Section 12 - Smokebox

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Neidrauer Adventures Photo Album and Blog » Building a Live Steam Locomotive - the Mikado Project » Section 12 - Smokebox

Finished enough to Run! The 'face' of a locomotive. Front-end work in progress - Throttle, petticoat, blast pipe. Custom smokebox support stays completed (Frisco used 4 stays, not the 2 like the USRA models), throttle modification and installation, a custom flaring tool - Winter 2011. Smokebox front, smokestack, headlight bracket, hinges, bell. February - June 2009. Plumbing May 2011 - finished Nov 2011.

16-Jan-12 The front end is getting closer to being finished! Hinges riveted on, braces complete and shroud fitted.

16-Jan-12 an amusement for me: I have been looking for these rivets to rivet the hinges to the smokebox for several months now. I have been scouring boxes on shelves and drawers without any luck. Resigning myself to purchasing more, I had Bill measure up what I needed.

14-Nov-2011 The finished piping in the smokebox.

15-June-2011 Alignment check with the stack, petticoat and blast nozzle/blower ring assembly. Looks Good! An air test with the blower also felt good, moving a feather around in the airstream showed a nice conical shape, all contained within the petticoat, with no negative eddy currents. When we did one air test with the assembly off the blast pipe, the assembly generated a vacumn at the bottom--10 lbs of air would hold a plastic bag to the bottom!

15-June-2011 A piece of threaded black pipe was turned down and threaded into the exhaust header.

15-June-2011 Water spray test outside after polishing the inside and outside blower ring openings with 600 grit sandpaper. It has a nice even ring of water with no tangents. At low pressure the water spray height was 4 feet, at high pressure over 10 feet.

15-June-2011 Water spray test at high pressure showed some streams off at an angle, and a 'dead' spot right where the water enters the assembly.

15-June-2011 Water spray test at low pressure. The assembly is upside-down for the test.

15-June-2011 Using 400 grit, then 600 grit sandpaper to put a polish on the blower ring body after water tests revealed an uneven distribution. Close examiniation with a magnifying glass showed tooling marks which made the spray uneven.

The finished blower/blast nozzle assembly.

8-June-2011 Drilling and counterboring holes in the blast nozzle ring. It is sitting on a piece of sacrificial aluminum since the holes must go through the part.

31-May-2011 Drilling and tapping three 5-40 holes which will hold the assembly together.

With both the top and bottom of the blast nozzel finished in the lathe, we bolt it down to thetable to drill some holes.

With the cross-compound set over 90 degrees square to the lathe axis, he is able to take accurate amounts off the end of the part for the final thickness.

A quick check with the dial calipers for the current thickness. We'd use a micrometer if we could get on between the part and the chuck.

After drilling, the part is turned around and chucked against parallels temporarily put in the chuck. This allows us to measure the thickness of the part without having to unchuck it.

31-May-2011 Drilling the upper half of the blast nozzle.

Without a taper attachment, all the taper boring is done with the cross compound set over.

Turning an inside taper for the blast nozzel. We picket 8 degrees taper for the one inch of length.

This is a two part assembly, the lower one is being turned now. The upper one will have the blower ring on it.

24-May-2011 Turning the 303 stainless steel blast nozzle

12-May-2011 After the pilot braces were installed, the rest of tonights shop work was devising a blast nozzle/blower combination. There is no doubt the pipe cap blast nozzle and crimped copper tube blower will work as the blueprints specify. My friend Tim built a powerful Mikado from the same drawings. I just see myself 'tinkering' with the front-end setup and want a simpler way to swap things out. So we are working on a body that is attached to the exhaust pipe and has the blower line connected to it. This part with the piping would always stay together. Our thought is a collar which integrates the blower holes and the blast nozzle would slide onto the body. It will have to be a neat fit as to not leak steam. The collar can be removed with the loosening of a couple set screws, no need to touch the plumbing. Proposed material is 303 stainless.

12-May-2011 Ten holes drilled & tapped later, all four pilot braces are installed. This is not their final installation, I need to take them down and finish paint them.

