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Foreman
1st Class Member
USA
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 Posted - 07 Dec 2005 : 22:26:51
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Got started the other day on my next scratch build attempt. This one the U.K. prototype, LMS Class V 4-6-0 mixed traffic engine, a.k.a. “Black Five”. It is based on the “Dot” design by LBSC. Plans are available from Sulphur Springs. My son named this engine “Flying Kipper” from “Henry” his favorite Thomas the Tank Engine character.
Here’s a basic side elevation example of the “Black Five”
The Kipper’s main frames are 13.75” long with tender frames 8.625”. The drivers are 2.25” diameter. The engine has two double acting D-valve cylinders with a bore of .500” and a stroke of .875”. Not sure what fuel to use, thinking about trying butane. Also not sure if I want to try an axle pump.
There will be two major deviations from LBSC’s original “Dot” design. First is on the valve gear. LBSC used slip eccentrics between the frames. I plan to use return cranks on the outside to produce a Walschaert “look-alike” affect. Second is the boiler, LBSC used a “Smithies” type boiler. I plan on a conventional locomotive type.
Definitely going to fix this driver-quartering problem that plagues the “Chingford”. I will build a jig and “loctite” those drivers in place for good.
A few weeks ago I had the frames and other flat parts cut out by water-jet. They look beautiful:
Started the wheels earlier this week, so should have something rolling real soon.
I am very excited about this one. Kipper should have a lot of power and torque on the drivers. I did some prelim calculations on the boiler using Martin Evans and KN Harris as guides. It should produce a ton of steam.
Take care, Bob
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Edited by - on 18 Dec 2005 00:42:48
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Engineer
1st Class Member
USA
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Posted - 08 Dec 2005 : 05:06:30
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Bob
Your offerings of building logs are excellent. The skills and outcomes are something to inspire too. Maybe a little insight on the calculations could allow for me (probably others) to better understand the process. |
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Engineer
1st Class Member
USA
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Posted - 08 Dec 2005 : 06:53:05
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Bob,
Looking good! At the pace you produce, are you going to run it at Clark's this weekend? (haha) |
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Foreman
1st Class Member
USA
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Posted - 08 Dec 2005 : 19:13:47
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Charles: The Kipper’s boiler will be my first try at a scratch design. References include “Model Boilers and Boilermaking” by KN Harris and “The Model Steam Locomotive” by Martin Evans. These are great reading and should be in every “steamoholics” professional library. The arithmetic gets complicated because of conversions between feet and inches and minutes and seconds. I may have made a mistake. That’s why Dave Hottmann always checks my math.
I want Kipper to operate at 50 PSI and a sustained scale speed of 80 mph (scale being 1:32). The scale speed works out to a real speed of 3.65 feet per second. The drivers are 2.25” diameter. To maintain speed the drivers must turn at 372 RPM. There are four power strokes for each revolution of the drivers. The engine has .500” bores and .875” strokes, so .687 cubic inches of steam at 50 PSI is consumed on each rev. In one minute the engine uses 255 cubic inches of steam at 50 PSI.
In Harris’ book there is a table that shows how much water is needed to produce steam at a certain pressure. For example, one cubic inch of water boiled away will produce 405 cubic inches of steam at 50 PSI. Therefore, Kipper’s boiler must convert 0.631 cubic inches of water into 255 cubic inches of steam at 50 PSI every minute.
The “size” of a boiler is really measured by its “heating surface”. That is basically the surface area of all the flues and firebox in contact with water. The more heating surface (HS) the more steam. So the question becomes, how much HS does Kipper need? Harris goes into great length about boiler efficiency, some boiler types work better than others. His measure of efficiency is how much water can the boiler turn into steam for every 100 square inches of HS. From what I read we should reasonably expect our Gauge 1 boilers to convert 1.5 cubic inches of water into steam for every 100 square inches of HS.
So, .631 (water volume to steam) divided by 1.5 (efficiency factor) times 100 (efficiency is per 100) is 42 square inches of heating surface. That’s how “big” Kipper’s boiler needs to be.
Looking at LBSC’s drawing I could get some basic boiler dimensions. The firebox can be 3.25” long, 1” wide and 2” tall. There is room for five flues, .375” diameter and 6” long. All that comes to about 53 square inches of heating surface. Only need 42. Should be enough.
The Evans book provides guidance on the relationship between the surface area of the firebox grate and the flow through the tubes. Five flues and this size firebox is just about right. Four flues would not provide enough flow.
This is all theory and may not work. I am going to “crunch” the numbers a few more times, but this is basically what I plan to try.
Bob
Dave: Thanks, hopefully the front bogey will be finished by then.
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Engineer
1st Class Member
USA
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Posted - 08 Dec 2005 : 19:41:22
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Bob
Great opening to the indepth overview of boiler numbers necessary to plan for the piece.
