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Steam valve -3d blueprints?


Hi --
pensioner in Africa ---still studying the wonders of Watts & other
atmospheric & steam technology --

DiY --Is my system in the backwoods --forgive my primitive approach

have worked on Diesel Petrol & military gas turbine engines --44 years -

ashamed to admit I,m only getting to know old steam technology --

I built my own Muzzleloader guns /lathes /circular saw & many
machines --DIY ( INTERNET is astounding!)

Now -hooked on steam----I ,m stupidly attempting to build a scale model -
of a dual action steam engine --horizontal ---circa 1940 or so --simply to see the POWER steam can create!

just cannot see how the steam valve looks /operates /seals
require 3D set of blueprints with accurate dimensions
to machine or fabricate the sliding valve --
piston & crosshead& flywheel are not too complicated to make

but I do not have x ray vision ----cannot see inside that steam valve
brass box attached to piston /cylinder--

was wondering if anyone can supply /post a clearer view of how this valve
appears /seals /functions ?--dimensions?-maybe asking TOO much !
anyhow --will keep searching for clearer images -that the poor B&white
fuzzy sketches I have d/loaded



ok --so no-one wants to help ?
no probs ---the Brits came thru ---great bunch OF STEAM enthusiasts--answered
all my questions on piston /valve 3 d blueprints for model engines --

this forum has ignored me for a week !!--

ok =---now we know you don't really give a toot to novices who want to learn !

no thanks for all the waiting --
steema 5


Dear Sir,
Actually if you would have just done a search for 'how a steam engine works'
you would have found so many videos and pictures illustrating what you were asking for. I have found the fellows on this forum to be quite helpful so maybe it was just timing that nobody got back with you. I personally only check in to this forum about once a week so I just saw your question.
P.S. and I guess I'm being more polite than you.


Last Subscription Date
Welcome to the Stak steema5 :wave:

Though by your 2nd post I'm not sure if you will stick around to see this.

Even those of us that are on here daily don't always see the new posts.

In my own case when I log on I generally scan down the main page with all the forums and see what the latest post is on each of them and then check out the last several updated posts on a few of the forums.

If you made your post and then someone else posted a few minutes later on another thread in the same forum their post goes to the top of that forum page and then shows up as the latest post on the main page with all the different forums.

Yours happened to be on the main page today when I logged on due to gbritnell replying to you yesterday and no-one else posting anything on this forum since then. . . So I found it today.

I for one would love to see some pictures and read about the Muzzleloader guns /lathes /circular saw & many machines --and other DIY projects you've built as well as the progress updates on your current Steam Engine project.

Don't be discouraged by the lack of response the first time through, though at the same time, I can understand your frustration with no response in 5 days not knowing what happened or why there was no reply.

Hope to see some of your work



Well thankyou OTTO --- finally ---someone read my question --
appreciate your help

unfortunately --have spent 6 weeks searching for decent /clear blueprints
for a standard horizontal /cross head model steam engine

I am not ignorant --have studied a huge variety of types /patents etc
the principle is not rocket science --
have downloaded THOUSANDS of sketches /fotos diagrams /schematics
in the last 3 weeks

however any architect or engineer --would be foolish to attempt anything without
detailed dimensions ---3D views exploded /dismantled steam models
but ---blueprints in 3D -- I am constantly reminded on 7 model steam forums
are very very rare ---
the ones I have are ONE dimension --very POOR schematics
the good fotos I have studied --have NO dimensions or scale --
no good guessing ---50 yrs I engineering /guns /aircraft --I always rely on accuracy

that steam "chest " inlet exhaust dual piston or "cup " sliding valve
is impossible to re-create sans DIMENSIONS ---or 3D
BUT I have decided to abandon the search ---

maybe one day -I will find decent blueprints ---
many thanks for the decent welcome & advice ---
( some forums cannot be bothered to help ---others have gone to great lengths
to find what I asked for ---
but -----sometimes --got to admit failure
at least the steam valve principle is permanently stored in my memory !
regards --- Steema 5


Last Subscription Date
Don't know if you tried this site yet, but it has a ton of free non copyrighted plans. I think some may be in 3D format ,however most are your typical blueprints. There are hundreds of plans here that will give you a good ideal of steam engines and their workings. Very good reading for those long rainy days.


