Front End Rebuild

Where users can chronicle their builds. Start one thread and continue to add on to it.

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Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Thu Jan 09, 2020 2:22 am

Hi Richard,

Very excellent suggestions. I appreciate your approach. I briefly considered pulling the smokebox early on. However it’s riveted to the boiler, so removal would entail a general tear down. In retrospect probably would have been infinitely easier, and a much shorter time commitment to pull it, as you suggest.

The throttle feed lines to the cylinder are drilled and tapped into the saddle castings. I don’t yet know what the innards look like, or how the steam feed actually enters the cylinders. Maybe lifting the boiler and smoke box would help solve the puzzle.

Good news is more progress, and I think Iam close to finishing.

Here’s a a photo or two of the wooden mock up of the blast nozzle I worked up this afternoon. It’s fitted to the starboard nozzle and drilled and tapped to accept the blast pipe at a known 5* angle. So I should be able to transfer the dims to the actual nozzle material with out incident.
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I used some scrap oak to turn three mock-ups on the lathe for the nozzle. It helped a lot to make several mock ups to visualize how the final assembly will go together. Also the wood models are quick and easy experimenting with drilling and taping proper angles and alignments for the pipe fittings. This morning, one of the gurus in our local club suggested making the mockups. It’s worked well so far.

Tomorrow, hope to solve the riddle of the second connection. Thinking about turning a small metal scribe to screw into the second blast pipe and scribe it’s arc centerline across the bottom of mock-up. Then, need to fix the angle of the fitting to get it to all screw together.

If that doesn’t work, might using flex copper pipe and flare fittings to bend and twist the second pipe connection into place. This could be a replaceable piece with flare flare fittings on both ends.

What a sweet deal it would be to not have the smoke box shell in the way! If this last bit doesn’t work, I’ll give that a try. Time is a bit of a constraint at this point. I only have another week until I have to button the loco up until spring. I have an offsite project starting that will last until April. So hoping to finish the loco up before I run out of time.

Thanks much,
Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Fri Jan 10, 2020 2:20 am

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Here’s the almost completed mock up of the new smoke box plumbing. I found a small, almost half size copper pipe Union in the plumbing section down at the local hardware store, and it just fit the limited space between the blast outlet in the saddle, and the bottom of the blast cap. The full sized 1/2” pipe fittings just wouldn’t fit the small space and align properly with the nozzle. But the small copper union fit the bill.

So mocked up the throttle intake lines for a rough fit, and laid in the pettycoat and stack to check the fit. All looks good!
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Tomorrow, start machining the blast cap and do final assembly of the steam intake lines to both cylinders.

All in all a pretty good day. :D

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Tue Jan 14, 2020 2:50 pm

Note: corrected entry, with new calculations.

Finished up the blast nozzle last night. Here’s a few photos and some comments about the design and build.

First, many thanks to Nigel Day for providing the design and geometry for nozzle and stack design. Nigel also sent along his preferred set of formulas for determining oriface diameter and length/width ratio and length of the tapered stack assembly - basically the diffuser immediately above the nozzles, and the evaculator (smokebox stack). Fortunately my existing stack and stack extension in the smoke box were very close to Nigel’s recommended dimensions for stack geometry.

Three short comments about the four nozzle design:

In the Lempor system, multiple small nozzles of the Kyychap design, are proven to be more efficient than the older, standard Master Mechanics Association 1895 standard single stack design. Any number of nozzles will work. Four nozzles are the most common. The set of small nozzles, acting in concert with each other, allow the exhaust stream to entrain up to 42% more exhaust gas per pulse from the smoke box, than the single blast nozzle design. Hence the Kyychap nozzle assembly produces greater velocity and vacuum with less back pressure - providing greater airflow through the flues and across the grates; burning the fire hotter and brighter. This results in greater evaporation, lower fuel consumption and a significant reduction in smoke discharge. Also, I think this will reduce the complexity and repetitiveness of firing the locomotive during operation - a significant and cumbersome process when running on a short track.

