Bending Steel Part 2: Forming the Throat Sheet

Gary Bensman and his team continued work flanging various sheets for the C&NW 1385’s firebox during the first half of April. Recent tasks included work on the 1385’s throat sheet and backhead.

This drawing of an Omaha Road Class I-1 boiler, a sister engine to #1385, identifies the location of the firebox, throat sheet and boiler barrel.

The backhead forms the rear end of the firebox and is located inside the cab. The fireman shovels coal into the firebox via a small door which will be cut into the backhead.

The already flanged (curved) sheet is the C&NW 1385’s new backhead. The backhead forms the end of the firebox inside the cab. Gary Bensman photo.

The throat sheet serves to connect the round boiler barrel with the firebox’s square-ish lower half. Such a transition requires the throat sheet to be a more complex shape. Where much of the bending of the steel sheets thus far could be accomplished via “cold flanging” by bending on a pneumatically-powered McCabe Flanger at room temperature, the throat sheet’s complex curves require a more hands-on approach. The “hot flanging” or “heat and beat” method involves heating the metal to make it more malleable and then using sledgehammers to pound it into the desired shape. The photo gallery below shows the throat sheet at various stages of progress.

Bending Steel

During the second week of March, SPEC Machine’s Steve Roudebush and Tyler Roudebush along with Brett Morley of Performance Engineering traveled to Tennessee Valley Railway Museum to meet with and assist Gary Bensman of Diversified Rail Services. Diversified Rail Services was contracted by Continental Fabricators to flange the four firebox sheets needed in building 1385’s new boiler.

Catalog page

The McCabe Flanger in a 1921 American Society of Mechanical Engineers Catalogue and Directory.

Flanging is a process to make a smooth bend in steel forms while the steel is cold. Flanging can also be done while the steel is hot but it adds more time, work and requires more people. The choice of whether to use hot or cold flanging is made largely on the shape being bent and where on the sheet of steel the bend needs to be made.

The machine seen in use here is a McCabe Flanger, a steam-era machine which uses pneumatic pressure for power. The bends are made a little at a time to prevent creating a wrinkle in the sheet.

The accompanying photos show the the aforementioned persons along with formation of the 1385’s rear tube sheet. The tube sheet forms the front of the firebox, meaning one side will be exposed to intense fire and combustion gases while the other side will hold back a wall of water. Before being installed, the rear tube sheet will have holes drilled for and support nearly 200 2-inch fire tubes and 24 superheater flues. The tubes and flues go through the water space of the boiler to conduct the combustion gases from the firebox to the smokebox at the front of the locomotive and allow the water and steam time to absorb more heat from those gases. The tubes and flues also serve to help support the tube sheet. Since the sheet is a large, flat surface, steam pressure is constantly pushing on it, trying to bow the sheet, but the tubes and flues mechanically tie together the front and rear tube sheets, providing strength and holding the sheets flat.

curved tube sheet

C&NW 1385’s new rear tube sheet takes shape. This is a view of a blend from a straight side to 12.5″ radius corner to 72″ radius crown sheet. Photo courtesy Gary Bensman. Mr. Bensman of Diversified Rail Services was contracted by Continental Fabricators to form the sheets for #1385’s firebox and tube sheets.

 

Above video courtesy SPEC Machine.

“Drawing” Conclusions on C&NW 1385

On the afternoon of Friday, February 24, 2017, the C&NW 1385 Task Force received the latest packet of shop drawings for the new boiler from Continental Fabricators for Mid-Continent to markup and approve. The painstaking process was started the following day at SPEC Machine and great progress was made.

Boiler review meeting

A C&NW 1385 boiler review meeting is held on, Feb. 25, 2017. The locomotive’s running gear and cab are just visible in the far left background. Photo courtesy Pete Deets.

Previously, Brett Morley of Performance Engineering had completed a SolidWorks™ 3-D model derived from countless hours measurements of the original boiler by him and others on the 1385 team as well as a study of the Chicago & North Western’s drawings for the locomotive, obtained from Lake States Railway Historical Association. The model provides a 3-D representation to check, among other things, whether and how well all the parts will fit together. Files derived from the model were provided to Continental Fabricators who then created their own preliminary construction drawings that are now being sent back to us to proof, mark up and return. The packet received on February 24th is the latest iteration.

boiler drawings

CNW 1385 boiler drawings undergoing review. Feb. 25, 2017. Photo courtesy Pete Deets.

The 1385 team must examine every minutia of the shop drawings to prevent any mistakes. It is a very painstaking and tedious process but the manufacturer will build precisely what is on the paper and it is Mid-Continent’s responsibility to make sure what is there is what we want and need.  

