Model Engine Maker

Supporting => Boilers => Topic started by: Florian Eberhard on January 19, 2016, 08:51:26 PM

Title: A small cochran boiler
Post by: Florian Eberhard on January 19, 2016, 08:51:26 PM
Good Evening to everyone!

I thought i'd write something about that little cochran boiler, I started long time ago. (and never finished up to now)
For those of you who don't know what a cochrane boiler is, i have attached a sectional drawing of one.
The boiler was started in 2008 and the first part was one of the plates that holds the flues, which is being formed with a hammer, after bending it twice into a "U" shape.
The according form was made from wood which has been first machined to a cylinder and then had some material removed to bring it into the required shape.
The first plate is completed - next to the boiler tube which has an outer diameter of 60mm.
You can see the beginning of the forming process in the picture where the u-shaped copper sheet is being held by a wooden spacer and a screw clamp.
The wooden form turned out handy to drill the flue holes into the tube plates. The tubes were cut by saw and then machined to get a smooth end. Tube dimension is 6mm outer diameter and 0.5mm wall thickness. After finishing the tubes, I have put together the tubes and the tube plates to see if it was going to work how it should. And it did!  :D

Have a nice evening and see you next time,
Florian
Title: Re: A small cochran boiler
Post by: Robert Hornby on January 19, 2016, 10:51:15 PM
Very nice work indeed there Florian, I will be following closely.

Robert
Title: Re: A small cochran boiler
Post by: oil mac on January 20, 2016, 12:07:53 AM

 Florian,
             Absolutely superb workmanship & genius on overcoming a very difficult task, Also glad to see someone building a model of a Scottish boiler which was widely used
Title: Re: A small cochran boiler
Post by: sbwhart on January 20, 2016, 06:40:45 AM
That's an interesting project Florian, its got my interest keep the progress reports coming please.

Stew
Title: Re: A small cochran boiler
Post by: Steamer5 on January 20, 2016, 07:54:58 AM
Hi Florian,
 Nice project! Watching & enjoying! Can't wait to see how you do the "Ogee" ring around the firebox

Cheers Kerrin
Title: Re: A small cochran boiler
Post by: Roger B on January 20, 2016, 09:44:54 AM
Hi Florian, glad to see you back in the workshop  :ThumbsUp: I'll be following along  :wine1:
Title: Re: A small cochran boiler
Post by: 10KPete on January 20, 2016, 11:16:45 AM
A most interesting boiler design. I'd not seen it before your post so had to go 'look it up'.

Keep it coming, I will be right here following along! 

 :cheers:

Pete
Title: Re: A small cochran boiler
Post by: Florian Eberhard on January 21, 2016, 05:48:21 PM
Hello Again

Thanks for the comments, the special design of that  boiler is what made it that interesting for me!
Back to boilermaking:
The next part was that ring I suppose Kerrin means whith "Ogee" Ring. It starts as a copper sheet disk as shown on the first picture. The round piece of brass is just used to clamp it as close to the edge as possible. On the second picture, you can see it while annealing it. It looks almost finished but the progress is always getting smaller.
After I finished forming, I did cut a hole into the ring to fit it onto a piece of tube. That tube is going to be part of the firebox.
Then the test if it still fits the boiler shell.
After that, I started cutting the openings into the boiler shell where the firetube plates are going to be located. As I was just using hand tools to work on the shell, I started by drilling lots of small holes. Then I made two cuts with the hacksaw to remove that piece of the shell. To get that opening into its shape, I used some files and again the hacksaw to complete it.
The top of the firebox will be a spherical copper dome that I found at an austrian onlineshop.

Cheers Florian
Title: Re: A small cochran boiler
Post by: zeeprogrammer on January 21, 2016, 10:06:46 PM
Following along Florian.
This is very interesting.
Title: Re: A small cochran boiler
Post by: b.lindsey on January 22, 2016, 12:34:26 AM
Very different and interesting design Florian. I am watching with interest. Nice work thus far on it too!

Bill

Title: Re: A small cochran boiler
Post by: Don1966 on January 22, 2016, 12:50:05 AM
Beautiful work going on in this thread and I will be following your progress....... :ThumbsUp:


Don
Title: Re: A small cochran boiler
Post by: Steamer5 on January 22, 2016, 04:21:46 AM
Hi Florian,
  Yes that the Ogee ring! Learnt about them when I did my steam tickets last century !
Yours is a neat way round the double compound curve that must have required considerable talent to get right.
 The guy that we had as an inspector at the place I worked knew all about them & they were one of his favorite items to check! We didn't have any.....seems they were used in small place like dry cleaners around here.

Cheers Kerrin
Title: Re: A small cochran boiler
Post by: Florian Eberhard on January 23, 2016, 09:31:58 PM
Yours is a neat way round the double compound curve that must have required considerable talent to get right.

Or just some good Ideas how to make it  ;) (Although it would have been quite difficult in this size!)
However, I can really imagine that these were critical on the "real" boilers as corrosion ususally is worst where two parts are being conected.
Especially this "Ogee" Ring (Where does that Name come from??)  forms a small gap getting narrower until where the ring is riveted together with the boiler shell.

I also bought a dome to use as a top of the boiler. To connect it with the boiler, i machined a step on the shell and also into the shpere.
The fit is machined so that the dome fits onto the boiler by using slight force. The intention was to avoid it moving around when soldering.
The two firebox plates will be held by copper wire for soldering. After soldering, I will just file away the wire that sticks out until it is flush to the shell.
Holding the firebox dome to machine an opening into it was quite difficult. I then tried to place it on top of a wooden rod and that actually worked pretty well for drilling. The hole for the smoke tube was also machined into the smoketube plate of the reversing chamber.
Then a mockup assembly of how the firebox, the connection and the smoketube-plate will look like in the boiler. Finally the part-soldered firebox witht he firing hole tube fitted to its side.
Title: Re: A small cochran boiler
Post by: vcutajar on January 23, 2016, 09:44:37 PM
Quietly following along.  Enjoying and very educational the way you do things.  Thanks.

Vince
Title: Re: A small cochran boiler
Post by: fumopuc on January 24, 2016, 06:41:58 AM
Hi Florian, a very nice build report of this extraordinary boiler concept. Waiting for the next steps.
Title: Re: A small cochran boiler
Post by: ths 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.
Title: Re: A small cochran boiler
Post by: K.B.C 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.
Title: Re: A small cochran boiler
Post by: Firebird 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
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: zeeprogrammer on January 25, 2016, 09:41:51 PM
That is impressive. It's going to look so cool!
Title: Re: A small cochran boiler
Post by: K.B.C 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.
Title: Re: A small cochran boiler
Post by: b.lindsey on January 26, 2016, 01:11:30 PM
That is some nice soldering work Florian. Still following along with this unique design!!

Bill
Title: Re: A small cochran boiler
Post by: Don1966 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
Title: Re: A small cochran boiler
Post by: tvoght on January 26, 2016, 04:05:37 PM
I'm following this interesting build, Florian. Workmanship is up to your usual high standards.

--Tim
Title: Re: A small cochran boiler
Post by: joe d 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
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: zeeprogrammer on January 29, 2016, 10:25:26 PM
Continues to be beautiful.

I like that lever!  :ThumbsUp:
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: b.lindsey on February 05, 2016, 08:08:47 PM
Really lovely Florian. Just amazing work on this boiler!!

Bill
Title: Re: A small cochran boiler
Post by: ths on February 05, 2016, 08:16:29 PM
Like Bill said. Hugh.
Title: Re: A small cochran boiler
Post by: zeeprogrammer on February 05, 2016, 10:23:38 PM
 :o

Wow.

I mean wow.
Title: Re: A small cochran boiler
Post by: Don1966 on February 05, 2016, 10:30:06 PM
Very impressive work Florin. You do have a handle at soldering, very nice............ :praise2:

Don
Title: Re: A small cochran boiler
Post by: Laurentic on February 06, 2016, 01:18:50 PM
The full size Cochran boiler was not that expensive, they were often found on UK motor ships in the 50's and 60's, fitted to provide steam in port when the exhaust gas (from the main engine) wasn't providing steam via the exhaust gas boiler.  Ship owners wouldn't have fitted them unless they were relatively cheap!

Chris
Title: Re: A small cochran boiler
Post by: Florian Eberhard on February 07, 2016, 08:14:47 PM
Hello

Again, thank you for your comments. Just to be clear about that: I always do some finishing work to the soldered joints after soldering. That Is why all these joints look that nice.
But it is true, I seem to be a little talented with silver-soldering. (Or do I just have the right equipment?  ;) )
It was/is also fun for me building that boiler. And I myself really am into these details that make the boiler look like id does (wooden handles, ...)

