Heisler Frame Construction Part I
Nelson Riedel, Nelson@NelsonsLocomotive.com
2/19/2007, last updated 02/24/2007

The tender frame construction was done in January when the weather was really nasty ----- below zero every day and plenty of snow and ice.    The coupler pocket for the link connecting the the locomotive to the tender was done first using on-hand scrap steel.  The bolster was next also using on hand steel.   Once those pieces were finished, a trip to the steel store secured the material required to finish the frame. 

Tender Link Coupler Pocket- HM434:  I didn't have 1.875" X 2" bar stock so I welded a 1/8" square bar to piece of 1.75" X 2" bar left over from making the smoke box saddle.  The photo shows the 1/8" square bar on the lower right side which will become part of the base.  Large pieces have been sawed off the sides.    A couple holes were also drilled in the end as a start on the hole for the link.  A hole was drilled in the side fo0r the link pin.
The next step was to use the mill to make the curved end.   The photo shows the  rotary table with collet fixture mounted to the mill table.  This was a convenient way to hold a mandrel vertical.   The mandrel was made by sawing the head off a 3/8" bolt.   The block of steel is secured to the mandrel with a locking nut.   The nut is snug but not so tight as to prevent the block from rotating.  A rod is inserted in a hole drilled in the base to both steady and rotate the block .  The mill X-Y table was used to move the block against the tool.  The block was then rotated using the rod to machine the curve.  Small cuts were taken --- on the order of 0.03" or less. The block was rotated in the same direction as the end mill so that the tool was always trying to push the block back.
The next step was to use the same setup as in the previous photo to mill the circular recesses in the sides.  The rectangular hole is the center was also opened up at this point using various sizes of end mills..  The  block was held in the milling vise for that operation.)
The next step was to mill the four sides while leaving the lip around the link opening. The edges were then smoothed and rounded with files and various cutters in the rotary tool.
The last step was to solder the side and bottom ribs to the pocket..  These ribs were made oversize (stick out too far) and then cut back after they were silver soldered in place.   Each piece was held in position by a 4-40 brass screw during the soldering process.  (Some of the holes for these screws are visible in the previous photo.)   The heads of these screws were removed when the outer edges of the ribs were finished with files and the rotary tool.  The finished pocket is shown in photo on the right.  This piece turned out better than expected.
Bolster - HM331:  This photo shows the finished under side of the bolster.  Pieces of 3/16" X 1" bar stock for the pads were welded to the main bar.  (Plug weds and welds on the ends)  The bar was mounted in the lathe 4-jaw chuck and the bottom turned to the correct thickness and the slope turned on the pads.   A 1.875" hole was turned to a 3/32" depth to position the rod that mates with the truck.   The rod is attached to the bar with a couple 10-32 socket head cap screws from the top.
This photo shows the top of the bolster    The recess on the ends were milled.  The recess in the center was bored on the lathe.
Tender frame Sides-HM330: This photo shows the tender frame sides.  The curved leg in the outside angle was cut on the bad saw and then smoothed on the belt sander.
Tender Frame Front (HM-332) & Rear (HM-333):  These simple parts were easy to make.
Tender Front (HM-334) & Rear (HM435) Supports:  These parts are similar in structure and made using the same technique as the locomotive front coupler support described in the locomotive frame pages.     The central bar is 1" square bar stock.    The  part of the bars that extend downwards was made from 1" square bar stock for the front support and 1" X 2" bar stock for the rear support.   These extensions were rough sawed to shape and attached to the top bar with a 1/4"-28 socket head cap screw .  A weld bead was run down the side joints.  The weld was then ground and sanded flat.  The ends were then finished to the exact shape on the mill.  The end plates were attached with 1/4" FH screws and silver soldered in place.

The photo above shows the under side of the finished frame.

The photo above shows the top of the finished frame except for the sills.  It is very rigid and exceeded all expectations.   This frame weighs 35 pounds.