2-May-2011 Tapping the smokebox for the two custom Frisco pilot support braces. Doing this by hand is a real pain! You are holding the drill at a awkward angle, we had to use a battery drill since it had the smaller body to get into the space right next to the cylinders and we have to free-hand tap all six holes with a long tap wrench since the handles interfere with the cylinders on the regular wrench. Ugh. A recipie for disaster.

2-May-2011 The main steamline to the throttle is plumbed!!!

2-May-2011 Tapping bolt holes for the custom Frisco pilot support braces

2-May-2011 Tapping the frame for the custom Frisco pilot support braces.

26-April-2011 The throttle bracket is installed in the smokebox and the throttle linkage arms fabricated out of stainless steel. We left a couple different holes in the handle and the linkage arms so we can see what feels best.

Drilling additional throttle linkage points in the valve handle.

20-Apr-11 This could be a real 'Whatizit?' shot. Using a small rod inserted into the inside of the 1/2

19-Apr-11 A SMAW (Mig) welder sure is nice! A couple of tack welds on each side and the bottom of the tabs, and the petticoat is done!

19-Apr-2011 I fussed with the little tabs which get welded on the petticoat while bill was making the throttle rod bushing. The stack is bolted down to the smokebox and the petticoat held tight with a smell block and a machinist jack underneath it. The tabs are bolted in place and readied for welding. Tip from Bill: put a small washer between the tab and shell when bolting up for welding. After the tabs are welded, remove the washer. The space left by the washer will pull the petticoat assembly up against the stack that much tighter!

19-Apr-11 bill turned a piece of bronze to make a bushing for the throttle rod. We are using a commercial 3/8 to 3/8 compression tube fitting because the staypipe in our boiler is 3/8 O.D. copper. This bushing fits inside the bored-out fitting and provides a nice guide for the throttle rod. We also made a tapered washer for the nut so we can put some packing inbetween and keep the soot and dirt out of the rod/bushing connection.

19-Apr-2011 Yer basic tail-pipe petticoat, 2.5

11-Apr-11 Drilling the throttle bracket mounting holes in the shell. The holes will be 10-32 tapped into the boiler shell, so we are drilling with a tap-size drill. Because the welding clamps do not have much presure to hold bracket in place (I added a shop-made 'Kant-Twist' clamp to help), we temporarily put a 6-32 bolt&nut in each hole to help keep things from moving.

We mark the ends of the bracket and hole locations.

12-Apr-11 The throttle bracket temporarily held in position for drilling with long reach welding clamps. Note the 'Single-use' petticoat - made of cardboard. I didn't have one made yet, but needed to check clearances and interferences, so a quick one was mocked up. Not very aparent is the fact we moved the valve bracket over to the left to better center the valve handle with the throttle rod. I used the angle grinder with a thin cut off wheel to break the welds, ground the bracket flat and repositioned the mounting ring. It was tricky to move since the mounting ring had to stay plumb straight, but not in line to the boiler centerline.

12-Apr-2011 Bill lays out where the throttle mounting bracket will be inside the smokebox, in preparation to drill mounting holes.

5-Apr-2011 with theflats milled in, the clevins has a nice rounded end from the corner rounding bit.

5-Apr-2010 Milling flats on the clevis.

The set up of the corner rounding bit in the tool holder. Getting the center height correct is important!

5-Apr-2011 We decided to make oure own throttle clevis, using 7/16

5-Apr-2011 Milling a flat on the handle for the throttle-rod clevis connection point.

After some hand dressing of the rudely broached handle, we have a nice, no slop fit. The throttle stem and handle that came with the valve were slopp and would have introduced more play in the throttle linkage that we wanted.

5-April-2011 Putting 1/4-20 threads and trimming the throttle handle to length.

29-Mar-2011 with the throttle brack completed, we are able to determin how long our replacement valve stem should be. We set the length and machine the four flats for the handle. Using the stop rod and square collet holder, this is very simple: machine one side, unclamp, turn, machine next side.

29-Mar-2011 We have bent a piece of flat stock to match the inside curve of the smokebox. this assembly will be bolted to top of the smokebox.

29-Mar-2011 The throttle bracket assembly welded up.

