I Don't Know Why I Ever Got Involved...

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Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

To complete the lubricator installation, a new 1/8" thick brass lubricator lid was machined up to be a close fit in the lubricator body.

The lubricator cover handle was bent out of a short piece of 1/16" diameter CR steel wire using a small commercial 3 pin wire bender. The underside of the lubricator cover had to be machined out in its approximate centre to clear the internal lubricator parts some of which stood slightly proud of the lubricator body. See the first and second photos.

The lubricator handle was fastened to the lubricator lid with Loctite after drilling the cover nearly through.

With just some careful fitting, the lubricator lid now just snaps into place.

I may have to drill a tiny vacuum relief hole in the lubricator cover as the cover was made a tight push fit in the lubricator body so the cover doesn't come loose when the locomotive is in operation.

Next up is to machine the LBSC rotary throttle handle which appears to be the only part missing on the throttle but we will see.
Attachments
73 Underside of Lubricator Brass Cover and CR Steel Wire Handle.jpg
74 The Complete Lubricator Cover.jpg
75 The Lubricator Cover Installed on the Engine.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

To finish the throttle, I first had to know and understand what was already there.

In the Josslin drawings the LBSC rotary throttle is not shown in detail but is drawn, in outline, at the backhead of the boiler.

So I removed the large throttle flange/spigot and stuffing box there only to discover the throttle rod disappearing into the depths of the boiler and no throttle. Also, the throttle flange/spigot had been drilled eccentrically for some reason. The throttle rod itself would turn but appeared also to be bent.

More digging into the boiler was obviously needed if I wanted to have a throttle.

The front end of the boiler is quite interesting and there is lots going on here as this boiler has three superheaters, two superheater headers, the downcomer headers and pipes to the cylinders as well as lubricator and other lines. I have photos of all of this but it is not quite relevant yet except that it all had to be removed to see what was holding the throttle rod at the boiler front tubeplate.

See the first photo. When all of the above was removed, the boiler did have the LBSC rotary throttle at the front end of the boiler which is a better location than on Josslin drawings. The second and third photos show the throttle details. Here, someone had done an excellent job with the machining and assembly of the throttle.

There is a somewhat detailed description of this type of throttle in LBSC's book "Shop Shed and Road" but it is not all that easy to understand and the construction notes which I have give no construction details except to say that it is a standard LBSC design and very similar to the rotary throttle on Ayesha.

Here I have to digress a bit because Ayesha was the model locomotive LBSC constructed when he engaged in "the battle of the boilers" and showed convincingly how superior his design was to anything which existed at the time.

Only when I tried to put back the throttle rod did I understand what was going on. I had a perfectly good throttle but there was a cross boiler stay over the firebox which was almost directly in line with the throttle rod. No matter what I did the throttle rod would not pass this obstruction.

It took every mechanical trick I knew to get the throttle rod back in. The dodge used was to attach the backhead end of the 1/8" dia. throttle rod to a long strip of boiler banding material with masking tape as seen in the last three photos. The banding material which was curved slightly acted as a pilot which, by turning it back and forth after inserting the entire mess into the boiler as far as it would go, I might get lucky and thread my way around the stay obstruction and then pick up the backhead opening. Yes, it did work after about 10 minutes of delicate turning and probing.

Now, I understood why the eccentric throttle flange/spigot as the throttle rod came out canted at a slight angle as a result of "bending" around the firebox stay. The throttle rod is somewhat flexible and still can be rotated as designed but one can feel a bit of resistance.

Now that I know the what and the why, I can get on with finishing the throttle.

To be continued.
Attachments
76 The LBSC Rotary Throttle Located In and Immediately Behind the Boiler Front Tubeplate.jpg
77 All of the Well Made LBSC Rotary Throttle Components.jpg
78 A Closeup of the Perforated Steam Collecting Chamber.jpg
79 The Backhead End of the Throttle Rod Taped to a Pilot Strip Made from Boiler Banding Material.jpg
80 An Overall View of this Dodge.jpg
81 After Threading Through the Boiler Frontube and Boiler Backhead Openings.jpg
Carrdo
Posts: 1444
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

Further examination of the rotary throttle parts revealed that the end cover port face had not been drilled for the 1/16" dia. stop pin which controls the valve rotation on the port face of the end cover.