Keep this up and one day I could give it a go!
Thanks |
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Foreman
1st Class Member
USA
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Posted - 10 Dec 2005 : 14:42:02
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Found this nice photo of a “Black Five”. This is what I will try to make the Kipper look like. Maybe just a different color.
Bob
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Foreman
1st Class Member
USA
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Posted - 10 Dec 2005 : 21:22:38
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Bob,
You sure have been studying your Harris. Looks like you've got your Black Five project off to a great start. Don't forget to calculate how many BTU's need to be generated per unit grate area to heat the 53 sq inches as required. That could govern your fuel of choice. I don't think that Gauge 1 loco burner design has been codified as completely as Harris has done for miniature boilers.
You might use Harris' formulas to analyse different locos you know - yours and others (as long as the owners allow you to take measurements inside the firebox and count the flue tubes). It could be enlightening to compare locos you think are good steamers with ones that are not. But pay attention to the fuel types and burner configurations as well. I learned a lot at last summer's NSS by getting close to a few locos with a flashlight and a small measuring scale in hand.
Keep us posted. Your work is great.
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Foreman
1st Class Member
USA
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Posted - 17 Dec 2005 : 18:36:56
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Made some big progress this week on the “Flying Kipper” wheels. Rough wheel fabrication is done and ready for final turning.
Normally we use cast iron castings for the wheels on our Ga 1 locos. Castings however present many problems. They can be difficult to find and very expensive. I found a set of wheel castings from a UK supplier that cost over $450. Machining is difficult if you don’t have the right lathe. Cast iron is cut at very low speeds and the first cut must be deep to get under the hard casting skin. Cast iron is brittle and Ga 1 wheels can break as you machine them.
Kipper’s wheels are fabricated from brass bar stock. Each wheel consists of a hub, rim and spokes assembled with silver solder on a jig. The process is not hard, but it is a bit time consuming. Total cost for materials was about $40.
The first step is to rough turn the rims. I used 1/4" thick flat brass bar. The inside diameter of the rims is the exact final size. The outside is about 1/16” larger than final size so you have a little to machine off to get the correct flange profile. Then cut the hubs to their final shape. Use 5/16” brass stock for the hubs. Here’s a picture of a roughed out rim and hub for a driver. I cheated a little bit and had these hubs cut out by water-jet. Tender and Bogie wheel hubs are straight round:
Next step is to cut 1/16” wide, 3/16” deep notches in the rims and hubs to accept the spokes. To do this make jig to hold the hubs and rims and bolt the jig to a rotary table on the milling table. The jig is a small brass plate with a recess turned in to hold the rim firmly. Notches for the spokes are cut with a 1/16” mill cutter by taking small plunging cuts to a depth of 3/16”. Here’s a picture of a driver rim in the jig on the rotary table. The drivers have 18 spokes so they are spaced 20 degrees apart on the rotary table.
These are the driver hubs getting slots cut for the spokes. The jig is just a square brass block.
After all the spoke slots are cuts, it’s time to assemble and solder. Put a rim and hub in the jig and fit spokes to each pair of slots. Spoke material is 1/16” x 3/16” brass strip. When all spokes are in, flux the wheel, drop in a short length of 1/32” diameter silver solder into the spoke notches and apply heat. This photo basically summarizes the whole process. The rim and hub on the left are ready for the assembly jig. The center wheel is getting stokes installed. Wheel on the right is soldered and on its way to the pickle tank.
Here’s the “Flying Kipper’s” entire wheel set fresh out of the pickle tank. The crescent shaped pieces of brass are driver counter balances that I will soft solder on the drivers later.
That’s it for now. In the next update I will finish machining the wheel profiles.
The other day our friend “Havoc” set me a picture of a Black V that someone in his local club owns. Isn’t that a beautiful machine??
Thanks and take care, Bob
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Foreman
1st Class Member
USA
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Posted - 25 Dec 2005 : 21:18:49
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This is part 2 on the wheel fabrication for the “Flying Kipper”. Before turning the wheel to the final profile I checked them to make sure they came out of the soldering jig fairly straight and square. I mounted each wheel on a temporary stub axle in the lathe and gave them a spin. The bogie and tender wheels came out of the jigs perfectly square. Four out of the six drivers, however, came out with a terrible wobble. I don’t think the jig was the fault, as 2 drivers were fine and the others wobbled differently. I bet they warped as they cooled after soldering.
To fix the wobble I drilled out the hubs to 1/4" and soft soldered in a brass plug. With the driver hubs plugged, proceed on to final machining.
These wheels are turned exactly to G1MRA standard.
Since rims and hubs come from bar stock turned on the lathe, they have sharp square edges and consistent size. First operation is to grip the wheel in the 3-jaw chuck and take a very light skimming cut across the back of the wheel just to clean it up. The drivers had new holes cut in the hubs at this point. Turn the wheel around and skim the rim and hub to their final thickness.
