R.W. Machine Model DAV-1
Beam Engine
This engine is under construction. Therefore, so is this webpage.
The R.W. Machine model DAV-1 is a kit I purchased around ten years ago. Now (2010) I'm finally getting around to putting it together. This kit represents my first attempt at "machining" something. R.W. Machine engines come as machinable kits requiring a minimum amount of hand tools to complete the machining. Or so says their website. But I have a hard time imagining how this kit could be built without at least a drill press. A lathe would be nice, but such a tool is beyond my scope at this time. Nevertheless, this kit seems to exist solely for the purpose of getting me to buy more tools.
Shown below is a sample of one of the drawing pages. There are 16 drawing pages and 9 pages of written instructions. The written instructions vary between vague and nonexistent. The provided information is probably adequate for a real machinist, but a machinist I am not. Mostly I just stare at the drawings until I think I know what I'm supposed to do and then dig in.
Most of the kit consists of generic raw material. But there are a few specific hardware items that are creatively repurposed. For example, the engine base is repurposed from a cast 6x6 post support.
I am not following the instructions in the order presented. My primary interest is in getting the engine up and running on air. So I skipped over boiler construction and other peripherals and got right to work on fabricating the flywheel frame. I have a second-hand scroll saw. After getting some blades I discovered that it not only works, but cuts metal. It's less than ideal and the blades don't last long, but it's the best I have for now. I also invested in a small bending brake.
Most of the plans are drawn 1:1. So I made photocopies to use as templates. I taped my flywheel frame template to the appropriate piece of sheet metal and started cutting. I also used the template to punch all the hole centers. The template held up so well that I even used it to line up the part in the bending brake.
Next I worked on the engine base. I cut a slot for the flywheel and drilled mounting holes corresponding to the flywheel frame. Note that the engine base is a 6x6 post support. Several bits of off-the-shelf hardware items are repurposed for this kit.
The kit includes various slivers of bar stock for the flywheel, crank disk, pulley and so on. The flywheel was supposed to have six ¾" holes. But I don't have a ¾" bit so I made eight ½" holes.
I spent a few hours trying to improve the appearance of the disks. The disks are just rough sawn from bar stock. I worked each face with a flat file to get rid of the saw marks. Then I put each disk in the drill press and ran it against course sandpaper. The sand paper created a nice circular grain. Well... It's not great. Maybe I'll take it all apart again and work on them some more. The graining can be seen in the pictures below.
I thought it was important to build the engine in such a way that it can be easily disassembled. Who knows what corrections or modifications I may need to make in the future? To that end I made some deviations from the instructions.
The flywheel frame was supposed to be attached to the base with what the kit calls "drive screws". They look something like threaded rivets and are meant to be hammered into place. I decided to use machine screws and nuts instead. But I had to grind away at the inside bottom side wall of the base to accommodate the nuts. What I should have done is drilled smaller holes in the base. Then I could have simply tapped the base holes and skipped the nuts altogether.
There's a pulley behind the flywheel. The flywheel is supposed to be fixed to the pulley by a roll pin. The pulley is then secured to the crankshaft with a grub screw. Instead of the roll pin I drilled and tapped for a 4-40 screw, which can be seen in the picture below.
Likewise the crank disk is supposed to be fixed to the cam disk (eccentric) by a roll pin. Then the crank disk and cam disk are supposed to be pressed and/or soldered to the end of the crankshaft. But again I used a 4-40 screw instead of the roll pin. And I drilled the crank disk for a grub screw just like the pulley. It's difficult to see in the picture below, but the cam disk is between the crank disk and the front of the flywheel frame. However, the screw connecting the two disks can be easily seen. And you can see the grub screw hole on the top edge of the crank disk. Here's my grub screw tip: Drill an oversized hole through most of the radius of the disk. That way you only need to tap threads near the shaft hole.
Next I decided to tackle the valve block. This was complicated! Holes are drilled from five of the six sides of the valve block. There are necessary ports and unnecessary ports. The unnecessary ports are needed to drill some of the necessary ports. Once all the necessary ports are drilled then the unnecessary ports can be filled back in with solder. But instead of soldering the unnecessary ports I tapped them and plugged them with grub screws. I did this only because I thought it might be more visually interesting. The valve block is the rectangular chunk shown in the picture below.
Also shown is the piston with soldered piston rod, the cylinder top and the cylinder. Note the elbow-shaped steam port in the cylinder top connecting the side and bottom of the cylinder top. This is the port that will act on the top of the piston.
Next is the valve. The valve is a rod (not yet cut to final length) with bits of tubing soldered on at just the right places. At the bottom of the pic is the main steam pipe, which threads into the bottom of the valve block.
