Up one level Neidrauer Adventures Photo Album and Blog » Building a Live Steam Locomotive - the Mikado Project » Section 8 - Motion Structure
Section 8 - Motion Structure
Completed! Guide Yoke, Link Support, Connecting Rods,Water pump. August 2007-Jan 2008

 August 15, 2007, we start section 8! Machining the Link Support brackets which will bolt onto the frame.  We machined the bottom first to give a reference surface for the remaining operations.  Using the angle plate, which fortunately is slightly smaller than the locomotive frame we have to bolt the link support bracket to, we hold the bracket square to enable machining the front surface.  We decide to cut as little as possible, but still holding the reference dimensions, so the aluminum part is as rigid as possible.  The crosstie brackets awaiting holes, next week.  22-Aug-07 Drilling the mounting holes.  The finished link support brackets installed on the frame.  Hey! These parts only took two shop sessions, that was pretty quick!  29-Aug-07 With fresh 3/4  Side milling a relief as called for on the drawing.  Shortly afterward, Bill said  Drilling the mounting holes.  The finished Crosshead Guide bars.  The little hole in two of the bars is for a lubricator line connection.  Labor day weekend I fabricate the front and rear Link Support braces.  A nice, simple, mark and drill operation.  5-Sept-07 We begin work on the Link Supports.  The is so little machined surface to reference from on these parts, yet they have to finished to length and a through hole drilled in them which has to be parallel to the other support and square to the frame to prevent binding.  The prints did not call for the inside (bottom in this view) to be finished, so we worked on them with files and sandpaper to get them reasonably flat to put in the vice. We used narrower parallels to hold it so we can drill the cross hole without hitting them.  After (top) and before we worked on the inside of the castings.  Checking the relative position of the through hole after machining some off the end.  Since you do not start with any reference or location points with a casting, you sometimes have to machine a little and check the rest of the machining operations to make sure things are going to line up where you need them to be.  Machining the Pillow Block base in the same clamping.  After drilling, we bore the through hole for the bushing, since I do not have a 9/16   25-Sept-07 Work on the tumbler shaft pillow blocks has begun.  Match-Machining the blocks for uniformity.  Cleaning up the backs  Boring the tumblershaft holes.  Using a pin to set the center line of the hole, the drawing reference mark for the oil hole.  Using a single pin in both bores to check the parallelism of the two pillow blocks.  Since a single shaft will have to turn in both parts, having the bores directly in line insures a non-binding fit.  10-Oct-07 Work on the cast iron Crosshead Guide Yokes is begun, after much study of the drawing, the reference lines and the casting.  The surfaces to be machined are marked with an 'X' to help keep from getting mixed up.  Once the inside and outside, or in this orientation, the front and back surfaces are machined to size, they are used to clamp the part square in the vice.  Machining operations top and bottom (by flipping the part over) are started with the fly cutter to achieve the proper thickness and center the casting per the drawing.  Milling the inside opening to print, which will be used later as a reference surface for the holes.  10-Oct-07 After boring, turning and pressing the oil-lite bushing in place, the oil hole is drilled.  10-Oct-07 The finished Link Support Brackets. four more parts completed!  Meanwhile on the big(er) mill, the upper crosshead jaw support is machined.  Using a bore gage to measure the jaw openings since I do not have inside micrometers.  Lacking either the proper clamping tools, or imagination, the angle plate and c-clamp is used to secure the lower jaw and minimize the chatter the clamping setup induces.  Using a vice stop (on right) to speed setup time for the repeat operations for these two parts. After clamping the second part, the edge finder is used to re-indicate and set the DRO zeros.  15-Oct-07 Finishing the Crosshead guide yoke.  Although the first holes were easy, the same holes on the bottom (of the picture) were more of a challenge, since we could not get a center drill in the correct position from either top or bottom.  Drilling a smaller hole in the top, we used a number-size center punch to spot the holes on the bottom.  Using a 6  Hey, let's bolt some motion structure together!  16-Oct-07 Hmm. There is supposed to be a 1/16th of an inch gap on the top and bottom crosshead guide bars.  Why is there no gap on the top and 1/8th on the bottom?  Uh Oh. Those holes are supposed to line up with each other.  We spend the next two hours going over the blueprints of various parts, measuring and checking them out, and finding no issues. So then we start pulling the prints from parts we machined a while ago to measure and check.  We even started checking the prints for errors, and found none.

Going back to the Frame print, the first machined piece, we suspect a machining error. But we'll have to take the whole locomotive apart to get measure it.  Which sounds bad, but actually I have to take it apart to paint it anyhow.  16-Oct-07  Here we are with section 9 bolted on.  It's starting to look like a run-able chassie.  7-Nov-07 We set the frames aside and start on the water pump.  Face milling the eccentric.  These castings are hard to hang onto when  you first start the machining operations.  Milling the sides to get a clamp-able surface.  Machining the other side doing our best to keep the part centered.  You can see how much of the boss we had to machine away on the left during the face milling operation.  After spending two nights pondering the mis-alignment of the frames/cylinders/motion structure support brackets, without much success, we set that aside and started on the axle water pump assembly. I cut the 2  To insure a straight bore, we leveled the lathe all around using the master precision level. After a half-hour of tightening, loosening and adjusting each of the four feet, we got most of the twist out of the bed and succeeded in getting it true within 0.0005 of an inch front to back and side to side. We spend the remaining time creating a clamping system to hold the bar to the faceplate.  Using the wiggler with the point in the punch mark for the piston center, we put an indicator on the wiggler shaft and move the part around on the faceplate until it is on center.  14-Nov-07. Drilling the piston hole out in steps to bore it.  With the first hole completed we start on the second one.  Measuing the first completed hole, we find .0004  One of the challenges of boring a 2-3/4  A crash while drilling the water holes.  All the holes look good except for the second on the top right, where the cutter dug into the brass and broke two flutes, making a mess of the hole. Luckily only the bottom of the hole is critical and we were able to clean it up, but we ruined two more cutters because pieces of the old cutter were imbedded in the brass.  The first cutter we blew up when it dug into the brass.  21-Nov-07 milling the water channels.  The finished water pump body and cover.  21-Nov-07 The finished pump body next to the exccentric straps, in progress.  15-Dec-07 Another Saturday work day. After drilling the hole for the piston ram, the eccentric strap is centered with the coaxial indicator for a finish bore.  The strap installed on the eccentric.  To bore the 2  3-Jan-08 A makeshift stock holder for the lathe.  This kept the end of the 1/2  3-Jan-08 Moving the tailstock over to remove the taper we are getting in the cut stock.  3-Jan-08 The collet holder is used for close work.  3-Jan-08 The set up to slot the pump ram and drill the clevis pin.  We are using a 5C square collet holder, the magnetic base as a stop. This will allow us to turn the part in the collet 90 degrees without losing our reference position.  9-Jan-08 Chain-drilling the slot first to save some milling time.  Unlike the first piston, we end-mill the flat instead of side-milling, which make things much faster.  9-Jan-08 Lights! Music! Applause! The finished dual-ram water pump!  13-Jan-08 Ball checks installed, water fittings installed, gasket cut and fitted, and o-rings placed on the two rams. Ready to go on the frame. I might not even paint it.