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Plans, projects and how-to's for home machinists

Jorgensen Steam


A model of Bernays's twin-cylinder steam engine (circa 1878), built by Bob Jorgensen


Pat Jorgensen recently posted a comment and I noticed that he had an interesting web site about steam engines.  So I invited Pat to be a guest blogger and to tell us more about himself and his site, Jorgensen Steam – Bob Jorgensen’s Steam Engines and Steam Engine Designs. — Rob

My story is that I am a professional engineer and run my own consulting firm in the Southeast USA.  My Dad (Bob Jorgensen) did most of the maintenance at his family lumber mill until he retired.  Since the lumber mill was originally powered by two large steam engines and associated boilers, Bob was intimately familiar with steam engines and such.  Being of a creative mind, Bob started making simple small toy oscillating steam engine models when he retired, and progressed to the point 12 years later where he had created from scratch (34) model steam engines, (3) hot air engines, (2) steam-powered bicycles, and a Stanley Locombile type steam automobile.

What Bob did not leave was a description of how he designed and machined all those engines and things, so my task since Bob’s death in 2006 has been to reverse engineer some of the engines that Bob built, and publish that information along with Bob Jorgensen’s original photographs and hand-drawn vellum sketches.

This process got me curious about steam engine design in general, so I began researching steam engines, and have a collection of about 1,000 old steam engine engravings on Bob’s website.

I also have gotten into steam engine animations, and can bring the engines of old back to life, like watching the actual engine run.  I am currently designing a twin-cylinder steam launch engine, and hope to built that some day.

So what started out as building a simple web site to share some of Bob’s photos has turned into quite a learning experience, and I continue to be surprised every day at the variety and complexity of the steam engines designed mostly in the 1800′s, and the sophistication of the engineers who did this work.  Luckily, there are a large number of public domain steam engine design books that can now be downloaded online in the US for free, and I have posted a list of about 100 of these titles on Bob’s website.  It is a fabulous story of technology from the past that changed and modernized our world in a huge way.

Plans: HMEM’s EZ Build Engine

You won’t need a mill to make this nice looking steam engine that was designed to be an easy-to-make project to teach basic machining skills to beginners.   The free plans come in both US and metric versions and they include 24 pages of helpful instructions.

It was designed by members of the Home Model Engine Machinist (HMEM) forum, led by “black85vette,” who proposed designing a very basic and easy-to-build engine that could be built by someone without a lot of experience or tooling.  What they came up with is an engine that uses tooling you probably already have or you’re going to need someday:

  • Lathe with a 3-jaw chuck
  • Parting tool
  • Hacksaw or band saw
  • 4-40 tap
  • 1/4-inch reamer
  • 1/2-inch reamer
  • Some drill bits
  • A drill press

You’ll also need some measuring/lay-out tools, a marker or lay-out dye, a center punch, vise and some files.  And a live center if you decide to make the flywheel from flat stock using the “special” technique.

The engine was also designed to be inexpensive to build and use materials and fasteners that are easy to obtain and easy to machine.

  • 1/4 x 2 x 10-inch aluminum flat bar
  • 3/4 square x 4-inch aluminum bar
  • 5/8 diameter x 2-inch brass rod
  • 1/2 diameter x  2-inch brass rod (you can use 5/8-inch brass rod and turn its diameter down)
  • 1/4 diameter x 4-inch rod in mild steel or brass
  • 1/4 x 1/16″x 6-inch flat brass
  • (15) 4-40 screws x 1-inch long (some of these will be cut to length)
  • You’ll also need aluminum or brass to make a 3-inch flywheel.  You can either use a 1/4-inch thick disk cut from 3-inch round stock or make it from a piece of 1/4-inch thick flat stock that’s at least 3-inches wide.  You’ll use an interesting technique if you make it from flat stock.  It is described in the instructions and I’ve also written about it.

You could also use steel for the flywheel but you’ll need a little experience to machine it.  One of the group’s objectives was to use materials that are easy to machine which is probably why it wasn’t listed as option.

The 24-page construction manual is well written, profusely illustrated and provides step-by-step instructions with lots of helpful tips for a beginning machinist.