Below is what it might all look like in the end. Don't forget this is a beam engine so the piston runs perpendicular to the valve. As you can see the valve is not even remotely square in the valve block. I simply didn't get all the holes drilled as straight as I would have liked. Hopefully this is a forgiving model. I still have a lot of filing and tinkering before the valve runs smooth in the block.
Next is the cylinder all cleaned up after the top has been soldered in place. Note the steam port in the top side of the cylinder. I left a drill bit in this hole while soldering. The bit not only kept the cylinder and top in alignment, but also prevented solder from flowing into the port. The piston is also in place with the piston rod protruding through the top of the cylinder. I spent a lot of time filing on the piston to get it to run well in the cylinder. Such is the downside of not being able to drill perfectly square holes. But now I can blow and suck on the cylinder port and get the piston to move up and down.
I made the bearing to connect the piston rod to the beam. The beam is a hammer-textured decorative strap. Gate hardware perhaps? Unbent drawer pull maybe? And I made the valve block frame. The frame was supposed to be more decorative, but I just cut it down blunt. I'd rather see the brass valve block. The valve block frame is made from an H-clip used to butt-join ½" roof sheathing. Note the unmodified H-clip in front of the engine base. At last I have enough parts to mockup what the finished engine might look like.
The main steam pipe is threaded into the bottom of the valve block. But it seemed like a potential weak spot so I soldered it too. Then I tried soldering the cylinder to the valve block. But as I was doing that the cylinder top caved in and melted itself to the piston. I had to take everything apart, clean all the components and try again. I learned the hard way that heat sinks are needed so finished areas of the assembly don't come apart as I'm soldering other areas. For heat sinks I used my vise and bits of wet paper towel. I got it all together on the second try.
The valve block serves as the bottom of the cylinder and has a port to act directly on the bottom of the piston. But to complete the assembly I needed to fashion a side steam pipe to connect the valve block with the top cylinder port.
To shape the side pipe I made a form from a wood board. I used a small round file to create a forming notch around three sides of the board corresponding to the shape I wanted. First I annealed the pipe. Then I clamped it to the notch in my form and bent it a little. I repeated this process four or five times before the pipe was formed to its final shape. I trimmed the ends of the pipe, soldered it in place and... The thing actually works! I hooked up the finished assembly to compressed air and was able to get the piston to pop up and down by manually moving the valve back and forth. I can also get it to sort of work on lung power.
Next I worked on the beam support column. The column is a copper pipe flared at both ends. There's a brass washer soldered to the top. Chalk up another $25 for the flaring tool I didn't have. A threaded rod runs down the column between the pivot bearing and engine base and clamps the column between the two. I cheated on the threaded rod. The kit includes material to make threaded rod, but I simply picked up a stick of threaded rod at the hardware store.
I must say I'm proud of the pivot bearing. It's the first part I made that felt like it was done with some measure of efficiency. Maybe I'm finally getting the feel for this. I used the drill press and files to turn down the bottom half of the bearing, which fits into the brass washer on top of the column. And I cut the ends of the part square by chucking it in the drill press and running a hacksaw blade at the cut mark. Up until now I've been fooling with a miniature miter box, which was less then effective.
I made the cam rod (i.e. the eccentric rod) from sheet brass using my template and scroll saw technique. I was concerned about how I was going to cut that big cam hole in such a delicate part. I used screws to firmly clamp the part to a scrap of plywood and drilled out the hole with a big 5/8" bit. Worked out great. All the smaller holes are just decorative.
I cut the valve rod to its final length and soldered on the bearing to connect the valve with the cam rod.
Next I did the connecting rod, which is also sheet brass. Again, most of the holes are decorative. The top of the rod has a 90 degree twist and is soldered to the beam connecting bearing.
I took a break from the engine to play with the boiler chimney, which is a piece of 3/4" copper pipe. I didn't have a tool big enough to flare the top of the chimney so I carefully cut the middle out of a reducing coupler and soldered it up as my chimney flare. Shown below are the top of the chimney and the remains of the reducer.
Epilogue
All the work shown above was done in 2010. The model was sufficiently finished to see that it was never going to work well (if at all). The model, my tools and my skills were all too primitive to amount to anything worthwhile. After a few weeks of tedium I had had enough. It was an interesting experience. I learned some new tools and techniques. Mostly I learned that I enjoy assembling kits more that fabricating parts. I think I'll stick with pre-machined engine kits from here on out. About ten years had passed between the time I bought this kit and the time I first started working on it. Perhaps in another ten years I'll unpack it and tweak on it some more...