"Nina", a Gauge 1, 0-4-0 live steamer. Progress and updates

[zeeprogrammer]

I have to report for jury duty on Monday. Federal District Court, must be a biggy. It may last 4 to 6 weeks, they said.

When asked a question..just say "hang 'em"...that should get you out.

But knowing you'll do the proper civic duty...I'm still hoping you're back quicker than you think. I really enjoy your thread.

 

[xo18thfa]

Dean: Dang, I did not think of that. It's round inside.

Carl: I got excused. They have you call in the night before to check. They excused two whole jury pools. I bet the charges were dropped or the trial postponed.

 

[xo18thfa]

Today is the second half of the lubricator. We are going to fabricate the lubricator stand and get it mounted on the boiler. The stand for the lubricator is basically the same process as with the smokebox saddle. The stand consists of a top and bottom plate and a curved spacer in between.

All the parts fabricate the same way as the saddle. You will have to set up the between centers boring bar to carve out the round portion just as before.

The only difference from the smoke box saddle is the spacer for the lubricator stand has the bulk of the interior material removed. Just for looks.

The lubricator assembly gets strapped to the top of the boiler. To make the straps, coax lengths of brass strip around a piece of pipe to the exact diameter of the boiler barrel. Cut the ends of the straps so they meet exactly. The brass straps can be from 1/32” thick strip, either 3/16” or 1/8” wide. If the brass strips get too springy and uncooperative, heat them to dull red and quench in water. That will soften them up.

Silver solder the stand assembly together. Do it in stages. First solder the base plates and spacer. Then solder on the straps. Finally, solder on a 3/8” length of 1/8” OD, 3/32” ID brass tube directly over the ends of the strap. This is the stand assembly, upside down.

Now with a fine saw, cut thru the brass tube and strap.

Attach the lubricator to its stand with some 0 x 80 screws. Disassemble the boiler and slip the lubricator assembly over the boiler barrel. Size 0 x 80 machine screws fit nicely inside a 1/8” brass tube. Sinch up the screws just enough to hold the lubricator in place.

Reassemble the boiler to the engine frame. With the lubricator in place we can mock up the steam and exhaust piping.

That looks cool. At least the horizontal boiler barrel has something useful to do. Brightly polished brass straps should look nice against a black boiler shell.

Next time we will do a safety valve and maybe start on the site glass.

 

[Deanofid]

It's looking good all put together, Bob.

Dean

 

[shred]

Very nice. Much fancier than my little Cracker. The lack of lubricator in those plans is a bit of an oversight I think, it could use one for longer runs.

 

[zeeprogrammer]

Nice Bob. I'm enjoying this thread very much. Learning a lot.

 

[xo18thfa]

Thanks guys. It's coming along. It's like eating an elephant, just do it one bit ant a time.

Dean: I ordered some of those watch bearings. Hopefully burner jets will come along soon.

In researching miniature safety valves, I looked at work by K.N. Harris, Martin Evans, LBSC, Tubal Cain and Kozo Hiraoka. The Nina boiler is so small in terms of steam production that it is off the low end of all the charts, graphs and formulas. I came to the conclusion that the only real design criterion is that it must release steam faster then the boiler can produce it. After looking at Kozo’s work some more, I think this one will do that.

This valve is the usual stainless steel ball type. Our valve will use a 1/8” diameter ball against a 15-degree beveled seat. It is not a true safety valve in terms of a “pop” valve; it’s more of a pressure release valve. Real pop valves close quickly when the pressure drops to the safe level. This type closes sometimes, sometimes they don’t.

Here is the exploded view of all the parts.

Here are the drawings for the safety valve:

http://1stclass.mylargescale.com/xo18thfa/Nina%2002/Safety%20A.jpg
http://1stclass.mylargescale.com/xo18thfa/Nina%2002/Safety%20B.jpg

Start with the valve body. Normally the valve body is turned from a single piece of hex brass stock. A specially sharpened “D” bit cuts the 15-degree for the ball seat. I am going to try an experiment with the valve body and make it in 3 parts. I want to do away with the special “D” bit and make all the parts with standard lathe tooling.

