Tina :- Engine and Boiler Build

[klank]

Not a lot done today.

I finished machining the flywheel and spent an hour or so on the bench with some filing and a little application of miniature sanding drums on my Dremel to finish the spokes, and triangular spaces between them.

It seems logical to make the crankshaft and main bearings next, so now is the time for slotting the bore of the flywheel (which I should have done earlier), since that part of the crankshaft going through the bore will also be slotted for a keyway to match.
I re-mounted the flywheel in the 4 jaw, using a piece of 1/2" bar in the tailstock drill chuck to get it in the ball park between the jaws, then using packing to protect the rim, set it to run true on the shaft with a clock.
Some time ago, I made a cross slide mounted slotting fixture from a casting (College Engineering). It is pretty meaty, but different diameter end bars can be mounted to the piston.
This is the set up (the slotter handle is pulled clear) :-





Here is the "business end" :-





And the finished (slotted) flywheel.




The crankshaft next.
It is not a "built up" one - rather it is a straight shaft with a "fat bit" in the middle to carry the flywheel, and a crank disc secured at the outboard end. This too will be slotted/keyed to allow easier dis-assembly.

More anon, but thanks for all of the kind comments.

Peter

[saw]

Again very nice build 

[gingerneer]

Very nice build so far. I am making just the boiler its almost ready to be silver solder together. looking forward to the seeing more of the engine.

William

[DeereGuy]

looks great Peter keep up the good work !

[klank]

Benni, Bob - thank you for the encouragement.

William - did you make your own flanges etc.?
If so, what material did you use? That is something I am going to have to think about.
How did the tube plates go?
I am very interested in how you get on with the build. 
Best wishes

Peter

[lordedmond]

Peter


Just had a look at starting the boiler build ( I need to test some scale injectors )  If you have the same drawing as I do check out the specs for the bushes mine say brass ( bad ) but the supply bronze  ( under size ) the ones for the top connectors do not thread match connector is 26 tip bush is 32 tip


the drawings also do not show enough bushes as to the layout

the drawings do not show the bush for the feed water clack ( should be two ) one for a hand pump and one for another means ( injector 1/2 pint per min should do ) my loco should only need 12 oz per min but that has two injectors )

What I am trying to say please look at your drawings and satisfy yourself that you have it firmly in your mine before you drill a hole in the shell ( note put an extra bush in round the back ,you can fit plug in it , you never know when you may need it )

good luck with the boiler build , your engine build look like it is coming along nicely , although I think you where near the limit on that chuck for the flywheel with the jaws out that far you run the risk of damage to the scroll and the jaws ( just a point for you to think on )


As I said I will be staying my fire box tube , for peace of mind on my part , but hey that me      two belts and braces 

I am  assuming that you have not done a boiler before but common practice is to feed the hand pump low down in the water space and the injector into the steam space , I will be step soldering the bushes into the outer tube as well as the fire hole to fire box tube to assist with the later work ( start with 700 deg c silver solder and complete the rest with 610 deg c stuff ) so you do not melt off the first things you stick on  use tenacity 5 for the high temp stuff and normal for the rest although you can use T5 for the lot ( recommended by Bogs ) dump the COLD boiler bits into citric acid pickle to clean up


Stuart

[klank]

Stuart
Thank you very much for all of the practical advice and advisory suggestions - especially about an extra bush.

I have scratch -  built one boiler before - a Tubal Cain design of a small "Smithy's/Babcock" horizontal boiler with underslung water tubes. Ceramic gas burner fired - I added a a "steam drier" in the heating space. All proper in copper with bronze bushes and stay. TC called it "Wenceslas". It powers a small stuart 10H. I posted a build thread on it in July (ish) 2009. I used "step soldering" on that and the clack was fitted down low as you say - fed from a simple hand pump. I made the "pop" safety valve from TC's design - blows off at 25psi, although the boiler was hydraulic tested to 100psi.

Thinking ahead, I shall be swapping most of the fittings over from Wenceslas to the Tina boiler as I cannot afford to buy another set at this stage but that's not for a little while yet. The extra bush could be used for the hand-pump (swapped from Wenceslas) in addition to the feed from the eccentric driven pump on Tina. Maybe another extra bush would be a good idea?
I am thinking also of fitting a "steam drier" coil in the smoke box space - seen it in a thread posted on the RC Forum web site.

There was certainly a goodly length of Phos. Bronze in the kit of materials provided for bushing - but I have not checked its dimensions yet. I imagine that today, model engineer's suppliers have to provide metric sizes as I have been told that now, in the U.K., imperial sized non ferrous stock is getting very hard to find from sources.

