Up one level Neidrauer Adventures Photo Album and Blog » Building a Live Steam Locomotive - the Mikado Project » Section 3 - Drive Wheels
Section 3 - Drive Wheels
Completed! Pictures, video and the Saga of the main drive wheels. Started July 2005, finished December 2007 with a break in the middle to find, move and restore a bigger lathe.

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 6-Jul-05 With the spring rigging done, it is time to work on the wheels.  The quality of the wheels from the supplier was good, but, we were not satisfied with the machine work completed by a previous machinist. We set out to make all the axle bores the same size, align the crankpins with the keys, and bring the thickness of the hubs closer to print.  6-Jul-05 The first step is to bore the axle shaft hole. Mounting the wheel on the lathe faceplate, we approach the capacity of my little lathe.  We used a co-axial dial indicator to true the wheel as close to center at possible.  6-Jul-05 Running a slow speed in back gear, we run a truing cut through the hub.  Since the keyway is already in the hub, this is an interrupted cut, but the finish turns out acceptable anyhow.  6-Jul-05 Using the beveled nose of a drill chuck, we rough-center the week on the lathe faceplate.  6-Jul-05 A few taps with a piece of soft copper for fine adjustment.  6-Jul-05 The massive counterweight of the main drivers caused the lathe to jump a little as it swung around, but nothing so serious that it actually moved.  6-Jul-05 In motion, here is what the boring operation looked like.  13-July-05 Once all the wheels were bored out, we made a close-fitting mandrel (or stub shaft) in the 4-jaw chuck to mount the wheel on. The friction fit drove the wheel.  13-Jul-05 Truing the back to the newly bored hub hole. You can see the end of the arbor in front of the live center.  13-Jul-06 Here's what is sounded like machining the wheel with all the spokes.  13-Jul-05 Machining a brass spacer to put between the two wheels. We discovered the crankpin holes on each wheel did not line up correctly when placed on a keyed shaft. We will put this spacer between two wheels, back-to-back, to bore out the crank pin holes.  20-Jul-05 Cutting a keyway slot in the mandrel.  20-Jul-06 Aligning the mandrel to be perfectly square and parallel to the spindle.  The parallelism of the crank pin holes to the hub shaft hole depends on accuracy here.  27-Jul-05 The 'wheel sandwich', ready to bore the crankpin holes.  Boring the crankpin holes using the automatic downfeed.  27-Jul-05 The bottom wheel placed on the mandrel, with the spacer in place.  If we had just stacked the wheels on top of each other without the spacer on the newly machined reference surface, the wheel backs might not be parallel, resulting in crankpin holes which would be cocked and not perpendicular.  3-Aug-05 With the axle and crankpin holes completed, we now have to face the front of the wheels.  Which calls for another fixture to hold the wheels. A large piece of aluminum has been turned in the lathe, we are drilling holes in the back for mounting to the faceplate.  3-Aug-05 Turning the piece to create another arbor to mount the wheel on.  3-Aug-05 This turning operation created a lot of swarf.  10-Aug-05  How the mandrel was mounted on the faceplate, including the offset.  If we had left the stub shaft on center we would machine the counter-weights off the wheel.  10-Aug-05 We barely had room to swing the offset wheel around without hitting the lathe ways.  10-Aug-05 The front of the wheel hub after machining. Not all the previous machining marks were removed.  25-Aug-05 Machining the crankpins.  We had to do some figuring since after machining the new crankpin holes that part of the pin held in the wheel did not match the blueprint.  23-Nov-05 Making an accurate dead center.  We will leave this in the chuck, undisturbed to turn the axles between centers.  23-Nov-05 The setup for turning the axles between centers.  23-Nov-05 I completed the eccentrics for the water pump.  25-Nov-05 Turning the axle shafts.  This involved turning to the correct diameter and length for one operation, then turning the axle around between centers repeating the same operation, then adjusting the diameter and stops for the next operation. In all there were 24 operations to be performed just in the turning phase.  I ended up with a couple of 'not quite right' parts for the scrap box.  7-Dec-05 Cutting the keyways in the axles.  7-Dec-05 Close up of the keyset cutter in action.  14-Dec-05 This is starting to look like a locomotive.  14-Dec-05 With so many parts completed I just had to line things up so see the progress.  Next we need to complete the axle boxes and assemble the wheels.  14-Dec-05 Time to start working on the axle boxes.  First step: chuck it up in the four-jaw and machine the reference surface, which is also the thrust surface against the back of the wheels.  14-Dec-05 We do what we can with the limited tools on hand, in that case we try to center the casting to rough bore the bearing recess.  