I found a picture from the main steam valve, though the picture is a little blurry. I then started building the doors of the reversing chamber. You can see my idea of how to do it on my scribbles that I made.
The doors are bent from 1mm brass sheet. Unfortunately I cant remember how I did this.  :embarassed: (well - its six years over since then) But i must have used some kind of round thing to form the radius. What I do remember is how I made that step into one door: I clamped the door in a vise and then made a square bend. Then I clamped it on the other end (while that was still beeing a little longer). To bend it back, I used kind of a wedge shaped tool.
The static part of the door hinge was made again with my soldering technique (basically a flat piece and two u-shaped pieces).
Oh and in case you need to deburr some holes that you cant reach witch a "standard" deburring tool, you can use these spherical dremel-cutters. They work pretty well as long as the angle doesnt get too big.
The part of the hinge that is going to be on the door will have a tee cross-section. Again it is going to be silver soldered from several elements. But I first had to bend the web for the t-profile. Then I solderd together the web and the flange and in another step added a piece of tube.
After that, I drilled holes into the flange, 4 per hinge. I want to rivet the hinges to the doors. And there are the completed doors (well - almost - I will have to make some kind of a latch)
That is how far I was, when I finished continuing with this boiler six years ago. Well, three weeks ago, I restarted work on it and that also is the reason for this Topic here. I wanted wo write that I was going to continue but couldn't find any topic about my cochran.  :o ;)

Cheers Florian
Title: Re: A small cochran boiler
Post by: ICEpeter on February 07, 2016, 08:39:26 PM
That is great work you are doing, Florian. Very much enjoy watching your build
and appreciate your first class workmanship. Will follow along with great interest.

Peter J.
Title: Re: A small cochran boiler
Post by: b.lindsey on February 07, 2016, 09:32:35 PM
The doors and hinges certainly turned out well and add a lot of detail too Florian.

Bill
Title: Re: A small cochran boiler
Post by: zeeprogrammer on February 07, 2016, 09:42:50 PM
That is how far I was, when I finished continuing with this boiler six years ago. Well, three weeks ago, I restarted work on it and that also is the reason for this Topic here. I wanted wo write that I was going to continue but couldn't find any topic about my cochran.

Perhaps on the previous forum?

What Peter said...first class.
Title: Re: A small cochran boiler
Post by: Dave Otto on February 08, 2016, 01:09:05 AM
Florian those doors are a work of art!

I remember this project from the other forum and will be happy to be able to see it finished here on MEM.

Dave
Title: Re: A small cochran boiler
Post by: RonGinger on February 08, 2016, 03:03:24 AM
Nice job on the doors. Can you explain a bit about how you held those pieces together to do the soldering? I have always had trouble doing small items like that.
Title: Re: A small cochran boiler
Post by: V 45 on February 08, 2016, 03:27:35 AM
That's a lot of fantastic silver soldering ! Great job
Title: Re: A small cochran boiler
Post by: jschoenly on February 08, 2016, 02:13:16 PM
Beautiful work!  I was a little confused how the flues worked on this guy, but I think I get it now.  Very interesting!
Title: Re: A small cochran boiler
Post by: Don1966 on February 08, 2016, 06:37:41 PM
Outstanding Forian, love the door and how they look on the boiler. Having the right equipment for soldering is a must but it still takes a bit of talent......... :praise2:

Don
Title: Re: A small cochran boiler
Post by: Florian Eberhard on February 08, 2016, 09:23:51 PM
Nice job on the doors. Can you explain a bit about how you held those pieces together to do the soldering? I have always had trouble doing small items like that.

Hi Ron

Well - I did not hold them in any way. But I did have to correct the position of the parts after the water of the flux evaporated. (that always moves parts arount)
I also flattened the silver solder rod on the tip so the solder did melt easily. And I ususally apply the solder on the part that is hard to move with the soldering rod. (I try to put it as close to the small parts as possible but without touching them)
After the solder closes the gap between several parts, they won't move around anymore and that makes it easier to add some more solder.

Another way of doing it (though I cant remember that I ever tried this) is to flatten the soldering rod with a hammer and then cut small parts and put them on the parts before heating up.
That is very useful for example for hardly reachable joints or for very small parts that would move at the first contact with silver solder.

Florian
Title: Re: A small cochran boiler
Post by: RonGinger on February 08, 2016, 11:50:55 PM
Thanks, I was hoping you were going to have some great new trick, but you did did very careful work.

If I tried to do that hinge pin tube even moving my torch toward it and it would blow across the shop and be lost as soon as the flux started to become liquid.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on February 09, 2016, 09:30:15 AM
If I tried to do that hinge pin tube even moving my torch toward it and it would blow across the Shop...

Well, it seems that you are using a blow-torch  :LittleDevil:
No, I mean, I have several different torches, in different sizes. And i've had that Problem too once or twice. That usually showed me that I was using the wrong torch.

Florian
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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.
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: Don1966 on February 18, 2016, 11:52:28 PM
Beautiful work Florian, that is one awesome looking boiler.

Don
Title: Re: A small cochran boiler
Post by: K.B.C on February 26, 2016, 10:47:12 AM
Florian,

Neat fire box and burner.

George
Title: Re: A small cochran boiler
Post by: Robert Hornby on February 26, 2016, 12:22:34 PM
First class job there Florian, I am impressed.
Bob
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: Roger B 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  :)
Title: Re: A small cochran boiler
Post by: b.lindsey on March 03, 2016, 09:25:01 PM
Once again that turned out beautifully Florian. Lovely job on the cover and handle!!

Bill
Title: Re: A small cochran boiler
Post by: Don1966 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
Title: Re: A small cochran boiler
Post by: zeeprogrammer 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.
Title: Re: A small cochran boiler
Post by: Dave Otto 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
Title: Re: A small cochran boiler
Post by: fumopuc on March 04, 2016, 05:18:47 AM
Hi Florian, nice progress. I do like that little Albrecht chuck.
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: IceFyre13th on March 18, 2016, 05:14:32 PM
Any more progress?
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: Don1966 on March 20, 2016, 08:48:37 PM
As always Florin some very nice setups and craftsmanship. I think the aluminum and copper under the heat of the flame caused it to act like a thermocouple and if the setup shorts circuits this action the results is what you seen. The current flow cause electoplating to accure and the hotter the flame the faster the action.

Don
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 20, 2016, 09:13:31 PM
Still enough time to continue:


The drawer front will have slots to let the air in. I like to put some good quality ply wood under sheet metal for machining.
The front and register are finished machinig - they yet neet to be bent though which is going to be a bit challenching because they wont bend equally because of the slots.
And they actually turned out to be a bit like a polygon (where the slots are) rather than a perfect circle. But I can live with that because making a fixture for machining them after bending would have been more time-consuming.
Soldering the drawer front to the rest was easy and also worked without any complications this time. Phew!
Then I had to solve another problem: There was still a gap between the grate and the lower end of the firebox. 1
I decided to machine a ring from mild steel to fit into the base. To get a perfect fit between the ring and tbe boiler bottom (which is not flat), I removed most of the material of the ring and used some  refractory cement. The boiler was then pressed down on that cement for the matching shape. 
After curing, I removed the excessive material and the ring should be ready for use.
The next step was to machine the grate which required several operations. The first one wasmilling the slots with a 3mm carbide endmill.
After that, I had to deburr the slots. I decided to do it with a deburring  cutter (which I have for quite a while now and I wouldn't want to miss it!). That was, I guess easier than doing it by hand considering the number of slots!
The next operation was to machine the slots into a v-shape so the small coal pieces don't get stuck in the slots. After that, I also deburred the slots, which in my opinion makes it look really good!
And a picture of the grate in its future place. The grate is made from mild steel because I didn't have anything else in a suitable dimension. I hope it is going to work like that, otherwise, I will propably use either stainless steel or cast iron. But lets try that first and see how long it is going to last.
Right now you are up to date about the progress but I am looking forwart to continue on tuesday.
The next step will be to fit a handle and a front onto the grate and to fix the air intake register to the drawer (and make a handle aswell).

Cheers Florian
Title: Re: A small cochran boiler
Post by: zeeprogrammer on March 20, 2016, 09:15:43 PM
Fabulous work Florian.
Always a pleasure to see your pics and results.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 20, 2016, 09:18:37 PM
Hey Don

The aluminium is not just on top of the surface, It penetrated the surface of the brass!
So I assume the aluminium was near to its melting temperature. I think some of the brass components diffused into the aluminium and also the other way round and created an alloy in the contact zone.
However, I am going to think twice about using aluminium for a soldering fixture in the future!

Cheers
Title: Re: A small cochran boiler
Post by: b.lindsey on March 20, 2016, 10:44:12 PM
Always a pleasure to see your updates on this boiler Florian. The results are always first rate.

Bill
Title: Re: A small cochran boiler
Post by: Don1966 on March 20, 2016, 10:51:40 PM
Hey Don

The aluminium is not just on top of the surface, It penetrated the surface of the brass!
So I assume the aluminium was near to its melting temperature. I think some of the brass components diffused into the aluminium and also the other way round and created an alloy in the contact zone.
However, I am going to think twice about using aluminium for a soldering fixture in the future!

Cheers
This action also causes the metal to pit because of the two different metals, a lot of movement accures and can pentrate the other metal. An electric process is also use to fuse copper and aluminum together.