Best wishes

Peter

[lordedmond]

I am sorry if I miss understood you your post regarding the flanging made me think that you had not done any yet

as to the PB supplied is .532 inches and the drawing ask for two bushes at .564 ( 9/16)


anyway hope you have a leak free build 


Stuart

[klank]

Stuart - I appreciate your kind help and advice.

Next up in the build is the crankshaft - or I suppose crank "axle".

A goodly length of 1/2" mild steel bar is supplied in the kit of materials.
Stan Bray recommends turning it up between centres - "old school". It is turned down each side of the 1/2" central portion, carrying the flywheel.
Here's my set up, starting on one side.





After bringing the bar to size/length, both the centre portion and the outboard end to carry the crank disc were slotted for the keys to hold the flywheel and crank disc.
Here is the axle on the flywheel :-





The crank disc, carrying the crank pin is very plain, and to my eye, looks a bit naff compared to the rest of this quite nice looking engine.
Stan Bray machined a rim around the periphery of the disc to give it some texture. Even so, in the photograph of that, shown in the ME, the disc still looks a bit odd.
There is a substantial boss on the inboard side of the disc, so cutting holes or spokes in the disc is not really feasable.
I decided to see what a "pie slice" crank web might look like, in place of the disc and drew one out full size (roughly!!).
The shading may represent a bit of fluting to add a bit more interest. :-





The disc, proper, is machined from a slice of solid 2" dia. mild steel - a generous length of this being supplied in the kit of materials. Plenty of meat to hold in the three jaw, with jaws reversed :-




It is a straightforward machining job then, to bring it to size and drill/bore/ream the hole for the axle.
This was subsequently slotted for the key to hold the disc on the end of the axle. Both outboard ends of the keyways in the disc and flywheel were carried around into the ends of their bosses so as to take the head ends of the keys (yet to be made).
The hole for the crank pin was drilled/reamed on the mill table using coordinates to get the required 1/2" off-set.

To satisfy my curiosity, I assembled the flywheel/axle/crank disc (no keys yet) and stuck the paper template on the end of the disc, to get an idea of what it might look like if I decided to butcher the disc.





I think I'll sleep on this for tonight and maybe attack the disc tomorrow?

Best wishes to all

Peter

[saw]

Good work.

[andyf]

You're right about that disc, Peter. Looking at the photo in your first post, it looks a bit utilitarian - more suited to a toy than a model. It shouldn't be too difficult to come up with something more interesting; maybe a crank arm with a counterweight to "balance" the big end would look a bit more interesting?

Andy

[Rob.Wilson]

Hi Peter

what about this sort of shape for the disc

Just a thought

Rob

[andyf]

Rob, you've drawn just what I was ineffectively trying to describe!

Andy

[loco]

Having just joined the group allow me to introduce myself. My name is Pete Smith and I write as the proverbial horses mouth as I am the poor soul who makes these boilers for GLR and the count is over 40 complete boilers and hundreds of flange plates so I think  that I know a thing or two. I cannot write everything is one session so will treat you to a number of episodes over a period of the next few weeks covering the comments made earlier by previous members. If there is anything you need to know then tell me and I will sort your problems.

The next section is the preface that you will find in the 'words and music' supplied by GLR with the boiler kits. See his website for the various kits available.

The drawings for the mill engine vertical boiler were first published in 1950’s. The construction series was written by Stan Bray and appeared in the Model Engineer from March 1997. Since first publication there have been various changes to the boiler codes with reference to construction and testing. Builders may also find that copper sheet has been provided in Metric thickness instead of imperial. This makes no difference whatsoever.

It used to be accepted practice to drill and tap the boiler shell to allow for the fitting of the firehole door and other items. This only allows about 2 or 3  threads in the soft copper and although is was possible to initially fit and make steamtight removal usually stripped the threads. This is no longer accepted practice and ALL screwed fittings to a boiler MUST be made using gunmetal or bronze bushes silver soldered in place. On NO account use brass. This gives you a safe fixing with many more threads and they can be made “blind” ( not drilled / tapped through ) so that even if the screw is removed no steam will emit.

The weighted safety valve shown in the drawings should be replaced by a spring loaded version – safer and tamperproof. It is shown for historical reasons. Irresponsible workers used to add weights to increase boiler pressure – with the expected results plus an explosion as an extra.

Ready flanged plates are available from GLR formed to shape and correctly spot drilled only needing to be skimmed in the lathe to fit as detailed in the series.

The boiler may be fired by gas or coal. The use of methylated spirit burners these days is frowned upon by the safety people as it burns with a clear flame and is uncontrollable and easily spilt. The solid pellets for use in Mamod type engines can be used but can be expensive and leave a nasty residue.

