Northern 4-8-4 Build 3/4”

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Bill Shields
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Re: Northern 4-8-4 Build 3/4”

Post by Bill Shields »

Keep in mind that you have to deal with thermal expansion.

The worst case is when you first hit the cylinders cold...the valve is going to expand and stick in the bore if you get the clearances wrong.

You didn't make the valve from stainless did you?

All in all -> rings are a good idea.
Too many things going on to bother listing them.
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Bill Shields wrote: Tue Oct 04, 2022 8:16 pm Keep in mind that you have to deal with thermal expansion.

The worst case is when you first hit the cylinders cold...the valve is going to expand and stick in the bore if you get the clearances wrong.

You didn't make the valve from stainless did you?

All in all -> rings are a good idea.
No the valve is 12L14 steel. I guess my polish job makes it look like SS! The plans specified 5/8" bore for valve and 5/8" diameter for spool. Not a lot of guidance on clearance needed. That was part of the issues today requiring multiple attempts. I arrived at a nice polished finish that I can easily push through bore. Shining a flashlight into bore I see very little light escaping around bore. There is a faint light peaking through so I imagine .001 clearance around bore. I lubed bore and it still pushes through. With Dykem on the valve it will not push through. I think I am good. I can always polish the spool in the future if it is too tight while running.
valve plans
valve plans
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
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Bill Shields
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Re: Northern 4-8-4 Build 3/4”

Post by Bill Shields »

The problem is that if it is too tight you may well damage the bore if they stick...or damage the valve gear.

Unfortunately running on air is not going to tell you how it will run hot..or in between. Cannot tell you how many lococ I have seen over the decades that run great on sir and bind up solid to when hot.

Then you have to pull the cylinders off or come up with a way to repair them in place which is a big headache..and brake cylinder hone is not the solution.

12L helps because of the lead. Is that what the drawing calls for?

We're it me...I would ring it.

You are going to need rings for the pistons anyway -> do it is time to learn 😀

Not that much work and well worth the effort.
Too many things going on to bother listing them.
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Four hours each is what it took for the valve spools. There were a few hours thrown away redoing and a pause to replace a throw out bearing in the lathe gear box. I’m happy with the fit, look and finish. I stated yesterday that the steel was 12L14 but realized today it is W1 tool steel when I started drilling it. That’s where the pretty finish came from. The man that said this is a thousand projects that bolt together to make a locomotive was right!
Valve spools complete
Valve spools complete
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NP317
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Re: Northern 4-8-4 Build 3/4”

Post by NP317 »

"The man that said this is a thousand projects that bolt together to make a locomotive was right!"

So true. Thats how I've gotten through several many-year steam projects:
One part at a time.

A good life lesson.
And still easier than raising kids, whose design constantly changes during construction...
RussN
Asteamhead
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Re: Northern 4-8-4 Build 3/4”

Post by Asteamhead »

Hello bushav,
A gap of 1 to 2 (max) thou of an inch should work. With my first engine I started with piston valves of 16 - 0.03 mm diameter with no rings, made of stainless steel.
They worked fine for years, as long as lubrication worked totally :!: reliable. The stem must not connected to the valves directly rather than by a lttle radial play :idea:
Anyway, as already said, piston rings will be more reliable and less critical then. Thus are recommended.
Some photos show a solution which makes assembly much easier. I used this construction with my elder class 44 and with my class A, too at good success.

All the best by
asteamhead
Attachments
A piston valves of diameter 22 mm. Due to construction, the rings are the steering edges!
A piston valves of diameter 22 mm. Due to construction, the rings are the steering edges!
A piston valves, parts and assembly. Made of stainless steel. The rings will be mounted without stress. The stem is fixed axialy in the center by means of a long bolt
A piston valves, parts and assembly. Made of stainless steel. The rings will be mounted without stress. The stem is fixed axialy in the center by means of a long bolt
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Wow! Those valves are a quantum leap in complexity over mine. What a genius solution. The good news is that I can press on according to my plans and the great books I’ve purchased. If, in the future my simple valves need improvement it will be very easy to modify.

Yours are beautiful!

Lane
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Building 3/4” 4-8-4 Northern &
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NP317
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Re: Northern 4-8-4 Build 3/4”

Post by NP317 »

Lane:
I also made the valve spindles on my Mikado similar to asteamhead's work.
They are working well.
RussN
Valve spindles.jpg
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Ahhh! Another work of art. Looks like you guys actually have plans for those neat valves. I may lean on you for a sketch in the future.
New to live steam
Building 3/4” 4-8-4 Northern &
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Asteamhead
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Re: Northern 4-8-4 Build 3/4”

Post by Asteamhead »

Hello
RussN, I am happy to see a quite similar solution of the same parts :)
Bushav, the simple plain valves will surely do for a while, too. Good luck!
Best regards
asteamhead
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Todays project was necessary as I didn’t have a way to saw small parts. I purchased a portable bandsaw and fabricated a table that allows for temporary mounting in the vise. I think this will work nicely as a replacement for my giant metal chop saw.
Portable bandsaw conversion
Portable bandsaw conversion
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Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
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Greg_Lewis
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Re: Northern 4-8-4 Build 3/4”

Post by Greg_Lewis »

Very clever!
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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