Author Topic: A small cochran boiler  (Read 33652 times)

Offline ths

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Re: A small cochran boiler
« Reply #15 on: January 24, 2016, 10:56:32 AM »
Florian, the model is a fantastic bit of work, the full sized original must have been a wretch to build. And very expensive. Cheers, Hugh.

Offline K.B.C

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Re: A small cochran boiler
« Reply #16 on: January 24, 2016, 02:29:03 PM »
Hi Florian,
You are making a great job of copper bashing and I am sure that the final build will be superbe.
I think that it will take a great amount of heat to keep it in steam on such a small boiler as I think that the copper gauge looks a  bit heavy for one so small, you are a very brave man to take on such a complex project, well done.

I have seen a full size Cochrane somewhere but can't remember where, it may be at the Scottish Maritime Museum at Irvine,
What amazed me was that the complete boiler was riveted and wondered how the Devil they managed to rivet the boiler together, without welding, and with the tools available.

There was a cut away section showing the horizontal boiler tubes and I just couldn't figure how they would repair or remove a horizontal tube if it started to weep.

If I have a chance I will stop in at the Museum and if the boiler I saw is there I will take some pics and post them.

Thanks for posting your work.

George.
Your never too old to learn.

Offline Firebird

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Re: A small cochran boiler
« Reply #17 on: January 24, 2016, 03:53:13 PM »
Hi Florian

Great work. I'm a fan of small boilers so I will be following along in the background  :ThumbsUp:

Cheers

Rich

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #18 on: January 25, 2016, 09:14:57 PM »
I think that it will take a great amount of heat to keep it in steam on such a small boiler as I think that the copper gauge looks a  bit heavy for one so small,


Hi George

Since the boiler was started long ago and I already made a steam test that time, I can tell you it is not a problem for the ceramic burner I got for that boiler. And this was even without returning the hot gases through the fire-tubes! But I am with you, the gauge is a bit heavy. But I was too lazy to reduce the diameter of the shell. I even think that the additional mass will make the boiler a lot easier to control compared to its size.
The next few steps were not caught on the camera, but after soldering i remembered to take a picture of the boiler. To remove the flux residues, I dipped the boiler into citric acid. After a bit of brushing and polishing, It was ready for another step of soldering. I also realized that up to now I didn't think much about how to attach the reversing chamber cover. I then came up with the Idea of using a brass frame which is going to be soldered onto the shell and has screws fitted into it. For the smokebox, I also made a frame from brass sheet which is going to be soldered onto the shell. The smoke box then will be pushed over that frame and fixed with screws. And the last picture shows heating the boiler before soldering the two frames.

Cheers Florian
« Last Edit: June 29, 2017, 09:43:13 PM by Florian Eberhard »

Offline zeeprogrammer

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Re: A small cochran boiler
« Reply #19 on: January 25, 2016, 09:41:51 PM »
That is impressive. It's going to look so cool!
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline K.B.C

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Re: A small cochran boiler
« Reply #20 on: January 26, 2016, 12:16:38 PM »
Hi Florian,
Super job of the boiler, the only problem that I thoght on was the heavy gauge which will only take a little more time and gas to bring it up to pressure but once there it will keep steaming economiclly all day.

The first boiler that I ever made was a Scotch return flue x  4.75" dia x 5" between the end plates, in my ignorance of boiler calcs at the time the shell was 10 swg ( .125" thk ) the burner being a plumbers blowlamp head.
It takes abot 15 mins to get to 60 p.s.i. but once there it steams a Stuart D10, all day as long as there is gas in the tank and feed water to the boiler, I use pond water thro' a filter and this boiler although about 15 years old and well used , fitted in a 42" long Tug is still as tight as the day it was first tested, now I make them with as light a gauge as possible but within the regulations.

Keep up the good work.

George.
Your never too old to learn.

Offline b.lindsey

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Re: A small cochran boiler
« Reply #21 on: January 26, 2016, 01:11:30 PM »
That is some nice soldering work Florian. Still following along with this unique design!!