Don
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 21, 2016, 05:10:36 PM
Thanks Zee and Bill for the comments!  :cheers:

@Don:
Then it totally makes sense. Does it probably also work faster under pressure? Because that effect only occured where the parallel clamp was applying pressure, not on the other spot where the fixture touched the brass plates.

Actually I could start an experiment to see if it happens again. And what happens if I let it cool down (if it is possible to connect brass and aluminium with that method!)
Title: Re: A small cochran boiler
Post by: Dave Otto on March 21, 2016, 05:24:32 PM
Maybe you could measure the voltage generated across the junction and figure out the exact temperature of the joint.  :lolb:

I'm still enjoying following along with your wonderful work on this project.

Dave
Title: Re: A small cochran boiler
Post by: Don1966 on March 21, 2016, 05:27:08 PM
I don't think that you will connect them together because the metal will crystallized and become very brittle. And yes applying pressure will cause it to increase the movement. Because you have two dissimilar metals and bonding them together with pressure, it acts like a battery and heat causes the junction to move the heat away from it as electric current. The only way this can happen is if the circuit is complete as a short circuit. In which case what you had with your setup.

Don
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 21, 2016, 08:28:05 PM
Maybe you could measure the voltage generated across the junction

Do you reckon I could run a small radio whith that  :headscratch:  :Lol:

Cheers ;)
Title: Re: A small cochran boiler
Post by: derekwarner_decoy on March 21, 2016, 10:00:10 PM
Florian.....unknowingly you created a few hot spots during the gas soldering process and fluidized the adjoining aluminium and brass/bronze into the small pockets of a semi homogenous aluminium/bronze alloy

The interesting point is that the brazing flux maintained its integrity and stopped the aluminium from oxidising and burning or spitting

Considering the temperatures [C] involved here, the quazi melt process is not surprising [Cu=1083, Al=658, Br=900, Ag=961]

As you will be aware Al/Br alloys can be a joy to machine, greater hardness, toughness & lubricity over plain old brass

This is why you found the filing of the alloyed material ...'like filing a silver soldered joint' ......... Derek

Title: Re: A small cochran boiler
Post by: K.B.C on March 24, 2016, 08:28:53 PM




I also wanted to see how the ceramic burner works with that setup. I only heated up for a short time because the boiler was empty. Though you can see the orange flames indicating that the ceramic burner works perfectly well:

(https://dl.dropboxusercontent.com/u/21771006/Hobby/Cochran%20Kessel/IMG-20160207-WA0025.jpg)


Cheers Florian
[/quote]

Florian,
I have followed your Cochrane boiler build from the start and have complemented you on it's construction in previous posts.
However there is one point that I must point out to you that you have created a very dangerous situation  by  pushing a plastig pipe or some other material over the thread of the jet holder straight from the L.P.G. tank, it only needs a small amount of heat to cause the tube to expand and the slightest of knocks  can disloge the tube and you are then firing straight L.P.G. at an open flame. I know it's very tempting to see if the burner works but I can assure you that I have sean a very bad fire caused by the plastic tube coming adrift so please make a proper machanical connection to the jet holder.

Some time ago I pointed out the very the same thing that you have done to  Ramon on his Wide Awake boiler and to his credit he commented that this problem had not occured to him and he has now corrected that  (http://www.modelenginemaker.com/index.php?topic=2851.180  ) post No 187 pic No 8

Please don't be offended by my comments but if you had seen the effect of the fire that I witnessed you would realise my concern.

Regards
George.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 25, 2016, 06:56:50 PM
Hi George

Thanks for your advice. I am never offended by security advices.

Basically, I am very careful when dealing with L.P.G. because I had experienced some dangerous situations with L.P.G. in the past (though not when using any kind of tube).
Luckily nothing ever happened.
I have been using silicone tube like the one on the picture for a long time and like Ramon never had any problems with it. Therefore, I never spent a lot of thoughts about how dangerous it could be.

Florian
Title: Re: A small cochran boiler
Post by: Florian Eberhard on March 27, 2016, 09:32:30 PM
Hello Hello

Its time for another update:

The first picture shows four semi-finished nuts for holding the register; the smaller diameter is going to be in the slots of the register. At the other end, I will machine a hex to tighten them.
This is the setup for milling the hex faces. I recently acquired this dividing head (which is an aciera f3 dividing head that uses the same collets as my lathe does) and actually was using it for the first time here. I am definitely happy with my purchase because it is really nice using it (Those of you who have been using Aciera tools know what I am talking about  ;D )
I tried to take a picture of the finished nuts, along with two of the screws I will use. The Screws are M1.2 screws and have a length of 6mm.
After putting everything together for trial, it is I guess obvious that the screws still need to be shortened.
The grate yet needed to be machined on the outline to fit the drawer front. Doing this was pretty easy on the lathe, I "only" had to position the grate on my "glue-Chuck" and then hold it while the glue was curing.
Like for the other drawer, I forged a handle - this time for the grate - and cut and bent a piece of brass sheet into an end cover for the opening of the grate. This should prevent the air to be drawn in right at the handle.
I also managed to cut the threads without breaking the tap and finally could assemble the three parts to the finished grate. I still have to first pickle the two brass parts and finish them using some non-voven abrasive. I ususally cut squares from it (length in about 18mm or 3/4 inch) and then take three of them on a mandrel and use them as a dremel tool. That works really well for cleaning parts from light oxide scale like it appears after glowing brass after beding or hard soldering. (It also works really well to remove the "copper spots" on hard soldered brass!)
Then you can see the two drawers, both turned out really well.
And finally the how-it-looks-together-with-the-boiler picture.

This is it, the drawers are done. Now I will need to get me some new brass sheet before I can start with the smoke-Box.
The next thing will be the firedoor, as I have already everything I need for that one. Its oval shape will be a challenge for machining, because I do not have cnc yet (Im dreaming about for a long time already, and it will come for sure sometime)

Cheers Florian
Title: Re: A small cochran boiler
Post by: Robert Hornby on March 27, 2016, 10:27:57 PM
Florian, I am just flabbergasted at the quality of your work. Really, it is a piece of exquisite art and should be on show for all to be amazed. The coal grate tray assembly is superb, you must be very proud.
Bob
Title: Re: A small cochran boiler
Post by: fumopuc on March 28, 2016, 07:43:42 AM
Hi Florian, great work as always. What kind of fixture is used there to keep the grate in the four jaw chuck ? I have seen it already in an earlier picture on your bench, but could not understand the function.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on May 19, 2016, 08:40:28 PM
So. Let me try if it works this evening:

Achim, that fixture you mention is simply a faced piece of aluminium, with some small grooves added.
The workpieces are held by superglue.

This kind of clamping fixture is very handy for thin and flat parts that are not easy to clamp.
Some advantages of it are:
- you can machine thin parts without any chattering
- its possible to machine the full length of a workpiece with no clamping possibility from the inside
- you can machine away the fixture - as it is just a piece of aluminium, it won't bother you. All you have to do is face turn it again for the next use (if at all)

The only thing to keep in mind is that you face turn the fixture when it has been out of the chuck.

Florian (to be continued with some progress on my cochran build)
Title: Re: A small cochran boiler
Post by: Florian Eberhard on May 19, 2016, 09:10:16 PM
It does work - thats fine.

I had the whole report written and already pushed the "post" button. Then I immediatley thought I might better copy all the stuff I had written as the website was not responding immediately. 
All fine until then.
But the mistake after that was that I copied something somwhere else and when I noticed the server was definitely not responding, I had only a small passage of a text I had written for somwhere else.  :Mad: Half an hour just gone for nothing  :facepalm:

Well - I hope I do it better tonight:
After quite a long break(7 weeks) , I started again with the cochran boiler. The firedoor will have a flange around the fire door that carries the hinge and the latch. To find out what shape I had "created" when making the fire hole tube, I first made a paper ring to see if the dimensions were in about right.
The easiest way would have been do machine that ring out from a piece of brass tube with a wall thickness of 4mm. But I did not have any brass tube like that.
So what - I decided to bend it from a piece of flat stock.
If you want to bend 4mm thick flat material, you need some kind of a fixture because just using the hammer wouldn't really work like it does with 1mm brass sheet.
I decided to make a die, you can see how I machined the hollow part of it (Using my new clamps!)
The convex part of the die is a round piece of aluminium machined to 60mm. Then I annealed the piece of brass and pre-bent it cold. Naturally there was quite some springback and I will have to bend again. For the second step of bending, I decided to bend the brass when it is hot. So I heated it up to cherry red and put it in the die. This turned out well, you can see that the vise has been released again and the die is still closed
I used the convex part of the die clamped in the vise as a superglue chuck to machine the ring. The ring shape is by the way generated by different radii. That makes it possible to machine that shape on the rotary table.
Then I positioned the vise to the right place on the rotary table, using the bore in the center of the part to relocate the center of the ring (and also to move the workpiece so the radius center was right on the center of the rotary table). The X-direction could be made by moving the part in the vise, the y direction was realised by moving the vise along the 124 blocks.
Then the outline is completed, the opening just startet with one radius done.
Not long and it looked like what you can see on the left picture at the bottom.
I am really happy with the result, which is by the way the second attempt. The first one went wrong on the second radius which I somehow machined too small. I have now Idea how exactly that could happen, but I was really pissed off - especially because I though that I would have to remake the convex die too. Luckily it was not so and then I acutally was quite the second time.
The ring only required very few sanding with a small dremel sanding drum to fit it to the boiler. I really like how it turned out (though it is not finished yet...).