This had to be carefully set, as the port face (the way it had been drilled), left precious little room for the pin. More on this shortly.

After locating the best position for the pin (by eye and by careful rotation of the rotary valve to see where the steam passages were fully open and fully closed, the final pin location on the end cover was drilled and tapped 1-64 NC.

As the drilling of the stop pin ended up next to a set of ports, the size of the rotary valve opening on one side of the rotary valve had to be increased by careful milling and filing to accommodate the stop pin. LBSC's drawing shows equal size openings on each side of the valve but this is not possible the way the ports had been drilled on the end cover. You can see this on the third and fourth photos.

The existing end cover had been drilled for four port openings versus two on the LBSC designs (see photos 92,93). This likely makes for a very aggressive throttle but I am not certain. The port openings are of two different sizes, the smaller opening, which is uncovered first, is there to admit steam into the cylinders and to give a "soft" start while the larger openings are for full throttle. On the LBSC designs the throttle valve is turned anti clockwise to open it while with the existing Uranus throttle end cover, the valve is turned clockwise to open it.
Attachments
88 Milling a Larger Cutout on One Side of the Throttle Valve.jpg
89 The Now Asymmetrical Throttle Valve Cutouts.jpg
90 Rotary Valve Stop Pin Set in End Cover Port Face.jpg
91 Valve Position with Steam Ports Fully Open.jpg
92 The Rotary Throttle Valve and Port Face Layout as Shown in LBSC's Book Shop Shed and Road.jpg
93 The LBSC Rotary Valve Throttle on Ayesha .jpg
Carrdo
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Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

To make matters more difficult for myself as usual, I decided to produce another rotary valve end cover/port face to exactly LBSC's design/drawings.

I used the Ayesha port sizes steam passages (1/16", 3/32") as the cylinders on the two locomotives are virtually identical in size. There is a video on the net of Ayesha running at what appears to be full throttle and the locomotive is really moving so I figured... I can always go back to the original 4 port end cover as seen on the Uranus if more performance is needed but I don't think so.

To make the new cover involves some tricky locating/drilling on an angle. Also, the two ports have to be drilled very close together radially and the stop pin located precisely as before. All LBSC says is, this is a "ticklish "operation and care is needed. There is no indication anywhere of what angle the steam passages have to be drilled nor at what spacing so one is left in the dark here.

Anyway after a lot of trig., (don't ask me how), I determined the drilling angle worked out to be 14 degrees 48 minutes so I used 15 degrees, with the two ports having a 1/64" bridge between the two port holes set 3/32" on centreline in from the OD. It was very tense work wondering if I got it right to have the steam passages come out in the correct spot on the other side of the cover (they had to) and then drill for the stop pin whose location was exacting also. It looks so easy on paper. I guess that is why LBSC had so few words to say about it.

In the end, it all came out good enough.

Then, if one managed to get this far without a disaster, LBSC says that the two port faces need to be lapped truly flat to have a steam tight seal. Lapping the end of the valve is easy because it is all flat lapping but lapping the port face which has the centre spigot on which the valve sits is not. So one has to get creative as LBSC has nothing to say about this.

The solution was to use an old sine plate which I have which has a series of tapped holes in its face. Use very fine abrasive paper, punch a small hole in it for the spigot to pass through and with some oil. The spigot is captive to the tapped hole and one can then lap in very tiny oscillations to produce the final flat port face.

To be continued.
Attachments
95 The Tricky Port Face Steam Passages Drilling in the New End Cover.jpg
96 After Drilling the Port Face Steam Passages in the New End Cover.jpg
98 The Throttle Valve in the Fully Closed Position in the New End Cover Port Face.jpg
99 The Throttle Valve in the Fully Open Position in the New End Cover Port Face.jpg
101 Lapping In the Port Face in the New End Cover.jpg
102 Lapping In the Port Face in the New End Cover.jpg
Carrdo
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Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

More tense work as I now had to pick up the spacing on the existing throttle cover mounting screws and transfer them to the new cover.

