Author Topic: CP-173 Boiler Build  (Read 10357 times)

Offline GWRdriver

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CP-173 Boiler Build
« on: May 13, 2014, 09:35:56 PM »
Some time ago I was asked by a fellow on the West coast to build the copper boiler for a 7.5" gauge Central Pacific #173, also known as Walt Disney's "Lilly Belle."  I began the project over a year ago it's been a long hard slog, interrupted by domestic responsibilities (as I'm sure many of our projects are) but I'm nearing the end and I thought I should begin to post a few photos of the process.  I'll start with a photo of the original Lilly Belle, and Walt in front of his barn.

This locomotive, and Walt's private railroad, were built to 1/8th scale, and 7.25" gauge, but all subsequent versions of the loco, of which there are a couple, are designed for 7.5" gauge.  The bare boiler is approximately 25" overall length with a front barrel OD of 6.125" and on completion will weight in at around 65lbs.  The original boiler design, which we followed, was NOT a tapered wagon-top.  It used a straight tube barrel over which the taper was built up.  This made the construction somewhat less difficult than it could have been but there were other difficult details to construct.  I used 1/8" alloy C-110 copper sheet or bar throughout and all bushings are either C-510 phosphor bronze or SAE-660 bearing bronze, and all stays are C-510 phosphor bronze.  The plate forms used are either steel, red oak, or yellow pine, depending upon their applications.  The silver solder will be Harris 45% non-Cadmium bearing.

The photography is not always the greatest, and no matter how careful I am to try to get a picture of every step, invariably some steps are missed, but there will be enough for you to get the picture.  This thread is going to take some time and will be in installments as I can get to them.

The first step was to review the original construction drawing (dated 1953) and redraw the design in Cad and bring everything up to current construction standards and MY standards) and flesh out all details, many of which are glossed over and left for the builder to figure out in early boiler drawings.
« Last Edit: May 14, 2014, 04:26:51 PM by GWRdriver »
Cheers,
Harry

Offline Robert Hornby

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Re: CP-173 Boiler Build
« Reply #1 on: May 13, 2014, 11:47:30 PM »
OK Harry, as a fellow 'boiler maker' you have got my attention big time. What you have done/doing is a BIG project especially as it is for another person. I look forward to seeing the build photos.
Robert
Age and treachery will always overcome youth and skill

Offline dnalot

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Re: CP-173 Boiler Build
« Reply #2 on: May 13, 2014, 11:49:56 PM »
I'm looking forward to this. I will soon be building my first boiler and I'm looking at and reading everything I can find. That building in the background must have been my inspiration when I designed my shop.

Mark T
Some times it's better to keep quiet and be thought a fool than to speak and remove all doubt.

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #3 on: May 14, 2014, 01:09:15 AM »
Beginning with the Cad drawings, which themselves were, and are still, a work in progress, I developed two sets of  templates (or cutting sheets) for the steel and copper material.  The first set of templates were for the steel forms over which (or in which) some of the heads would be formed.  The second set was for the sheet copper blanks for the heads and wrappers.  So far as I was able, I included the necessary machining, forming, bending, and trimming allowances in the templates.  The templates were then arranged in Cad to produce the smallest sheet of copper which would make all heads and wrappers.  The material was ordered accordingly and the patterns were laid out on the plate and the head blanks were cut.

Photo 001 shows a paper template adhered to a blank of 5/8" steel plate which would become the outer firebox front head former.  This was made in steel for reasons you will eventually see.
Photo 002 is of a the copper plate marked out for cutting.
Photo 003 shows a paper template adhered to a copper blank which will become the firebox front head.  (PS - Sometimes the most expedient way of doing a job is the most primitive, in this case chain drilling out the hole in the blank.)
« Last Edit: May 14, 2014, 04:15:16 PM by GWRdriver »
Cheers,
Harry

Offline zeeprogrammer

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Re: CP-173 Boiler Build
« Reply #4 on: May 14, 2014, 01:47:16 AM »
Nice story to start with and I like the fact you called out the specifics on the metals being used. Very helpful.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #5 on: May 14, 2014, 09:47:48 PM »
Starting the Head Forming Work

Relatively long-term projects like this never run in a straight line for me.  I always have two or three operations (or even projects) under way at any given time so if I get tired (or bored) with one, or if the work needs more thought or drawing before cutting metal, I can move to another task.  I mention this because my sequencing may seem to bounce around a little bit but then that's the way it was built.

I'm going to skip ahead of the next logical step, making the head formers (or flangeing plates) and show you a few finished formed heads.  These were the most critical ones and should give you a better understanding of what and why I did what I did when I made the forming plates.  The flangeing process wasn't all that complicated, but considerable planning, specialized forming plates, multiple annealings, and lots of hammering were required to get them where they are at this point.