Before starting on the valve body, there is an important accessory you need for your lathe. We have used a tap holder for threaded holes, now we need a die holder to cut threads on a rod. While dies holders are commercially available, you can make your own. Here is the “temporary” one I made 30 years ago.

My die holder is an old 1” bolt, cut off, with a 1/2" hole drilled thru it and a recess for a 1” diameter die. Dies under 1/4" are usually 1” diameter. Smaller dies are 13/16”. I made an adapter to hold smaller dies. The short length of rod goes in the lathe tailstock and the die holder slips over. A set-screw holds the die in the holder. Here’s the die holder in the lathe ready for work.

The tailstock lines up the die just like a tap holder does the tap. To use it, hold the lathe chuck stationary with the left hand and turn the die holder with the right. Go about 1/3 turn and back out to clear the chips. Use oil, even on brass. After a while you get in a rhythm with this thing, and threads cut in a hurry. It is impossible to cut accurate threads on a rod by hand. Invest in a ready made die holder or fabricate your own.

First part to make is the valve seat. Chuck a length of 1/4" brass rod in the 3 jaw. Drill and #39 ream about 1/2" deep.

The reason for #39 is that the hole thru the valve seat is 80% the diameter of the ball. #39 is .0998”, which is the closest to 80% of 1/8. You could get by with a 3/32” ream, which is probably what the commercial makers do.

Using the die holder, cut a 1/4 x 40 thread for about 1/2" long.

Next, set compound slide on the lathe to 15 degrees and face off the end of the valve seat. Run the bit outwards to pull burrs away from the reamed hole. Face deep enough to get into the good, clean reamed hole. This 15-degree edge needs be clean and sharp. Part off the seat to 3/8” length.

Now make the bonnet nut. Drill and tap 3/8” hex brass with 1/4 x 40. Turn a nice chamfer on the edge. Rough hacksaw it off.

Putting a little nut like this in the lathe chuck to face off the rough-cut is nearly impossible to do. Instead make a chucking spigot with a jam nut.

Assemble the work piece on the spigot, secured with the jam. Chuck it up and face it clean.

Make these kinds of spigots as you need them. Over time you will end up with you’ll end up with a set. This particular spigot has 5/16 x 40 on the other end.

The valve bonnet is an easy turning job from 5/16” hex brass.

Here’s all the parts for the valve body.

Assemble the body by jamming the bonnet nut and the bonnet.

That’s enough for today. Next time we will finish the safety valve. The next installment will have some very serious mathematical content. Have some scratch paper, stubby pencil and dirty eraser ready. No calculators allowed.

Take care.

 

[xo18thfa]

In the last installment we carefully machined a sharp 15-degree bevel on the edge of the ball seat. Now it is time to seat the ball to the valve seat. The ball we use is a precision stainless steel bearing ball. It has very close tolerances and a hardness approaching “Chinese Arithmetic”. It should do fine.

To seat the ball, set the valve body on a flat hard surface. Drop in a ball. Use a length of brass rod as a drift punch. Get everything lined up and give the drift a pop with a hammer. Here is the set up.

The ball will make a slight spherical impression in the ball seat. The question is: how hard do you hit the drift with the hammer? I don’t know how to describe it, “medium light”(?) If done right, the ball will make an air tight seal if you suck on the bottom of the ball seat with your mouth. There should also be a very slight indentation left on the seat edge by the ball.

The valve stem comes next. It is a straight turning job from 1/8” brass rod. Turn the stem between centers on the lathe. Drill a #60 hole in the end of the rod to a depth of about 1/16”. Follow up with a 5/32” drill bit to cut a shallow “V” notch in the end of the stem to center the ball over the valve seat. The #60 hole serves as a center hole for the lathe tailstock.

