Don Young's Black 5 Blast pipe

[runner42]

The drawing shows the blast pipe entering the saddle and smokebox through a hole with unspecified dimensions but shows it to be a snug fit. The blast nozzle is affixed to the blast pipe by a 1 1/4" dia flange which is presumably affixed to the blast pipe by silver soldering and then the flange is affixed to the blast nozzle by six fasteners. The blast pipe flange to much greater dia than the blast pipe so once silver soldered the blast pipe cannot pass through the saddle and smokebox aperture, making assembly impossible. Can anyone resolve this issue for me.

Brian


blast pipe issue by Brian Leach, on Flickr

[peteh]

Hi Brian,

Don't know that particular loco but wonder if the blast nozzle could be screwed on with either internal or external thread? Would seem the simplest solution.

[runner42]

Hi Pete,

I in the words of the Bard, have been hoisted by my own Petard, but maybe stretching a long bow to what really occurred. DY required that the blast pipe arrangement be integral with the smokebox saddle and so the saddle and blast pipe could not be separated after construction. This enabled the flange to be silver soldered to the blast pipe because it was never intended to pass through the hole in the saddle after completion. I did not like this arrangement because it did not guarantee face to face contact with the hole in the main frames. The fixing screws were too distant from the area needed to be clamped. So I opted for the making of two flanges on the ends of the blast pipe that screwed directly to the mainframes, same as Steve (Springcrocus). This modification introduced the problem reported above so the use of a flange arrangement was no longer viable and required a method of being able to mate and de-mate the blast nozzle. A threaded mechanism was the obvious solution. I did not have a tap and die of the requisite size to produce a male and female thread as Pete (Greenglade) did or take the trouble to cut the threads on a lathe as Steve (Springcrocus). Today visiting the local hardware store I found two brass assemblies which I can use to provide the male thread to the blast pipe and the female thread to the blast nozzle. The cost of A$ 5.00, much less than the cost of a tap and die, so I am pleased that I have solved this issue.

Brian


blast pipe issue1 by Brian Leach, on Flickr

[runner42]

I have completed the modified blast pipe and nozzle, although the important dimensions are unchanged, viz the height above the saddle/smokebox and the size of the aperture at the nozzle and the taper over the length of the nozzle. Although I had trepidation about drilling the 4 off No 70 holes for the blower, it turned out to be easy using the mill. Having had previously only the pillar drill which was far too big for a No 70 drill it also lacked the high speed and incremental movement of the Z axis. Both features available on the mill.  An aside, how was a No 70 drill selected by DY? Was it to provide a scaled feature from the prototype or was it based on the performance required for a 5" gauge locomotive? Either way it appears to be rather small and easily clogged in the less than benign environment of the smokebox. I think that I have improved on the maintainability of the blast nozzle because it is easy to remove by one large threaded section than 6 off fasteners three of which are at the back and difficult to access.

Brian

Blast Nozzle by Brian Leach, on Flickr

[timo]

Brian,

At least if the No. 70 holes are too small you can open them out!

Tim

[jma1009]

Hi Brian,

I haven't built a 5"g LMS Black Five to the Don Young design, though I drove the first example finished made by my old late friend John Edwards, Secretary of what was then the Whitchurch and District MES at Highfield Road, now the Cardiff MES at Heath Park.

The smokebox draughting of Don's 'Black Five' could really do with revisiting. It does not comply with the Ell Formulae Don went on about, neither does it comply with the Jos Koopmans formulae.

Just one example - the 1 3/16" petticoat throat diameter does not extend to the top of the chimney as 2 times 1 3/16".

You ought to have followed the Laurie Lawrence type of blower ring with inclined jets screwed into the blower ring. Never understood why Don did not adopt the Laurie Lawrence type blower ring, other than pure obstinacy, and lack of experience of dealing with blower rings getting their jets blocked with crap.

As at some part of the revolution of a 2 cylinder loco, both exhausts are emitting exhaust steam at the same time, the blast pipe above where the exhaust pipes meet ought to be greater than the ID of just one exhaust pipe.

I haven't done the maths on the Don Young 5"g 'Black Five' smokebox draughting, but it could do with a few tweaks and improvements to make it optimal.

Cheers,
Julian

[runner42]

Aug 23, 2019 23:23:57 GMT jma1009 said:

Hi Brian,

I haven't built a 5"g LMS Black Five to the Don Young design, though I drove the first example finished made by my old late friend John Edwards, Secretary of what was then the Whitchurch and District MES at Highfield Road, now the Cardiff MES at Heath Park.