In Photo 004, heads A and B are the Backhead and the rear inner firebox head, both of which were required to have a forward offset in the water leg of 11/16" and maintain a minimum water space of 3/8".   The reason for this was never fully explained ("Mine was not to reason why, mine is but to do and die" - Tennyson) other than the owner wanted a replica of the Disney locomotive.  I assume the offset was needed to clear the rear axle and/or bearing blocks.  Other than this offset the forming of the back heads was fairly conventional and straightforward, as was the forming of the front firebox head and the front flue sheet.

The Throat Sheet (head C) was another kettle of fish.  As you can see it was made in one piece and this required a fairly complex sequence of forms, backing plates, and clamping which I will describe in upcoming installments.  The base forming plate and the sheet copper blank for the Throat Sheet are shown in photos 001 and 003 above.
« Last Edit: May 14, 2014, 09:53:01 PM by GWRdriver »
Cheers,
Harry

Offline Rivergypsy

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Re: CP-173 Boiler Build
« Reply #6 on: May 16, 2014, 12:09:13 PM »
Looking good, Harry.

(are you sure i can't tempt you into a Scotch or 57XX boiler build too?  :Lol:)

Offline mikemill

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Re: CP-173 Boiler Build
« Reply #7 on: May 16, 2014, 03:16:31 PM »
Mark

They say everything is bigger in America and your workshop certainly confirms the saying, a building that big would be a three bed house in the UK. By comparison I would guess many model engineers here work out of 8’ x10’ sheds!!!

Harry
Good luck with the boiler

(Envois) Mike

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #8 on: May 17, 2014, 05:38:27 PM »
Now that all the copper blanks are cut I usually start with forming the heads, beginning with the front flue sheet.  I already had a steel form from a previous project (A - Photo 005)   The other blanks and forms in this photo are for another 6" boiler for myself, a 7.5" gauge Double TICH with Belpaire boiler, but that's a story for another day (or year.)

Most of you will be familiar with the forming process, but for those who don't the first step is to anneal the copper by heating it to a dull red and then quenching (plunging) it into cold water.  Annealing is a necessary part of the process and will need to be repeated several times during the forming of each head.  From time to time there is discussion about what the best way to cool copper after annealing is, whether to quench or let it cool in the air.  The answer is, it doesn't matter, the results are the same, but I prefer water quenching for two reasons, it's much faster, and the flash of steam created by quenching will blast off much of the black oxide created by heating.

In Photo 006 the front head blank is clamped in place on the form ready to begin flangeing, but what the photo doesn't show is the steel backing plate on the back side of the blank. This backing plate is required in almost every flangeing situation to prevent the copper sheet from puckering or rolling up when it needs to remain flat. The backing plate is clearly visible in the next photo.

Photo 007 shows the blank (and the backing plate) and the state of the flange after the first hammering and the first annealing will normally allow the flange to be laid over about 1/3rd of the way.  The second annealing and hammering will take the flange to 2/3rds of the way, the 3rd annealing and hammering to closing tight and finishing.  Copper will quickly work-harden from the hammering and must never be forced beyond the point where it won't bend further, and 1/8" copper will definitely let you know when it doesn't want to move any more and at this point needs to be annealed again.  The annealing and hammering is repeated (usually three times) until the flange lays completely over and is tight to the form.  If the flange doesn't lay flat and tight over the form then a fourth annealing may be required.  Photo 008 shows the front head completely formed and ready for machining.

The same process will be used to form all the heads although the more complex heads usually need to be annealed more than three times.  The hammer I use for copper (Photo 009) has replaceable rubber and plastic faces (Vaughn Mfg. #SF6) which can deliver quite a blow but won't damage the copper.  I never use a steel faced hammer on copper.
Cheers,
Harry

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #9 on: July 06, 2014, 04:31:44 AM »
Some of you may be wondering what's happened to this thread, the answer is I've been very busy building the boiler, trying to get it completed, and then there will be lots of photos to sort through, and a narrative to write.  I'll get back to it as soon as I can.
« Last Edit: July 06, 2014, 02:53:46 PM by GWRdriver »
Cheers,
Harry

Offline ths

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Re: CP-173 Boiler Build
« Reply #10 on: July 06, 2014, 11:20:36 AM »
Looking forward to it. Hugh.

