Author Topic: CONWAY 0-4-0 3 1/2" GAUGE LOCO  (Read 94794 times)

Offline Tennessee Whiskey

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #495 on: June 25, 2018, 07:49:32 PM »
Great fab work Rich. I suspect it will be painted, but, that sil-bronze fillet looks great against the polished metal  :ThumbsUp:

Cletus

Offline Jasonb

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #496 on: June 25, 2018, 08:02:31 PM »
It will be interesting to see how the Sifbronze holds out in that position. You are not allowed to use it on coal fired boilers as something in the coal fumes attacks it and it will get a lot of smoke up the chimney, at least it is not under pressure.

J

Online Jo

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #497 on: June 25, 2018, 08:11:46 PM »
Sifbronze is basically a brass with a little tin added to improve the flow characteristics i.e. it has no silver. As we know in certain circumstances the very hot boiler water can remove the zinc (dezincification) and cause dangerous porous/weak joints. The lack of silver means it is difficult to attain an even heating to promote the desirable capillary flow, which again is not good if it formed part of a pressure vessel  :ShakeHead:

That joint looks ok for what you are using it for Rich  :ThumbsUp:

Jo

P.S. Sifbronze No 1 conforms to BS 1845 CZ6: Composition 57 -61% Copper 0.25 - 1.0% Tin balance Zinc.
Sifbronze No2 conformed to BS 1845 CZ8: Composition 46 - 50% Copper 9-11% Nickel balance zinc
Usus est optimum magister

Offline Jasonb

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #498 on: June 25, 2018, 08:15:47 PM »
It is not the water that affects it Jo, That is why I said it can't be used for coal fired boilers, think it is the sulphur that does the damage.

From Keith at CuP Alloys

"ON NO ACCOUNT USE ANY PHOSPHORUS BEARING BRAZING ALLOY ON A COAL FIRED BOILER. THE SULPHUR IN THE FUMES WILL GO THROUGH THE JOINT LIKE A HOT KNIFE THROUGH BUTTER.

Keith"
« Last Edit: June 25, 2018, 08:19:40 PM by Jasonb »

Online Jo

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #499 on: June 25, 2018, 09:06:05 PM »
 :headscratch: Sifbronze does not contain PHOSPHORUS

Jo
Usus est optimum magister

Offline NickG

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #500 on: June 25, 2018, 09:51:48 PM »
A lot of boiler designs back in the day specified sif bronze joints, presumably to avoid melting when soldering later ones with lower melting point material. These boilers by the likes of lbsc must surely have been made and steamed by a lot of people?


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Offline Tennessee Whiskey

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #501 on: June 25, 2018, 09:57:44 PM »
Good Lord, alls I was trying to say was the contrast looked nice.  Metallurgy aside.

Cletus

Offline Jasonb

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #502 on: June 26, 2018, 07:04:43 AM »
Great fab work Rich. I suspect it will be painted, but, that sil-bronze fillet looks great against the polished metal  :ThumbsUp:

Cletus

I blame it on Eric saying "Sil Bronze" and got me confused with Silphos

Offline Firebird

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #503 on: June 26, 2018, 07:57:45 PM »
Hi

Thanks Jo, Carl, jakdaw43, cletus, Jason, Nick  :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp:

Without wishing to start a big debate I am well aware that bronze/brazing is not allowed on boilers but it doesn't hurt to raise the subject every now and then, especially if there are any new comers watching. ONLY SILVER SOLDER ON BOILERS AND ONLY BRONZE/GUNMETAL FITTINGS.

But this is not actually on the boiler and has no pressure in it. Also if you look closely at the part you will see that the smoke/steam goe's straight through the steel and does not come into contact with the brazing which is just a filler externally.

Cheers

Rich

Offline Firebird

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #504 on: July 01, 2018, 12:06:50 PM »
Hi

The smokebox floor is a bit of a challenge. It must be as air tight (or should that be steam/smoke tight) as possible. I have the 3/8" square brass on the outside for mounting to the frames already drilled and tapped so I decided to use that instead of trying to silver solder or rivet brass angle to the inside. It might be helpful to have the smoke box floor removeable anyway.

Firstly prepare some 5/16" brass square to bolt on the inside. 5/16" not 3/8" so that the 1/16" floor sits level with the outside 3/8".









Square up a piece of 1/16" brass plate



File and fettle to achieve a good fit





Hold a piece of card on the inside and mark out the shape





Use the template to mark out some 1/16" brass sheet leaving a little extra to fold over



Cut out, fold and fit to the floor plate. I used a couple of 2mm stainless screws and nuts





Silver solder the parts together with an extra thickening piece at the foundation ring









Note the chimney base has been fitted to the smokebox with 10 x M3 button head stainless steel screws







Cheers

Rich
« Last Edit: July 01, 2018, 05:49:02 PM by Firebird »

Offline Kim

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #505 on: July 01, 2018, 05:01:58 PM »
Looking good, Rich!
Great the work on the smoke box.
Kim

Offline Tennessee Whiskey

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #506 on: July 02, 2018, 01:28:08 AM »
 :cheers: Rich; that last photo shows just how far itís come. Beautiful work  :ThumbsUp: :ThumbsUp:. Really looking to be a proper loco  :DrinkPint:

Cletus

Offline Jakdaw43

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #507 on: July 02, 2018, 07:27:42 AM »
Great work Rich...real craftsmanship on display. 
Stuart
Stuart alias 'Jackdaw'

Offline Firebird

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #508 on: July 08, 2018, 10:32:02 AM »
Hi

Thanks Kim, Cletus and Stuart  :ThumbsUp:

Continuing with the boiler/smokebox fittings

We need a snifting valve  :headscratch:  Oh yes we do  :thinking:

Heres an explanation clipped from wikipedia

When the driver shuts off the steam to the cylinders of a steam locomotive while it is in motion, the moving pistons could create a partial vacuum in the cylinders. This would give rise to two problems. Firstly, the pumping action would absorb energy and prevent the engine from coasting freely. Secondly, when the exhaust valve opened, soot and cinders from the smokebox could be sucked down the exhaust pipe and into the valve chest or cylinder, causing damage. (The exhaust is open to the smokebox because in normal running the exhaust steam is sent through the blastpipe to draw the fire and eject the combustion products from the chimney.) These problems are avoided by using snifting valves to allow air to be drawn into the cylinder. On railways which did not use snifting valves, drivers were instructed to keep the regulator slightly open when coasting to avoid the creation of a vacuum.

Ok.

Actually I had to make 2 because my mate Julian needs one for his Simplex so he said while you are at it make me one ::)

This is it



I think I have mentioned before I don't much like making this miniature stuff but it has to be done. Careful measurement and  accurate machining is the order of the day. What follows is a series of photos which will hopefully show the procedure I adopted without me going into a blow by blow account















Cheers

Rich

Offline NickG

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Re: CONWAY 0-4-0 3 1/2" GAUGE LOCO
« Reply #509 on: July 08, 2018, 08:06:04 PM »
Somebody advised me that the automatic drain cocks will act like sniffing valves. The vacuum probably isnít enough to seat the balls so will draw in fresh air.

I am hoping so as mine doesnít have a snifting valve - will soon find out I guess, I might have to make one too!


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