Over the last few years there has become available excellent ceramic burners and control valves to fit disposable gas canisters and other cylinders. Clean, efficient and safe, especially where the children are around.
Should you decide to go for gas then there is no need for the  firehole, blower  or grate as the burner is designed to fit inside the boiler with a flexible pipe to a remote gas supply passing through one of the 3 slots. The air for combustion comes from underneath. This does save a great deal of work and simplifies construction. You can of course make a false door and fit to the cladding afterwards to maintain the appearance.

For those of you who prefer the “smell” of steam and intend to use coal then the construction of the firehole ring, creating the curve and perhaps the oval and still get a good fit can be problematic and does little for your confidence. There is an easier way. Instead of using the copper ring supplied use a suitable length of 1 1/8th diameter by 16 gauge thick walled copper tube. The hole is made to the tube diameter by any suitable means. Do not use a hole saw of the same diameter as they always cut oversize. It does not matter how much sticks out on the fire side and it can be left square. Using a triangular file make a few nicks in the hole to allow full penetration of the silver solder. When assembling,  file the tube end to allow it to fit. Again use the triangular file, assemble with the foundation ring and final soldering to secure. If your hole is slightly oversize then the tube should be annealed and the ends expanded to fill the gap,  The outside can be finished afterwards. This will not affect the strength of the boiler but certainly allows easier construction.

If you use blind bushes to hold the firehole door in place consider how to get the holes to line up. They are radial to the boiler. I suggest cladding that part of the boiler on a temporary basis, placing the door in position and transferring the holes through the cladding just to mark the boiler. They can then be drilled and the blind bushes soldered into place at the same time as the ring is secured. Perfect line up afterwards.

There is another clever little way – lateral thinking. Make the firebox door in the usual way but silver solder onto it a length of steel tube approx 1” diameter which is a push fit into the hole. The curved shape will align the door and it can be secured with small woodscrews. Much easier.

A few moments to consider the fine stationary engine you have just built. In real life such engines rotated at 30 to 100rpm. The bearings – and those on your model – are designed for slow speed. Running with the motion and flywheel a blur may be exhilarating but you will soon be facing a rebuild!!!! Most of these engines will tick over at a realistic speed on 20 plus psi.
I suggest setting the safety valve to 40 psi and see how it goes. The nominal working pressure for this boiler is 80 psi but its initial test should be to 160 psi.
When testing your boiler do remove the gauge glasses and plug the holes as they may fail at test pressures. If you live in a hard water area – look in your kettle – then the small area between the firebox and barrel will soon get clogged with scale. Visit your local chemist and  get  some citric acid crystals – used for cooking – mix up a warm solution and fill the boiler. It will bubble away merrily converting the chalk to carbon dioxide. Flush out thoroughly afterwards. Happy steaming.

The next exiting episode will cover stays,  boiler testing and fittings.

[klank]

Andy, Rob, Benni - thanks again for encoragement - and suggestions.
Peter - thanks for taking the time and trouble to write.

Rob, the superb (is it a cad rendering?) sketch is what I too was thinking of at first - but got sidetracked into picturing "locomotive driving wheel centres - with fluting".
Originally I had a mental picture of a "nodding donkey" kind of pump crankshaft with counterbalance weights.
Tomorrow, I'll try and draw it long hand - (I am not clever enough to use a cad programme!!) and stick it on the disc. I like your rendition - it "feels" right - and looks quite simple to make from chopping up the disc.

Well, now we've got chapter and verse straight from the horses mouth on the boiler - thanks Peter. Looking forward to your next bulletin.
I was afraid the Copyright Police might object if I posted what is written in the up-dated GLR boiler build handbook - it does put things in a better perspective with regards to current good practice and regulation.

Best wishes

Peter

[andyf]

Is there more than just a passing resemblance between Tina and the "Suum Cuique" engine by Stan Bray, the construction of which was shown in "The Best of Model Engineer Vol 1" which I bought from the local newsagent 18 months ago?

Andy

[klank]

Andy - good point.

Insofar as the BASIC DESIGN goes (not the scrap/surplus materials/methodology) - I think there is a lot of similarity between the two - although the Latin one is very much smaller than Tina. Presumably this was deliberate so it could be built using the smallest of lathes. Interestingly - cyl. bore/stroke/flywheel dia. etc. are all just about exactly 1/2 Tina sized - ?coincidence?
Tina does have the advantage of an eccentric driven pump.

As someone said - "I suppose there are only so many ways to design a mouse trap"?

