that this is a comment not advice as you have said before that you will ignore my advice if given.
George.

If you are going to assasinate my character George, at least get your facts right. You expect that because you give advice on things that can be changed without detrment if the right care is taken that it must still be taken as writ and not ignored, well it doesn't, and as I actually said, your expert advice is very welcome, but if I choose to ignore it is my perogative and not a reflection on the motives behind, the quality of the advice or your character.

That is enough digression on this thread, if you wish to carry it on in Chit Chat then feel obliged.

Greg

[ooyah/2]

Greg,
I had no intention of assassinating your character, you do  a good enough job yourself.
Good night and God bless.
George.

[Patternmaker]

This topic has now turned into a slanging match, I respect and follow all the advice received by engineers with a lifetime of experience and can understand their feelings over comments by a younger member, I was annoyed to be told basically that I cannot recognise a good casting.

I served a 5 year apprenticeship as a Patternmaker which included a Comprehensive course in Metallurgy, and worked with skilled engineers and foundry workers for most of my working life. I respected their skill
and Expertise as they respected the skill of a patternmaker who has to work to a tolerance of 1/64”, a patternmakers rule has 4 different measurements to allow for contraction on castings of different metals.

As I have said this is only my second venture in model steam, and will only take on board advice of experienced engineers who have actually built a working steam engine.

Most of my engineering has been on converting small petrol Engines for model power boats, which I have built and raced for over 50 years, many recently posted on MBM.

I was going to post pictures of every stage of machining the 10V but have now decided not to I will post pictures of the all the parts machined on completion and the finished engine with a video of it running.

MBM is a great platform for knowledge Thanks to those for your constructive comments and advice.

[Patternmaker]

Hi Mick,

One recent D10 mod that I've made is a two-part piston.
With the original pistons, when I wanted to renew the silicon 'o'-rings, I would have to unscrew the piston from the piston rod  and then screw it back down to its exact previous location and and then tighten a lock-nut (another previous mod), otherwise I would get piston slap. Also, I always had trouble fitting graphited yarn without it jaming or coming loose (hence the 'o'-rings).
The new piston has the lower two-thirds permantly screwed to the rod and the top part is a threaded disk with two counter-sunk 8BA locating screws that holds both parts of the piston together. To change the 'o'-rings now, I just remove the two 8BAs undo the top disk and replace the 'o'-ring.

Last Sunday the engine was a bit difficult to start, but today  they have bedded in and the engine is turning over at about 7psi (forward and reverse).

I tried to get plans for a steam launch from the Windermere museum, but they were no-longer available. I've managed to get plans from a full size boat yard near Bath called Selway-Fisher who also supplied and excellent instruction book on strip planking.

Ian

Hi Ian,
Have you tried PTFE, I made some O rings for Miranda's Engine they seem to work very well, good suggestion
of the piston mod

Mick



















 of yours
to mod the piston for ease of replacing O rings











 for gland seals, I

[flashtwo]

Hi Mick,

Thanks very much for your suggestion regarding the PTFE 'o'-rings. I had forgotten about using them as an alternative and I suppose with my two-part piston I could just drop them in without having to cut them to fit over the piston.

Would you suggest a simple rectangular section and should the PTFE 'o'-ring be machined to fit firmly in the groove or does it need room for expansion, since I understand PTFE can absord moisture.


Ian.

[derekwarner]

Guys...I know we back in OZ are in the back blocks  ...but I was not aware that poly-tetra-fluro-ethelyne [PTFE] was available in a bar stock that could be machined into o-rings ...I do understand that virgin TEFLON is available in bar stock....however the chemical properties nor the physical endurances of these materials are equivalent

I understand that PTFE tape could be wound around a piston seal cavity....but considered the material to be void of memory & without resistance to pressure energisation....

PTFE is fine in a static environment with steam @ pressure

VirginTEFLON at elevated temperatures [100 degrees C] has an extremely low abrasion resistance & mechanical strength in a dynamic function + yes it does absorb water  ........Derek

[Patternmaker]

Hi Ian, I have some PTFE bar to machine O rings or washers 1/2" Dia, if you want some send me a PM and a will willing send you a 2" length piece.

Regards Mick

[gondolier88]

Macc Models also supply 12" lengths- though last time I used them I real problems with the time it took to deliver the order, however when it eventually arrived it was in good nick and everything was there, and you can't grumble about the price. You pays your money...

Here's the link- www.maccmodels.co.uk/index.php?cPath=311

Greg

[Patternmaker]

Crankshaft machined from !” Dia EN1A  Steel, easier than making up from 4 separate pieces.

[Patternmaker]

Finished engine. Link to Video below

http://www.youtube.com/watch?v=GG8f0BxmNZc

[ooyah/2]

Hi Mick,
Grand job you have made of the 10V, very much an exhibition piece or maybe you just want to sit it on your mantle piece.
Your video certainly lets us see how well it runs and with the quality of your workmanship a launch engine will be easy peasy for you.
It looks much better with the flat bars on the revers linkage, rather than the Stuarts st/st rods that's one improvement on the engine design.
I am so glad that you didn't make longer bearings as it would have thrown the reversing eccentrics so far out it wouldn't have lined up with the valve rod.
Having just completed a set of bearings for a D10 I must say that the material of the extrusion is far harder than brass and therefore gives much longer life.

Once again well done for your first Steam Build.
George.

[gondolier88]

Well done Mick- a very lovely engine you have there. I particularly like the reversing gear in brass. Just wondered what the (1/4"? AF) cap on the valve chest is for?

Greg

[Patternmaker]

Top man George has designed a boiler for me and helped source materials to build, also offered some of his own stock. I rely on his expertise to help me through the process to build a boiler which is very much appreciated, This is what MBM is all about helping each other.

Mick

 

[Circlip]

Don't let him con you into putting it into an open topped speedboat Mick 

  Regards   Ian.

[ooyah/2]

Circlip,

L.O.L. imagine a steam launch at 30 mph, you wish.
George.

[Patternmaker]

The person who bought my 10V informed me that he has got a vertical boiler for it, 3.5 inches diameter by 5" high, do you think this is large enough for a 10V ?

Mick