29-Mar-2011 the machined collar with two 8-32 holes drilled an tapped for set screws. I've welded a standoff on the collar, we're about to machine the welds flat.

26-Mar-2011 Back to work on the throttle. We have been thinking about how to mount and install this quarter-turn gate valve for some time. We decide to build a brack to hold the throttle using the hex flats. First step is to put a good machined surface on the flats.

Milling a small pocket in the top of the foot for the pilot brace rod to set into. This should help stablize the rod and keep it in position while I tack weld it.

5-Jan-2011 Doing our best to match the angle of the brace rod coming down from the smokebox with the machinists protractor

5-Jan-2011 Using the edge finder to pick up the edge of the foot so we can drill the two mounting holes. The stop rod is set since we have a second identical part to do.

Cutting stock down to size for the pilot brace foot. (2)

Efficient operations here: Drill, unclamp, turn part, push against stop rod, clamp, drill & repeat! 8 holes in a jiffy!

8-Dec-2010 The upper brace flanges are square and symetrical. Bill puts a stop rod in the vise and starts drilling.

8-Dec-2010 When you don't have a drawing, you have to make one. Or something that you can follow!

8-Dec-2010 The assembled pilot braces, silver soldered at one end, welded at the other, all blended with a small file and sanding belt!

8-Dec-2010 I don't know how anyone could weld or solder this assembly up on the workbench. I ended up bolting the foot to the pilot deck and Bill held the rod in position on the smokebox, then I tack-welded it with the Mig welder.

8-Dec-2010 The silver-soldered brace.

The flange and rod are bolted together with a 5-40 brass bolt before silver soldering.

Bill uses a magnifing glass to get close-up on the end of the wiggler.

Using the wiggler to pick up the edge of the end of the pilot stay rod for drilling

We use the bolt-circle program in the DRO, which makes the layout easy.

1-Dec-2010 Laying out and drilling the pilot brace smokebox flange.

28-Nov-2010 Shot of the boiler check used on the prototype.

A nice clear shot of the 5-bolt round flange and 4-bolt square flange. We're guessing the pilot stay rod was forged to the flange.

How the vertical stay is attached to the frame. This is important since the USRA prints only have two pilot stays and we are going off-print to match the FRISCO design.

Vertical and angled pilot stays.

Bill went to the Trnasportation Park and too a few pictures of our old nemesis, the FRISCO 1522 and the pilot stays used. There is a square and round smokebox mount.

Machining the end of the brace flat. We used a machinist protractor to match the angle best we could.

22-Nov-2010 Starting on the Pilot Brace.

13-Oct-2010 Using a piece of wire and scriber to lay out the peticoat radiuses

14-July-10 The parts of the 1/4-turn fast-opening gate valve on the bench. There was waaay too much slop in the valve stem - gate connection (center part), so we will make a new stem to replace it.

Turning a piece of brass with a specially ground tool to make the new valve stem. The special tool is needed to put an inside-cup face on a shoulder, which holds the rubber washer in place.

The first 45 degree bend is completed for three pieces and I sneak a picture while the fourth is bent. After this a 90 degree bend is put on the ends with the two close holes.

With the holes drilled in the bracket, the old box brake is put to service for two bends each bracket has on it. He is actually bending the 3/16

10-June-09 We start on the smokebox running board brackets. Bill has machined four pieces of stock to size and has stop set up for in the vice to make the identical pieces. This allows him to put the next piece in the vice and not have to re-indicate the location. Just clamp and re-use the same numbers on the dial!

The smokebox section is the start of several sections with a lot of little things to do. Here Bill is drilling the handrail for the headlight bracket. I still have to get the brass rod and thread both ends to put in the holes.

Drilling the holes in the sheet metal really calls for a drill press, not a mill. Since my 1930's era Barnes 14

3-June-09 Using a step drill bit to cut the holes in the cylinder jacketing. Each hole was piloted before using the drill, the advantage of this style is it does not 'grab' the sheet metal when breaking through to the other side.

27-May-09 The welded steam shrouds ready for fitting to the smokebox shell.