To turn the final wheel profile, make a jig with a stub to hold the wheel truly. Here is the jig for turning the drivers.
And here is a driver mounted on the jig
Make all cuts without removing the wheel from the jig. You gets better results by re-setting the tooling rather than taking the wheels out of the jig.
The drivers need one more machining step; drilling for the crank pins. The Kipper’s stroke is 7/8”, so the crankpins are 7/16” offset from center. Do this operation on the milling table. Again, use a jug to ensure the drivers are drilled consistently each time. Before drilling thru the hubs, I like to spot drill with a centering drill first. This keeps the drill bit from wandering. Here’s a shot of a driver getting ready for a spot drill.
And here’s a ‘family portrait’ of the Kipper’s wheel set ready for axles. They turned out very nicely.
Next time will get the front bogie done, so something can turn on the track.
Thanks and take care Bob
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Foreman
1st Class Member
USA
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Posted - 26 Dec 2005 : 08:37:34
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| Having a mill and lathe opens up a whole 'nother world! I love mine-don't know what I would do with out them. Your wheel set looks great-I wish I had that much patients(and time!) Happy holidays Keith |
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Conductor
Belgium
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Posted - 26 Dec 2005 : 09:23:38
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| Thanks Bob for this wheelmaking lesson. I think I'm going to follow your example for my next loc. Have been looking around for wheel castings but they are expensive, and if you want to make a loc that is not popular you don't really find what you need. |
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Brakeman
1st Class Member
USA
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Posted - 26 Dec 2005 : 15:07:23
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Very nice job on the wheels. A bit like the Kozo method, but you didnt use a backplate and screws as he did. Did you have any trouble holding all the loose pieces together while you soldered them?
Did you round the ends of each spoke to fit the milled slots, or just let the solder fill the tiny round end?
Do the milled slots go the full depth of the rim and hub, or stop short? The photo looks like they are short, does that help in holding it all together?
I started my Mona with cast iron wheels and CNC machined the spokes, but I cant get as nice sharp corners with that method as you did. I am just about ready to do the 6 drivers, maybe I will try your method. |
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Foreman
1st Class Member
USA
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Posted - 26 Dec 2005 : 15:14:29
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Johan & Kieth: Thanks for your kind words.
Ron: Yes the slots stop short. The spoke material is 1/16" x 3/16" so the slots go 3/16" deep from the back. The rims start 1/4" thick then work down to .236" which is G1MRA standard. I put a little chamfer on the spokes which greatly helps pushing them in. Solder fills the rest. BTW the driver hubs were cut by waterjet, much nicer consistency and shape then I could do by hand.
Bob |
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Foreman
1st Class Member
USA
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Posted - 28 Dec 2005 : 18:39:56
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Got the front bogie done and rolling on the track. The bogie frames being cut by water jet made the job a whole lot easier. I was pleasantly surprised at how well the frame came out of the water jet. There was a little burr on the edge that came off quickly with a light file. The cut holes were right on for size and only needed a little ream to final size.
Here’s a shot of the bogie parts ready to assemble
The first assembly step is to soft solder the bearings onto the frame. To do that assemble the frames and use the axle as an aligning jig to line up the bearings. The axle is stainless steel so there is no way to accidentally solder the axle in too. This technique keeps bearings in line every time. Here are the bearings ready for solder in:
And the final bogie. I decided to paint it now. Figured I had best paint as I go or it will never happen.
Next phase is to lay down the main frames and get a rolling chassis going.
Happy New Year to all Bob
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Brakeman
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Posted - 28 Dec 2005 : 20:21:58
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Bob,
Very nice, you are progressing very steadily. I have a half finished Diana (a 4-6-2 that is a very close cousin of Dot)that is back in the 'some day' part of the shop.
The water cutting intrigues me. What did you have to provide the shop that did them? CAD files or hard copy drawings? I take it they didn't have a problem doing a small run like this. If you do not mind, may I ask how much it cost to have the pieces cut out? Sorry for all the questions but it seems like that could be a real time saver.
Regards and Happy New Year,
Roger |
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Foreman
1st Class Member
USA
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Posted - 28 Dec 2005 : 21:24:28
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Roger: I made up CAD files using TurboCAD Deluxe version 9.2 The program was about $10 and fairly easy to learn. Files are usually in .DWG or .DXF format. The waterjet guy used a special CAD program to make sure all lines met and everything connected. Then he had to program the direction of cut, how to cut the holes and material type and thickness.
I actually had parts for 2 engines cut out. Total came to $165. The fellow that cut these does nothing but small runs and "one offs"
Here's a post that has more detail:
http://www.mylargescale.com/forum/topic.asp?TOPIC_ID=34737
Thanks Bob |
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"Flying Kipper" LMS Class V 4-6-0, Project Update
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