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NP Z3 Compound Mallet

12K views 62 replies 13 participants last post by  bobrstrong 
#1 ·
The Z3 ran in the Northwest servicing the areas around Couer d' Alenes lake in Idaho in the fifties. This area produced wealth in silver and gold exceeding the famed Comstock Lode of Nevada.
I love doing these standard gauge compounds. Although they can be tricky, when they are running correctly, they are a thing of beauty and awesome power.
The photo below shows the size of the low pressure cylinder on the Z3
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And here is the whole engine in operation
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The only drawing I was able to find is this from the NW Historical Society which doesn't show much detail so I will need to rely on photos for most of my detail. There were a couple of HO models of the engine and they are usually pretty good about detail but if they had to go by the same info I have there could some discrepancies.

I have the wheels on order and Dennis is cutting out the frame rails on the CNC mill. So I start with the cylinders.
A trip to the metal yard gets me started on the job.
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The cylinder is machined from square stock. The bores will be .750" and 1". The LP cylinder used slide valves so the valve ports are in the cylinder block Wood wedges are cut to hold the block at the right angle while the ports are drilled out. The drill bit shows the path the drill will take. Note the wide valve ports needed for the LP cylinder
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The LP cyl has a piston rod extension. I duplicate a non-functioning one and make a cylinder cover that covers the cylinder head.
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The HP cylinders had piston valves. I am using slide valves with a cross port plate. To duplicate the piston valve appearance, I first make my cylinder and valve covers from aluminum stock. The cylinder cover fits over the cylinder head which is 1" in diameter. I then cut a 1" hole in a .032" brass sheet with a step drill and spray it with layout dye. I place it over the head and scribe the outline.
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And on the band saw and 1" belt sander I trim it to fit and cut and shape on the belt sander Poplar strips which are taped on for fitting.
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Finally, a side cover is rivet embossed, annealed, and bent to shape and soldered on to the front sheet.
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And here are the two engines as they will appear on the frames.
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#3 ·
Thanks
A little more time involved in the planning as there are no real plans available. The good news is that some of the parts are similar to the N&W Y6 which helped on the cylinders.
I have about 9 days so far in the actually machining and another week in drafting which I am still working on.
 
#7 ·
Really looking forward to this build.
I was reading your previous threads again and i noticed that a lot of photo's are gone.
Especially your early builds that you posted: Quadruplex, Garratt, Uiutah 2-6-6-2 and the eerie triplex.
I wish i saved some of those pictures.
You are a big inspiration to me, keep up the good work please, dreams do come true for sure.
Thanks for sharing your mind blowing work, effort and time that you put in and to show details.

With best regards Igor from the Netherlands EU.
 
#8 ·
Thanks
many of the photos were lost when they converted to the new design
I use them myself to see how I did something back then. Now is is like reinventing the wheel

If you go to the informative threads index at the top of the forums, there are PDF copies of some of my builds. You need to scowl down a bit but I just looked and The Quad build is there with photos.
 
#9 ·
I got some real nice drawings from Richard
Bruce brought over some goodies yesterday A calendar from his welding shop in Idaho, an HO model of # 4023 and a spike from the railroad he found while hiking along the route.
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I am machining the wheels today
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#13 ·
@ Billy,
I have more questions than answers and i would like to follow up and walk in your shade(if possible! but hey: if you dont do anything, nothing will happen).
I hope it wont bother you that i am going to put some questions in now and then.
As stated earlier, i am going to follow this one with a lot of interested.

You let the wheels cast in cast iron, or is it a special alloy?
I was thinking to cast mine of a hardened aluminium alloy sinds i can cast up to 1400c/2550f, i should be able to do cast iron, but this would need some tricks and perhaps a extra oven.
The alu alloy i have in mind is the same alloy that they use for rims on car wheels and "sweeting/harding" it up with some copper zinc or just use plain zamac.
I think solid brass hardened with extra zinc will wear my (alu) rails very quick

Sorry that my technical English is not top notch.
Thanks in advance, with best regards Igor
 
#15 ·
@ OldNoob.
I thought Billy used a band saw and a table saw to cut his own metals
You wont get away with a regular wood saw blade, not even a with very fine teeth.
You must have a saw blade with teeth that are special made to cut those kind of metals= non ferro metals, but dont cut lead or inox with it, both need different saw blades.
You can also try to adjust the speed, it is thin stuff, you pushing slower and the machine at max speed.
Option one
Clamp it between to thin sheets of wood, could also help against the up and down.
Option two
Or strap some wood to your fingers to push the piece down on the table half a inch to a quarter of an inch away from the blade.
I dont know your skills that is why i said two pieces of wood.( i can trim my nails with a mature table saw, but i am on a different level :cool:)
Option three
The hole in the table must be as tiny as possible, take a piece of wood and just run it over your table, to cut a line in it.
this piece of wood you can screw (from above) with help of two other pieces of wood to clamp it on the table, those two pieces will act with help of the screws as a c clamp.

This is all i can think about atm to assist you, hope this was of any help.

