Author Topic: A small cochran boiler  (Read 29761 times)

Offline Zephyrin

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Re: A small cochran boiler
« Reply #120 on: November 30, 2016, 01:13:17 AM »
This boiler gradually takes the shape of a masterpiece,
lot of skill in this work, very instructive thread, thanks to share.

Online Dave Otto

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Re: A small cochran boiler
« Reply #121 on: November 30, 2016, 01:53:19 AM »
Beautiful work Florian!
It's always enjoyable to see an update on this project.


Dave

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Re: A small cochran boiler
« Reply #122 on: November 30, 2016, 02:42:30 AM »
Hey Florian,

Sabino's boiler   ( SA BINE OOOO is the pronounciation)  you'll see the simple door latch on the smoke doors...lets you open them with the end of the steam lance when it's time to blow tubes.....( either side of the steam drum in the top middle)



Just an example.....

Dave
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Damned ijjit!

Offline 10KPete

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Re: A small cochran boiler
« Reply #123 on: November 30, 2016, 05:52:29 AM »
That boiler is a real beauty, Florian. I'd never seen one until you started this build. Great work!!

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #124 on: December 12, 2016, 11:26:09 PM »
Good Evening!

Thanks everyone!

Well - the bad news first:

I cannot use the reversing chamber doors. The radius is not right and because of that it would be very hard to fit them to the boiler without having a gap between boiler and door.
Furthermore they are not "good enough" compared to the rest of the build quality..  :embarassed: AND they would not be how the real boilers were made. There was "just" a cover and no doors.
I was also struggling to find a solution to hold the doors closed.

Well the decision then was not too difficult to make a new cover. This time I am going to make it as a one-piece part and the cover will be held by small clamps around it.

And the good news:
A curved cover is the perfect workpiece for bending rolls! So guess what, I paused the cochran build and started with my bending rolls!

So, see you over in the other thread ;)

Cheers Florian
« Last Edit: December 12, 2016, 11:31:08 PM by Florian Eberhard »

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #125 on: August 16, 2017, 08:53:40 PM »
Hi all

And here we go - bending rolls completed, picture issue is solved - this can only lead to continuing with the cochran building log!  :happyreader: :stir:

As I have announced in the last post, the reversing chamber doors were not really up to being used in a working boiler since they were not closing good enough.
So what I did is i started cutting off these threaded rods left and right of the reversing chamber.
The plan is now to thread new stays into that frame around the reversing chamber and 1mm deep into the boiler shell (which leaves 1.5mm of untouched wall thickness on the shell) And 2mm should be enough thread length for new M1.2 stays.

I also had to rework that brass frame because it also had a somehow wavy curved surface which would be hard to get airtight. I mainly used a file for this job and that worked pretty well. On the picture with the pencil you can see that almost the whole brass frame surface has been touched by the file. Only a few more strokes and this will be good enough.

I then started making the new reversing chamber cover. And here is the first real use of my bending rolls. Well - they work perfectly well! I still made the blank a lilttle longer than the final cover because I found out that also with this principle of bending rolls there is a beginning and an end with a slightly different radius.
Before the final few passes, i annealed the cover blank again to make bending easier and also to release any stress that was built up during the rolling process.
The radius of the boiler was finally met pretty well and i started trimming off the surplus material around the cover with a cutting off blade. Then again used a file to get the cover to its (almost) final shape.

So much for now, see you with the next update!
Florian

Offline zeeprogrammer

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Re: A small cochran boiler
« Reply #126 on: August 16, 2017, 11:35:15 PM »
Awesome stuff Florian.
I always enjoy coming across your stuff.
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 #127 on: August 17, 2017, 09:16:04 PM »
Thanks zee!

The next thing i started was making the radiation shield from a piece 0.5mm stainless steel sheet.
And again the bending rolls were used. And they do work! The radiation shield will be mounted with four spacers, pretty similar to how I did it with the smokebox radiation shields.
I then decided that I was first going to make the clamps to hold the door and started with cutting little blanks from a brass bar. That was done on the lathe because this is the easiest way to clamp a long bar.
When I wanted to start machining those blanks, I also found out that a backstop for my little vice would be very useful and make that work a lot easier. Well - i grabbed a piece of steel and machined one, the rod in it which will touch the parts is acutally a dovel pin.

See you next time,
Florian





Offline Ye-Ole Steam Dude

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Re: A small cochran boiler
« Reply #128 on: August 17, 2017, 09:43:44 PM »

The slip roll is doing a beautiful job and the Boiler looks great.

Thomas

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #129 on: August 19, 2017, 02:34:53 PM »
Thank you Thomas.

In my last update, I just started with those clamps, which are finished in the meantime. This took several steps though:

I first machined the step on the bottom side, then drilled a hole, using a carbide drill which does work withouht punching a small center into the workpiece. Those drills are rigid enough that they don't bend away when you start drilling (unlike hss drills do)

To finish them, i chamfered some of the edges with a chamfering tool (did I mention i really love those?)
And thats those 11 clamps finished, laying on a piece of block square paper (5mm wide) - which gives you an idea of the size.

Then i marked the postion of the threadholes for the stays. They will be M1.2 and 2mm deep, which leaves 1.5mm to the inner side of the boiler shell - that should be enough.

So much for today, see you with the next update
Florian

Offline b.lindsey

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Re: A small cochran boiler
« Reply #130 on: August 19, 2017, 08:09:15 PM »
The slip rolls look great Florian and did a nice job too. Still following along and enjoying your progress on the boiler!!

 Bill

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Re: A small cochran boiler
« Reply #131 on: August 22, 2017, 08:32:03 PM »
Looking great Florian, nice to see you have returned to showing updates of your work :-)

Offline steamboatmodel

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Re: A small cochran boiler
« Reply #132 on: August 23, 2017, 01:36:58 AM »
"using a carbide drill which does work withouht punching a small center into the workpiece. Those drills are rigid enough that they don't bend away when you start drilling (unlike hss drills do) "
Carbide drills do work great, but I never use them unless I have 2 or 3 spares as I manage to get them twisted and they snap. Most of the hobby equipment is not rigid enough for them.
Regards,
Gerald.
Be wary of strong drink. It can make you shoot at tax collectors--and miss. Lazarus Long

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #133 on: August 23, 2017, 08:00:25 PM »
Peter and Bill, thank you!

Gerald, my milling machine should be rigid enough for such drills - at least at the size i am using them (1.2mm or smaller)
I guess I should finally present my milling machine - to show off a bit - of course not (or not too much  ;D )  but to finally meet the promise I made a long time ago when I introduced myself here on this forum  :o

Cheers Florian

Offline Roger B

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Re: A small cochran boiler
« Reply #134 on: August 23, 2017, 08:22:29 PM »
I'm still following along  :ThumbsUp:  :wine1: and may be asking for a go in your bending rolls sometime  :)
Best regards

Roger