The final part to make is the stem adjuster nut. This nut bears against the valve spring and adjusts the valve to open at the desired pressure. Pressure adjustment on this valve can go from zero to total lock down.

The adjuster starts out from a short length of brass rod. Thread the rod with 1/4 x 40 for a length of 1/4". Drill a #50 hole for a smooth slide fit with the valve stem.

The safety valve drawing shows six holes, #57 in size, drilled in a hex pattern thru the nut. These are steam relief holes allow the escape of steam thru the valve body when the ball lifts. These holes are needed or the valve doesn’t work. The are spaced at 60 degree intervals from the center. They lay on what is called a pitch circle. The diameter of the Pitch Circle in our case is 9/64” or .140”. That puts them about half way between the outside edge of the center hole and the root of the thread.

There are a number of ways to layout and drill the relief holes.

1. Use a CNC machine.
2. Set up a rotary table or some indexing device on the mill to space out the holes on a 60-degree interval.
3. Use a drilling spindle on the lathe cross slide and index the lathe on 60-degree intervals.
4. Do a mathematical “bolt circle” calculation and use the X – Y table on the milling machine.
5. Layout the holes by hand, center pop and drill.

Option #5 is easiest way to go and will produce a perfectly satisfactory result. But, instead of doing it the easy way, we are going to use method #4. The challenge is converting angles from the center to X – Y coordinates for the milling table.

The following diagram shows the layout of the relief holes as if the stock were clamped in the mill vice. Holes #1 and #4 are easy to drill. They are simply plus and minus 0.070” from the center. Holes #2, #3, #5 and #6 require a combination of X and Y movements. It is those values of X and Y we need to find.

The diagram shows a convenient 30-60-90 degree right triangle that includes hole #2. As you know from your High School trigonometry class, the sine of an angle multiplied by the hypotenuse give the length of the side opposite the angle. In this case, the sine of 30 degrees is 0.500; the hypotenuse is 0.070”. The Y distance from the center to hole #2 is 0.035”. Similarly, the cosine of an angle multiplied by the hypotenuse gives the length of the adjacent side. The cosine of 30 degrees is 0.866, hypotenuse is still 0.070”. They X distance from the center to hole #2 is 0.061”. Since the remaining holes are equally spaced around the pitch circle, the values of Y=0.035” and X=0.061” will reach all of them.

Let’s drill some holes. Clamp the adjuster nut stock in the mill vice and center it under the mill spindel. Use a center in the drill chuck to center the stock. Lower the center into the hole and adjust X and Y until center. You eye is a precision instrument and will get this right on.

Traverse the Y-axis by plus and minus 0.070” to drill holes #1 and #4. Use a center drill to spot the holes before switching to the smaller bit.

Now, using the values of Y=0.035” and X=0.061” traverse from the center to drill the remaining holes.

They came out spot on. The lead screws on my mill have a lot of backlash in them. That prevents me from simply running around and drilling the holes. I started from the center on every hole.

The last part is the spring. It is a precision stainless steel spring, with a diameter of 0.120”, length of 0.250” and a wire diameter of 0.016”. It has 5 full turns. The spring and ball came from McMaster Carr.

Here is the safety valve ready to set.

The final thing to do on the valve is to set for pressure. We will do that later when we fire the boiler on steam. Next time we will work on the site glass.

 

[4156df]

Bob,
She's a beauty! Thanks for taking the time to post. Very interesting and informative.
Dennis

 

[bearcar1]

"I hear the train a comin' ........ she's roaring(?) 'round the bend........"


Won't be long now. Looking real good, I do appreciate the fine work on that safety valve.


BC1
Jim

 

[xo18thfa]

Thanks Dennis and Jim. I am getting nervous. It's close to steam test time. I hope this thing works.


The design for the site glass, or water gauge is from LBSC. It is a design that he used on many of his Gauge 0 live steamers. His original plan called for 1/8” diameter glass tube. 5/32” glass is more widely available and I have a bunch of it. So we will increase LBSC’s design by 25% to take advantage of larger glass tube.

