Up one level Neidrauer Adventures Photo Album and Blog » Building a Live Steam Locomotive - the Mikado Project » Section 10 - Drive Rods
Section 10 - Drive Rods
Completed! Drive Rods. Main, Side and Intermediate rods. Jan-June 2008

 17-July-09 I experiment using the belt sander to clean up the appearance of the rods. Note the fancy coathanger retaining clip holding the shop vacume hose to the sander to contain the aluminum dust.  9-July-08 Here's a setup I've never done before: Chucking a chuck to hold the part.  Bill did not want to make an expanding mandrel just for two parts, so we took this smaller chuck off a horizontal divider. It could hold the thin spacers just fine.  A finished spacer in steel.  9-July-08 Turning the rod spacers from a piece of mystery steel from the scrapbox.  A Milestone!! The rods are fitted to the wheels and the chassie still rolls!  Yea! 25-June-08  25-June-08 Using a reamer in the lathe (held by the chuck) to open and debur the bearing brass bushings in the intermediate rods. We used the nose of the drill chuck in the tailstock to keep the rod perpendicular to the reamer.  The finished knuckle pin and aluminum washer for the rods. The head of the pin is slightly crowned with a neat finish.  25-June-08 The finished end rods with knuckle pins and washers in place.  Finishing the knuckle pins. After all the turning operations, the pin is held in the chuck, faced to size.  To put a slight crown on the bolt, Bill left the tool at the center, engaged the cross-slide feed out and as the tool pulled away from center, put slight pressure on the carriage handwheel towards headstock.  The result is a domed knuckle pin. Very nice.  19-June-08 Threading the knuckle pin.  I used lead-bearing steel for the pins, I can get a better surface finish out of this steel than plain cold rolled.  19-June-08 The finished knuckle pin with it's rod.  The finished intermediate rods with the bushings in.  Boring the bearings out of bearing brass.  Turning the bearing brass down to size  19-June-08 The end rods bored and cut, ready for bearings.  Slotting the end rods. The rod is bolted from the bottom to the t-shaped fixture under the clamps, a 1-2-3 block is placed against the side of the rod to futher secure it.  Setting up to use the side-cutting saw to cut the slot.  11-June-08 Boring the rod end.   11-June-08 With the end rod securly held at the crankpin end, under the stack of washers on the tool holder, the other end is drilled so we can tap and bore the hole.    14-May-08 Progress on the intermediate rods.  Using an endmill to enlarge the hole before boring.  14-May-08 Drilling the holes in the intermediate rod. The left side is bolted down to the fixture, the right side is lightly clamped.  We used a drill with 'blunt' flutes to keep the drill from digging into the soft aluminum. This did cause the unsupported rod end to flex under presure but did not cause a problem.  The set up to drill the crosshead end of the main rod. The fixture is the same height as the parallel at the other end.  Having bolted the fixture to the table, we indicate all around to center and make sure it is perpendicular to the table.  A minor adjustment to the bridgeport head was needed.  Turning the diameter to a sliding fit for the rods. The part is held between centers.  8-May-08 A piece of hot rolled bolted to the side creates a lathe dog for turning between centers.  Having completed the facing operation, the bolt is turned around and centered in the 4-jaw chuck, the end faced, deeply center drilled and then center drilled and tapped for a 1/4-20 bolt.  23-Apr-08 Turning an old bolt to make a holding fixture. First we turn the end flat since it will go down on the table.  23-Apr-08 Here's where we are on machining the rods.   The bored connecting rod hole.  23-Apr-08 Centering the connecting rod to bore the other end. We've moved the blueprint distance from the drilled end to the other end and are centering the other hole left to right.  The setup for boring the Intermediate rod.  17-Apr-08 Main rod with bearing installed.  Cutting the pressed-in bearing to size.  We later decided that cutting the bearing to size THEN pressing it in was a better approach.  Here's what we ended up with: A very flat thick washer (brass in this case) on the table, lifting the rod off the table with clamps holding it tight.  17 Apr 08 Preparing to bore the Main rod. ?How to hold the rod?  Milling the bearing ends to the finished size.  This clamping solution turned out to be the best, the parts were solidly held to the table, without introducing any more twist or taper relative to the other finished side.  The side rods with the clamping screw holes.  Using a cutter which has been profiled to drill and countersink a 1/4-20 hole in one operation.  Previous clamping attempts did not work. We needed a way to hold the bearing ends of the rod down to the table which allowed us to machine the very same spot at the same time. Well, we have to bore a hole for the bearings anyway, so let's put in a smaller hole and use a screw as a clamp.  Since we have four rods to machine, we clamp a v-block to the table which allows us to indicate and move the head over the centerline of the hole for all parts.  With the one machined side down on the table, we try to clamp them down to machine the other side.  The  2-Apr-08 On to the side rods. Another set of castings, more challenges.  Where to start? Using the center web as a rough guide, we clamp the rods on the vice and rough machine the bearing ends.  With the bearing ends machined to finished size, the tabs are then finished machined.  With the part clamped  26-Mar-08. The Intermediate Drive Rods are another pair of challenging castings. The thin tabs at either end were warped and there was a twist between either end.  Such is the nature of castings.  With a rough finish all around, but only a few surfaces marked on the print to be machined, holding the parts is yet again a challenge.  After taking a light cut on both tabs, Bill clamps them  11-Mar-08 We start a new Section!  Like all castings, the question is where to start - nothing is smooth or straight.  11-Mar-08 Rough machining the Drive Rod.  Castings are a pain for work with, especially something like this where the surface you want to clamp on is also the suface you want to machine. And all the dimensions are around the centerline of the part, but like all castings, things are bent, warped or twisted. Clamping on the 'webbed' portion of the rod causes the ends to flex (see shims under part to compensate).  Probably a better method would have been to drill a through-hole to screw the part to the table and machined around the screw.  See connecting rods pictures.  Trying to compensate and adjust for the twist in the casting and clamp with a neutral impact.  We machined only one side first to get reference surfaces.  With a machined, and hopefully true, side, we clamp it to the table to machine the other side.  Since we could not clamp over the machined portion, which would have been ideal, we spent a lot of time fussing with the clamps to hold the part without moving the ends to be machined around. It worked, sorta. We ended up with tapered surfaces when we measured across both machined sides.