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #11 on: December 12, 2015, 05:18:32 PM »
Hello Lads,
I am VERY sorry I haven't posted anything here for over a year and a half  :embarassed: but life (and boiler work) got in the way.  However this boiler has been finished and more construction details will be posted when I can get the photos organized.
Cheers,
Harry

Offline 10KPete

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Re: CP-173 Boiler Build
« Reply #12 on: December 12, 2015, 07:29:50 PM »
Good to see you back Harry!! And the boiler is looking great!   :whoohoo:

Pete
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Offline Bearcar1

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Re: CP-173 Boiler Build
« Reply #13 on: December 12, 2015, 09:14:33 PM »
I too am looking forward to the remainder of the story Hugh. Life sure does have a way of getting tin the way of our play time doest it. Its just not fair, you would think it would have sense enough to not butt-in while one is trying to make something,  :Jester:


BC1
Jim

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #14 on: December 16, 2015, 03:36:30 PM »
(5a)    Throat Sheet Forms & Forming

The fairly complex forming needed for the firebox end of this boiler required some careful thinking through and planning to insure the allowances mentioned in Installment 02 were provided for.  Ending up with a bit too much to trim off is far better than coming up short, which would be fatal.  As we all recognize, from time to time there is more work involved in making the forms (jigs, fixtures, etc) than in making parts themselves.  Such is the case here.

Two formers were needed to form the throat sheet, a male, and a female, and for these I used 5/8" hot-rolled steel plate because the target flange depth was 1/2" and formers need to be thicker than the depth of the flange.  The reason I used steel, rather than say Oak, was that the female form would have to endure a considerable pounding on its I.D. (putting the wood in tension) and I didn't want to have to have to bother with a broken former.  I started with the male former which was rough-sawn to size (Photo 001), then the edge profile machined (Photo 010 and 011) and dressed smooth (Photo 012).
Cheers,
Harry

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #15 on: December 16, 2015, 03:43:45 PM »
(5b)
The female form (Photo 013) was also of 5/8" steel plate, bored, and radiused so as to form a generous fillet in the barrel-side flange.  This former was also left over from a previous boiler project and only needed minor ID modifications.  Frankly I don't recall how I originally rough-cut the center hole, but do recall there was little joy in it!  The copper blank (Photo 003) was annealed around the center opening and sandwiched between the two forms. (Photo 014)  At this point accurate aligning of the two formers and the copper blank became critical, the symmetry of the boiler depended upon it, and this was achieved using scribed register lines on the three pieces.
Cheers,
Harry

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #16 on: December 16, 2015, 03:55:59 PM »
(05c)  Finishing the Throat Sheet Forming

To begin forming, the male form is required as a backing plate to keep the copper blank flat while the inside flange is raised.  The inside flange is slowly raised by first picking up the copper edge by tapping in a thin bladed screwdriver.   Once a spot is raised I continued raising by tapping thin hardwood wedges under the copper, working them all around, followed by a thicker hardwood wedge.  I anneal again at this point and switch to seasoned Oak sticks with mitered ends which are hammered all around to raise the flange further.  (Photo 015)   Gradually the flange is raised and the process is repeated until the flange is fully layed over.   (Photo 016)  To finish forming the barrel flange I.D. I used a short piece of 2"+ diam mild steel bar placed inside the open hole as a hammering "dolly" and working around the opening I snugged the copper tight to the former hole.

To complete forming this head the male former was turned over and the outside flange was hammered in the usual way, annealing as necessary, using the female former as a backing plate, until the flange was fully layed over.  (Photo 017, 018, 019)  The formers were then used as jigs to hold the head for machining and the overall result was excellent and exactly what I was trying for.  (Photo 020)

PS - The final finish on the head pictured, as will be other copper surfaces, wasn't produced by pickling but by burnishing with a 3M Scotch-brite VF abrasive wheel.
« Last Edit: December 16, 2015, 04:00:37 PM by GWRdriver »
Cheers,
Harry

Offline ths

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Re: CP-173 Boiler Build
« Reply #17 on: December 16, 2015, 09:45:39 PM »
Good couple of posts, lots of hammering evident, great result. Cheers, Hugh.

Offline zeeprogrammer

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Re: CP-173 Boiler Build
« Reply #18 on: December 16, 2015, 11:09:44 PM »
My dream is to build a loco someday. Your threads and education is so helpful.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline joe d

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Re: CP-173 Boiler Build
« Reply #19 on: December 16, 2015, 11:28:35 PM »
Harry

Good to see you back!  I will follow along with interest.

Joe

Offline GWRdriver

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Re: CP-173 Boiler Build
« Reply #20 on: March 16, 2016, 10:58:33 PM »
I apologize to all those of you who are following this and have expected more sooner, and there will be more, but lately "Life" has gotten in the way and I'll resume as soon as time permits.
Cheers,
Harry

Offline b.lindsey

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Re: CP-173 Boiler Build
« Reply #21 on: March 17, 2016, 12:49:28 AM »
Happens to all of us Harry. We will be here when you have the time and still admiring that boiler :)

Bill

Offline zeeprogrammer

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Re: CP-173 Boiler Build
« Reply #22 on: March 17, 2016, 09:17:31 PM »
Happens to all of us Harry. We will be here when you have the time and still admiring that boiler :)

Ditto.

I hope nothing serious and we see you soon.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
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