Heisler Frame Construction Part IV
 Nelson Riedel, Nelson@NelsonsLocomotive.com
Initial 1/15/2007, last updated 02/23/2007

 

The fabrication of the frame side channels, the front coupler pocket,  the front coupler support and the locomotive-tender link are described in this page.  The design details for these parts are at Frame Design II  and Frame Design III.

Side Channels   I'd just finished assembling the frame sides, rear sill and front sill bracket so it seemed appropriate to finish the frame outline by building and attaching the side channels. 

Photo above shows the side the side channel.     Also note that a length of 1/2" angle is attached to the frame side opposite the side channel.  This angle is at the same height as the side channel to provide support to the cab floor.    

The photo at right shows the rear of the side channel attached to the rear sill. 

 
Coupler Pocket: I needed to nail down the the front coupler pocket before making the front coupler support so it was next.  As mentioned in the design pages, the same pocket is used on the locomotive front and the tender rear.  The pockets were machined from aluminum.

The first step was to make the two blocks to the correct dimensions (2.625" X 2.25" X1").  I sawed the bocks from larger bar stock and squared and machined the blocks to the exact dimensions on the mill.   The next step was to drill out the slots with a 11/32" drill and then finish with a 3/8" mill and then a 3/16" mill to square up the corners.  The photo shows the blocks  after the slots were finished.     

The next was to narrow the sides.   Note that once one side is machined , the same settings can be used to finish the other three sides.  It goes very quickly. 
The next step was to machine the recess in the sides.  The recess was made about 1/8" too narrow to leave material for later machining of fillets on each side.  The photo shows machining one of the recesses.  Once the mill is setup, the four sides can be machined with the same settings.
The next step was to machine the ends.  Extra material was left in the inside corners so that fillets can be machined later.   Photos shows the machined ends. 
Fillets were machined in all inside corners using a 1/8" ball end end mill.   Photo shows one of the pockets after the fillets were machined.    
The front was finished next.  Photo shows using a 1/2" ball end end mill  to make part of the curve in the front.  The outer edges were then milled flat with the bottom of the cut that was made with the ball end mill.   
The next step was to use a 3/32" radius corner rounding mill on the front sides edges as shown in the photo. A  1/8" radius corner rounding mill was then used on the corners of the back plate.   The last step was to drill the 1/4" hole for the pin.  I drilled the hole from one side on the first pocket and found the drill wondered to one side at the bottom.  On the second pocket I drilled a slightly under size hole half way from each side and then finished the hole with the 1/4" reamer from one side. 

The final finishing was done with sand paper, a small sanding drum on the rotary tool and a small file.   The rotary tool sanding drum was used to rough in the front curvature and to round the back side of the protruding part of the sides.  These were then finished with sandpaper.  

This photo shows the finished couplers.   They had been bead blasted to give a uniform finish.  I'm deferring drilling the mounting holes until I know for sure the correct position to give the correct coupler height. 

These parts turned out much better than anticipated.  Thanks to Bob Reedy for describing the technique.
Front Coupler Support:  The first step was to rough saw the sloped part from 1" X 2" HRS bar stock and attach it to the main bar with a 1/4" socket head cap screw.  A weld bead was then run down the seam and the bead was then filed smooth.  In hindsight it'd probably been easier to solder rather than weld. 
The ends of the bars were then finished to dimension on the mill.  The final step was to attach the end plates with  1/4" FH screw through each and then silver solder the joint.

 

Frame tray:  The tray was assembled from a 1/8" steel plate and 1/8" thick sides.  The sides were attached to the base with two 4-40  FH brass screws per side.  The photo on right shows using welding magnets to hold a side to the base while a drill is run through the holes in the side to mark the correct spot for the hole in the base.   

After the four sides were attached with screws all joints were silver soldered.    The flat head screws were only partially counter sunk with most of the head protruding.  This protruding head was filed off after the soldering. 

This is the finished tray positioned against the saddle and held in place with a couple 4-40 socked head screws into the saddle.   The socket head screws will be replaced with hex head screws on final assembly. 

 

Swivel Pocket: The swivel pocket fabrication was straight forward.  The slotted hole in the one side was made by drilling a hole and then enlarging it using an end mill at the appropriate angle.   The copper-;like color is from pickling after the silver soldering.

Tender Coupler Link:  The photo above  shows the link and the pocket.  This pocket is described in the tender frame pages.   The link was turned from 1.25" square stock .  The end which fits into the pocket was then milled to the correct shape.   The retaining disk was turned per the drawing and then modified slightly as needed to allow the link to rotate and slide side-to-side freely.     

The photo above shows the rear of the frame with the link and swivel in place.  

The bolster and associated brackets and the boiler supports are the only missing pieces and the subject of the next page.    

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