Cheers Florian
Title: Re: A small cochran boiler
Post by: zeeprogrammer on May 19, 2016, 10:14:11 PM
Very nice part Florian.

And thanks for posting your process. Educational.
Title: Re: A small cochran boiler
Post by: b.lindsey on May 20, 2016, 12:15:56 AM
Great to see an update Florian. Beautiful work as always.

Bill
Title: Re: A small cochran boiler
Post by: Don1966 on May 20, 2016, 01:08:11 AM
Florian that is some beautiful work and well thought out......... :ThumbsUp:


Don
Title: Re: A small cochran boiler
Post by: Florian Eberhard on July 17, 2016, 11:07:31 AM
Hello Everybody

Yeah i know, once more it has been a while since my last post. And the reason is not that there was no progress. I was simply too lazy to write something in here!  :embarassed:

So at the moment, I guess you can be happy that there is a moment when I am NOT too lazy to write  ;D:

After i finished the shape of the firehole ring, I started with the door. I first copied the inside shape of the ring onto an already bent piece of 1mm brass.
I then marked an offset of 5mm (I think) and roughly cut out the door using a cutting disk.
The outline was shaped using a file and comparing it to the shape of the ring. Then I immediately had the Idea that the ring was too strong and kind of looked not like it should. I then decided to machine off 1mm of the ring by using the fixture which already helped machining the ring. Once more, I used instant glue to fix the ring to the piece of aluminium.
Then I machined the ring on the lathe using the powerfeed on the lowest feed rate available (in order to keep cutting forces low). Now that is much better than before.
The fixed part of the firedoor hinge will be made from two pieces. The ohter art of the hinge is also soldered together and then cut into stripes. Those stripes got their riveting holes drilled on the milling machine. After that, they were copied to the door.
The latch itself is a one-piece part machined from  square brass. The mounting flange was made using my boring head.
Then I machined the rest of its shape in different settings (but only by tilting the part in the vice)

To be continued right away..:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on July 17, 2016, 11:27:08 AM
On the first picture, you can see the latch put together with the rest of the firedoor.
A lever had to be designed and made. I first machined the outside using a small piece of aluminium and two M2 allen screws for the setup.
After milling part of the shape, I filed the rest and I got a lever. But - actually I wasn't really pleased by how the lever had turned out. In the meantime, I also made a hub for the lever (which is also going to carry the heat shield of the door). So I could test the lever for the first tme and I had to find out that it was too short. Well this lead to the decision to make another one
Same setup as for the first one but with a different Idea of how to make it. And it is looking much better. The shape is also a lot more pleasant looking (in my opinion at least)
I also made a heat shield from a piece of 1mm stainless steel sheet to keep the door cool (still to be proven that it works though  ;D )
The door also needs a **thing** (I don't know how to call this in english - its that piece of bent sheet metal which is around the door lever and limits its way as well as holds it close to the door).
I decided to try out something and made a die and a punch to form the **thing**
Finally, the firedoor is complete. I made a small wooden handle out of boxwood and riveted the **thing** to the firedoor
Title: Re: A small cochran boiler
Post by: Jo on July 17, 2016, 11:49:42 AM
Thank looks the part  :)

The door also needs a ***** (I don't know how to call this in english - its that piece of bent sheet metal which is around the door lever and limits its way as well as holds it close to the door).
I decided to try out something and made a die and a punch to form the *****.

"Baffle plate "

Jo
Title: Re: A small cochran boiler
Post by: Florian Eberhard on July 17, 2016, 12:45:59 PM
Hey Jo
Thanks so far - but I am somehow bemused by the name,

That thing I marked red is actually called baffle plate? (when searching for pictures of a "baffle plate" with google, then it shows everything else than this...)

(https://dl.dropboxusercontent.com/u/21771006/Hobby/Cochran%20Kessel/IMG-20160619-WA0014%20-%20mod.jpg)


Florian
Title: Re: A small cochran boiler
Post by: tangler on July 17, 2016, 01:05:54 PM
I'd call that a "staple".  The baffle is your stainless steel plate on the inside of the door that has an air gap between it and the door and acts as a radiation shield.  Lovely work by the way.

Cheers,

Rod
Title: Re: A small cochran boiler
Post by: fumopuc on July 17, 2016, 03:18:06 PM
Hi Florian, a really lovely work, as mentioned by Rod already.
Title: Re: A small cochran boiler
Post by: Kim on July 17, 2016, 03:45:44 PM
I agree with Achim and Rod; lovely work!
You put so much time and care into those small door pieces.  The door being curved in two dimensions makes all of the parts very difficult to machine. But you came up with ways to do it all.  Thanks for sharing your process. Very fascinating.
Kim
Title: Re: A small cochran boiler
Post by: b.lindsey on July 17, 2016, 04:31:10 PM
Beautiful Florian...glad to see an update on this one!!

Bill
Title: Re: A small cochran boiler
Post by: Gas_mantle on July 17, 2016, 05:02:03 PM
Hi Florian,

I've got to agree with the others, it's an impressive piece of work and something to be proud of.

Any idea when it will be fully completed ?
Title: Re: A small cochran boiler
Post by: Bluechip on July 17, 2016, 08:09:42 PM
I don't know what they're called on a boiler, but if it were a standard arrangement on a door the red bit is the limiter, 'cos that's what it does. The bit being limited is the latch arm and the part with the notch is the strike. No idea why.  :headscratch:

It may be that other names exist for what is after all a common item.

Dave
Title: Re: A small cochran boiler
Post by: mnay on August 05, 2016, 07:55:07 PM
I just went through the complete thread
Wow!!! great work. 
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 18, 2016, 08:26:46 PM
Thanks for all the compliments, they are an additional motivation to continue further with my project!  :cheers:

I barely did anything on my boiler for the last few weeks - the wheather was just too good everytime I had some spare time.
Instead, I did other beautiful and fun things  ^-^  (The first picture gives you an impression  ;) )
Until last week when the wheater turned cold and a little more humid. This was also the point when I picked up the work again. And that means sheet metal work for the smoke box. 
But first, a piece of wood was cut off from a pear log. That piece had its sides cut off and got squared.
With two faces cut off in different agles, the shape of the typical cochran smokebox slowly becomes visible. For machining these faces, I used a vice in another one and tilted the vice itself as well as the piece of wood in the vice. Now that the form is ready, I switched back to metal working:
To find out what shape the raw sheed metal piece had to have, I used some paper and folded it to a smokebox. After I was pleased with the shape, I started working on the metal version of it. Bending metal is of course not as easy as folding some paper and doing it without a sheet metal bending machine it is even more difficult. This finally also resulted in one failed attempt where the smokebox finally was 2mm to large.
So, I had to start again. I have done the beding with a block of aluminium and a mallet. The flange was clamped between two other pieces and then I started holding the aluminium block almost flat on the sheet metal. Then I hammered down the front of the smoke box until it had reached the correct angle.
The second attempt was succesful and the height of the smoke box wall was machined on the milling machine.
The first "test" on the boiler also looked good, so its clear for further machinig

But thats gonna come next time.
Have a good, Florian
Title: Re: A small cochran boiler
Post by: b.lindsey on September 19, 2016, 12:55:26 AM
Nice to see you back on this project as well as the new roller project Florian. Everything you do adds to the beauty of this boiler.

Bill
Title: Re: A small cochran boiler
Post by: metalmad on September 19, 2016, 01:57:47 AM
Hi Florian
This is Fantastic Work !!
Pete
Title: Re: A small cochran boiler
Post by: Dave Otto on September 19, 2016, 02:23:51 AM
It's always nice to see an update on the boiler project Florian.
I enjoy seeing your progress.

Dave
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 20, 2016, 08:52:14 PM
Good Evening

Thanks Dave, Pete and Bill!

I am not only trying to making every part as good looking as possible - I also try to refine my techniques for further projects. The next project that I am planning (after finishing a few other unfinished projects including the bending rolls) is a scale G locomotive.
And since locomotives include a lot of sheet metal work, this is good practice I guess   ^-^

To cut out the smoke box openings, I screwed the part onto the wooden negative. Then clamped it in the milling machine and started milling (always milling along the x or y-axis and adjusting the vertical axis in the same time)
During machinig I actually wished I had a cnc machine - but however, it turned out well.
Then I again started with some round material with a drilled center hole. Then I milled a step into the material. That is to position a piece of sheet metal which then gets silver soldered to the round bar.
After that, I used the slitting saw to cut stripes for the hinge.
The doors have been made from the first smoke box bending-attempt. (In order not to waste brass sheet metal  ;) )
To get the riveting holes drilled identically on both doors, I quickly made a fixture for postioning and holding them. The "clamps" are improvised since I had nothing that small (and didn't want to make them at that time)
The hinge stripes have been drilled in a small vice. After that, I made a first test - setup:
And here we are, the doors are fitted to the smoke box "walls".
Coming up next is the bottom- and top piece of the smoke box and soldering all parts together.

