Hardware store steam engine

[chucketn]

I thank you so much for taking the time and effort to make this list and the explanation of the build.
I will study it and assemble the parts to hopefully build a working engine with my Grandson. I have asked if he was interested, but have not had a reply yet.
You are an inspiration to all Grandpas.

 

[The_Paso_Kid]

These are photographs of the final version of this engine.

 

[The_Paso_Kid]

I would like the list as well. I think my grandson would like this too

I have added a parts list to this thread.

 

[The_Paso_Kid]

It is a little slow going having to draw up some diagrams and remembering why I did things a certain way. So it might be a few days in posting items to adequately describe the building of this engine.

Step #1 – Please refer to diagram #1 (attached). Take the floor flange and draw a line along the edge of two of the holes. Measure and locate the center point on this line and then draw a line perpendicular towards the edge of the flange. Draw another line (red in diagram) across this second line approximately 5/16 of an inch from the edge. This measurement is not critical it could be ¼ of an inch or 3/8 of an inch from the edge it depends on the size of the tubing you will be using for the valve and how much material that will be left between the tubing and the edge of the flange. Measure the diameter of the tube to be used for the valve and using a drill that will produce a slight press-fit drill a hole at the spot indicated by the crossing of red and black lines in the diagram.

 

[The_Paso_Kid]

Step #2 – Thread the brass pipe nipple into the floor flange. This will form the cylinder. I placed the pipe nipple in the jaws of the 3-jaw chuck on the lathe to hold the pipe while I turned the pipe flange to a tight fit. I could have clamped the flange in the vice and used a pipe wrench on the pipe nipple to accomplish the same thing. It was just that the brass pipe had such a nice finish that I did not want to scratch it all up tightening it up with a pipe wrench. Although the pipe could slip in the chuck and get scared up as well.

Step #3 – Make the brackets. I am placing this step here as I have the brackets directly underneath the floor flange in my final version of the engine. If you plan to attach the braces to the bottom of the axle blocks as I had in the version that I had posted a video of it running, just set the brackets aside after making them. Measure the distance between the holes on the floor flange. The one I had it was 1-1/2 inches between centers. Take the (2) four inch corner braces and mark where to drill the holes. The first hole was 1 inch down from the top of the brace and ¼ of an inch from the side. The next is 1-1/2 inches from the first hole and ¼ of an inch from the same side. See Diagram #2. The holes on the left brace are towards the right and the holes on the right brace are towards the left. Refer to photo IMG_1650.jpg from my previous postings of the final version. If you plan to attach the braces to the axle blocks then the large notch on the brace on the valve side is necessary to provide clearance for the movement of the eccentric. If you are planning on placing the braces under the floor flange Instead of cutting the notch you could secure the brace to the flange and drill through the hole previously made in the flange for the valve cylinder tube.

 

[The_Paso_Kid]

Step #4 – The frame. Install the four carriage bolts through the holes in the floor flange. [Slide the braces onto the bolts only if you are building a model similar to my final version]. Thread four regular ¼ inch nuts, one on to each bolt. Securely tighten the nuts. This will form the basic frame that the other parts will be attached to,

Step #5 – Building the crank/axle. Any piece of thin 1/16” steel (slightly thicker – no more than 1/8” would work better as the 1/16” steel I used would slightly flex when running at speed with the unbalanced flywheel , however you have a limited amount of space between the frame for the crank to fit in)will work for the two crank pieces. Refer to diagram #3. I used a flat corner brace to make the two pieces. Drill ¼” holes ¾” apart as shown, this will give the engine a 1-1/2” stroke which is about the maximum you would want for a 2 inch long cylinder to provide air space above and below the piston at the top and bottom of its stroke. You can reduce the stroke by placing the holes closer than ¾” however you must take into account the size of the carriage bolt heads that are used. It should be noted that carriage bolts have a squared section just under the head (see diagram #4). The advantage to this is that using a file you can square up the round hole drilled into the metal strip so that the square section of the carriage bolt fits snuggly into it. This will prevent the metal piece from turning and causing the cam to become misaligned [At least in theory, however in practice it is a challenge to make a perfectly square hole that snugly fits the square section of the carriage bolt]. It should also be observed that the squared section of the carriage bolt is of a greater thickness than the metal strip that the cam is being formed from. The excess that protrudes above the metal strip needs to be removed by rounding it over with a file or by turning it in a lathe. Or if the protrusion is slight the use of a washer may be all that is needed. When a nut is threaded on it should be able to compress the metal strip fully against the head of the carriage bolt with no gap or play in the parts.