With best regards
 
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#16 ·
Thanks for the questions
I don't cast my cast iron wheels. I get them from Walsall in GB. You can get them as bare castings or finished wheels. I get the castings, attach the counterweights with JB Weld, paint and quarter them. I will be posting something on that later.
On the Four Cylinder Heisler I did, we cast the wheels on Zamac 3 as the spoke design wasn't available. They came out pretty good but it was a lot of work.
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Cutting brass sheet isn't as hard as one would think.
Most of the sheet I use is .020" or thicker, This can be cut on a band saw or table saw. Any carbide tipped table saw blade will work but I use the attached blade as it gives a finer cut and can be used for mild steel also.
The throat plate on table saws has a wide slot to allow for tilting the blade. I made an insert out of MDF and then raised the running blade to make a zero clearance slot. This prevents the sheet from bending down during the cut. On very thin sheet, I sometimes lay it on top of a piece of plywood and cut through both at the same time. I use the band saw for curved cuts.
Here is my old crosscut sled which has been replaced with an aluminum one and the zero clearance throat
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#17 ·
The rough castings require several machining steps. Here are the wheels during the machining process. The wheels in the front have the tread roughed in and still need the hub turned and the final tread plunge cut. The ones in the rear have only the face done and are in the process of receiving the tread cuts.
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The tread then gets its final cut, counterweights are CNC cut and JB'ed on and they receive a coat of low sheen paint.
Here you can see the three different counterweight sizes
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The pilot has an interesting bracket with vertical slots to, I assume, allows it to be raised or lowered somewhat.
I cut the slots on the mill with a 1/16" end mill. I don't have any drewings of it so I just eyeball it and scribe the vertical lines with my calipers and freehand scribe the curves. I then cut it out on the 1/8" band saw blade and finish up with the 1" belt sander
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The headlight is made by boring out a piece of 3/4" round to 5/8". A concave is made in a 5/8" aluminum bar with a drill bit in the lathe. it is smoother out with 600 and up to 2000 and finally polished with SemiChrome. The glazing is 1/16" polycarbonate and the bezel is turned from 7/8" aluminum stock.
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It is hard to tell from this photo but to make the curvature of the number boards, I did something new to me. I usually use a fly cutter to cut large radii or an end mill for small ones but here one was too big and the other too small. In the past, I would use the drum sander which got it close but not perfect. It finally dawned on my that as my end mills only go up to 1/2", why not use a router bit. So here is a 3/4" carbide tipped router bit doing the job nicely
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So here is the front deck to date. I haven't explained everything here so, please ask any questions you like
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#18 ·
Looks great so far, Bill! One relatively minor nitpick though, NP had a pretty distinctive style of headlight with a lighted forward-facing number board on top, with the top tapering down to the rear of the headlight body. They used this style on all of their road locomotives in the electric headlight era. Here's a close-up of the headlight on NP 328 as an example...

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#22 ·
WOW It is starting to get shape! Well done and good looking!:)

To bad that the thread: four cylinder Heisler was not stored in pdf form, photos are lost.
About the cylinders and the power of steam:
Do you use or imply formulas to calculate the size and stroke, the free swing(the back pressure of "old steam") ect or just copy the real life size and scale it down?
Perhaps i am over complicating.

I don't think it is doable to buy for every project different sized reamers.
What is your tolerance between the piston and cylinder walls?
And why dont you use ?gasket/gaschecks? around your pistons

It seems to me also that you have a solid "recipe" for the cylinder and valve sizes.
Your valve, the steam regulator on top of the cylinder is also a very tight fit, or you have a blade spring mounted on top of it?
Probably you wrote a thread on it, i did not have a lot of time lately to read all of your fine threads.

A bold question:
Do you have by chance of this built some pictures of the "fresh steam supply/connection" to the cylinders?

I fully understand the technical working principle of real live steam engines, per part and the whole machine, but i must work on my technical English for this subject, all my study books are in my native language sorry i hope you understand what i am trying to translate:)
Scale models are a bit different than there real life working counterparts:cool:.

Thanks in advance, Best Igor
 
#23 ·
Thanks Igor
Live Steam & Outdoor Railroading have a multi part series covering the Four Cylinder Heisler build starting next issue.
I usually scale down the actual cylinder size unless it doesn't make sense. Compound engines used very high pressures (300psi) and mine will be operating at 50 psi most of the time do the 2:1 diameter ratio needs to be reduced in our engines. This one is 3/4" HP and 1" LP which is the same as I used on the Y6 engines I built.
I have reamers up to 5/8" so I just rely on my boring tool to get a nice finish. I usually finish off with a piece of 600 sand paper wrapped around a wood dowel.
Piston clearance isn't critical. I use 0-rings on the pistons and fit them for a smooth sliding fit. I have used rulon rings in the past but prefer Viton o-rings
Not sure what you mean about piston gaskets. I use gaskets on the cylinder end caps.
Because the engine is outside admission, the steam pressure holds the valve down.
I will show the steam connections later in the build.
 
#25 ·
Love your work, fine eye for detail, my compliments, really amazing!
To order a magazine from the internet, i would like but due to some nasty experience i would not like to order from the internet anymore.
Your cylinder built, you made a single tread about it? or am i wrong, sorry did not have time enough to read all your work(own company, end of the year ect)
I think(almost sure) we are giving different names to the same parts, my incompetence of technical English sorry.
Monday i will have some time on my hands and make a picture of which part i was referring to.
Thanks for the detailed pictures!
If it is not to much trouble, can i ask you to post some pictures from underneath the front engine?
Where the steam enters the cylinders, many thanks in advance....many!
I am not going to question your experience, but from my point of view, the "fresh steam supply" to the rear engine, is that pipe not a bit to small in diameter?
And is that steam heated again by running a pipe thru a "flame pipe" or is the steam still hot enough to power up those cylinders?
Or you just use super dry/heated steam to power them all, so the "cold used steam" from the front engine is still hot enough to make the rear cylinder to work?

Thanks in advance, Best Igor
 
#26 ·
Thanks for your feedback
The standard pipe size used by most manufactures is 3 mm which is 2 mm (.078") inside for a cross section of .00485"
I use 5/32" which has a 1/8" (.125") inside for a cross section of .01228"
This gives me over 2.5 times the cross section of what is normally used.
The tubes probably look small because the cylinders are so big.
In the full scale locos, the steam piping is usually insulated and there is a small pipe surrounded with insulation and then covered with larger piping
The steam will be superheated by running the pipe through a flue in the boiler.
 
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