This is a bit challenging to be consistent since one side had grinding marks where the casting sprue was cut off.  14-Dec-05 Take a skim cut across the back.  14-Dec-05. Grab the boring bar, fiddle with the center height, rake angle and point to reduce the chatter for a good finish.  This is not the final diameter, but all boxes are made to the same size for machining the tabs in a later step.  11-Jan-06  We make another fixture for machining the outside of the axle boxes.  Shown here is the rough-bored box and on the fixture.  11-Jan-06  We turn a chunk of aluminum down to be a sliding fit to the inside of the rough-turned axle boxes.  The gray iron angle plate is drilled and tapped, and the aluminum plug is bolted to it.  18-Jan-06 Here's the setup for machining the axle box 'ears' or frame guides: Angle plate bolted to the table, axle box held to the plate with a C clamp, expandable parallels on the bottom used to maintain parallelism of the axle box.  18-Jan-06 Bill at work at the Bridgeport machining the axle boxes.  22-Feb-06  We would machine the top of one axle box, then loosen the C clamp and rotate the box around the aluminum plug, use the parallels to square things up again, then cut the other side.  We had to pay close attention to the dimensions from the 'As Built' frames, which were not the same as the blue prints (no fault of the prints).  The prints also called for a 12  1-Mar-06 Finish machining the thrust surface of the axle box.  1-Mar-06 Using a depth mike to measure the thickness of the thrust face.  The print dimensions are from the centerline of the  1-Mar-06 Finish bore the axle boxes to be 0.002  1-Mar-06 Using a bore dial indicator to check the bore size and runout.  1-Mar-06 Here's how we rough-centered the axle box before using the indicator for fine-adjusting.  We put the aluminum plug, which we used during previous steps, inside the rough bore, and use the tailstock to press and hold the axle box in place while we set up all the clamping blocks.  3-Mar-06 Here they are: eight finished axle boxes!  22-Mar-06 Time to press the crank pins into the wheels.  We went to my friend Joels shop because he has a 10 ton hydraulic press.  Since our crank pin holes were oversize due to the previous machining misalignment, our crankpins do not have the called for shoulder to press against. For the front and rear wheels we use a spacer to get the correct press.  22-Mar-06 Pressing the crank pins into the wheels.  For the main and intermediate wheels, we press them in from the back.  The electric hydraulic pump made quick work of things.  22-Mar-06 The main driver with the crank pin pressed in.  Bill wipes away the excess oil (we did not want the steel pin to gall on the cast iron, possibly ruining the pin and wheel).  Also visible on the end of the pin is frost--I put the crank pins in the freezer to get just a little more shrink for the press fit.  29-Mar-06 Using a rotary chuck given to me by Jim H. back in my parents neighborhood, we gently chuck up the wheel by the crank pin to drill, tap and setscrew the crank pin to the wheel.  Since the crank pin holes are so much bigger than called for in the print, we were concerned about how much 'grip' the cast iron would have on the pin.  Setting two shoulder screws right at the interference point between the pin and wheel should anchor them solidly.  29-Mar-06 Using a wiggler to find the exact point between the pin and wheel.  We will drill, tap and Locktite a shoulder screw that is half in the pin and half in the wheel.  1-Apr-06.  The wheels are coming together.  Here they are all lined up with the crank pins solidly anchored. Now it is time to press the wheels to the axles!  20-Apr-06 Wa-hoo! Check out the locomotive now!  The wheels have been pressed together and put under the frame.  The suspension comes to life and the size of the whole locomotive starts to become visible.  Also visible is my new engine stand, my first major welding project.  It turned out pretty good.  20-Apr-06 A closer shot of the wheel, frame and suspension.  1-Dec-07 Making a drive dog for the wheels.  The dog is bolted to the lathe chuck.  A threaded bolt will go in the hole on the right, through the spokes in the wheel. The bolt will turn the wheel and not the finished crankpin which is sticking out of the wheel because we do not want to mark or damage the crankpins.  1-Dec-07 The dog is bolted to the chuck and the wheelset is held in the lathe between centers.  The geartrain in motion on the big Rahn-Larmon lathe.  The very noisy chain drive on the overhead pulleys.  Machining the wheel tread to match the other wheels.  Bill at the controls.  While the motor runs continuously, the lathe does not until the overhead clutch is engaged.  Tightening the shop-made carriage stop.  Setting the cutter stop to insure all the flanges are the same width.  Setting the cutter stop to insure all the flanges are the same width.
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