On one of the strips both holes will need to be squared. The second strip only needs one square and one round hole.

 

[chucketn]

Excellent write-up. Much appreciated.

 

[The_Paso_Kid]

Excellent write-up. Much appreciated.

Thank you, I am still writing up steps and drawing diagrams. I sometimes have to look over them several times before posting as I know what I have done, it is just trying to explain such in a clear and understandable manner. If there is any questions or confusion feel free to ask.

 

[chucketn]

I'm compiling your pictures and instructions to study. My major problem will be to find a real hardware store still in business... There is currently only one that I know of in a 50 mile radius!
The big box stores are such a pain to find anything.

 

[The_Paso_Kid]

On two of the three 2 inch long carriage bolts you will need to file down (or sand down on a belt sander) the rounded head in order to provide some extra clearance for the piston rod. Please refer to diagram #5. These two bolts will become the axle. The third carriage bolt (shortened down) will become the cam. Insert one carriage bolt into one of the two metal strips on the opposite side of the strip slide on a washer (if necessary to cover over any part of the squared shank of the carriage bolt protruding above the metal strip) then thread on a nut. Tighten the nut to insure that it compresses the metal strip securely against the head of the bolt. If it does not, you may need a thicker washer or to file down more of the squared shank. Repeat this step for the other side. Set these two aside for now as it will be necessary to build the two axle blocks as this will provide you with a gauge as to how much space you actually have to work with.

 

[The_Paso_Kid]

Step #6 – Axle bearings. Please refer to diagram #6 this illustrates the two parts used on the original version. On my final version I used a solid piece of ¾” square aluminum bar stock which provided for a greater bearing surface for the axle. No notching was necessary for the nuts to clear as needed with the aluminum angle. The only disadvantage would be the large amount of material to be removed so that the eccentric could have unimpeded movement. It would be a good deal of material to saw out or file away if you do not have a milling machine.

The axle bearings are 2-1/4 inches in length. Mark the places on the pieces where the two ¼” holes are to be drilled. Mark the location for the first hole 3/8” from the end and 1/8” from the inside. The ¼” drill should be touching the wall when drilling. Using the first mark go 1-1/2” and make the mark for the second hole. I feel that this would produce a more accurate result rather than making a mark 3/8” from the opposite end as the piece might be slightly longer of shorter than 2-1/4”. Follow the same procedure for marking the drilling locations on the second piece. Now measure the mid-point (3/4”) in-between the two and make a line. Draw this line on the opposite side and then cross this line 3/8” from the edge. This will be the hole for the axle to ride in. Measure the outside diameter of the brass tubing that you will be using to cover over the threads on the carriage bolts used as an axle. Find a drill that will produce a hole slightly larger than the tubing. Too tight of a hole will result in friction that can slow down the engine. Too loose of a hole will cause the axle to wobble around in the hole and lead to excessive wear on the bearing surfaces. It will probably be best to clamp the two axle bearings together and drill the axle hole through both pieces at the same time this will insure that the axle will be perfectly aligned. Likewise the ¼” holes could be drill in both pieces at the same time by clamping them together in the proper orientation. It would be helpful to mark these two parts “Left” and “Right” with permanent marker or other means to identify these parts as well as a mark indicating the top. As it will be necessary to remove and install these pieces multiple times during the build and testing and will prevent the pieces from be switched around. See diagram #7.

Next cut away ¾” from both sides of each piece so that the nuts have room to lock down on the flat part of the aluminum angle.

 

[The_Paso_Kid]

Step #7 – Completing the crank and piston rod parts: As mentioned in the parts list I used a small open ended wrench holding a nut for the piston rod. I thought that it was quite whimsical and appropriate for the “hardware store” theme I was going for. The wrench was stamped-out of 1/16” thick sheet metal.