Here is the drawing. It is LBSC’s drawing, but I added the plus 25% dimensions.

The valve on gauge lower end is a blow down valve. The purpose of it is to ensure a proper reading in the gauge glass. Weird science happens sometimes in these small gauges that prevent accurate readings. Opening the blow down causes the water glass to drain out. Closing the valve allows the glass to fill back up to its actual level. While operating the engine, occasionally crack the blow down open for a half-second and close it. That will ensure an accurate reading. Sometimes small gauges work fine without a blow down. Sometimes they don’t. It’s better to have it and not need it, then to need it and not have it. Besides, they are too easy to make, so go ahead and do it.

Start work with the gauge lower end. It is a brass and silver solder fabrication. Thread all the required parts before silver soldering.

The boss for the gauge glass goes into a blind hole. The boss for the drain is straight thru. You can do them either way. Going straight thru is better I think. It ensures the silver solder goes all the ways thru and makes the part solid. I cut the lower end stock off a bit too short on the drain end. Leave it about a quarter inch longer then I did, you see why shortly.

Silver solder the lower end together.

Instead of threading the lower and upper end into a shoulder, I decided to use a jam nut instead.

Chuck the lower end in the 3 jaw by the drain end. This is why you need to leave it a bit longer. Fortunately I was able to grip it securely. Drill #31 9/16” deep. This is the water passage.

Grip the lower end in the drill vise. Drill #19 1/8” deep. This is a generous O.D. fit for the gauge glass. Drill # 40 just breaking into the water passage. #40 is the I.D. of the gauge glass.

Make up a female threaded chucking spigot to accept the gauge lower end.

Chuck up the gauge lower end in the spigot. Machine of the excess material to the final length of the gauge lower end. Drill and tap for #4 x 40 to a depth of 3/8”. Lastly, drill #55 thru into the water passage.

Make a blow down valve spindle from a #4 x 40 machine screw. Turn the screw down to 0.080” diameter for a length of 3/16”. File or turn a 60 degree included angle point on the spindle. Loctite or silver solder a knurled nut to the spindle. With that, the gauge lower end is done.

Next, fabricate the gauge upper end, it’s done the exact same way as the lower end.

Silver solder the parts together and machine as with the lower end.

The packing nuts for the glass tube are actually a silver solder fabrication. Drill and tap a 1/4" x 40 hole into some 5/16” hex brass. Part off a 5/32” length. Cut some brass scrap, any size will do.

Silver solder the threaded hex to the scrap. Use the least amount of solder possible. Too much solder can capillary up into the thread and ruin it. Find that threaded male chucking spigot you made earlier.

Chuck the blank nuts and spigot in the lathe. Drill #19 thru.

With the nut still on the spigot, face to a total length of 3/16”. Turn the waste brass off. At this point you can file the remaining brass off so the whole nut is hex shape. I left it round, looks OK.

Make a plug nut for the gauge upper end. I could not find my 10 x 32 die, so the plug is a machine screw silver soldered into 1/4" hex brass. Of course, after doing the plug, I found the die. Cut a 1 5/16” length of glass tube. The best way is with an emory cut off wheel on the Dremel tool. Just lightly score the tube all around. It will snap off cleanly. The site glass is all done.

Put it on the boiler for a look see.

That’s lookin’ sexy. We will eventually do a drainpipe for the blow down. Probably after the cab is done.

Plumbing is almost done. Next time we will get on the throttle valve.

 

[bearcar1]

Nice!, Bob. A really slick write up on how to make that blow down valve. I'm going to copy that one down for future reference. I have always questioned the ability of some of those single tube gages for being accurate. Usually OK I suppose but still, this method insures a good water level display.

BC1
Jim

 

[zeeprogrammer]

Absolutely interesting Bob. I really enjoy your posts.

I have to ask a newbie question...I've seen a couple of members make a glass water level gauge. That's supposed to show the amount of water left in the boiler right? But what about the pressure? Why doesn't the glass break? I'd really appreciate a little education on that.