Hope this helps


Many thanks Brent --appreciate--
I have spent weeks --studying Elmers & jon tom mindboggling variety
of vertical /oscillating wobbler steam models --
nothing is really clear ---all one sees is OBJECTS -- all shapes & sizes of bits & pieces?
no real idea of what I am looking at --no descriptions --?
YES -- superb dimensions --but what are we looking at ?
no 3D view of how these parts all fit together or assemble

I have searched in vain ---for this standard horizontal sliding valve engine( see foto )
and the plans or blueprints for this model ---just do not appear --some LOOK similar
but--most like that awful OPITEC wobbler see saw engine that has a single hole/see saw cylinder---
for steam in & out ---requires precision milling machine --very easy to go wrong

many of Elmers blueprints are murky one dimension --confusing pieces not labelled
clearly ---black & white objects are a mystery

all I wanted really --is this machine --in 3D or clear plants to turn parts on lathe
looked simple enough at first ---
just the STEAM VALVE "CHEST " piston /valve port location /spacing for inlet & exhaust
I cannot find anywhere ---
some strange ox or cylinder objects DO appear in soe of the thousands of blueprints
but are not identified or are clear in various angular views
maybe old fashioned --but as a engineering draftsman ---long ago

ISOMETRIC & ORTHOGRAPHIC PROJECTIONS --show all facets /sides of parts
some bits require Xray vision --like the steam valve in this side view
this pic is what I would love to make ---but --

hang on ---er -- oh dear --no "UPLOAD FILE " link ?? cannot post pic from my
foto /stored files ----
URL ? -- click on that icon --they want URL ? --BUT that's a website address?
oh hell --
now I cannot show you what I want you to see !!
--apologies ---this forum does not show how to upload stored pics /schematics I have saved in my PC does not say ---upload from PC !
OK never mind ---I think u see my problem now
thanks for the assistance --appreciate
steema 5


OK -- found the relevant paperclip icon for uploading fotos
from your PC storage files
( These images are for Hotrod Brent & others )

to see if I can get any detailed dimensions of the "steam chest" in these
illustrations of std crosshead dual direction piston steam models I am presently building

Simply stuck ---on that STEAMCHEST ! cannot find blueprints or alternate
VIEWS ---- of that cup shaped strange looking sliding valve that )appears"
to cover 2 ports --at a time
exhaust & inlet holes diam --location size ---is nowhere to be found from
hundreds of images /scale modes /blueprints - d/loaded from hundreDs of

OK -- IF anyone can find me a detailed 3D blueprint with relevant
DIMENSIONS of that steam valve ( see fotos ?)
would appreciate enormously ---but so far --6 weeks later

have failed ---
no probs mate ---
my fascination with steam models will have to fade -

regards --steema 5



I know that my post is not much help, but you have to consider the fact that when these engines were originally built, 3D CAD systems weren't around and neither was the internet. The CAD system was a guy at a drafting board with a pencil and his file storage was a filing cabinet, not a hard drive.

You may have to find an engine somewhere and take it apart to determine the proper working principles and dimensions for the valves. Reverse engineering the original parts and making 3D models is part of the fun. You could share your models with the rest of the internet and "pay it forward."



