Building a Steam Engine & Steam Safety

Did you ever wonder what it would take to build a steam engine?

The first thing you should do if you are interested in working on such a project is purchase a simple steam engine kit that is already machined and put it together. "PMR" makes a small horizontal engine model 3BIM. This is a machined engine designated BIM (B=brass, I= iron, M=machined). It is easy to assemble and runs on very low pressure air or steam. It has a brass piston with teflon rings and an eccentric which moves the slide valve and a nice brass flywheel. Why start here? It gives you a sense of how the engine works and how it goes together. You will also get a feeling of how each part is going to look when it is completed in the maching process. It also gives you a standard to work toward in the machining process.

Now if you want to machine one yourself you have an idea of what the parts are and how they are assembeled.

Many steam engines have been machined with just a drill press, files and other hand tools. It is much easier if you wish to build your own steam engine to have the following equipment. This is not a complete list, just a starting point.

1. Drill Press: One that is heavy and can be adjusted for speed and it should have a stop so you do not drill to deep in your part. A 1/2 inch chuck is really mandatory. You need a set of both numbered 1- 60 and fractional drills 1/16" - 1/2". A small vise that sits on the table of the press will enable you to be more precise in holding parts.
2. Lathe: A small lathe like a "Smithy" is what I use, it is a combination lathe and mill in one unit so it takes up less space. There are other lathes that are small and would work great for machining, search the internet for models in your price range. You will need various cutting tools a 4 jaw chuck is preffered but a three jaw chuck is much easier for the beginner to set up. A drill chuck for the tail stock is also necessary. You need a cutoff tool and many other small cutting tools for the lathe. These can be purchased when you purchase the lathe or as you need them. Most lathes come with a suggested kit of cutting tools to purchase at that time.
. 3. Mill: A milliing machine is necessary for cutting slots, surfacing metal and precise drilling. Purchase a set of end mills from 1/8" to 1/2" to start with

4. Measuring: A set of calipers is mandatory, I use a digital set purchased on the internet. These are invaluable for measuring inside and outside dimensions of the vaious parts. I also use a dial indicator and other vaious tools some, of them shown here.
5. Hand tools like files, small screw drivers and others that become obvious as you start working are necessary. If you are thinking about machining a steam engine probably already have much some of these items.

6. A Dremel tool can be vary handy for griding, final finishing and polishing.

Where to start in the process? Get the engine kit and read the plans carefully. Most kits come with full size plans and a parts list that is labeled. It is very helpful to be sure you understand the various parts before beginning. It would be great if the kits came with building instructions and suggestions, they don't. So how you build it and what is done first will not be spelled out for you there are no instruction manuals. Measurement can be in fractional inches or decimal form, you need to understand both and have a converison table available to go between the two.

I like to begin with a few of the simple easy to make parts first. Go slowly and measure several times before proceeding and as you work along. Ask questions of anyone you know who has used a lathe or mill, you can also purchase mnay books amied at the beginning machinest. These can help with set up, speeds to use and tools for the lathe or mill. The brass and iron parts are easily machined and if you make a mistake most companies will send you replacements parts for a nominal fee.

There are several companies that make steam engine kits see my links page for suggestions. There are several companies that make small lathe and milling machines check the internet for ideas.

This page is a work in progress and I plan to eventually add a section specifcally on how to machine a PMR#3 step by step with photos. Comments and suggestions for this page are welcome, please email me.


Steam Boiler Safety

Steam in a tea kettle is hot at 212 degrees F and can be dangerous. Steam in a boiler is under pressure and called live or superheated steam. It can be much hotter, up to 300 degrees and because it is under pressure can shoot from a broken steam line unexpectedly. Live steam can easily burn you in a mere second or two. Model boilers have a safety valve normally set at about 60 lbs or less per square inch. These valves are very important and should be checked often. Always have an adult around when running steam engines and never leave an engine running and walk away even for a moment.

Safety Valves can be gumed up with scale or corroded from water deposits and the seals can dry out. Look over your safety valve carfully. Take it out of the boiler and see that its opening is clean and not clogged. You can test it using compressed air with a known pressure. If in doubt replace the safety valve before firing a boiler.

Burners for boilers can be one of four types: 1. Electric burners; are easy to use and as long as you check the plug and cable going to the boiler and they are in perfect condition, these are relatively safe to use. There certainly can be internal shorts so be careful. 2. Alcohol burners; are good sources of heat, but alcohol is open flame and must be treated with great care. Alcohol is invisible when burning and can not be put out with water. If your buner tips over you could have alcohol all over the surface you are working on. 3. Solid Fuel; is used for many burners. It is smelly and should be used out doors. This is also an open flame it must be treated with great care. 4. Gas Burners; can easily be regulated at the source to help vary the amount of steam produced. The burners can be ceramic or metal and get very hot. They are my preference for heating a boiler because of the ability to regulate the heat and shut them off instantly. Electric burners are probably the safest form of heat for your boilers, the next safest would be gas, they are also the most expensive. Having a fire extinguisher nearby is a very smart thing when firing a burner of any type.

Damaged Boilers can be a source of steam leaks and a hazard to anyone around them. If you have any dents, missing rivits, cracks or suspected poor solder joints do not use the boiler. It must be checked carefully and properly tested by someone who knows how to test a boiler under pressure. Testing is normally done by filling the boiler with water and then applying pressure up to two times the expected steam pressure. Never run a boiler out of water. They must have water either to a minimum of 20% full or over any fire tubes. The water prevents the boiler from getting hot enough to melt solder.

When in doubt about any aspect of using live steam, seak out someone locally who has worked with it and has knowledge about burners, boilers and steam engines. Follow the manufacturer's instructions with all steam machinery. Steam engines can be a source of a lot of fun but remember to wear eye protection, long sleeves and leather gloves, when working around live steam.

The items above are posted as a few suggestions for helping you enjoy steam engines. This is not intended to cover all the details of using live steam, so get help from local sources, books or online.

by Allan Dake 2008