1/4-scale model of the 5 HP Red Wing

By Staff
1 / 7
Editor's note: This article is the first of a planned four-part series by Richard Allen Dickey on building the scale 5 HP Red Wing engine.
2 / 7
The author's initial multi-purpose machine did not have the vertical or horizontal travel necessary to do the job. Make sure you have or have access to the right equipment!
3 / 7
Clockwise from top left: Red Wing flywheels; piston, cylinder head, muffler, drive wheel and bearing caps; miscellaneous pieces and parts; water hopper and engine base casting; raw materials used to make crankshaft, linkages, etc.; mixer, timing lever, go
4 / 7
Milling machine required to perform basic operations.
5 / 7
Base shown in the process of being cut down.
6 / 7
Everything is set up to mill the bottom of the base
7 / 7
Photograph of 3/4-inch end mill used in the machining process.

Editor’s note: This is part one of a planned four-part series.

In the fall of 2002, I made it to my first tractor show. I expected to walk around for a few minutes and see some old tractors. If I was lucky, I might even see one or two that had been restored. There were a few old tractors as well as some beautiful restorations.

What I didn’t expect to see were steam tractors and a sawmill – and an assortment of things called ‘farm engines.’ Before that day, I had no idea what a farm engine was. I was fascinated. I stood next to several of these old, massive chunks of metal. All of my worries drifted away as I watched the flywheels spin, the pistons slide and crankshafts rotate. The sound of the engines with their ‘hit, miss, miss, miss, miss, hit’ was almost hypnotic in its rhythm.

This was much more than a tractor show – it was history in action. I spent hours walking around enjoying myself as I made it from booth to booth. That’s when I saw the most fascinating thing of all – it was a little gas engine that was barely a foot long. It looked just like the big ones with its flywheels and paint. That was just too cool in itself. When the owner gave the flywheel a spin, this little toy engine came to life. It really worked! I spent over an hour talking to the owner and watching this little working model. This engine was without a doubt the one thing that impressed me most. I enjoyed everything that day, but the thing I kept thinking about was that little model engine from the Red Wing Motor Co.

It took over a year before I was able to track down a source for the Red Wing model. I found it by getting my hands on a magazine I had not heard of before. It was called Gas Engine Magazine. Inside, I found an advertisement for what I was looking for. I drove to the Red Wing Motor Co., which is located about 75 miles north of Springfield, Mo. I spent a couple of hours talking with the owner, Vic Greenwood. He was able to give me a little history of where the idea for the model started.

Somewhere around 1996, a guy by the name of Jim Foster, from Minnesota, wanted a scale model of a 5 HP Red Wing stationary engine, so he made a set of scaled-down prints and casting molds. Others saw what Jim was doing and also wanted castings. There seemed to be a demand for this little model engine.

Vic Greenwood bought the company about six years ago from Jim, and has been running it since. During my conversation with Vic, he told me that over 550 of the 1/4-scale models of the Red Wing engine have been sold. That told me the engine has proven itself. I felt lucky to have run across this particular model at my first tractor show 18 months earlier. By the end of our conversation, I was sure this was a project I wanted to do. I purchased a casting kit (less than $400) and an accessory kit ($45), which included material that would save me a trip to the store. The casting kit includes almost all the pieces needed to build the engine. The cast iron pieces are the engine frame and base, flywheels, head, and some miscellaneous parts.

There are 10 brass castings that are used for the governor, air/fuel mixer, etc. Included with the casting kit is a small box that has springs, a spark plug, timing gear, piston rings and a lot more.

The accessory kit is loaded with many different types of material. If you have a big shop, these pieces are probably in a box under your bench. If you’re like me, you would have to go looking for each and every one of these pieces when it came time to use them.

Last, but not least, are the eight pages of very good blueprints and an 11-page document that should help you get started. Speaking of getting started, this is where I needed to set some ground rules.

Getting prepared
I am not a professional machinist. I am one of those guys who likes to play in the shop. I am self-taught and do make mistakes. If you’re a professional machinist, you will probably get a chuckle or two at the way I try to do things. That’s okay, because I may surprise you before this is done.