We center the boring head as best we can and bore the angled hole in the curved flange. We advance the cutter after each pass until it just barely reaches 2

The chuck is clamped in the vice. We want the middle of the flange (left-right when the finished part is mounted on the smokebox) to be in line with the front to back motion of the table. With the part in the correct orientation and supported by parallels, we indicate the one jaw and rotate the chuck around until we can move the table l-r without any change in reading.

We decide to use the 3-jaw chuck. It has tall enough jaws to allow for the 1

27-May-09 After rolling the shroud flange the 2

We used my antique roller to roll the casing and casing flanges. These are 2

The casing parts

A trial fit of the steam pipe casing.

Cutting the outside of the steam pipe casing flange make chips fly all over our faces (ouch! hot chips), so we clamp a piece of plastic in front to deflect them.

13-May-09 Preparing the Steam Pipe Casing Flange for boring.

120 Rivets later, the smokebox shell has all the decorative rivets in place. This was actually fun to do!

13-May-09 Satisfied that the hinges are correct, we rivet them to the front cover.

With temporary bolts holding the hinges to the front cover and the shell, we test the hinges -- And the work smoothly without any binding or excessive slop! Yea!

Turning down a piece of O-1 oil-hardening tool steel to make a riveting buck.

The convenience of a second machine in the shop. Without disturbing the setup in the big mill, we use the mill-drill to drill the front cover hinges, relying on a parallel and the flat surface of the casting for alignment.

6-May-09 With the hinge pin holes drilled in the shell hinges, we set the front cover hinges in place and using a transfer punch mark where they should be drilled. You can also see in this picture the socket-head screw we put between the two hinges. Because our shell hinges did not end up exactly where the print calls for them to be, our front cover hinges actually cover the two front bolt holes, rendering them ineffective. Our solution was to fill the holes with dummy bolts like the rest of the front cover has and just put one new one in the shell.

There was no way to reach the bottom hinge - not enough quill travel and too many things in the way. We had to turn the shell over and cut from the 'underneath' to finish the bottom hinge.

4-Apr-09 We also decide that the little end mill we used to cut the slot in the hinges did not cut deep enough. We re-bolt the shell onto the table and using a slitting saw finish the slots to the correct depth.

4-Apr-09 Looking at the smokebox front print, we realized we did not turn it to the correct thickness and put the relief step in the back. So back onto the big lathe it goes again.

Using a resharpened carbide bit (the only way I can afford carbide cutters are by getting used ones) we oh so gently cut the back of the hinges. After a single pass we could see the hardened parts of the hinge which tore up the drill bits earlier.

We decided to lower the front hinges to make it line up better with our thicker front and the shell hinges. Here they are clamped to the table.

1-Apr-09 We tried to use the regular drill chuck in the mill, but with the long drill bit and the table all the way to the bottom, we couldn't make it work. We ended up using a small chuck held in a collet.

Using the wiggler to get the outside reference surface.

Using the milled surfaces for reference, we bolt the shell to the table and align it to vertical using the combination square. It is a pain clamping the shell down (on the inside), it rolls a little each time we tighten the bolt.

The 1/8

Using a larger ball-end mill, we finish the lower hinge support. We also skim the outside of the hinge to get a vertical reference surface.

We start by just skimming the outsides of the hinges to get reference surfaces

1-Apr-09 With the shell hinges temporarily bolted on and the smokebox shell held down on the table vertically, we use a carbide ball-end mill to cut the bearing surfaces on the hinges.

We figured the only way we could hold the shell hinge brackets was to rivet them to the shell then mill the slots, insuring parallelism to each other. Here we bolted the shell to the table again and using the wiggler to line the shell up with the top and bottom marks on the shell (back and front on the table).

The supplier now provides these brackets in aluminum only, due to the case-hard skin these thin sections have. We chewed up a HSS and a TiCN coated drill bit before finding a small Carbide ball mill we could use. Even though this little mill had one damaged flute, and really wasn't a center cutting mill, it chewed through the tough cast iron without complaint. Sometimes it is all about getting the right tool for the job, and in this case, it is carbide for cast iron.