Cheers Florian
Title: Re: A small cochran boiler
Post by: b.lindsey on September 20, 2016, 11:56:23 PM
Very nice Florian. I can see now where you are going with this!  The doors look great!!

Bill
Title: Re: A small cochran boiler
Post by: Dave Otto on September 21, 2016, 12:12:14 AM
I love the way you fabricate your hinges; I will file that one away for the future.

Amazing work!
Dave
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 26, 2016, 07:08:34 PM
Good Evening Dave, Bill and all the others.

I can see you two are following pretty closely. Dave: If you also want to make the hinges like this - I cut them in several passes so the cut gets straight.

Over the last few days, I managed to get some shop time again:
Have a look at what came out:

This is the smokebox being completed - at least as a raw piece. Top and bottom sheet are being soldered to the walls.
I like this technique - you don't need to work extremely exact, you can just cut away the excess material afterwards and therefore you are pretty quick. Soldering went really well too.
Then I prepared the boiler for the smoke box. I had to trim the frame which is going to hold the firebox. I also needed to file away some silver solder which was at the wrong place.
After that, I started fitting the smokebox to the boiler. I used a rotary file bit for this work. That took quite a while and produced a load of very sharp but extremely small brass splinters - I must have pulled out about 20 of them from my fingers  >:(
After some sawing and filing, the smoke box starts to look like it should. Also on the boiler it does add to the look of a cochran boiler. With the smokebox so far done, I needed to start thinking about the chimeny. I had the idea to make a flange which will hold the actual smoke tube.  I machined the shape from a piece of brass, then clamped it on the rotary table and drilled the screwholes. Then i was going back to the lathe and carefully finished the inside. 
And there is everything arranged for a picture (I still need to drill the screwholes and machine the smoke exit opening into the smoke box)

See you next time!
Florian
Title: Re: A small cochran boiler
Post by: Admiral_dk on September 26, 2016, 09:33:29 PM
Still following along on your great project  :praise2:
Title: Re: A small cochran boiler
Post by: b.lindsey on September 26, 2016, 11:55:20 PM
More fine work Florian. It just keeps getting better!!

Bill
Title: Re: A small cochran boiler
Post by: Don1966 on September 27, 2016, 12:00:35 AM
Beautiful craftsmanship ........ :praise2:

Don
Title: Re: A small cochran boiler
Post by: crueby on September 27, 2016, 12:40:09 AM
The boiler is coming along great! Your sheet metal work is definitely up to a locomotive! Do you have a particular one in mind to build?

 :popcorn:
Title: Re: A small cochran boiler
Post by: ozzie46 on September 27, 2016, 01:49:38 PM
Still following along and the workmanship is excellent.   :whoohoo:

Ron
Title: Re: A small cochran boiler
Post by: joe d on September 27, 2016, 02:57:48 PM
That's turning out great.

I'm looking forward to see what you come up with next!

Joe
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 15, 2016, 09:43:09 PM
Good Evening Everyone!

The boiler is coming along great! Your sheet metal work is definitely up to a locomotive! Do you have a particular one in mind to build?

Yeah well I have started drawing one in my CAD program a long time ago.
But it will be a freelance locomotive without a full scale model.
It will be coal fired, in Scale G (45mm gauge)
I have attached a picture of my construcion.

But now, lets talk about the progress on the cochran Boiler:
I first drilled a hole into the smokebox for the chimney. Since my biggest endmill has a diameter of 16mm and the chimney has got 19mm on the inside, I had to use my boring head for the finish.
The mounting holes were drilled with thelp of the flange.
Next up were blower and blast pipe. And I was thinking about it for a long time. The really good Idea only just showed up after I had made a blast pipe jet, which resulted in a new jet.
The jet has got three blower holes and in the middle there is a big hole for the blast pipe.
Sticking three drills into the blower holes clearly shows that they meet at a point above the blast pipe/blower nozzle.
The blast pipe and blower asssembly will be located in the smokebox like illustrated in the picture where you see the smokebox from the inside.
Then I made some flanges for connecting exhaust steam and blower steam line to the smokebox using the integrated dividing jig of my lathe spindle and a dremel (acutally dremel-like tool).
And finally on the smokebox, shown from both sides

Will be continued right away...
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 15, 2016, 10:08:07 PM
To form the connection between Flange and blast pipe body, I made a small bending tool from a piece of wood since the 4mm tube will be quite difficult to bend around such sharp corners as required in the smokebox
To show where the tube will have to connect to, i have inserted two cylindrical pins into the connection holes.
Bending was successful, though I have realized that a tube bending tool should be on my todo-list aswell. The tubes then were silver soldered to the blast pipe body.

In the meantime, I shortened some M1.2 screws for the chimney flange to screw the flange to the smoke box.
And there is the blast pipe and blower assembly built into the smoke box after pickling.
The Door hinges are not yet finished, so I screwed them down to a piece of brass for finishing (first cutting off the excess material and then file the end into the desired shape)
And this is the point where I got sidetracked quite excessively. I realized that i cannot reach the rivets with a straight punch. I then decided to build a riveting tool like it is sold by ateliermb (a swiss guy)  (http://www.ateliermb.ch/shops/gussteile/ch/contents/en-uk/d31.html).
The picture shows what came out. (I am going to open a seperate thread about building it)
Now riveting in the inside of the smokebox was really easy and I am extremely pleased by the tool i had built.
(The shaft of the rivets was a little too short so the head is not completely formed. But that works good enough for this application)
And there you go, all the hinges riveted to the smokebox. I really like the result!

Cheers Florian
Title: Re: A small cochran boiler
Post by: b.lindsey on October 15, 2016, 10:50:43 PM
Most impressive Florian, it just keeps getting better with each new update. Can't wait to see it in action now!!

Bill
Title: Re: A small cochran boiler
Post by: Dave Otto on October 16, 2016, 12:03:37 AM
Wow that looks nice Florian.

The rivet squeezer is also a beautiful tool; I really need to make something like that someday.


Dave
Title: Re: A small cochran boiler
Post by: crueby on October 16, 2016, 12:40:42 AM
The boiler is coming along great, also I am VERY interested in the rivet forming tool construction and use, as I have a project coming up with a lot of rivets! I have not seen a tool like that before.

 :popcorn:
Title: Re: A small cochran boiler
Post by: Kim on October 16, 2016, 03:38:00 PM
Wow Florian, this looks great, as always.  I've been following along since the beginning, though I haven't commented much.  But I just wanted to say, VERY impressive work.  And I too, am interested in your riveting tool.  I'd love to see how you made it, and see it in action.

Those look like copper rivets your using there?

Kim
Title: Re: A small cochran boiler
Post by: Roger B on October 16, 2016, 06:34:32 PM
Beautiful work, as ever  :praise2:  :praise2:

Do you have a G scale layout to run your Locomotive on? Are you going to insulate the wheels so it can be run together with electric locomotives? I had a couple of G scale garden lines in England but currently all my stuff is in the attic.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 16, 2016, 08:45:26 PM
Good Evening! Thank you everyone for the compliments!

Kim, you are right, i am using copper rivets. I once bought an unfinished locomotive project off from ebay and in the parcel there was also a box with approximately 500 copper rivets. That is even the reason that I started using rivets!

Roger, I don't have a layout (would love to have one though) but up to now i (almost) have no reason to have one. Though I still have an LGB Mogul on the shelf but never had the intention to run it (I wanted to build a livesteam copy of it. But that project is quite far away right now...)
I honestly didn't think about the insulation of the wheels yet. But that would be quite some effort to do it properly because the axle is not the only thing that conducts electricity (also the linkage which would have to run on an insulated pin aswell as it should not be possible that it touches the wheels in any position!)

I guess I am rather not doing that but maybe - who knows - If I have some good ideas coming up?

Cheers Florian

Btw: I just wrote the first (of two) part of the building log about my riveting tool : http://www.modelenginemaker.com/index.php?topic=6497.msg132888#msg132888
Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 28, 2016, 09:16:06 PM
Hello Everyone

Yeah i know, I was quiet for a looooong time (at least about that boiler).
BUT i only wasn't writing, the boiler was proceeding nevertheless  ;) ;D

You may remember my thread about making the square broach, now I guess it is more than time to show you what I made it for:
I needed some rotating latches to hold the smoke box doors closed. They started as a small piece of brass. The first step was drilling them.
Then I clamped them on a small mandrel (made from a hex head screw) to machine the step.
Finally this is where the square broach was used. Some filing after broaching the square hole and they were finished.
The handle is directly added to one end of the axle and I first machined the square onto both ends of a piece of brass rod and drilled a M1.2 threaded hole into them.
And the moment of truth: The latches go on the axle with a slighly snug fit - exactly as intended  :whoohoo:
The levers have been turned using a form tool (which is not easy because of the huge overhang of the small brass rod. I also broke off the first or the second lever and had to start again.
There you go, the levers are bent too now. But somehow they look out of scale compared to the rest of the boiler.  :rant:
So this is it for tonight. I will have to redo the handles, the Idea how they shall look is not yet here though..!  :thinking:

See you next time, Florian
Title: Re: A small cochran boiler
Post by: b.lindsey on November 29, 2016, 02:07:12 AM
The handles look very nice to me Florian, but of course you are the one that needs to be happy with them. More great work on the boiler though. Thanks for the update.