Peter

[lordedmond]

loco

Peter
 
thanks for the write up look forward to you further instalments

my problems started when GLR did not supply any documentation with my kit , they then supplied a set of drawings that show the bushes in brass with some shown with the wrong threads to match the top connectors.
nor do they state the SWP or test test Pressure ?  (which I believe is illegal for a pressure vessel )
I did not get any documentation ( reprint form Stan Bray )

In my kit was supplied 18 1/8 x 1 inch copper rivets that is what lead me to calculate the stress on the fire box wall in a fully annealed state and concluded that it could yield at a TP of 160 for a 80 psi SWP during the interim period I noted that the WP on there site had dropped to 40 psi

These are my opinions and are based on my findings and the kit that I was supplied with, which still has note been completed my last build was for "doris" but the boiler for my class 4 tank 5 inch G was farmed out to big for me to handle from a wheel chair  


Stuart

[gingerneer]

Hi Peter
I bought the kit with the flanged plates, but i am building a larger boiler and have used MDF formers to flange the plates (end plates are in 2.5mm copper) they last long enough to shape the copper providing you keep annealing the copper. I have been working on the boiler for a 18 months on and off, i don't have any photos of the work. I just need to drill the holes in the barrel and form the foundation ring. I will try and put some photos on my thread, i and hoping to get back on the build after taking time out to get married. The fly wheel is looking good, Tina is a nice engine but i have enough projects........

William 

[klank]

Thanks William - very best wishes for your wedding.

Peter

[lordedmond]

getting married , watching the royal wedding whats the whorl of ME coming to 

only joking our wedding was in 1968 


Peter ( Klank )

just to let you know I have cleared the bench for this little boiler build , just done the foundation ring what a job, got the outside fitted then inner would not go in ( metric / inch materials me thinks ) so a delicate job to skin out the inside for a slightly loos fit got to leave a little room for the SS

Should be done by the end of the week if we get a dull day to do the soldering ( have to do it outside the WS is to small for big burners inside ) I cannot see the colour ( color for across the pond ) of the metal in the sunshine

I will alert you if I run into any big loo loos

then its time to make all the fittings WG  etc


Stuart

[Rob.Wilson]

Hi Peter 


Looking forward to seeing what you decided to do with the crank , ,, yes that was just a quick example i drew  in CAD   ,, easier to draw than describe     .

Stuart ,,, i hope you will decide to start a thread on your boiler build   

Rob

[lordedmond]

Rob

its getting the pic's to the correct size I am beta testing a new OS for the Mac called Lion at the moment coupled with the camera takes a 21 - 50 meg file they are huge but good Qi




Stuart

[klank]

Trying to stay on topic :-

I used Rob's very nice CAD type sketch, and set to with a hack-saw and file on the plain-Jane crank disc having used a paper template.
I am quite pleased with the result, and in a fit of "creativity" turned up the crank pin and keys.
Here are the components :-





Here it is assembled :-




One glaring error shows here - the "reveal" in the crank disc for the head of the key locking it to the shaft looks dreadful. Its too big and badly spotted. (I did say this was a "warts and all" diary).
I have subsequently mixed up a blob of Stabilit Express (good quality epoxy) with some iron filing dust, and back filled that orifice and re - cut it to a better fit. After sanding/polishing/painting it shouldn't look too bad - I hope!

Next up is the connecting rod.
According to the basic plan, a goodly length of 3/4" X 1/4" mild dteel bar (flat) is supplied. The basic con. rod is just this, drilled/reamed at each end for push - in brass or bronze bearings. To say it will look a bit naff is a kindness - but it is very simple - this IS a beginners' engine. In real practice, a straight bar rod was never used.

Stan Bray suggests using the supplied material as a basis for something better.
He turns the bar up to a round(ish) cross section having drilled/reamed the flat ends, turning a slight taper up to the centre of the rod, leaving two flat ended big/small ends. These are given a bit more dignity with "dummy" bolt heads and scribing across the centre to look like proper split - end bearing caps.
He also suggests another alternative would be to leave the rod as flat, with dummy ends, but with a "fish belly" double taper down top and bottom edges - plus a bit of fluting if you are so inclined.

I am including a couple of pics. of this type of con. rod which I made for a "double side rod" engine - although these rods have "proper" wedged marine type small ends and split big ends. (That engine is not yet finished - lots of plumbing and governor to do yet). :-





and I tried to get a closer view of the fish belly rod here - not very good :-





For this build (Tina), I think I'll go the Bray way and turn the rod round(ish) section and tapered. To fit a split big end is quite feasable, but I shall take the "easy" option and try and dummy it.
The marine/wedged small ends, each held by a strap on the double side-rod engine was a bit of a bother - not to be willingly repeated - especially as Tina is about 1/3rd. smaller - the job wouldbe really fiddly.

I shall post more later - got "family stuff" to take care of first.

Best wishes, and thanks for the encouragement

Peter

[sbwhart]

Comming along nicely Peter.

Thats also a good looking engine was it made from castings ?.

Stew