Tina :- Engine and Boiler Build

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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 :D 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 :D

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. :clap: :clap:

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