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 the R-1 class #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.

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.

 

Hot Flanging a New Door Sheet

Early February Mid-Continent members Jason Sobczynski, Dave Wantz, Bob Ristow, Don Angles and Jim Connor traveled to Tennessee Valley Railroad Museum in Chattanooga. At the TVRM shops, they assisted Gary Bensman in flanging a new door sheet for the WC&C #1 fire box.

Pictures show the McCabe Flanger is use and hot flanging (heat and beat) operation.

The heat and beat operation was a very intense 45 minutes from starting to heat (two rose bud torches) to completion.

The metal is heated to bright red, almost white. One person guides the flatter and one person administers hard blows to the flatter with a sledge hammer for 30 to 40 seconds. Metal is heated again and the pounding continues.

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Riveting Work Weekend

Work this weekend included installing 8 rivets in the WC&C #1 fire box patch. Friday afternoon and Saturday morning was spent in preparation. A backer plate was fabricated. Then a test plate with 4 holes was formed and used to determine the rivet length needed. All the tools were lined up and test hole riveted. Testing went perfect and all 8 rivets in the patch were installed in an hour and 15 minutes.

Rivet crew of five; Bob Ristow, Pete Deets, Roger Hugg, Ed Ripp and
Jim Connor.

Pictures show Pete Deets welding on the backer plate. Pete and Bob Ristow reaming rivet holes. Ed Ripp running the rivet gun. Completed patch with 8 rivets installed. The patch will be welded in place in the near future. Also a picture of Bob’s progress on the boiler check valves.

–Jim Connor