ALL my fotos are in my PC - FOTO storage file
click on above sunny mts -----
asks for URL ?
---why not a paperclip icon ? nowhere to be seen --so cannot show fotos

---------- Post added at 04:45:53 PM ---------- Previous post was at 04:39:10 PM ----------

As I live in the African bush --
there are few museums within a 400 KM radius
-never had the benefit of actually pulling one to pieces --as in over -civilised
Europe & USA

That's why I am on a dozen steam forums

ALL I need are details of a STEAMCHEST ---- whatever blueprints I have are
very poorly drawn /laid out
like the dark side of the moon ---only seen by astronauts--!

got to be a superb illustration of steam in /out system --with dimensions

yet ---- --will keep looking --3rd week now --cannot give up


Grateful ---thanks Kevin--
will try that grabcab .com link --appreciate enormously

maybe they will have exploded views --of the ELUSIVE STEAM CHEST /BOX
valve assay & dimensions ---
found a very clear schematic diagram 3D --of that steam box

very very complex === scary ---have a look at this! so many parts !seals /weird valves --still no dimensions attached to any of those exploded parts --

may as well simply try guessing & making huge errors /takes years !
regards Steema5

---------- Post added at 08:47:27 PM ---------- Previous post was at 08:23:59 PM ----------

here are the diagrams of that complex steam chest valve assay for KEVIN-

oh heck --now that paperclip icon --does not respond ?
trying to attach those 2 schematic illustrations --

keep clicking on above paperclip icon --

FORUM RULES below --say I can POST or attach files !
24 times --nothing happens --

no idea what the URL thing address of a website?
just my own d/loads --from MY PC files

but that paperclip worked earlier --
now what ?clicked on attach files below ---nothing!

Bill Hazzard

Last Subscription Date
I couldn't find any 3D measured drawings but this link should explain how the slide valve works along with these drawings. When you click the Post Reply button you should see the paper clip attachments button at the top of the box.


This is an excellent book to read as well.



Last edited:


Nothing shown on that book site --
Thanks bill----appreciate
but still no 3D blueprints on any of those steam valve drawings /dagrams
again --all I want is THIS pistob steam valve details --both sides of the steam chest
are essential --distance between ports --piston length /shaft diameter inlet hole ID
EXhaust hole diam etc (?
how on earth can anyone build this steam box valve sysem without ANY blueprints -
is mindboggling --
thanks anyway steema 5

Bill Hazzard

Last Subscription Date
The book that I posted is "The New Catechism of The Steam Engine". Try finding a copy online, it should be able to answer your questions. You should also be able to scale the drawings that I posted. You can also search Google images for steam engine slide valve, it will show you many images. There also might not be any 3D drawings out there.


Quite correct --Bill

there are really no exploded 3D dimension filled schematics of both PISTON and
SLIDE valve STEAM CHEST ---OF A simple stam engine HP steam supply
YES many many great fotos diagrams animations --of all kinds --
but now irealise BLUEPRINTS are TOP SECRET --anyone who claims otherwise --
is blind or seriously ignorant ---must be closely guarded or cost a small fortune to
purchase the PATENTED idea ---for model building --

well --if I had known that b4 istarted on this massive futile search ---
would have been aved 2 months of blind faith --
will scrap this idea ---
taken the wind out of my enthusiasm --now simply despise the word STEAM !

only for purists --
thanks anyway ---at least know how it works --best to forget ASAP!


Last Subscription Date
Seems to me the ORIGINALS of most of the parts we use were created in blacksmith shops with nothing more than an idea in mind of what they wanted to accomplish and then hammering and forging and machining what they envisioned.

The Wright Brothers didn't have access to ready made blueprints when they built the first airplane.

We now have a wealth of pictures and drawings and cut-away views that they didn't have to begin with, and even the parts that were designed and patented complete with patent drawings and/or blueprints, those blueprints were nothing more than a hard copy of they originally came up with in their minds and then put down on paper.

If you are making a production-run of interchangeable parts or a single replacement part that needs to mate up with an existing part then you need the original blueprints with all of the dimensions and tolerances. If you are building a single unit then just go by the drawings that are available and scale them to suit yourself making each part fit the next. If instead of a 1 inch bore you choose to go with a 7/8ths bore then simply draw yourself a sketch or full-blown blueprint showing it as 0.875+.0015-.0000 and make the mating part 0.875+.000-.0015 and you will have zero to .003 clearance depending on how you close you hold your own self imposed tolerances.