If you are a hobby machinist or a person with limited machining skills, my job is to show you that you don’t have to be an expert to do this. It will take a little time and money to get started, but the self-satisfaction of having built something that actually runs is something you will cherish for the rest of your life.

These model engines sell for around $2,000 when finished. If you had to buy a milling machine, tooling and engine kit, you will still have less money invested than if you just purchased a completed model engine. Let yourself have some fun! The fun was about to start for me until I ran into my first problem – my milling machine was not big enough to do the job.

I purchased a multi-purpose machine for less than $500 several years ago and have used it for small projects. It has a mill head that will swing out of the way so you can use the lathe. The problem is that it had nowhere near the vertical or horizontal travel needed to mill the bottom of the engine frame. I saw right away that I was wasting my time trying to use my mill and decided to get a new one.

A trip to Grizzly Industrial and $1,000 later, I had a milling machine that had 18 inches of vertical travel, and a table travel of 7 inches-by-23 inches. Wow! Now I could get started.

Machining the frameI wanted to put this big new milling machine to the test on the engine frame and base. Before I could start I had to clamp my vise into position. I squared it with the table edge and clamped it down in four places. Next, I clamped the engine frame in the vise upside down so I could mill the bottom. I used a level to adjust the bottom of the engine frame so it would be square with the table. This is the first part of the engine frame that has to be milled, as it will be attached to a jig for all the rest of the milling steps. I used a 3/4-inch, four-flute end mill and set my new machine to its slowest speed of 120 rpm. I used a cutting depth of 0.020 per pass until I had a nice, smooth surface. I could’ve removed more material with each pass, but I wasn’t sure how secure the engine frame was in the vise. For this first step, I tried to exercise caution.

One modification that Vic has designed into the engine frame is to turn its bottom into a fuel tank. This is much simpler than making one from scratch. This information is not on the blueprints, but it is very simple.

To do this, a small edge is milled into the bottom. It should be 1/8-inch deep (0.125) and about half the thickness of the sidewall. I used a 3/8-inch end mill for this part. The idea is to cut a 1/8-inch piece of sheet metal to the size of the area that was just milled. The sheet metal is held in place with JB Weld. We won’t close off the bottom until much later into the build.

Drilling the mounting holes
With the milling finished on the bottom, it is time to drill the mounting holes. The best way to do this is to locate the center of the work piece and measure everything from center.

I used an edge finder to locate the edge of my work. I took the actual length and width of the part, divided by two and came up with the center. I don’t have any automatic equipment or fancy digital readouts. I wish I did, but you can do just fine without them. Just don’t forget to zero out your dial on the adjustment wheel and write down all your numbers on a piece of paper. If you don’t, you’ll get lost in the spinning of the adjustment wheel.

By dialing out from the center to each hole that needs to be drilled, they should end up in the right place. Just be cautious, and take a look at where you are about to drill before taking the plunge. Each turn of the wheel is 0.010. Your eye should be able to see that. If you just moved your work 6 inches, you spun the wheel 60 times. Or was it 61 times? Take the time to look.

Machining the baseThe base is also milled while it’s still in the vise. I milled the bottom first and then drilled the mounting holes before flipping it over. Next, I milled the top of the base and drilled holes to be tapped. Everything lined up just fine and looks good, too. The most important thing is, I had fun!

Next month, we’ll finish off the milling on the engine frame, bore the cylinder and work on a few more things. I will try to keep the information in each article related so it won’t seem like we are jumping around too much. At the end of the series, this little engine will be singing ‘hit, miss, miss, miss, miss, hit’ just like the big ones!

Continue to Part 2

Contact engine enthusiast Richard Allen Dickey at: 246 Skyview Lane, Yellville, AR 72687, rad2001@leadhill.net

Contact the Red Wing Motor Co. at: (660) 428-2288; www.modelengines.com

Gas Engine Magazine
Gas Engine Magazine
Preserving the History of Internal Combustion Engines