Bill
Title: Re: A small cochran boiler
Post by: steamer on November 29, 2016, 01:44:58 PM
Hey Florian,

From a 12" to the foot scale, If I was firing that boiler perspective..............,

Opening the doors would be for clean out, and perhaps blowing/punching tubes

That said   I would make them small and fit close to the face of the door.   Simple handles

Additionally, again .....if I was swinging a shovel on that boiler in full scale, I'd want the handles as far away from the fire box door as I could get to avoid catching a shovel, or my shirt sleeves...or anything else on the handles...



...but that's just me......you own the Florian Cochran boiler company....build any way you like!!  8-)

Dave
Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 29, 2016, 07:14:30 PM
Hey Dave

You are talking about the same points I had in mind. The levers are too big and not close enough to the doors. Thats what i don't like about them.
I'll keep them until i have a better Idea how to make them and how they should look like exactly.

So whats next:

To keep the smoke box doors at reasonable temperatures, I decided to also mount heat reflectors on them. The reflectors are made from 0.5mm thick stainless steel sheet. Somehow there were no pictures around from making them. I then positioned them on the doors and fixed them with a little bit of superglue.

Then I took out my fixture for the doors (and made two clamps to hold the door-reflector sandwich) and drilled the mounting holes for the reflectors.
And once again, I made a mistake. The marked hole has a diameter of 3mm instead of 2.5mm. I have no Idea why i picked the wrong drill but that meant making a new door. The new door is already cut off from some 1mm brass (Above the ruler are the reflectors).
Drilling the new door went pretty fast since the fixture was already in the vice.
Meanwhile I used the crap door to test how to make the spacers between door and reflector. The attempt below was to rivet some nuts with a rivet-pin end into the door. Well that one did not work, you can see how the brass around the rivet head was distorted.
Now, I really did not want to have anything else than a rivet-head on the outside of the door. Finally I decided to make bolts with a rivet head and a conical section between thread and head so the bolt won't turn free when tightening. And that luckily turned out how I had imagined.
The bolts are held by some overlong nuts that I made. The reflector will then be fixed with anohter nut.
And again I made a mistake. The bolts are one millimeter too short..!  :facepalm: -> I needed to get some more sleep and after that everything worked again. Well - I should know that actually  :slap:

Ok, so much for now - I'll continue here a bit later.
Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 29, 2016, 09:01:03 PM
Back again!


I just took two more pictures from the doors, one with closed and the other with opened doors.

Finally the smoke box is done, lets see what there's left:

1. making the "foundation ring" (is that the right expression for it?)
2. finishing the reversing chamber
3. making new handwheels for the valves (since the wooden rings got loose - I've got to find another design..!)
4. shortening the chimney and probably make a ring for the top of it (I am not sure yet if I want one)
5. some pipework

I started off with the first task (thats why it has the numer 1  :LittleDevil: ). This hollow gunmetal piece was just perfect considering its dimensions. So I machined ID and OD and cut off a short ring. 
Once more I used my superglue chuck to finish the second side.
Drilling the holes was pretty easy with my dividing head. Just had to watch out to get the right divisions.
After drilling the holes on the flat part of the angle section ring, I milled off the excessive part.  Luckily I had to remove part of the ring because it had become loose when I drilled the second last hole (and the hole was a little egg shaped. The drill survived though). So for finishing I just clamped the ring down, since the forces were going to be rather low:
The last step was riveting the ring onto the base of the boiler. (I of course used my riveting pliers for that 8) )
And here is the last picture for this time: a preview on how the boiler will look finally:

Cheers Florian
Title: Re: A small cochran boiler
Post by: Don1966 on November 30, 2016, 12:35:58 AM
Beautiful piece of work Florian....... :praise2:

Don
Title: Re: A small cochran boiler
Post by: Zephyrin 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.
Title: Re: A small cochran boiler
Post by: Dave Otto on November 30, 2016, 01:53:19 AM
Beautiful work Florian!
It's always enjoyable to see an update on this project.


Dave
Title: Re: A small cochran boiler
Post by: steamer 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)

(http://i164.photobucket.com/albums/u27/mcandrew1894/Steam/Img18-1.jpg) (http://s164.photobucket.com/user/mcandrew1894/media/Steam/Img18-1.jpg.html)

Just an example.....

Dave
Title: Re: A small cochran boiler
Post by: 10KPete 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
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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 (http://www.modelenginemaker.com/index.php/topic,6423.0.html)!

So, see you over in the other thread ;)

Cheers Florian
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: zeeprogrammer on August 16, 2017, 11:35:15 PM
Awesome stuff Florian.
I always enjoy coming across your stuff.
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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




Title: Re: A small cochran boiler
Post by: Ye-Ole Steam Dude on August 17, 2017, 09:43:44 PM

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

Thomas
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: b.lindsey 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
Title: Re: A small cochran boiler
Post by: Gas_mantle on August 22, 2017, 08:32:03 PM
Looking great Florian, nice to see you have returned to showing updates of your work :-)
Title: Re: A small cochran boiler
Post by: steamboatmodel 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.
Title: Re: A small cochran boiler
Post by: Florian Eberhard 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
Title: Re: A small cochran boiler
Post by: Roger B 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  :)
Title: Re: A small cochran boiler
Post by: Florian Eberhard on August 23, 2017, 09:03:08 PM
Hey Roger

Sure - I would say if you wait until the beginning of winter, I should have moved my shop to the new place. (I hope so :P )

I was continuing work on the cochran boiler last weekend. The radiation shield (made from 0.5mm thick stainless steel) has been machined to fit the reversing chamber as exact as possible. To check if it works together with the cover, I took two spacers totgether with douple-sided adhesive tape and sticked the cover and the shield together.
I had to remove some material again but it seems to work. Then I drilled the holes for the stud-threads that will hold the clamps.
And as always when it seems to work pretty nice and you get a little careless, the disaster happens!  :facepalm: :zap:
The drill tip broke off in the boiler shell  :Doh: :facepalm2:

Well - I started research on how to remove a tap and it seems you can use sulphuric acid (I could ged some battery acid) to dissolve the drill redidues.
I haven't done it yeat and will of course test it on something else than the boiler but it should work, since some people use it to remove the residues and oxides from soldering.
I will of course let you know when I was successful.

I contintued with the other 10 holes, cut threads and took some cut-off M1.2 screws to make stays from. I first determined how long they had to be and then cut them to legth on the lathe.
Finally a test assembly with the reversing chamber cover and 10 of 11 clamps looked good and seems to work.

See you with the next update,
Florian


Title: Re: A small cochran boiler
Post by: crueby on August 23, 2017, 10:40:25 PM
Looking fantastic, very interesting shape to that boiler, almost like Captain Nemo's scuba tank!

 :popcorn:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 17, 2017, 01:23:08 PM
Thanks Chris!

As mentioned in my last post, I had a piece of broken off drill in my boiler. In the meantime i got some sulphuric acid and gave it a try. I positioned the boiler with the whole pointing upwards and then put a drop of acid onto the hole. Then used a needle to get the air out and waited. There was a little bubble of hydrogen gas growing - but rahter slowly. So I heated the boiler up to in about 50C and there we had the bubbles coming out of the hole pretty fast. After half an hour not much happened anymore, so I heated up again and after another 30 minutes i had to replace the acid. Then again, heating up the boiler and with the new acid, the bubbles were produced pretty fast. This whole game was continued for another 2 hours and then when I came back to check, I saw that the tip of the drill was laying on the boiler, right next to the hole. So the bubbles must have lifted it out of the whole. And I must say that worked pretty good! Not the copper,  nor the brass or the silver solder has been attacked by the acid but the drill tip came out without any effort!  :whoohoo: :cartwheel:$

Okay, this also raised my motivation further up an the next step was to make a few spacers for between the reversing chamber cover and radiation shield. And I made two brackets that were used for lifting of the cover on the real cochran boilers.
Those brackets were made from sheet metal, that was bent into an angle first. Then I machined all of the sides in the milling machine, drilled the three holes, machined the beveled side and rounded the corners with a file.

See you next time,
Florian


Title: Re: A small cochran boiler
Post by: Gas_mantle on September 17, 2017, 06:20:04 PM
Looking great Florian  :)

Are you intending to marry up the boiler with a particular engine or is it a general purpose item ?
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 20, 2017, 09:29:35 PM
Thanks Peter!
I am not yet sure what I want it to connect with, originally I thought about my little stephenson engine but i will have to figure that out yet.