I would not recommend using an actual wrench as tools are made using hardened steel which will make drilling and filing much more difficult. However some tools steels can be annealed [softened] by heating the steel to a high temperature and allowing it to cool down very slowly over a number of hours. The wrench I used was approximately 2-1/4 inches in length. If you have sufficient material remaining from the flat corner braces used to make the cam parts you could fashion the piston rod from that same material. Drill a small hole slightly larger than the brad nail that will be used to the pin to hold the rod to the piston shaft approximately 1/16” from the top. The top edge should be rounded over sufficiently so that it does not bind in the slot cut into the piston shaft. If you happened to have such a wrench find a nut the will snuggly fit it. Next remove the threads from inside the nut by using a drill that is slightly larger than the outside diameter of the brass tubing that you will be using to cover over the threads on the carriage bolt to be used as the cam. Soft solder, braze, or weld the nut to the wrench. I used soft solder.

Take the two axle pieces that were previously made. Insert the remaining 2 inch long carriage bolt into the piece with the remaining square hole. Take a piece of the brass tubing approximately 3/8” in length and run a ¼” x 20 tap through it making threads on the inside of the tubing. Now screw this piece of tubing onto the threads of the carriage bolt and tighten it down as much as possible. Put the nut attached to the wrench (piston rod) over the brass tubing. Check to insure that the fit is loose enough to allow for free movement of the part. If necessary you could use fine grit sandpaper or a file to remove any burs on the outside of the brass tubing or a round file to slightly ream out the inside of the nut. I originally had one washer on each side of the nut on the wrench to keep the piston rod centered. I later removed these as they were causing a bind. Next put the round hole on the other axle part over the threads of the carriage bolt acting as the cam. Then thread a ¼” nut onto the bolt and tighten it down. Using a hacksaw clamp the cam into a vice and saw off the excess length from the carriage bolt.

Thread one lock-nut onto each of the four carriage bolts approximately 1-1/4 inches up from the ends. Take the left axle bearing and test its fit, it may be necessary to gently realign the carriage bolts by either bending them in or out until the axle bearing easily slides on and off. Measure between centers on the ends of the carriage bolts, they should be exactly 1-1/2 inches up and down, left and right. Test the right side axle bearing. Once both can slide on and off easily you will be ready to insert the completed axle and cam assembly.

Side the axle bearings into place you can thread a regular nut on to the ends of each of the carriage bolts forming the frame and run them up until they hold the axle bearings against the lock-nuts. Take a measurement of the space in between the two bearings and compare that with the completed axle and cam assembly. If the assembly is too wide to fit in that space you could remove and file down the nuts on the two axle pieces until you have some clearance. Or you can remove the threaded tubing in the cam section and shorten it up enough to provide the necessary clearance and still provide for the freedom of movement in the piston rod. Be sure to align the parts so the two sides of the axle are perfectly aligned with one another. Tighten down all of the nuts holding the assembly together. Check for any play or movement in the assembly.

My assembly had a very slight bit of movement. I was able to correct this by peening the heads of the carriage bolts over the edge of the metal strips thus locking the two pieces into a fix position. See diagram #8.

Make another two threaded sleeves to go over a portion of the carriage bolts used for the axles. This will prevent the threads of the bolt from enlarging the hole in the axle bearings as they spin. If you are using the aluminum angle you will only need about 3/8” of tubing for each side as the thickness of the bearing surface is only 1/8 of an inch. Once the two sleeves have been threaded onto the axles you can remove the bottom nuts that were holding the two axle bearings in place. Remove the axle bearings. Take the axle/cam assembly and put one side through the left bearing and the other side through the right bearing. Slide the axle bearing back and axle/cam assembly onto the carriage bolts and use the nuts to hold them in place.

Rotate the axle assembly checking for any binds or misalignment of the axle blocks. It should rotate smoothly.