Download the Plans

  • From HMEM (There are two versions.  You want this one, the “13Nov09” update.)

Bogstandard’s “Paddleduck” Engine Plans

Two Paddleduck engines - one plain and one fancy

This is not just a set of free plans for a working model steam engine.  It’s a well-written, well-organized, profusely illustrated 113-page tutorial about machining metal.

If you’re an inexperienced machinist who at least knows the basics I would strongly encourage you to download these plans and build this engine.  Don’t let the picture fool you – this is not a difficult engine to build.  It will definitely take some time and patience, but if you follow Bogstandard’s step-by-step instructions I think you will probably find it’s not as hard as you might think.  By building this engine you’ll learn a lot more than you would by making the typical “wobbler” engine many beginning machinists often build.  You’ll also acquire the confidence you need to tackle much more complex machining projects.

There are two more reasons for building this engine.  First, it was intended to be made inexpensively out of junk or scrap materials.  So it ‘t probably won’t cost you a lot, even if you’ll have to buy all the metal for it.  You’ll also find that Bogs tries to help minimize the cost of tooling by suggesting cheaper alternatives when he can.  The second reason is that you’ll be able to find help if you have questions or need some advice.  The designer is well known for sharing his knowledge and experience and I’m sure that if you have a question, he or one of his friends will try to help you.

I am not a beginner anymore, but I’m not that experienced either, so I’ve decided to start building it when I finish the Stirling engine I’ve been working on.  I think I’ll learn a lot because Bog’s tutorial is full of techniques and methods that I’ve either never tried or haven’t practiced much.

The plans use metric units, which could be an issue if you’re in the US or another country still using the Imperial system.  I’m in the US (upstate NY) but I don’t think it’s a big problem.  I’m building an engine now from metric plans and most of the time I just convert the dimensions to inches and machine the metal to whatever size that is.  But I have had to substitute SAE sizes for fasteners and threads because I don’t have much metric-size tooling.  I’ve also had to make some substitutions when I’ve wanted to use standard-size material, like drill rod for shafts.  Those substitutions require a little bit of extra thought and planning, but it’s not a big deal.

“Bogstandard” is a pseudonym for John, the engine’s designer.  He can regularly be found on the MadModder forum.  He was also on the Home Model Engine Machinist forum for a long time and you can find a lot of his writing there.  I don’t know why John picked the name he did, but I do know that he goes out of his way to share his knowledge and help others, and he does it with a wonderful sense of humor.  I’ve learned a lot from his posts, which almost always include lots of good photographs illustrating what he’s talking about.  When I asked him for permission to make his plans available here for download he said:

“I have made it my life’s ambition to at least give the new people in model engineering an insight into the easy or alternative ways to do things, rather than the usual methods employed by the ‘elite’ and ‘know it alls’, who seem to think that newbies are there purely for ridicule and tongue lashing in public.”

John’s design is for a marine style twin-cylinder slide valve steam engine that could be used to power a model boat.  It’s about 4.5-inches high, about the same in length and about 2-inches wide.  It’s known as the “Paddleduck” engine because it first appeared as a series of posts on the Paddleducks steam engine forum from May to July 2007.  The construction of each part is described in a simple and easy-to-understand manner.  Bogs also includes the answers to questions that others had, along with some of the suggestions and comments he received.  Here’s an excerpt where he describes how to finish the cylinder bores:

Reaming the Block Holes

I said last time that we had finished with the blocks for the moment.

I forgot that not all of you will have the means to get a good enough finish on the bore: they will most probably vary from a slightly dull surface, thru what looks like screw cutting to digging out the hole with a hammer and chisel.

If you can borrow a reamer, and your hole is still slightly undersize, use one, otherwise this is how I would get an acceptable finish.  You can go out and buy adjustable laps, but that costs a lot, just to get a couple of holes cleaned out, this isn’t the totally correct way but it will be better than what you’ve got at the moment.

Start with the largest hole, stick the last drill you used through them and wiggle about side to side, the one with the biggest wiggle is the biggest hole.