I have done this before using the original part as a drill bushing guide but I never really know if it will work as it has to work perfectly to to be able to mount the new throttle cover and have the fasteners thread in per as the original.

One has to set the two covers exactly on top of one another but fortunately, as they are the same part, I had machined the new cover OD exactly the same as the original so I could mate them in the vise with a toolmakers clamp set at 90 degrees to the vise jaws. They look co-incident but one never really knows until all of the screw clearance holes have been spotted through.

Fortunately, everything did work as hoped (this time).

I had some trouble though making the new cover gasket, having made three attempts before finally producing something useful. All I can say is with the thick gasket material used, anything which can move out of place will. I will just leave it at that.

As I recall, having started this topic, I mentioned all that seemed left to be done was to make a new throttle lever. Well, I guess I am now back at that point again. I did finish the 1/8" dia. throttle rod handle end by threading it 3-48 NC and machining a 7/64" square section for the handle. But how does one produce a non standard internal square of this dimension?

To be continued.
Attachments
104 Spotting Through the Existing Throttle Cover to the New Throttle Cover.jpg
105 The New Throttle Cover After Spotting Through and Countersinking.jpg
106 First Attempt  at Making a New Cover Gasket.jpg
107 All of the Gasket Making Tools After Three Attempts.jpg
108 The New Final Gasket and Gasket Cutter.jpg
109 The Throttle Rod Handle End Now Machined.jpg
Carrdo
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Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

So, how does one accurately produce a non standard internal square of any dimension without a commercially bought broach? I certainly can't precision file something like that.

I am not the inventor of this tool as it is part of TSME history but yes, one can produce an internal square using the shop made single tooth broach shown in the photo. There is a limitation on part thickness as I doubt it would work on a 1/4" thick piece of mild steel or something thicker but with the throttle handle thickness of 1/8" it certainly will do the job.

The single tooth broach is made from drill rod and hardened. I don't temper it as it is a single use tool. It is best also to have a good arbor press to do the pressing and everything must be aligned square when pressing.

One needs to make a very narrow nosed turning tool (or one could shape a parting tool blade as well) to produce the cutting edge.

To be continued.
Attachments
110 Custom Made Single Tooth Broach.jpg
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Bill Shields
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Re: I Don't Know Why I Ever Got Involved...

Post by Bill Shields »

I broach small hexes with sharpened hex wrenches per your example.

Regarding your throttle woes.. all of which is why I converted to screw throttles decades ago. May not be prototype but..
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Carrdo
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Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

The part machined Uranus rotary throttle handle (with sketch) and the new 7/64" HSS single tooth square hole broach made up from a broken end mill.

This one worked much better than the drill rod broach as it didn't collapse under the pressing pressure but one must align the broach dead square to and centred on the drilled hole and support the workpiece fully underneath it or it can bend with the pressing pressure also.

The position of the square hole (diamond shape) in the throttle handle was set to the square machined into the throttle rod so as to have the throttle partially open when the throttle handle was straight up and down.
Attachments
112 The Part Machined Rotary Throttle Handle with Sketch and the New HSS Single Tooth Broach.jpg
Last edited by Carrdo on Wed Oct 27, 2021 4:59 pm, edited 1 time in total.
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Bill Shields
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Re: I Don't Know Why I Ever Got Involved...

Post by Bill Shields »

Wouldn't a round pilot help...or does that make the shaping of the square a headache?
Too many things going on to bother listing them.
Carrdo
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Location: Toronto, Canada

Re: I Don't Know Why I Ever Got Involved...

Post by Carrdo »

Hi Bill,

In this case the new HSS broach was simply used to clean up the previously made square test hole(s) made by the drill rod broaches.
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Bill Shields
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Re: I Don't Know Why I Ever Got Involved...

Post by Bill Shields »

Ah....cool
Too many things going on to bother listing them.
LouStule
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Re: I Don't Know Why I Ever Got Involved...

Post by LouStule »

Your tenacity is impressive. You obviously follow Henry Ford's advice..."Never give up".
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