The second significant design feature is the Kyychap plenum design. In the bottom of the plenum (nozzle body), a small vertical partition separates the steam exhaust in the port and starboard sides during each pulse. This partition creates a momentary vacuum in the non emitting cylinder exhaust line. The vacuum reduces back pressure in the opposite cylinder during its cyclic discharge. Reducing back pressure in the cylinders increases the driving force to the drivers.

Finally, I decided to experiment with replaceable nozzles. Each nozzle is made of bronze, turned to 1/2” OD x 20 TPI. Each set of four is drilled and reamed to a specific diameter. Each nozzle hole is drilled and tapped to a 5* offset from centerline. This offset creates a slight separation between each jet stream, improving all around exhaust gas entrainment, and ensuring vacuum through early contact of the four jet exhaust cones with the diffuser wall.

The calculated, theoretical, Lempor oriface diameter for the Ottaway (2.5” diameter cylinder) nozzles is .216” each. (I verified Nigel’s formulas and corrected my original calculations in my excel sheet.) For testing purposes, my other two nozzle sets will have oriface diameters one drill size above, and one below the theoretical .216” diameter - approximately 5% difference, either way.

So the Lempor will enable me to operate with a total oriface surface area of 1.234 square inches, versus a traditional single blast nozzle area of .881 square inches (.561" Diameter). Almost twice the blast nozzle surface of the original .650” diameter nozzle set. The replaceable nozzles allow me to easily change oriface diameters during optimization testing; unscrewing each nozzle and replacing with a different diameter. I plan on converting to propane in the next year or so. This should also allow me to adopt the new front end to propane with minimum reconfiguration - hopefully.

So overall, published benefits of the Lempor system are improved efficiency of the boiler, e.g. more steam generation, and greater locomotive hauling capacity. The Lempor should increase the horsepower of the existing locomotive by reducing back pressure on the cylinders, reduce fuel consumption create a hotter fire, improve evaporation, and reduce harmful, wasteful smoke.

Last step will be to install in the smoke box, hook up the new throttle intake plumbing, and run tests to confirm optimum oriface diameter.

And the photos:
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(The photo below also depicts the original oak prototypes I made up to verify the nozzles and blast cap would fit together in a 1.80” diameter envelope)
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Attachments
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Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Mike Walsh
Posts: 700
Joined: Sun May 06, 2007 10:14 pm
Location: St. Louis, MO

Re: Front End Rebuild

Post by Mike Walsh » Tue Jan 14, 2020 3:17 pm

Glenn Brooks wrote:
Tue Jan 14, 2020 2:50 pm
Last step will be to install in the fire box, hook up the new throttle intake plumbing and run tests to confirm optimum oriface diameter.
You're putting this in the firebox? Odd.... :shock: :D

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Tue Jan 14, 2020 3:31 pm

Oops, should be firebox.! Or, a new innovation!
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

User avatar
NP317
Posts: 2424
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: Front End Rebuild

Post by NP317 » Tue Jan 14, 2020 8:56 pm

Double Oops:
smokebox.
Have some wine and relax this evening.
RussN

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Tue Jan 14, 2020 10:45 pm

What, what! This is a real brain freeze. Time for the hard stuff - chamomile tea and a basket of chocolate chip cookies.
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Sat Apr 25, 2020 1:11 am

After winter hiatus, finally getting back into finishing my front end rebuild. Installed the Lempor exhaust nozzle in January, now pipe fitting the steam inlet plumbing from the boiler into both cylinders.

Lots of fiddling with fittings to big for the small space available. But tis coming together, with “thousanths” to spare.

I made up a new bronze plenum and installed on the end of the steam feed pipe coming out of the boiler. The last big task is to properly align the two inlet pipes with the end of the plenum (10 o’clock position in the photo) then drill and tap so that everything screws together properly.

So far, quite happy that the plumbing all fits, and leaves more room to swab out the fire tubes than the original design.
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Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Sat Apr 25, 2020 10:06 pm

Pulled the little bronze plenum out of the smoke box this afternoon, and brazed the pipe thread fittings into the ends.