Bill

Offline Don1966

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Re: A small cochran boiler
« Reply #22 on: January 26, 2016, 03:55:30 PM »
That soldering Job came out great Florin. Did you use different temperature solder as you progressed or the same for all? I find that fast and concentrated heat can work with same solder temperature but you have to work fast. I also use clamps as heat sinks in areas close to the new soldering area I am working on.

Don

Offline tvoght

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Re: A small cochran boiler
« Reply #23 on: January 26, 2016, 04:05:37 PM »
I'm following this interesting build, Florian. Workmanship is up to your usual high standards.

--Tim

Offline joe d

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Re: A small cochran boiler
« Reply #24 on: January 26, 2016, 08:41:16 PM »
Hi Florian

I've only made one boiler to date, not so sure I'm ready for the complexities of one of these ones.

Much enjoying following along.

Cheers, Joe

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #25 on: January 29, 2016, 09:18:25 PM »
Good Evening!

Thanks for the nice comments!

Don, I used the same solder for everythig. I found out a while ago that the flux "helps" if you put it only to the required spots. Means that if i do a soldering job right next to an already soldered spot, the silver solder will melt a little earlier where there is flux. Oh and a small soldering gap helps to keep the silver solder on the right place aswell.

Joe, the only "real difficult" thing on this boiler are the two firetube plates. At least if you have some practice with soldering. The rest is more tactical, deciding in which order you work is everything on more complex soldering jobs. (and a little knowledge about it).
It is easier if you use a soft (and big) flame than a small but very hot one, as it spreads the heat more equally.

So, lets get back to work: Its fitting time!  The safety valve is an open construction with a 3mm stainless steel ball. On the second picture you can see the blow-down valve body which has been soldered together from two pieces. The spindle of the valve has a flat cone for sealing and no tip to release the full width as fast as possible. The Valve lever has been turned, milled flat on the middle part and then bent on one side.
I had to start twice with the clack valve.  The bore of the shut-off valve got out of center the first time.
The spindle for that valve has been made from stainless steel, I wanted to have two different materials for better wear behaviour (and I thought it may get stuck a little harder than with identical materials)
Finally, you see the finished valve, the lever is made from boxwood (machines extremely well!)
Be prepared for more fitting-work, and see you next time!  :atcomputer:
Florian
« Last Edit: June 30, 2017, 09:24:04 PM by Florian Eberhard »

Offline zeeprogrammer

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Re: A small cochran boiler
« Reply #26 on: January 29, 2016, 10:25:26 PM »
Continues to be beautiful.

I like that lever!  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #27 on: February 05, 2016, 07:13:55 PM »
Good Evening - I just found out that alreday another week has passed since my last post. Well - here we go: 

One of the still missing fittings is the water level gauge. The glass tube will have 4mm diameter and there will be a drain valve in case there are bubbles somewhere in the glass tube.
The lower body has a quite small bore (1mm diameter) to the boiler. I found out with another boiler that this slows down the movement of the water level (due to boiling water) and also helps for greater accuracy.
A test assembly of the gauge and a piece of glass tube showed that it was going to fit.
The pressure gauge syphon tube has been soldered together from three pieces and the hollow screw was made from stainless steel.
A water level drain valve was fitted to the bottom cover of the water level lower body. The cover will compress an o-ring against the glass tube to get a tight seal.
That small valve on the next picture is the blower valve, I am planning to use the boiler with coal aswell as with a ceramic burner.
The picture with the loose components shows the parts for the main steam valve. It will have a sperical body like the blowdown-valve. But this one has a full tip on the spindle to be able to control the flow pretty sensitive. Finally you can see all the fittings mounted on the boiler, the main steam valve wheel is still missing though.

Cheers Florian
« Last Edit: June 30, 2017, 09:44:29 PM by Florian Eberhard »

Offline b.lindsey

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Re: A small cochran boiler
« Reply #28 on: February 05, 2016, 08:08:47 PM »
Really lovely Florian. Just amazing work on this boiler!!

Bill

Offline ths

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Re: A small cochran boiler
« Reply #29 on: February 05, 2016, 08:16:29 PM »
Like Bill said. Hugh.