The Cover and the brackets were riveted together and four holes to connect the radiation shield with the cover were drilled.
I am using rivets to connect those parts and made four spacers from a 3mm dia. brass rod. Riveting was done with my rivet squeezer and once again I am happy that I built it.
Oh and who finds the mistake on the third picture?  :facepalm: Well - its on the inside so I decided to ignore it.
And of course the picture together with the boiler, with all the clamps mounted.

This was another step closer to the finishline. Now there are only 3 major tasks to be completed:
- Handwheels. The ones I made a long time ago came apart because the wood didn't keep its dimensions (which I should have known before). So I am going to make new ones.
- Base plate. I want to make a base plate and then connect it to the base of the boiler using rivets.
- Upper end of the chimney. I want to have some kind of a cap ring or so on the end. I will yet have to find a pleasant form though. (Or have an Idea how to do it)

I did begin with the handwheels 2 weeks ago. First I machined the Handwheel body. Then the wooden collar was made, also in the lathe. And (no pictures) a clamping ring was made too.
The hanwheel is then screwed together with six M0.6 screws.
What you can see on the pictures is the main valve handwheel. There are two more to be done, the one for the blower and the one for the water gauge drain valve - but more about those two next time ;)

Florian
Title: Re: A small cochran boiler
Post by: crueby on September 20, 2017, 10:19:56 PM
Really looking great! Your surface finishes are excellent.


That extra hole jn the inner heat shield? Call it an inspection hole, or a locating hole for the holding jig!  If there was no mistake anywhere, it wouldn't be handmade!   :cheers:


 :popcorn:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 21, 2017, 06:08:34 PM
Your surface finishes are excellent.

Hi Chris

I guess you are talking about the finish of the brass cover?
That is only because the sheet metal had a very good finish from the start. That finish was even improved during the bending process since my bending rolls have an excellent surface finish (ground rolls).
For the end finish, I first reduced any oxides by pickling. Then I threaded the surface with the dremel, using some abrasive fleece in a mandrel (I usually take 3 squares and line them up on the screw). After the fleece, I finish by using some fine grate steel wool. And then you get that finish you can see in those pictures.

Quote
That extra hole jn the inner heat shield?
You got it! Inspection hole sounds good, I like it!  ;D

And here are the other two handwheels:

First I made the wheel bodies, then the clamping rings. Those smaller wheels will have an outer diameter of 12mm over the wooden collar. The wheel body has an outer diameter of 10mm.
The wheel bodies had to be turned around and were rounded on the bottom, just like I did it with the bigger wheel (which has by the way 16mm outer diameter). The wooden collars were cut off and test-fitted to the wheel bodies.
To finish the collar outside, I quickly made an arbour to clamp them on the inside. The rest was then done with a file.
On the last picture, you can see all the valves with wooden handwheel and the old wheels right behind.

So this means I am done with one of 3 points! And I am looking forward to complete the boiler within the next 2-3 weeks. At least so that I can fire it up for the first time!

Cheers Florian
Title: Re: A small cochran boiler
Post by: crueby on September 21, 2017, 07:16:50 PM
Those handwheels are great - the wood really sets them off. What kind of wood did you use? Is there a risk of such a thin rim cracking along the grain lines with heating/cooling/moisture/oil? One thing I have done on small bits on carvings (talons, beaks, etc) was to harden them by soaking in some super-glue.

 :popcorn:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on September 21, 2017, 07:30:39 PM
Thanks Chris

I don't think that they will crack, boxwood is pretty tough and has a very fine grain.
In addition, i am going to soak those rims with some beeswax. I have done this before and it works pretty well. I usually melt the wax, put the wooden handles in and let it soak for 15 minutes to half an hour.

Florian 

Title: Re: A small cochran boiler
Post by: crueby on September 21, 2017, 07:37:41 PM
Thanks Chris

I don't think that they will crack, boxwood is pretty tough and has a very fine grain.
In addition, i am going to soak those rims with some beeswax. I have done this before and it works pretty well. I usually melt the wax, put the wooden handles in and let it soak for 15 minutes to half an hour.

Florian
That will give them a great sheen as well.    :ThumbsUp:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 08, 2017, 09:18:17 PM
Good Evening

Well I might need to extend those 2-3 weeks a bit. But I do have some progress to show:

I finally decided against a cap ring on the chimney top. I remembered almost no horizontal boiler which had a cap ring and I also didn't have an Idea about how to design it so it looked good. The solution was this:
I first machined a former and a plug - the plug should support the end of the tube so it doesn't get damaged when pressing the tube onto the former. The chimney tube was cut to lenth before. Then I annealed the tube at one end, applyied some grease and pressed the chimney onto the former.
After using some fleece and steel wool afterwards, the chimney came out pretty nice - and I like how it looks together with the boiler.
-> Another point completed! :)

Cheers Florian
Title: Re: A small cochran boiler
Post by: Ye-Ole Steam Dude on October 08, 2017, 09:27:36 PM
That looks really nice.

Thomas
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 30, 2017, 08:17:41 PM
Thank you Thomas

I have been pretty busy in the shop for the last few weeks, but now its time again to show the progress.
I startet making the base plate. After cutting ouct a piece of 3mm brass sheet metal from a bigger piece - using a hacksaw - I first machined all the sides.
Then I used a chamfer mill to machine a decent chamfer around the upper side. The aluminium plate supports the brass - I first tried without but the surface was not so good due to vibrations.
The next step was cutting off the four edges using a small slitting saw. I first wanted to use the vee block in the vice but that didn't work. So I used the supporting plate from the previous step together with the vee block which was only used to position the base plate.
As i want to rivet the base plate to the boiler base, i had to drill a few holes into that plate. Having drilled the riveting holes before with the rotary table, I chose to do it the same way with these holes. Those holes were also countersunk to allow the rivet head to be completely inside the base plate.
Unfortunately i was not able to use my riveting pliers for those rivets. They were just too close to the base to have any chance getting there. And riveting while holding several things is not very funny and can lead to unwanted marks pretty quick - so I made an anvil to support the rivet. The anvil was made from a M10 bolt (8.8 grade) and then screwed into an aluminium plate to hold it at the right height. The boiler base close to the anvil was slightly lifted from the aluminium plate to ensure the rivet would sit where it should.
Riveting then went pretty easy, I have not been as fast as with the riveting pliers but it only took me about 10 minutes to do all 18 rivets.
The result is perfect - making that fixture definitely payed off!

Florian



Title: Re: A small cochran boiler
Post by: b.lindsey on October 30, 2017, 11:01:24 PM
The end result looks very nice Florian. You should be getting close to completing it now I would think.

Bill
Title: Re: A small cochran boiler
Post by: Florian Eberhard on October 31, 2017, 06:34:08 PM
Hey Bill

You are right, I am getting very close! (Finally!!  :) )

The firedoor was still loose because I first needed to do the final finish on the boiler.
That included filing away some surplus silversolder. Then I used a dremel abrasive brush (EZ473SA) for the first step. That was followed by some abrasive pad (used on a dremel mandrel) and finally I used some fine grade steel wool. This results in a pretty nice finish, as you can see on the third picture.
I then could also mount the firedoor ring permanently. I filed the firedoor ring hole slighly tapered. After putting the ring onto the firehole tube, I expanded the tube slightly with a piece of plastic and a hammer. That resulted in a pretty good conection, so this is a method I may use again!

Since I didn't plan that kind of boiler base from the beginning on, I had to make a fitting spacer because to be able to mount the blowdown valve. For sealing the fittings, I came up with a new (to me at least!) Idea: I machine a ring that goes over an o-ring. The height of the ring is about 0.8 times the crosssection diameter of the o-ring. Then you simply put the two onto the thread of a fitting and mount it on the boiler. By varying the ring height, you can slightly adjust the fitting position. (For bigger adjustments, you can machine the end face of either the ferrule or of the fitting)

Next up is the boiler feed valve and some pipework aswell.

Cheers Florian
Title: Re: A small cochran boiler
Post by: simplyloco on October 31, 2017, 07:27:59 PM
Delightful! A really classy job.
John
Title: Re: A small cochran boiler
Post by: b.lindsey on October 31, 2017, 08:20:09 PM
Love the family shots Florian. Have sure enjoyed following along on this one....first rate in every way.

Bill
Title: Re: A small cochran boiler
Post by: Dave Otto on November 01, 2017, 12:36:57 AM
Beautiful work Florian!


Dave
Title: Re: A small cochran boiler
Post by: Kim on November 01, 2017, 04:19:05 AM
Amazing work there Florian!  It's just beautiful.  The trick will be to keep it that shiny now!
Kim
Title: Re: A small cochran boiler
Post by: Zephyrin on November 01, 2017, 09:05:52 AM
Beautiful work all along this thread, and very interesting boiler, never modelled as far I know, congratulations...
Do you know what was the main use for such a tall boiler ?
It would be interesting to see her steaming !

Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 01, 2017, 07:22:09 PM
Thank you for your praises!

Kim, I don't want to keep it that shiny, acutally I want it to get some patina, only exhibits stay like that  ;)

Zephyrin, there are at least two models of that boiler that were built before I did it. But they are somehwere from Germany or/and the Netherlands. I have never seen in real though.
And there has at least been another one, which is shown in "Handbuch Modell-Dampfmaschinen", that is kind of the "steam bible" in german Language.
I don't know much about where they were used but wikipedia says it was mainly used in marine applications, either fired by solid or fluid fuel or used for heat recovery from large combustion engines.

The movie of it under steam will come, I promise!

Now where have i been.. Right, fitting and pipe work:
I had to make those sealing "spacers" (used together with the O-ring) for most of the fittings. I also needed to solder a few pies into flanges and reproduced the pressure gauge syphon (the old one was bent too often and not looking good anymore).
To seal the connection between copper tube and pressure gauge, I tried making a 2mm compression ring and well - I was successful! Oh and I never want to do it any other way, because this is so easy in use. No soldering and cleaning off flux, no fiddling around with teflon tape.
You only put your nut on the tube, followed by the compression ring and then screw everything together and tighten it. And there you have your connection.

But i was not just doing well this evening. I managed to break one of the wooden wheels when trying to mount it. Why this happened? Well I had been treating the wooden parts with bees wax before (i acutally threw those parts into the molten wax) and well the wood changed its shape. It acutally shrinked a bit and when I started tightening the screws, the wooden ring was split immediately.  :facepalm:

Well - i'll need to make a new one then!
To be continued in a few monents..!

Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 01, 2017, 08:25:45 PM
So here we go -

As I mentioned,  that evening was not good in every aspect - and I managed to also break the second wooden ring!   :facepalm2:
Well - I was lucky that the lathe tools were still set up and making another one went pretty quick.
So with this last wheel completed, I could finally do a quick testrun on gas!
And well - the boiler is performing extraorinary well!!
I could run my middle size steam engine (14mm bore and 30mm strocke, no expansion) at 2.5 bar boiler pressure and the ceramic burner still wasn't at its limit.
That test was on last sunday - well today I went for the first test using real coal!
I have added two pictures of that aswell - and well - it is even running better than with gas (which I expected acutally).

I have no video ready yet, need to collect some more material first  ;) ;D So this is it. The boiler is running!

A few things are left to be done but this is the end of a pretty long journey which was anything but straight forward! But the result really makes me happy  :Love:!

Cheeeeeeers  :whoohoo: :cheers: :cheers: Florian
Title: Re: A small cochran boiler
Post by: crueby on November 01, 2017, 09:16:57 PM
Excellent job on the boiler!
Title: Re: A small cochran boiler
Post by: Zephyrin on November 01, 2017, 10:43:29 PM
Great picture of the roaring coal fire in the furnace, clearly you could be happy and proud of the result !
Title: Re: A small cochran boiler
Post by: b.lindsey on November 01, 2017, 11:25:00 PM
I can certainly see why you would be very happy with that Florian. Well done!! :ThumbsUp: :ThumbsUp:

Bill
Title: Re: A small cochran boiler
Post by: Dave Otto on November 01, 2017, 11:28:09 PM
Masterpiece of model engineering!
Very nice Florian.

Dave
Title: Re: A small cochran boiler
Post by: 10KPete on November 02, 2017, 12:28:56 AM
Outstanding!! Beautiful workmanship. Love the detail.

Congratulations!! :cartwheel:

Pete
Title: Re: A small cochran boiler
Post by: Kim on November 02, 2017, 01:21:28 AM
Just an incredible job on this Florian!

I love the picture of the simulated coals you have in there. That is a stunning picture!
Is that the kind of rock that you'd find in a gas grill?

Kim
Title: Re: A small cochran boiler
Post by: crueby on November 02, 2017, 01:32:55 AM
Just an incredible job on this Florian!

I love the picture of the simulated coals you have in there. That is a stunning picture!
Is that the kind of rock that you'd find in a gas grill?

Kim

Those last two pictures were actually running on coal, not simulated! Very nicely done!
Title: Re: A small cochran boiler
Post by: Gas_mantle on November 02, 2017, 01:37:11 AM
Looks great Florian, definitely something to be proud of  :)

What is the intended working pressure ?
Title: Re: A small cochran boiler
Post by: Kim on November 02, 2017, 01:54:53 AM
Just an incredible job on this Florian!

I love the picture of the simulated coals you have in there. That is a stunning picture!
Is that the kind of rock that you'd find in a gas grill?

Kim

Those last two pictures were actually running on coal, not simulated! Very nicely done!

Sure enough! Now that I re-read Florian's post, he says exactly that!   I just remembered the "test run on gas" part and completely missed the "first test using real coal" part!  That's even more amazing  :ThumbsUp:
Kim
Title: Re: A small cochran boiler
Post by: bent on November 02, 2017, 07:36:42 PM
Wow.   :o

Great work, Florian!  Your boiler could easily be on display in a museum.  :praise2: :NotWorthy:
Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 02, 2017, 08:11:02 PM
Thanks guys! I am definitely flattered by your praises! But you will have to reduce your expectation a bit for the next project, because this boiler was also meant to be a piece of art!
What I am talking about is that you will not have to expect any bad workmanship in the future but that I will probably keep things a bit simpler or will go a bit less into details like I did with this boiler. My next projects are more about tools and equipment (like a knurl milling tool for the lathe) and about completing a milling attachment for my lathe.
But first you will get some video footage of my cochran boiler! And I need to build a few wooden boxes - one will be for storing and transporting this boiler !

Regards Florian
Title: Re: A small cochran boiler
Post by: MJM460 on November 02, 2017, 08:46:08 PM
Hi Florian, a truly beautiful piece of art, and a demonstration of incredible craftsmanship.  It deserves a beautiful wooden case.  And great to see it completed after following closely the build process.

Of course, being me, I have been wondering if you allowed room for insulation around some of those fittings, but even I have to admit it would be a pity to cover it up.  And I am looking forward to seeing what engine you will choose to drive with it.

Also looking forward to those future projects, I am sure they will still be a master class for me.  So do keep up the excellent documentation.

Thank you

MJM460



Title: Re: A small cochran boiler
Post by: Steamer5 on November 02, 2017, 11:57:20 PM
Hi Florian,

A piece of art it surely is! Pity to have it sitting on a shelf, but all the same a pity to get it all covered in coal dust & water droplets.

On the knurling front must post up my new set

Cheers Kerrin
Title: Re: A small cochran boiler
Post by: derekwarner_decoy on November 03, 2017, 01:29:44 AM
Yes Florian....

Words fail to describe your work.......this is a snap of your image below....is this water that has condensed from the atmosphere on the  valve handle & flange during the steam up?

Derek
Title: Re: A small cochran boiler
Post by: Florian Eberhard on November 03, 2017, 06:18:36 AM
Hi Derek

No, that water came from the exhaust steam. The Hose I used to connect the steam engine to the exhaust blower was not very tight and spit out this water from the steam engine.
The small size of the boiler delievers pretty wet steam and thats What you can See there.

Florian
Title: Re: A small cochran boiler
Post by: gary.a.ayres on July 19, 2018, 06:23:24 AM
Florian -

your skill and attention to detail in this project have resulted in a truly beautiful piece of engineering.

Congratulations!  :cheers:

Did you ever make the video though? I have searched but can't find it anywhere.

All the Best,

gary
Title: Re: A small cochran boiler
Post by: Florian Eberhard on July 19, 2018, 08:11:31 PM
Hi Gary

Thank you! It was a pretty long journey and I even wasn't happy with some things I did at the beginning of the build later on. But I guess this is something you have to deal with if you are building over a longer period of time.
The video hasn't been made yet though. The reason is that I never really heated it up for a longer session since then. I'll need to do this as soon as i can - but at the moment i am way too distracted by the good wheather  ;)

Florian
Title: Re: A small cochran boiler
Post by: Gas_mantle on July 19, 2018, 08:19:12 PM
Hi Florian,

It's a great boiler that you built and something to be proud of  :)

How well does it run on coal?  I have a vertical fire tube boiler of a similar size but find mine struggles on coal  :( 
Title: Re: A small cochran boiler
Post by: Florian Eberhard on July 19, 2018, 09:06:17 PM
Hey Peter

Well it runs pretty good actually. What I experienced up to now is that you have to focus on all details and react fast because the small amount of water results in a pretty quick reacting boiler. That may also come because I am using anthracite to fire it which is anything but easy to handle.
But once you get to know it good enough, you can ceep the pressure pretty good and constant.

Florian
Title: Re: A small cochran boiler
Post by: gary.a.ayres on July 19, 2018, 09:34:00 PM

The video hasn't been made yet though. The reason is that I never really heated it up for a longer session since then. I'll need to do this as soon as i can - but at the moment i am way too distracted by the good wheather  ;)

Florian
Well, I look forward to seeing it in due course, but for now you are quite right - enjoy the sun!