The smokebox draughting of Don's 'Black Five' could really do with revisiting. It does not comply with the Ell Formulae Don went on about, neither does it comply with the Jos Koopmans formulae.

Just one example - the 1 3/16" petticoat throat diameter does not extend to the top of the chimney as 2 times 1 3/16".

You ought to have followed the Laurie Lawrence type of blower ring with inclined jets screwed into the blower ring. Never understood why Don did not adopt the Laurie Lawrence type blower ring, other than pure obstinacy, and lack of experience of dealing with blower rings getting their jets blocked with crap.

As at some part of the revolution of a 2 cylinder loco, both exhausts are emitting exhaust steam at the same time, the blast pipe above where the exhaust pipes meet ought to be greater than the ID of just one exhaust pipe.

I haven't done the maths on the Don Young 5"g 'Black Five' smokebox draughting, but it could do with a few tweaks and improvements to make it optimal.

Cheers,
Julian

Hi Julian,

thanks for the information, as you have only told me WHAT is wrong without stating HOW to correct it I cannot make any changes at this juncture. You are right about the curvature of the exhaust pipes should be shallow enough to require a greater hole in the saddle/smokebox because it shouldn't combine into a single pipe diameter below the entry point. The diagram depicts this. However, he mentions using 90 deg bends of copper or stainless to fabricate the blast pipe which I have done. They are tighter than he depicts so I am stuck with this arrangement, unless and until I can find some really long curve 90 deg elbows


Brian
smokebox front by Brian Leach, on Flickr

[ettingtonliam]

Julian
With the greatest respect for what you say about the exhaust pipe after the joining of the 2 pipes needing to be a larger diameter than the individual pipes, what happens immediately after the joining? It goes through the blast nozzle which is a considerable constriction, so providing the exhaust system is a smooth flow, which this one seems to be, is the diameter really that critical?

[builder01]

Sorry this information is a little bit late, as it seems like you already have your blast pipe and exhaust pipes finished.

For the exhaust elbows, you do not need to be restricted to what you can fine at a hardware store. If you make them out of copper, it is quite easy to make them from straight copper tube, and form them into a wooden "wheel" to get the sweep, or, curve you need. Here's a photo of the exhaust pipes I made for my loco. These were formed from straight copper pipe and the entire assembly silver soldered together.

DSCN0957 by Builder16, on Flickr 
Another copper pipe was silver soldered into the pipe that holds the two curved pipes together. This pipe was threaded, (very fine thread) to allow the blast nozzle to screw directly onto the end of the pipe. This makes removal and disassembly fairly easy. The blower ring is incorporated into the blast nozzle. The blower jets are installed at a slight angle so they converge at the bottom of the smokestack, not just pointing upward. I would not worry about debris blocking the jets, 100 psi steam seems to keep mine pretty clean!  
DSCN1045 - 4 Blast Nozzle & Jets by Builder16, on Flickr

The position of the blower steam supply pipe was marked and installed after the blast nozzle was screwed onto the blast pipe. That way you can position it so it is not in the way of any of the other piping.

DSCN1050 - reduced - 2 by Builder16, on Flickr

Here's the finished piping inside the smoke box.
DSCN1449 - 2 Smokebox Piping by Builder16, on Flickr

It looks like the flues are blocked from being cleaned. There are 14 flues, 10 can be cleaned through the smoke box door, and the remaining 4 are cleaned through the fire box door. The gap around the steam pipe and the smoke box floor has been covered by a split ring not shown in the photo. I did get some help from Julian for setting a more correct distance for the blast nozzle to the choke. - Thank you again Julian!

David




 

[jma1009]

Richard and Brian both make valid points, though forgive me I did I hope make it clear I have not done the maths (yet) for Don Young's 5"g 'Black Five' smokebox draughting.

A certain length of (larger) straight pipe above where the 2 exhaust pipes join is preferable to 'straighten out' the exhaust, before the blast nozzle is reached. (Holcroft noted this phenomenon in 'Locomotive Adventure Part 2).

I think I was quite clear about the benefits of the Laurie Lawrence design of separate blower ring, and with screwed in and slightly inclined nozzle jets. This design is very well known, and well proven. And if you do get crap in the blower ring blocking the nozzles, they can easily be unscrewed and the blower ring and removed nozzles blown through in the workshop.

Cheers,
Julian