If you can build your own ""Muzzleloader guns /lathes /circular saw & many machines --DIY"" then you should be able to handle a steam valve from a rough sketch or cut-away drawing with or without any dimensions.

You could start by laying it out on a graph paper grid or better yet print out a good clear picture and start measuring point to point with a caliper and writing down the dimensions. You'd be doing the same thing if you were able to cut open an existing part and take dimensions off of it. Even if you had an existing part to cut in half you wouldn't know for sure what the tolerances were so you have to use your best judgement on it, and if the part had been rebuilt at any time over the years you wouldn't know what the original sizes were if it had been bored out or other changes made. Plus if the part you took your dimensions from was too big for your application you would have to scale it down to what you needed anyway. As I already noted, you aren't making interchangeable parts for existing pieces of equipment so once you get even a rough dimension on something all you need to do is give it the appropriate tolerances for the mating parts so they fit together.

If a blacksmith can forge a bolt and then form a thread on it and then hammer out an odd sized square nut punching a hole in it and 'tapping' it from both sides with a tapered tap to make it fit then you should be able to make what you need to suit yourself on an individual project.



Harvey Teal

Last Subscription Date

There is no "standard" dimensional spec for a slide valve steam chest.
The valve system is designed for a specific steam cylinder, which in turn is designed for a specific engine. Shape, placement, and dimensions of the cylinder valve ports are developed for the pressure, size, temperature, and service class of the cylinder.

For a given cylinder, valve types and arrangements are myriad. For a working steam engine, selection of materials and dimensions are important. For a model, these are not so important.

For model work, the shape and size of a basic non-balanced D valve can be easily derived from 2D drawings that are readily available all over the web.
The basic shape can be scaled to match your model's cylinder size.

For an unbalanced D valve running at "low" pressure (below 80 PSI), the steam chest is nothing more than a box that completely surrounds the valve, with a removable cover.

The working face of the valve rides against the working face of the cylinder casting. Both working faces are lapped to become reasonably flat. The mating surfaces are held together by steam pressure inside the chest. Steam pressure acts upon the upper body surface of the valve, and pushes the valve against the cylinder face. The valve/cylinder working surface is lubricated via oil which is mixed with the inlet steam.

In this basic configuration there are no seals other than the flat sliding face of the valve against the flat cylinder face. Also a seal must be provided for the cylindrical valve stem as it passes thru one side of the valve chest.

Typically the valve is not firmly attached to the valve stem. It is allowed to "float" free of the valve stem, so that the valve stem may move the valve back and forth but not interfere with the valve's mating pressure against the cylinder.

As long as the steam pressure and valve body size are relatively small, valve friction and wear will be minimal. This is a very simple setup, not at all complicated.

Higher pressures and higher performance will require more elaborate valving. Designs for balanced slide valves, riding cutoff valves, etc require more precise dimensioning of the valve chest and its cover.

Piston , rotary, and poppet valves involve totally different architectures.

Hope this helps. Don't give up hope yet...this is much less complicated than it seems.

Bill Hazzard

Last Subscription Date
I don't understand why you are upset that you can't find blueprints, just make it up as you go. If you can't get past that there are no drawings made up for you so you don't have to do the work yourself then you were doomed to fail from the start.


Back at the beginning of this thread you stated that the Brits (as you put it) came up with all the information you needed,

ok --so no-one wants to help ?
no probs ---the Brits came thru ---great bunch OF STEAM enthusiasts--answered
all my questions on piston /valve 3 d blueprints for model engines --

this forum has ignored me for a week !!--

ok =---now we know you don't really give a toot to novices who want to learn !

no thanks for all the waiting --
steema 5

If this is the case then everything that has been offered up by the more than courteous fellows on this forum has just been a waste of their time.