Now to drill the rivet holes. We lift the brackets off the table with a parallel and clamp away from where we have to drill.

Using a ball-end mill, we clean up and machine the hinge tabs. Since these brackets are cast iron, we use a carbide mill. I think the results look good!

28-Mar-09 The smokebox front hinges are easier to clamp, just line up the straight side with a square to the vice.

Another clamping conundrum, how to hold the bracket to the shell to match drill the shell holes to the bracket.

25-Mar-09 These smokebox shell hinges are just plain hard to hand onto! Here we are making a cleanup cut on the shell bracket portion to fit nicely up to the end of the shell.

We have not removed the alignment block (left) from the table since drilling the other holes in the shell, so we just roll the shell around to line up the punch mark and then drill.

18-Mar-09 Laying out the decorative rivets the old-fashioned way: Layout dye, calipers and a center punch. 4 done, 116 more to go!

Success! With the handrail, headlight and bell holes drilled in it, the cover fits on the shell without needing adjustment.

Drilling the handrail holes.

Drilling and tapping for the headlight bracket.

Running the same bolt circle program with the same dimensions as the smokebox shell, we hope everything lines up during assembly. We find some radial differences in the placement of our holes and the casting marks, when all was done, the cover and shell lined up properly.

11-Mar-09 With the back of the smokebox cover marchined, it is time to drill some holes. Setting the cover on the table, we indicate the outside to center it. We tried this without clamping at first so we could swing the whole diameter uninterrupted, but we couldn't put the clamps on without moving it. This cover is also at the limits of my table travel, we had to move the Ram out to reach both front and back holes.

I've been running the numbers for the RRS heavy mike I'm building and finding differences between what is drawn and what I calculate. I'm not trying to second-guess the draftsman, just how to best set up my blast nozzle/petticoat.

I have done the calculations, drawn the 1:6 and 1:3 cones, and found significant differences making me wonder if I am doing something wrong.

If you don't mind, I'd like you to double-check what I have figured.
Cylinders: 2.375

The big question: Do all the bolts holes in the cylinder saddle fit nicely with the drilled and tapped smokebox holes? Answer: YES! we could start all the bolts by hand, indicating there was not interference.

Here's what the smokebox shell looks like after 24 iterations (about 4 hours) of align, drill and tap operations.

Two holes down, 22 more to go. Here's how it went: Using the pointed wiggler, line the punch point on the shell up under the spindle. After checking the front and side alignment with a magnifying glass, bolt the shell down and check the alignment again. We found the shell moved slightly each time we tightened the hold-down screws. Keep adjusting until things are tight but still true to the punch mark. Center drill a hole, Tap drill al the way through, Tap for for a 10-32. I wanted the extra security of a threaded hole in this nice thick smokebox shell instead of just a through-hole nut and bolt assembly. After that hole is done, loosen the clamps, rotate the shell until the next punch mark is on top and repeat: wiggler, center drill, tap drill, tap.

The transfer punch. For these holes under the cylinders, we put a piece of stout steel bar on the punch and the other end on the table. Using a 3 lbs. hammer, quickly strike the steel bar as close to the punch as possible, transferring the center mark.

With two holes drilled and tapped, we put temporary bolts in to hold the cylinders to the shell so we can punch-mark the rest of the holes, insuring the cylinders do not move during the punching process.

Using a homemade close fitting transfer punch, we mark two holes in the shell then remove the cylinders. We use the wiggler to line up the head exactly over the punch march, rolling the shell around until things line up. We do not ever move the X-axis (l-r) to position the hole.

With the right (or wrong) light, the scribed center line and casting halves mark almost disappear.

28-Feb-09 The painted cylinder saddle is brought down from the cold garage and into the shop to match drill it to the smokebox shell. We have scribed a center line on the shell to match the casting halves joint, and another line where the center of the front row of bolts should go to position the saddle front-to-back properly.

Another Saturday of bad weather means more time in the shop and less out at the track. Good for shop time, bad for getting the track ready for the April start of season run. Using the eyeball

We drill just the two holes perpendicular to the smokebox front at first. Our holes are okay, but the cumulative errors between the rotary head, the angle of the tilt and the not quite on center part cause us to adjust the holes with a small round rat-tail file.