A few of the many details being reviewed include:

  • Diameters and shapes of each course
  • Overall length of the boiler
  • Mud ring size, shape, placement, and material
  • Shapes and placements of clearance holes
  • Size & placement of washout plugs
  • Placements of the throttle/superheater header/branch pipes
  • Size and placement of the safety valve outlet and appliance manifold outlet
  • Placement and size of cutouts in the smokebox

Every dimension on every drawing is going to be checked. Every description of every weld called out will be cross checked. The material listed for each part will be checked. These things will each be cross referenced against the C&NW drawings, actual measurements of the old boiler, and the SolidWorks™ model.

CNW 1385 drawings on table

The CNW 1385 boiler review meeting team sets up shop at SPEC Machine. Feb. 25, 2017. Photo courtesy Pete Deets.

With a project this scope, any mistakes are forbiddingly expensive so the team is proceeding as swiftly as they can without rushing the job. As the first round of checking concluded on Saturday, a fair sized chunk of the job has been completed. So far the Task Force have been quite pleased with what has been supplied from Continental and when finished, all the corrections will be sent back to them. Once those corrections are applied, Continental will send another packet and the process will repeat until there are no more corrections. Despite the intense workload on the Mid-Continent volunteers and partner contractors, the project is staying quite close to the manufacturing timeline and we are getting ever closer to the actual build.

News Article: Big (and Expensive) Period for Steam Locomotive Begins

Wisconsin State Journal reporter Barry Adams dropped in for a visit to SPEC Machine late last week to see what was new on the Chicago & North Western No. 1385’s restoration since his last visit to see Mid-Continent’s flagship steam locomotive one year ago. You can read the full Wisconsin State Journal article and view the numerous photos at Madison.com.

A few highlights from the article:

  • Steel for the new boiler will be cut this week (February 20, 2017) at Continental Fabricators in St. Louis.
  • Additional steel will be cut and shipped to Tennessee Valley Railway Museum where the new firebox is to be crafted.
  • The firebox will be delivered to Continental Fabricators in St. Louis, Missouri, attached to the boiler, then shipped to SPEC Machine in Middleton, Wisconsin where it will join the running gear and cab for final assembly.
  • Arrival of the finished boiler is now expected for June 2017.
  • This is the most costly phase of the locomotive’s restoration. The new boiler and firebox will cost roughly $700,000. (Please consider visiting our donation page!)
  • SPEC Machine is building a 1,500 square foot expansion to their shop to facilitate final assembly of the 1385 on-site.
  • Other upcoming projects at SPEC Machine include refurbishing brakes, installing pistons, rehabbing the superheater header, refurbishing the sand dome, and the many other parts that are yet to be installed.
  • Mid-Continent’s goal is to have No. 1385 fully assembled and returned to the rails in 2018.

 

C&NW 1385’s Boiler Design Review Meeting Held

A design review meeting was held at Continental Fabricators in St Louis, Missouri on Tuesday January 24, 2017  Members of Mid Continent’s 1385 Task Force were in attendance as were Gary Bensman of Diversified Rail Services, Steve Roudebush from SPEC Machine, and Brett Morley of Performance Engineering. The meeting covered all of the details necessary to build the new boiler as well as provided a platform for everyone involved in the design process to review the fabrication plan with the team at Continental.  It was a very productive meeting with everyone having input into the planning of the new boiler and Continental coming away with some clear direction enabling them to proceed with the task at hand.

Action items to come out of this meeting include the development of Continental’s final production schedule. Fred Steinkuehler, Vice President of Plant Production at Continental is currently developing their schedule. He is basing the plan on Mid Continent’s detail drawings and expects to be finishing up within a few days. While the production department work out their timeline, the engineering department will continue the preparation of internal shop drawings. We expect Continental to be wrapping up their engineering phase over the course of the next few weeks.

With the boiler process well underway with Continental Fabricators, and the major parts of the running gear and cab near completion, the Task Force identified the many remaining accomplishments still needed. Completion times were assigned to each and a general schedule was outlined. It has been determined that, excluding any major unforeseen concerns, the 1385 can be returned to Mid-Continent next year (2018).  Timing can be determined more accurately as these projects move along.

 

CNW 1385 Boiler Drawing 3D View

CNW 1385 Boiler Drawing 3D View

At this juncture of the 1385 restoration, it was decided to forgo hosting an Open House this year. The many hours otherwise required by Mid-Continent volunteers and staff to organize and host the event will instead be spent toward expediting the completion of 1385. In place of the Open House, there will be additional volunteer work day opportunities during the year.

The Task Force is very enthused and motivated, and thanks everyone for their support.