Step #8 – Making the piston: My original idea for the piston was to use the truss head machine screw with a stack of alternating diameters of washers – 1/2” and 3/8” outside diameters to form the piston with built-in oil grooves. However with the washers the holes are made slightly larger to allow them to easily slip over the threads of the bolt. Being able to perfectly align the stack of washers and secure them to the screw to form a working piston seemed to be too much of a job. Instead I took a small piece of solid brass rod with a diameter over ½” and turned it down to the inner diameter of the brass pipe. I drilled a hole through the center and tapped it for the machine screw. The piston was approximately 1/2” in height. I threaded the piston onto the truss head machine screw and used a bit of soft solder to hold the piston in place up against the head of the screw. Due to the length of the exposed threads on the machine screw I had to make 2 brass sleeves using the brass tubing ¾ of an inch in length each as the tap can only tap about that much distance. I suppose that I could have chucked the piston into the lathe and removed all of the exposed threads on the machine screw and thereby eliminating the need for the brass sleeves. However I was trying to limit my use of the lathe and milling machine in this build.

Test the piston in the cylinder. It should slide up and down the length of the cylinder but not be loose. I found that the cylinder was not uniform in its inside diameter throughout its entire length. I took some valve grinding compound and put a small amount on the piston and I clamped the floor flange into the vice and using an electric drill I rotated the piston in the cylinder while also moving the piston in an out. I eventually was able to lap the inside of the cylinder to a slip fit. I removed the piston and thoroughly cleaned it and the cylinder to remove all traces of the grinding compound. Cut a slot in the end of the machine screw to accommodate the piston rod. Drill a small hole perpendicular to the slot approximately 1/16” from the end. Take a washer with a smaller hole than the diameter of the sleeve on the machine screw and drill a hole through the washer with a drill that will produce a close fit.

Slide the piston into the cylinder so that the shaft protrudes out the bottom of the cylinder. Use one of the small brad nails to pin together the shaft of the piston to the piston rod. Do not bend the brad nail at this time as you will need to remove it. Turn the axle and observe the stroke of the piston in the cylinder. The piston head should stop short of both the top and bottom of the cylinder during its stroke. There should be an even amount of space above the piston at the top of the stoke and under the piston at the bottom of the stroke. You may have to move the nuts up or down on the four carriage bolts to move the axle blocks until this desired motion inside the cylinder it achieved.

Remove the pin and slide the washer over the shaft and push the washer up against the bottom of the floor flange. Replace the pin and cycle the piston up and down observing if the washer moves in any direction. If everything is true there should be no movement at all. If this is the case use some soft solder to solder the washer into place underneath the floor flange. After the solder has cooled down again test the movement of the piston there should be no binding in its stroke. We have formed a chamber underneath the piston where air/steam can be introduced to push the piston upwards. By threading the cap on the top of the pipe we have formed a chamber above the piston where air or steam can be introduced to push the piston downwards.

 

[The_Paso_Kid]

Step #9 – making the valve. Take the eye bolt and measure the inside diameter of the eye and then the outside diameter. Check the eye bolt, the one I had the inside end of the rod used to form the eye was slightly sticking out of the side. I placed the eye bolt on a flat piece of steel and hammered down the end to get it to lay flat. I ended up also filing and sanding it down some to insure that the end would not catch on the eccentric.

These measurements will be used in making the eccentric. Find a solid brass rod or steel would also work that is approximately the same as the outside diameter, if it is slightly smaller it will work as well. The eccentric I made was less than the outside diameter. Turn the piece in the lathe down to the inside diameter of the eye bolt. While the rod is still chucked in the lathe test the eye of the bolt. It should be able spin freely. The inside of the eye might be slightly out-of-round and a little file work maybe needed to provide for a smooth movement of the eccentric in the eye. Check the fit it should not be too loose as it will affect the movement of the valve. Use a parting or cut-off tool to remove the eccentric from the rest of the rod leaving a thin 1/16” rim. You could also hacksaw the part off the rod as well. Clean up any rough spots or burrs on the eccentric. Next drill a ¼” hole close to the inside edge of the eccentric. As seen on my pictures, I drilled so close to the edge that the drill hole actually came out the side slightly. See diagram #9.

Trim the eyebolt so that it is about 2 inches from the end to the beginning of the bend forming the eye. Place the eccentric onto the axle it will tend to catch on the threads of the carriage bolt. Next gently press the brass tubing to be used for the valve cylinder into the floor flange so that 1/8” sticks out from the bottom of the flange. I applied a bit of soft solder to the top and bottom of the brass tubing where it meets the floor flange as this will prevent the brass tubing from moving. If the tub slips up or down it will affect the timing of the intake and exhaust and may result in a poorly performing engine.