How to lay out the hole pattern? I had a difficult time determining if the print was a straight overhead view (showing the curve of the smokebox) or a plan view. In the end we used a tilting rotary chuck. First we indicate the part to get it on center with the rotary. An adjustable chuck like the Buck 'Adjust-Tru' models would be nice here. Then we center the mill head over center and drill the holes with a small drill.

25-Feb-09 With the six-jaw holding the end of the smokestack and a boring bar in the toolholder, we turn the recess for the petticoat per the print.

Another good days work! The smokebox shell has the smokestack, blast pipe, steam pipes, handrail and boiler step holes in it.

When we advance to the next larger cutter, we have to look around to find a carbide cutter to put in it. We can run carbide twice a fast and take a heavier cut each time, speeding each boring pass up considerably. Unfortunately, this cutter which looked like it had enough clearance, did not perform well in this setup at all, producing lots of chatter and a lousy finish. We have to switch back to a HSS bit.

The high speed steel cutters are okay, but slow. We can't take very large cuts - about 0.010 each pass.

Having quickly reached the size limit of the boring head with boring bars, we start a progression of larger flycutters mounted in the boring head to enlarge the hole to the 2

All the holes (not counting rivets) are done except for the smokestack hole. We add a center bolt in the blast pipe hole to help secure the pipe and start a series of larger holes for the smokestack.

After a hole is drilled, we loosen the top bridging clamp, roll the pipe and line up to the next scribe mark. Here we are drilling the holes for the side step.

With a 4

Next to make a clamping fixture. My mill table is way too small to clamp over the shell by resting it in a slot, and I probably couldn't lift a vee-block large enough for the 12

21-Feb-09 It's lousy weather outside today, nothing can be done at the track so into the shop we go. Using the same DRO bolt circle program, we have made marks on the rim of the shell for the steam pipe, handrails, and smokestack holes to go on the side of the shell. Using the rim marks and the combination square, the hole locations are marked on the side.

A bit of figuring with the DRO bolt circle program and soon we are drilling and tapping the 5-40 holes for the smokebox cover.

With the bridgeport knee all the way to the bottom and the ram pulled out a bit more, we do our best to center the pipe in the mill. We discover the pipe is not completely round by about 15 thou. Not a problem since the boiler is almost 1/8

Finishing the centering operation with the dial indicator. Next we clamp down a nice sharp piece of high speed steel in the lantern style tool post and face the end of the pipe.

11-Feb-09 This old Rahn-Larmon lathe still has the factory-issued 14

The cutting was going well until we hit a piece of sand or a stone in the aluminum which destroys the edge of the HSS cutter. You can see the defect in the middle of the casting - the small black dot in the middle. You can also see the smooth finish on the left and the rough finish on the right which was after the cutter edge was ruined. We try switching to a tougher carbide bit, but it does not have enought relief clearance and the bottom edge drags on the metal, cutting poorly.
We end up digging the stone out with a pointed chisel which allows us to finish the work with the resharpened HSS cutter.

Running in open belt, about 258 rpm, we take light cuts from the inside working out with a nice sharp high-speed toolbit.

Here's how we chose to hold the smokebox front: Using a 6

Our 'live center' is a shop-made affair of many years ago using an open-cage tapered roller bearing. I had to dunk it in the solvent tank to clean out the gunk and dirt, then greased it up a bit. The inner race is not captive so if you back the tailstock off, the bearing will fall out, which also gets it dirty again. It needs to have a proper live center made. You can spend your time making tooling or making parts, this time it was parts.

4-Feb-09 We start a new section - the Smokebox! It's always fun to start a new one--fresh drawings to look at, new castings to puzzle out how to hold. We put the big Rahn-Larmon lathe to use to turn the OD of the smokebox front true, and clean up the back. Although we have the casting clamped from behind, we use the live center and a spacer block for additional pressure to keep it in place.

9-Feb-08 Thanks to my friend Tim M., who is also building a Mikado and having a boiler built, I was able to get a cut of the boiler pipe for my smokebox. It is 12