Heisler Universal & Shaft Construction II
 Nelson Riedel, Nelson@NelsonsLocomotive.com
9/29/2009, last updated 10/02/2009

The shaft ends of the HM304 Round Shaft Us and the HM305 Square Shaft Us were finished in the Construction I page.   The finishing of the yoke end of the Us is described here as well are fabrication of the HM303 Universal Cross.

Finishing the Us:   The material on the sides of the yokes was left in place during the finishing of the shaft end to make it easier to grasp in the vises and chucks.  The first step in finishing the yoke end was to make saw cuts from the open end to the 1/4" holes as shown on the right.
A cutoff disk was then used to make a slot between the two holes.  It is not necessary to cut all the way through --- 75% of the way through works fine.
A whack with a hammer easily breaks out those sides leaving the the U as shown.
The square shaft Us are a little over 1.25" wide and the round shaft Us are a little over 1" wide.  The finished yoke ends are 7/8" wide.   The next step was to mill off the sides of the forks to a width of 7/8".  The photo shows this operation on a round shaft U.
The next step was to finish the inside of the yoke with a 3/8" diameter end mill. The end mill is plunged down in the corners as shown in the photo which leaves a 3/16" radius fillet.   The side of the mill is then moved along the side and back to finish the inside of the yoke to the correct dimensions.
When the sides of the yoke were finished a tab was left in the middle.  An end mill was used to  make the shape of the tab as close as possible to the shape of the shaft end.   The out-of-focus photo shows this operation on a round shaft U.
This is the same operation as above only on a square shaft U here. 
The lathe setup on the right was used to turn the 7/8" hub on each side of the yoke.  That is a 1/2" rod with the roll pin next to the U.  The tail stock is used to push the rod into the chuck forcing the side of U against the chuck jaws.  The chuck is then tightened and the clamp, (which serves as a dog) tightened on the U.  Note that the back of the clamp is over one of the chuck jaws.  This worked really well when small cuts were taken.    
Next, a corner rounding end mill was used to finish the rear outside corners of the yoke as shown in the photo.

The photo also show the setscrew hole in the shaft end.  

The setup on the right was used to round the ends of the yoke.   That is a 1/2' diameter bar clamped vertically in the vise and V block.   The bar runs though the bearing holes in the U.   A 3/4" expanding mandrill in the shaft hole serves as a handle.   The U is brought against the side of the mill and the U then rotated to round the end of the yoke. 

The force of the cutter is such that the U is forced down and in the counter clockwise direction.  The vertical square bar clamped to the vise serves  as a stop to prevent the U from rotating CCW too far. 

Only the upper side is cut in this operation.  The U is reversed to cut the other side.        

This work was done about 6 months and I failed to take a photo of doing the ends of the square shaft U. The operation was basically the same except a pair of vise grips were used the the shaft end handle.
The machine marks on the end of the U were removed on the belt sander using that expanding mandrill as a handle.   The little cut on the finger was not made doing this operation.  However, gloves might be a good idea.

 
The final finish was done using 1/2" diameter and 1/4" diameter sanding drums in the rotary tool as  shown in the photo.   Course #36 or #50  grit drums were used initially to remove most of the material and then finer grit to finish up. The object is to remove machining marks and round all corners so that the pieces look like castings.

 

HM303 Universal Cross:  The crosses are made from two pieces of 3/4" diameter brass rods silver soldered together.   I started with two rods each at least a fool long and drilled/bored holes about 1 3/8" deep in the ends of each rod.  The holes were about 23/64" diameter --- slight undersize for the 3/8" pins. 

The mill was set up so that center was 5/8" from the end of the vise and 3/16" off the center of the 3/4" diameter rod.   The photo shows using a wiggler to locate the side of the rod. 

  

The next step was to plunge a 3/8" diameter  end mill thorough the rod.  Note that the hole is 3/16" off the center of the rod.  This will be the hole for the intersecting pin.   A 1 1/4" length was then cut off the end of the rod.  This is one side of the cross ---- 1/16" too long on each side.  The ends will be finished later.  
The is a setup just like the previous one only this time after the 3/8" diameter hole was cut the end mill was changed to a 3/4"  diameter cutter and the hole is enlarged to 3/4" diameter.
This is the finished 3/4" diameter hole.  The mill works slick, just make sure everything is tightened down.  
These are the two pieces of a cross.    The long end is left on the second piece to ease the soldering operation.
Next, the parts were cleaned.  In the past I used a pickling solution.  The new shop has a bead blaster setup which I now use to clean the parts.

The areas where the two pieces are joined were fluxed, the parts put together and then the little lip in the long piece center punched to prevent the smaller piece from sliding during soldering.   

A setup like this was used to make sure the two rods were perpendicular to each other.

(I forgot to take a photo doing this operation --- this photo was taken after the last piece was soldered.)

The long end was secured in the vise and a couple pieces of silver solder were laid on the top of the joint
This shows the red hot joint just after the solder flowed.

The pieces were blasted again, and the part put back in the vise with the little piece on the top.  Flux was applied to the joint and, pieces of solder places on the joint and the whole piece heated again to the point where the solder flowed.

The resulting joint is very strong. 

It is nearly impossible to keep the two shaft holes perfectly aligned during the soldering operation.   The hole in the long piece is the one which might be slightly obstructed by the small piece. 

The photo shows boring the hole in the long piece again to get grid of any obstruction.

 
The two holes for the pins were then reamed to 3/8" diameter.  The brass tends to grab a drill so a drill should not be used to finish the holes --- use a reamer.

A 3/8" rod was inserted though the hole for the pin as shown in the photo.   The pin is resting on little blocks one each side of the cross.  This setup was used to finish each end on the cross to the correct length. 

The last operation on the cross is to drill and tap the setscrew hole. 

 

 

HM300 & HM301 Universal Pins:  The machining of the 3/8" diameter steel pins is straightforward.   The one unusual operation is cutting the notch in the side HM301.   A setup like used to notch the crosses was used.  The milling cutter is shown plunging through the side of the bar.
There are oil holes through the side of each end of each rod.   The previous setup was used to center drill these holes in the side of the rod.  The rods were then moved to the drill press vise to drill the holes. 
This shows a pair of finished rods with a HS300 bearing, a HS301 Oil Hole Cover and Outside Retaining Ring on the end of the HM300 pin.  

   

Drive Shaft-HM302:   The photo above shows one of the drive shafts.  It has a good resemblance with the prototype shaft.  Making the middle part slightly smaller than the ends is worthwhile.   Unfortunately, one might not notice the shaft on the finished model unless they are run over by it.

Photo above shows the finished U joints plus a few spare parts.  These worked out really well!

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