Place the eye bolt onto the eccentric and holding the end up so that it is centered with the inside of the tubing then rotate the axle and observe the movement of the end of the rod. At the top of the stroke the end of the rod should be no closer than 3/16” to the end of the tubing. This will allow for some clearance in the joint between the rod and the valve piston and will allow for the exhaust to escape. If necessary trim the end of the eyebolt down. Once the proper length has been achieved place the eye bolt onto a flat surface and start to file a flat 3/16” in width on the end. Flip the eyebolt over and start to file a flat on the other side. Continue to flip and file from both sides to insure that the tenon being formed is centered. Keep filing until the tenon is 1/16” in thickness.

The eye bolt could also be clamped into a vice to be held while filing. Just take care to file perfectly horizontally to achieve a uniform thickness to the tenon and not form a wedge or dovetail profile to the tenon. Drill a small hole to fit the small brad nail used as the pin to secure the eyebolt to the piston valve about 1/16” from the end of the tenon. Round the edge of the tenon over to insure that it can rotate freely in the slot to be cut into the end of the valve.

If you were able to find a solid brass rod that has a nice sliding fit inside the tubing that will save a bit of work in turning down and polishing a rod to fit smoothly. Unfortunately that is what I had to do. Please refer to diagram #10 for a view of the piston type valve. The measurements on the piston-type valve are those that work best for the engine I built. The engine that you are building may require slightly different measurements depending on the length of the stroke produced by your eccentric as well as the placement of the brass “nuts” onto the valve cylinder.

I actually marked the locations for the intake and exhaust for both the upper and lower portions of the cylinder while the “valve blank” was inserted into the valve cylinder and attached to the eccentric. I will describe this process a little later in this build.

Take the solid brass hex rod and drill a hole through the center about 1-1/2 in depth. The drill should produce a hole that is a slip fit to the outside diameter of the brass tubing serving as the valve cylinder. Measure 3/8” from the end and make a mark on the rod this will be where it is to be cut off. If using a cut-off tool in the lathe measure the width of the cut-off tool and mark that width from the 3/8” mark. From that mark go another 3/8” and likewise mark the cut-off width and then another 3/8” form that mark. This will mark the 3 parts to become the “Nuts” attached to the valve cylinder tube to provide for the connection of the steam lines to the top and bottom of the cylinder and for the intake line. See diagram #11.

Drill the holes for the ¼” copper tubing as per the diagram. Once all holes have been drilled the individual nuts can be removed from the hex rod. Prepare the outside of the valve cylinder tubing by heating the tubing and applying a small layer of solder (tinning) where the first nut will be secured. Decide how you want the hole in the side of the nut oriented. This will determine the side where the tubing going to the bottom of the piston cylinder from the valve will be located. For symmetry I placed the tubing for the bottom cylinder on one side and the tubing for the top of the cylinder on the opposite side, please refer to IMG_1649.JPG that I had posted previously. You can choose to have both pipes on the same side if you like. As far as the center nut goes, it is the intake and I placed it so that the tubing is roughly horizontal. Place yours in the position best for your situation.

Once you have planned the placement of these holes slide the first nut over the tubing and “sweat” the nut into place. On my engine there was ¼” of space between the nut and the floor flange. While the tubing is still hot tin another section of the tubing where the second nut is to be secured; Make sure to orient the side hole according to your piping plans. Slide the nut over the tubing and sweat it into place. On my engine it was a “hair” less than 3/16” from the top of the first nut. Tin the outside of the tubing where the third nut is to be located and sweat it into place orienting the side hole per your piping plans. You can also add some additional soft solder around the outsides of the nuts to insure a good bond.

Instead of using the brass tubing and affixed brass nuts for the valve cylinder one solid part could be made from the brass hex rod. Drill a hole thru the center the size of the piston valve. Turn down one side to fit into the hole drilled into the floor flange. I would recommend a slightly larger hole to keep the walls from being cut too thin. The hole in the flange could also be tapped and the matching threads cut with a die onto the lower section of the valve cylinder. A cut-off tool can be used to place notches between the “nuts” and the top section turned to a smaller diameter thus giving the illusion of the “nuts.” The side holes can then be drilled into the “nuts.” Like those shown in the diagram. Be sure to run the drill back thru the center hole to remove any burrs formed when the drill penetrated from the sides.

