Author Topic: A small cochran boiler  (Read 47658 times)

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #45 on: February 18, 2016, 07:41:01 PM »
Hello - how are you doing?

No, I didn't forget about you ;) and here is the proof:

At a certain point of building the boiler, I decided to make a base for that boiler which allows me to switch from gas fired to coal fired and back. The first step was getting the raw material ready, which is a piece of brass tube, cut from a brass check valve (like this one: http://www.amazon.co.uk/BRASS-CHECK-VALVES-NON-RETURN-FEMALE/dp/B00MHSIBFE):
I had to make a supporting disc to clamp the brass tube safely. I then first machined the ends of that piece of tube. After soldering a ring (which was cut from the chekc valve aswell) on top of the tube, I first face turned that ring and then machined it until the boiler was held firmly. There is also a rounded cut-out for the blow off valve - I didn't think about putting the boiler on a base when I started with that project.
The last step on these pictures shows milling the opening for the coal or gas firing "device".
And finally the boiler on the (almost) finished base.
« Last Edit: July 04, 2017, 08:52:19 PM by Florian Eberhard »

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #46 on: February 18, 2016, 08:30:58 PM »
The first picture shows where the ceramic burner is going to be. I am going to make two drawers of which one will hold the ceramic burner and the other one will be equipped with a grate to be able to light a coal fire inside of the firebox.
The drawer itself will be made from five pieces of sheet metal. Two of them rounded by hand, over a piece of round stock. I think I managed to get the radius pretty close as you can see on the picture with the drawer front blank together with the boiler base. It took quite long though to get it there and I think it would be much easier to do this with some bending rolls.
I made a fixture from an aluminium blank to solder all the pieces together.
The soldering was done in two steps; after the first step I cut and filed the bottom and the backside of the drawer to the required size. This would have been a lot more difficult with the front already attached to the rest.
The Ceramic burner has four holes to mount it somewhere. I then decided to use them and to put some countersunk screws into the drawer bottom. The pattern was copied by using the burner as a jig. This reduces the possibility of making mistakes  ^-^

Well, see you again next time!
Florian
« Last Edit: July 06, 2017, 08:33:35 PM by Florian Eberhard »

Offline Don1966

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Re: A small cochran boiler
« Reply #47 on: February 18, 2016, 11:52:28 PM »
Beautiful work Florian, that is one awesome looking boiler.

Don

Offline K.B.C

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Re: A small cochran boiler
« Reply #48 on: February 26, 2016, 10:47:12 AM »
Florian,

Neat fire box and burner.

George
Your never too old to learn.

Offline Robert Hornby

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Re: A small cochran boiler
« Reply #49 on: February 26, 2016, 12:22:34 PM »
First class job there Florian, I am impressed.
Bob
Age and treachery will always overcome youth and skill

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #50 on: March 03, 2016, 09:06:04 PM »
Hi again

Im quite busy these days and only few times get into the shop. Nevertheless, I can show some progress (though that one has been made a while ago already):

So, the mixing tube of the burner needed to get out of the drawer somehow. I held the drawer front on top of the tube and aside to mark the upper and lower limit of the future bore. Then made a rectangle from the limits and got the center by connecting the diagonal lines of the rectangle. The hole was first drilled to 6mm and then enlarged to the final size using a handle reamer. This way, the cutting forces were kept low, otherwise I would have had to make a round piece of wood or somehting else to clamp the drawer front onto.
Then I had to find a way to make a handle. I decided to use 3mm brass rod and to bend and forge it into that shape. I was working with a small torch, reheating the brass piece after every two or three taps with the hammer. After the flanges were big enought, i shaped them with a file so they were more or less equal on both sides.
I then had to stop what I wanted to do and take care of my little albrecht chuck. It could not be closed anymore (I wanted to drill the riventing holes into the handle). So I had to take it apart, clean everything and reassemble it. Not sure why it got stuck but its working again now.
With the reassembled chuck, I was able to drill the four holes. The rivets have a diameter of 1mm at the shaft (and I think 2mm on the head) so I used a 1mm drill.
But before riveting it to the drawer, I had to solder drawer and its front, using my selfmade tip on my oxygen torch.
After pickling, some filing and cleaning up the surface, I could finally join the drawer and the handle.

I also wanted to see how the ceramic burner works with that setup. (I only fired the burner for a short time - with no water in the boiler)
You can see the orange flames indicating that the ceramic burner works perfectly well.