Thanks.

 

[Deanofid]

Nicely done gauge, Bob. It looks great on the boiler!

Dean

 

[xo18thfa]

Thanks guys.

Dean: I can't wait to try the watch bearing trick for the burner. They are sitting on the bench ready to go.

Jim: I think blow downs should be used. I don't recall blown downs available on any commercially made gauges, except in the large "ride-on" sized train engines.

Carl: The glass is pretty strong and can take the pressure. I've never seen one break during operation. Usually they get dumped and break. If one breaks under pressure, all the steam and water goes shooting. There is nothing to stop it. Actually, most of them are broken during installation.

The water gauge shows the water level in the boiler. The pressure is measured with a pressure gauge. The miniature steam suppliers sell very small pressure gauges. They are 3/4" or 1/2" diameter. I use small pressure gauges from fire extinguishers. They are kind of big, but work fine and are very cheap.

Pressure gauges connect high on the boiler, above the water level. In the pic below, there is a "U" shaped pipe called a siphon. Steam goes into the siphon during warm up and condenses back into water. The water remains in the bottom of the siphon and blocks steam from directly going into the gauge mechanism.

The original plan was to not have a pressure gauge on this engine. Maybe I will put one on. I can modify the boiler fill plug to accept a gauge.

Thanks, Bob

 

[SAM in LA]

Bob,

Very nice level gage.

Does anyone ever make the sight glass with valves between it and the boiler?

SAM

 

[xo18thfa]

Sam: I have never seen sight glasses like that in Gauge 1. The "ride-on" sized engines sometimes have them. I have never seen a gauge glass break under pressure either. I am sure it could happen, but not so far.

After a short break for another project, it’s time to get back on Nina. Throttles for many Gauge 1 engines are simple screw down valves. Let’s do something different and make a piston style throttle. Here’s the completed throttle ready for the boiler. This view is from the bottom. The hole towards the left end goes into the boiler. The threaded portion facing downward goes to the engine.

Here’s the drawing for the throttle assembly:

http://1stclass.mylargescale.com/xo18thfa/Nina%2002/Throttle.JPG

Fabrication of the throttle is almost exactly the same as the water gauge. The throttle body is a brass/silver solder fabrication, consisting of 3 parts. Here they are:

Silver solder the throttle body parts together to form a “pseudo” casting.

Chuck the throttle body in a chucking spigot. Drill and ream 5/32” thru.

Grip the throttle body in the drill press vice and drill both passages 1/8”. Everything so far, just as the water gauge.

The throttle spindle is from 5/32” stainless steel. Lightly polish the rod with fine emory cloth and oil for a smooth sliding fit in the throttle body. Chuck the stock in the 3 jaw, securing the end with the tailstock. A #60 drill is sufficient for a center hole. Turn the slot in the spindle. Square the corners with a parting tool.

The fork end of the spindle assembles the same way as the piston and piston rod. Use a 2 x 56 machine with a dab of “Loctite” to secure the spindle and fork. The usual practice is to hacksaw and file the slot in the fork. Let’s try something different. Make a little holding jig for a length of 3/16” dia brass rod. Use a parting tool to take a plunging cut to form the slot. A set-up something like this.

This is way easier then with saws and files. Trim the fork to length and tap the end for 2 x 56. Assemble the spindle rod and fork.

The remaining parts are straightforward. The two links are from 1/32” x 1/8” strip brass. Drill them identically with #53 drill. #53 is a very close fit for 0 x 80 machine screws. The throttle handle is from 1/16” x 3/16” strip brass. The only thing critical about the handle is the 3/8” between holes. “Jazz” the throttle handle as desired. Two cap nuts are needed. Make them both the same way as for the water gauge glass. One cap is “blind” to seal the end of the throttle body. The other is a gland nut drilled #19 for a very generous fit for the spindle. Finally, a jam nut to lock the throttle body to the boiler bushing. Here are all the parts:

Assemble the throttle. The pivot points are all 0 x 80 machine screws. Hang it on the boiler.