Continuing with the soldered together valve cylinder after allowing it too cool down take a hand drill and insert a drill bit the size of the smaller hole drilled into the side of the nuts. Carefully drill thru the thin wall of the brass tubing in each of the three nuts. Be sure to clean any burrs on the inside of the tubing.

Take the brass rod that is a slip fit to the valve cylinder and check the fit once again. The heating and soldering operations may have slightly deformed the inside of the brass tube. Make any adjustments as necessary. Carefully cut a notch centered in one end of the valve blank and check the fit with the rod connected to the eccentric, the tenon should easily slip in and out of this notch. Drill a small hole slightly larger than the nail to be used for the pin perpendicular to the notch and about 1/16” from the end. Then file or sand the end round, pin the valve blank to the eccentric rod and swing the valve side to side to insure that it has a free range of motion and is not hitting or binding anywhere. Remove the pin and slide the valve blank into the valve cylinder. Reconnect the valve and rod with the pin. Slide the eccentric in or out on the axle until the rod travels straight up and down and is not canted in or out. Measure the space between the eccentric and the axle bearing. You could place a washer or two on the axle to fill in this space.

 

[chucketn]

Again, my thanks for taking the time to write up this project.

 

[The_Paso_Kid]

Again, my thanks for taking the time to write up this project.

No problem. Been a little busy lately and have not been posting regularly. I've have to finish typing up the last few items to finish this model as well as drawing up a few more diagrams.

 

[johnmcc69]

Nice work & documentation!
I know everyone here really appreciates all your efforts!

John

 

[lathe nut]

now that is one cool engine, I really like that, that is going into the hardware store with the engine in mind and coming out with a bag of parts, not seeing what it is but what it can be, its great when you can see it in your mind and then it comes to life, you have a good imagination, that is so cool and kind enough to share with us and all the write up, this is a copy and paste and engine of the future projects, when I was younger I would go to the scrap your and look around and leave with what was called junk, and built something, one of the last projects was an air tank out of a boomer, truck air compressor two cylinder, 3/4 angle Iron and a round disk, made a great air compressor it was up right took up only 16" in diameter, been 25 years still use it, thanks again you tinkerer man, Joe

 

[Murph]

I used to build firearms that way, bits of this and that off the hardware store nut and bolt bins. A good spring selection to go with, and I was all set for a weekend of building!

 

[The_Paso_Kid]

Now the eccentric needs to be aligned on the axle and secured in place. Normally on a smooth shaft a set screw would have been used to secure the eccentric to the axle. However with the threads of the carriage bolt I found it easier to soft solder the eccentric into position. The eccentric must be placed at a 90-degree angle in relation to the cam. Having it 90-degrees in one direction will result in the engine revolving the flywheel in a clock-wise motion. Placing the eccentric 90-degrees in relation to the cam in the opposite direction will result in a counter-clock-wise movement of the flywheel.

With the cam in the up position the piston is at the top of the cylinder. Rotate the eccentric so that it is 90-degrees in relation to the cam. Secure the eccentric to the axle.

Rotate the axle until the valve is at the top of its stroke. Using a scratch awl, a small nail, or a sewing needle insert the tip into the hole in the side of the top nut and using a circular motion following the inside diameter of the hole make a circular scratch mark onto the valve “blank.” Do the same for the bottom nut. Scratch a line on the valve blank where it meets the end of the brass tubing on the bottom of the floor flange. Next rotate the axle until the valve is at the bottom of its stroke. Make scratch marks through the holes in the top and bottom nuts onto the valve blank.

Remove the pin connecting the eccentric to the valve “blank” and then remove the valve blank from the valve cylinder. Insure that there are four circular scratch marks on the valve blank. These will be the guide marks to where to form the pathways for the intake and exhaust sections on the valve blank. The pathways could be formed by turning them down on a lathe as I did on my engine. Or they could be made using a file making a small flat surface on the valve blank. See diagrams #12 and #13.

I suppose that you could measure the stroke distance produced by the movement of the eccentric and then marked a reference point on the valve and then measured the distances between the various ports in the valve cylinder and then on paper calculated where the steam passageways need to be. I believe that my method is probably faster.