Mark the largest hole with a felt tip.  Now chuck up a piece of material to make the lap out of, have it sticking out of the chuck by 1.5 times the length of the hole plus 25mm (1″), I use hard nylon but aluminum or brass will also suffice, I get better results with the softer materials.

Figure 13Carefully (no heavy cuts here, material sticking a long way out of chuck) and turn down the rod until it just pushes through the hole for a length of 1.5 times the length of hole (like Pic 13).

Now we need to spend a bit of money unless you are from the old school and have some in your garage.  We need to buy some fine and coarse grinding paste, Halfords is about the cheapest at about £3 and you get a grinding stick with that as well.  This quantity will last you for the rest of your life.

Dab a bit if the coarse stuff along the length of the lap, you don’t need a lot.  Get a piece of hardwood and with a rolling action in combination with turning the chuck by hand (you have stopped the lathe I hope) embed the surface of the lap with grinding paste, what you are doing is making a very accurate round file.

Select the lowest speed on your lathe and switch on.  Keeping well away from the chuck feed the hole to be lapped onto the lap, get ready to let go on this initial feed in just in case it bind up and sticks.  If all is well the lap will be turning (without you going round with it) in the hole.  Now just gently move the block up and down the lap in a sort of rotary twisting motion.  You need to keep the lap fully into the hole at all times.

Change the block position 90 deg around the lap every so often, eventually you will get the feel and a rhythm going.

Do this for a couple of minutes, stop machine and check the bore, it should have started to smooth out.  Repeat as necessary, wipe off, recharge, turn the block around and come from the other end of the hole, until the rough stuff has gone, then wipe off coarse grinding paste with white spirits and recharge with fine.  Repeat the operation.

You should after a while end up with a nice round, parallel bore showing slight scratch marks on the surface, these scratches will help the bedding in process as they retain oil while the pistons and bores are wearing against each other.

Clean off the grinding paste and turn down the lap to fit the smaller hole, and repeat the process again.  When finished give the bores a very good clean out to get rid of any remaining grinding paste.

If you remember from before, the pistons are going to be made to fit the bores, so they don’t need to be the same size.

Put the lap you have just made in a safe place, you might make something else where you can readjust the size and use it again.  I will do the pistons in the next article; it will give time for the batteries to recharge on my camera.

In addition to a large assortment of tips and tricks, Bogs covers topics such as safety, engine turning, climb/conventional milling, turning eccentrics, drilling deep holes, silver soldering and more.  Again, I’d like to suggest that you download the plans and at least take a quick peek at them.

Download The Plans

Individual Chapters (PDF, 1.6 – 3.7 Megs)

Chapter 1 – to page 14.  Includes the Table of Contents

Chapter 2 – pages 15 – 29

Chapter 3 – pages 30 -45

Chapter 4 – pages 46 – 60

Chapter 5 – pages 61 – 73

Chapter 6 – pages 74 – 84

Chapter 7 – Appendix 1/Part A – Design Sketches, pages 85 – 100

Chapter 8 – Appendix 2/Part B – Design Sketches, pages 101 – 113

All Chapters

Zip File (22 Meg)

Self-extracting File (22 Meg)

DXF/DWG Component Files (18 Meg, self-extracting) – Richard Harris and Nigel P. Henry took Bog’s hand-drawn part sketches and created DXF and DWG files that can be opened by almost any CAD program.  If you don’t have one then you can use the free viewer they included.  Bog’s hand-drawn plans are pretty good bu if you would like a more formal set of  drawings then get these.  They can also be used to construct the engine using CNC machines.

Related Links:

YouTube video of the Paddleduck engine running

Blogwitch’s (Bogstandard’s) YouTube Channel

Another Paddleducks build log (MadModder.com)


A Beautiful Steam Engine with Construction Details

John Bentley made this beautiful half-scale vertical steam engine.  He also did a great job of documenting most of the process on his construction page.  I was surprised to see how he fabricated the rim for the 7½-inch diameter flywheel out of a 1½-inch diameter drive shaft salvaged from a boat.

Random Quote

Two months in the lab will save you two hours in the library.

— Unknown