That’s lookin’ sweet.

The “full throttle” position is with the handle straight back, as shown in the photo. The “throttle closed” position is either full left or full right. Either way shuts it off.

Next time we will get on the steam and exhaust piping and finish up the plumbing.

 

[xo18thfa]

There are probably as many ways to install steam and exhaust piping as there are ways to cook chili. The primary method I use is a nut to compress a flange against a flat fitting face. A small, thin Viton O ring serves as the seal between the flange and the face. Viton is a reasonably high temp rubber that works wells in Gauge 1 steam applications. This method has worked well for me on all my scratchbuilds, so we’ll stick with it.

An alternate method to install piping is with a “banjo bolt”. Banjo bolts are used to install pipes into boiler bushings, and in our case to the engine manifold. A banjo bolt is essentially a very thick washer with a tube soldered into it. The banjo is attached to the bushing with a special hollow and cross-drilled bolt. More on banjo bolts in a moment.

First up are some 90 degree elbows. We need 2 “Street Ells” (male-to female thread) for the lubricator and one as a fitting to go thru the smokebox wall. The elbows fabricate and solder together just as with the water gauge and throttle. The street ells consist of 3 parts; all threads are 1/4" x 40 TPI. Here are the parts for one and another just out of the pickle tank:

The exhaust elbow thru the smokebox has a long leg and a short. The long leg goes thru the smokebox wall and is secured with 2 jam nuts.

For the piping, start at the throttle and work towards the exhaust end. From the throttle, I came out with 5/32” diameter thin wall copper tube. 1/8” will probably work fine, but I did not have enough 1/8” on hand to do the whole engine. Anneal to copper tube to soften it. Then with your favorite tube bender, bend and trim the tube until it fits between the throttle and the lubricator. Make up two nuts just as with the water gauge glass nuts. Turn and part off flanges about 1/32” thick and diameter that is a good close fit inside the nut. Here are the parts for the first pipe.

The O-rings are 3mm inside diameter and 1mm wall. They are available from McMaster-Carr and fit perfectly for this job.

Slip the nuts over the tube and silver solder the flanges.

The next pipe from the lubricator to the engine manifold has a nut-flange on one end and a banjo on the other. Here’s the drawing for the banjo bolt.

http://1stclass.mylargescale.com/xo18thfa/Nina%2003/Plumb%20Banjo.JPG

And here it is soldered up and ready to install. This is 1/8” OD, thin wall copper tube.

And from the manifold exhaust side forward to the smokebox elbow.

Now install all the pipes, starting at the throttle. There are no O-rings used for now. Those get out in at final assembly

I decided to change location of the throttle by placing it on the side. That centers the handle better, should work out OK.

And now install the 2d-steam pipe and exhaust pipe. Loosening the lubricator helps get the pipes installed.

Last pipe to go in is the blast pipe. It’s not really a blast pipe; it just gives the exhaust steam something decorative to do. Install it with a nut and flange. Trim the length so it is near the top of the stack.

So here is where it’s at so far.

Lastly, fabricate a water fill plug for the last bushing on top of the boiler. I am thinking about making up a riser section with a nipple on the side and the water fill on top. Use the nipple for a pressure gauge outlet.

Looks more like a “moonshine still” then a steam locomotive.

The plumbing phase is all done. Next is the butane fuel system. I am trying to figure out where to put the fuel tank. Either inside the open top cab, or on the fender, forward of the flywheel. What do you guys think?

 

[ariz]

xo18thfa I don't know where to put the fuel tank, I'm sorry, but replied anyway to say that your work of silver soldering and plumbing is admirable :bow:

the result is a fascinating ensemble, really a work of great craftsmanship, very beautiful and well shapely

thanx for sharing it

 

[kustomkb]

You're doing some really nice work there Bob!

What a great idea, slotting the fork like that. Man, ya really do learn something new everyday.