The fittings are the threaded ends of 1/2” NPT bronze pipe nipples with a short length of smooth pipe sufficient to just fit into the depth of the holes bored into the plenum.

Ran out of acetylene so couldn’t use the torch. So tried the weed burner again and with the part buried in the forge. Seemed to work fine, so long as I directed the heat from the torch sort over the top of the part. I silver soldered a previous fitting into one end of the body last fall and didn’t want that to get so hot that the brazing would run out.

Sort of overkill, but it worked. That’s Railroading, after all. Everything is a big hammer, even when the parts are miniature scale...
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Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Thu Apr 30, 2020 12:06 am

Couple of photos of the steam intake plumbing to wrap up this phase of the rebuild. The two photos show the routing of the right and left steam lines that come off my shop made T fitting (refered to as a plenum in the previous post) emerging from the boiler. Interestingly the boiler tubing is iron 1/2” NPT , then necked down to 3/8” inlet port at the bottom of the smoke box- where the steam flows into the saddle and steam cheat. Not sure why Ottaway did this. But it required stepping up in size to 1/2” pipe to replace the old, original iron pipe.

Anyway, what you are looking at are the right and left steam inlet lines running from the little bronze plenum attached to the boiler exit pipe, and then running down to the bottom of the smokebox, thence feeding steam through the saddle into the cylinders, where the steam is a moment latter exhausted back up into the Lempor multi-port (4 blast nozzles) nozzle, and ejected up the blast pipe and out the stack.
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Just to reiterate, the Lempor design, as a minimum, utilizes at least 4 small nozzles, spaced equal-distant around the top of the nozzle, to eject the combustible smoke box gasses drawn through the flues. The Austrian and Nord (France) railways experimented with up to 6 and 7 blast nozzles at one point. However four nozzles were found to be nearly as efficient and proved to be a less complicated design. The whole idea is that four cone shaped exhaust jets, working together entrain up to 40% more exhaust gases per blast cycle, than a traditional master mechanics single pipe blast nozzle. Hence the loco fire box burns hotter, because of better draft, and produces up to 40% more horsepower for the same amount of coal and water.

In a prototype 4-6-0 tested by Eng. Porta in the mid 1950’s, the actual horsepower rating of 900 hp, increased by 325 hp (total 1200 hp) when fitted with this design. Iam hoping to see at least some noticeable increase in my Ottaway. My primary goal is to achieve more highly efficient combustion thus producing a higher, continuous rate of steam generation.

My last phase of writeup will be a short summary of my test firing results- hopefully sometime in the next week or so.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

Glenn Brooks
Posts: 2079
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Front End Rebuild

Post by Glenn Brooks » Thu Apr 30, 2020 8:28 pm

Whoops, forgot to reinstall the new blower. The old one was a simple straight tube pointing up the stack, behind the two old blast nozzles. Quite a bit off center and to the rear of the smoke stack - causing a noticeable negative pressure zone in one side of the stack, and poor drafting - likely with excess steam loss when building boiler pressure. This circular nozzle, with 7 ports drilled into the tubing is the preferred style in our local club. It should more evenly distribute steam up the stack, and contribute to better drafting.

So wrapped the tubing around the blast nozzle- approximately 2” diameter, then removed and drilled 7 exhaust ports on top. Then re fit with the tail headed down the nozzle and under the port steam line to connect to the original fitting in the side of the smoke box. It lays pretty well on the little journal I machined around the top edge of the nozzle back in the beginning. Not perfect, but good enuf with the material at hand to fire the loco and run a few tests.
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This second photo shows the alignment of the nozzle looking down through the top of the smokebox. Little bit of a kink in the tubing occurred where the heat affected zone annealed the tubing while silver soldering the end closed. The tubing is softer down stream from the kink and the anneal area tubing reacts differently to bending stress... oh well... I don’t have any more copper tubing in this diameter, so will have to do...
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Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

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NP317
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Location: Northern Oregon

Re: Front End Rebuild

Post by NP317 » Thu Apr 30, 2020 9:08 pm

You might need to make those blower holes much smaller.
A little goes a long way...
RussN

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