Heisler Boiler Construction I
Nelson Riedel, Nelson@NelsonsLocomotive.com
2/26/2010, last updated 02/27/2010

Wayne Godshall (http://godshallscustommachining.com/)  made the boiler.  The drawings in the Boiler Design page match the boiler.   This page shows photos of the boiler as well as photos of the fabricated firebox door, the water glass, pressure gauge and steam manifold. 

 

The photo above shows the boiler side.  The fire pan is in place in this and the next photo.

This is the boiler back.    The round opening for the firebox might not be appropriate if one is burning coal.

The two holes in the upper portion are stay tubes which run to the front tube sheet. 

The two holes in the mud ring are cleanouts.
This in the front tube sheet.  The 31 tubes are 5/8" OD  copper (1/2" copper pipe).    The large hole in the top is for a compression fitting that seals around the throttle output pipe.  The two smaller holes in the upper part are the stay tubes that tie the front tube sheet to the boiler back. 
This is the inside of the fire box  --- not very exciting.
This angle of the fire box is a little more interesting in that the flues are visible. 111

The boiler probably weighs between 100 and 150 pounds.   The engine hoist pictured above comes in handy to install and remove the boiler making an unpleasant task quick and easy.

Firebox Door:  The firebox door was constructed over a period of at least a year and it was not one of my favorite projects.    The actual construction was fairly straightforward.  The only complex part is the unusual shapes involves.  The following photos should help with understanding the shapes and how they all go together.  

The handles were made much larger than shown in the design drawing and very much out of scale as are the engineer's fingers.  The base is attached with 4-40 screws into 1/8" deep holes into the boiler back head.   The pair of (#2) screws in the boiler side of the door serve as stops for the damper plate.   

Water Glass:  The water glass pictured at the right was machined from  1" square bar stock by Wayne Godshall.  The top nut is threaded 9/16-18.  There is a 1/4" OD brass tube inside the nut that has a 1/2" diameter flange below the nut and 1/4-40 threads above the nut.  The glass is sealed with 3/8" ID- 1/2" OD Viton O Rings at each end.  Those 14 screws are #2-56 and only decoration.

The two valves screwed into the boiler are 1/4" and the blow down valve is 3/16"  Note the positioning of the valves.  Each valve and pipe to the boiler can be tested by closing the other boiler valve and opening the blow down.  The  differential pressure across the water glass in only a few ounces so the pipes & valve can be easily plugged by a bit of debris.  Hence, I try to remember to test the water gauge plumbing each time I fire up.

Steam Plumbing:  The initial pan was to have a separate webpage section for the steam plumbing.  However, I since decided to to describe the steam manifold here and to describe the individual runs from the manifold with the description of the appliance on the other end.    

The photo above shows the plumbing from the steam dome to the steam manifold.  The  tees, 1/4" valve and compression fittings are standard plumbing fittings from McMaster-Carr.   Note that the valve can cut off the whistle and the steam manifold for maintenance.  The  pressure gauge is before the valve so that it can't be cut off.  

The manifold is made from a 4" length of 1/2" square brass bar stock.  It was drilled lengthwise and the ends tapped 1/4-40.  Three holes were drilled and tapped 3/16"-40 in the top.  (There is room for additional ports if required.)  The stub out the back is 1/8" NPT.   Two 6-32 studs extend out the front.  The studs and stub out the back were silver soldered to the manifold.  

The manifold is attached to the support plate (1/8" X 4' W X 4.754" H HRS) via the two studs.  The stay tubes were tapped 7/16-40 and fitted with 7/16-20 to 6-32 brass bushing.  The pair of screws  near the bottom of the support plate are into these bushings.

The support plate is very sturdy with the screws in the bottom and the tube to the steam dome steadying the top.   It is a handy place to hang the pressure gauge bracket and a bushing for the throttle shaft. 
Feed Water Heater:  The coils of 1/4" tubing shown at the right are the feed water heater which is described in the Water Plumbing section.   It is mentioned here because the coils appear in the background of some of the photos of the inside of the smoke box.  Water enters the heater through the side of the boiler tube in the lower right of the photo.  This is on the smoke box side of the front tube sheet so this is unpressurized. The output of the feed water heater is via a 1/4" tube compression to  1/8" NPT fitting on the middle right of the photo.  This fitting goes screws into the front tube sheet.  The two bolts are 3/8"-24 threaded into the ends of the stay tube --- it's a sloppy fit but OK for these light duty supports.   

This is a good place to stop.  The story continues on the Boiler Construction II page where the smoke box, throttle and superheater are discussed.

 

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