Cheers Florian
« Last Edit: July 06, 2017, 08:59:51 PM by Florian Eberhard »

Offline Roger B

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Re: A small cochran boiler
« Reply #51 on: March 03, 2016, 09:11:58 PM »
Lovely work  :praise2:  :praise2: As you may have seen on another thread I have noted that you have some bending rolls so I may be making a visit  :)
Best regards

Roger

Offline b.lindsey

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Re: A small cochran boiler
« Reply #52 on: March 03, 2016, 09:25:01 PM »
Once again that turned out beautifully Florian. Lovely job on the cover and handle!!

Bill

Offline Don1966

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Re: A small cochran boiler
« Reply #53 on: March 04, 2016, 12:32:22 AM »
I am quiet intrigued with the gap between to gas jet and the intake to the ceramic burner. What type of jet are you using and how much pressure is being applied? This is a self aspirating burner but the distance from jet to intake looks large are am I missing something? By the way nice work.

Don

Offline zeeprogrammer

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Re: A small cochran boiler
« Reply #54 on: March 04, 2016, 12:49:48 AM »
I am quiet intrigued with the gap between to gas jet and the intake to the ceramic burner. What type of jet are you using and how much pressure is being applied? This is a self aspirating burner but the distance from jet to intake looks large are am I missing something? By the way nice work.

I was wondering that too. I hadn't seen something like before.

And like everyone says...wonderful work.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Dave Otto

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Re: A small cochran boiler
« Reply #55 on: March 04, 2016, 12:56:45 AM »
Very nice Florian,

Add me to the list of guys wondering about the large gap between the gas jet and the rest of the burner assembly.

Dave

Online fumopuc

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Re: A small cochran boiler
« Reply #56 on: March 04, 2016, 05:18:47 AM »
Hi Florian, nice progress. I do like that little Albrecht chuck.
Kind Regards
Achim

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #57 on: March 04, 2016, 07:10:13 AM »
I have noted that you have some bending rolls so I may be making a visit  :)

Hi Roger

Not exactly, I am only planning to make them up to now.

Now about the burner:
I bouht that burner so I can only guess about its design. Fact is, it requires only a low pressure ( I think it was less than 0.5 bar)/

I suppose the long distance between Gas jet and Gas mixing tube is due to the fact that these type of burners only require primary oxygen for a complete combustion. Therefore, the gap for drawing in air needs to be rather long compared to a regular torch.

Florian

Offline IceFyre13th

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Re: A small cochran boiler
« Reply #58 on: March 18, 2016, 05:14:32 PM »
Any more progress?

Offline Florian Eberhard

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Re: A small cochran boiler
« Reply #59 on: March 20, 2016, 08:37:08 PM »
Good Evening!

Yes, there is some progress!

I had to collect material for the second drawer. You can see what I found, though still missing one piece of sheet metal for the drawer front.
I used the milling machine to chamfer and cut slots into the drawer sides. They are going to hold the grate.
Two pieces are complete, the rest of the drawer yet has to be brought into shape.
And thats what I started with. The piece was clamped in the vice using some parallels to adjust it so it only sticks out as much as needed to machine it.
As I mentioned earlier, the soldering fixture was way to massive, so I decided to machine off some material (-> challenge: who can find the fixture on the photo ;) )
Soldering went quite well this time. Though I still had to warm up everything before I was able to reach the required temperature at the soldering joints.

However, It seems like I should just not get happy with that soldering fixture. After I had to pull the fixture away from the soldered part very hard, I found out, that the aluminium started alloying with the brass! I was quite bewildered that this had happened, because if someone asked me what would happen I certaily would not have foreseen this!
That unintentionally created "alloy" felt like silver solder when filing, so It would be quite hard I guess.
Unfortunately, the soldering fixture got compressed a little because of that and this resulted in non parallel drawer-sides. The difference between front and backside is in about 1mm. I am going to use the drawer anyhow.
You can also see it on the fixture that some of the material got taken away by the workpiece:
So, If you are using aluminium for soldering fixtures, be sure to keep them away from the hot area as far as possible. In addition, I suppose it does help to keep the fixture massy so that it does not get hot enough for such strange effects!

Cheers Florian
« Last Edit: July 06, 2017, 09:14:55 PM by Florian Eberhard »

 

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