Step #10 – making the connections. Drill a ¼” hole through the upper lip on the floor flange but not through the brass pipe forming the cylinder for the piston. Use a smaller size drill bit to drill through the brass pipe. This will form a shoulder similar to those in the nuts and will prevent the ¼” copper tubing from entering the cylinder and interfering with the movement of the piston (or the valve). It should also help prevent the soft solder from entering the cylinder as well.

Screw the cap onto the top of the brass pipe. Drill a ¼” hole towards the top of the cap. As the brass cap is very thin so that it will not be possible to produce a hole with a shoulder. As the inside of the cap does not go all the way down on to the threads due to the tapered nature of the pipe threads there should be sufficient head space so that any of the 1/4'” copper tubing that enters the cylinder should not make contact with the piston. Look through the hole and rotate the axle and check to see if the piston comes up to or past the hole. If it does then you will need to trim down the top of the piston to provide some clearance.

Using a short length of ¼” copper tubing gently bend the tubing trying not to crimp or pinch the tubing. Form a “U” shape where the two ends of the “U” match up with the hole in the floor flange and the hole in the bottom nut. Adjust and trim as necessary to achieve a good fit. Do the same for the top of the cylinder. Cut another length of ¼” copper tubing for the intake pipe. Solder all of the ¼” copper tubing into place. Take care not to overhead the nuts when soldering the ends of the copper tubing into them as excessive heat can loosen the nuts and cause them to move out of place. This can be solved or prevent by using two different types of solder. The nuts can be soldered to the valve cylinder with a high-temperature (high-melting point) solder and then the ¼” copper tubing can be soldered on with a low-temperature (low-melting point) solder. Doing so the heat necessary to solder the copper tubing into place will not be sufficient to melt and loosen the high-temperature solder. This technique is often used in jewelry making and the different temperature solders could be obtained from a jewelry supply house.

After building this engine I came across some 3/16” copper refrigerator tubing and used it to form a superheating coil for one of my boilers. I found the 3/16” copper tubing to be much easier to make the tight bends. If I had it to do all over again I probably would have used the 3/16” tubing to make the connections to the top and bottom of the cylinder.

Secure the flywheel to the axle. I tapped the axle hole in the flywheel so that I could thread it onto the carriage bolt. I then threaded on a lock-nut to insure that the flywheel would not spin off. Using a light oil, 3-in-1, or air tool oil lubricate all moving parts and joints. Also put a few drops into the intake pipe on the valve to lubricate the valve and cylinder as well. Rotate the flywheel by hand to work the oil into place. I added a small counter weight onto the flywheel placing it 180-degrees in relation to the cam. The engine you make might not need a counter weight.

If you are only going to run the engine on compressed air I would suggest making the quick connection as seen on my engine. Start by placing a compression nut onto the intake pipe and then slide on a ferrule. Connect the nut onto one end of a needle valve and then use a coupler on the other end of the valve to connect it to the quick connector to fit your air hose. Tighten all the nuts. The needle valve will allow you to adjust the air flow to the engine rather than having to adjust the air flow from the air compressor.

Hook up the air hose and open the needle valve then give the flywheel a push in one direction or another. If all goes well the engine should run. Adjust the needle valve to increase or decrease the speed of the engine. It may take a little breaking in time so run the engine for awhile.

After the break-in period start to close the valve and see how slowly the engine will run. A well-running engine with no binds should be able to run at “fairly low” pressure. Due to the mass (weight) of all of the moving parts of the engine it may need to run at a slightly higher RPM in order to maintain the momentum of the flywheel.



After running my engine for awhile I noticed that the bottom of the cylinder started to develop a leak. Apparently when I ran the tap thru the thin-walled tubing, instead of the tap actually cutting the threads into the tubing it pushed the walls of the tubing outward slightly forming a spiraling ridge on the outside of the tubing so when I measure it to determine the proper size of drill bit for the drilling the hole in the washer, it turned out that this hole was slightly bigger than necessary as the continued running of the engine wore these ridges away leaving a slight gap between the tubing and the washer. So although this is a double-acting engine the top of the cylinder is providing the majority of the power and the bottom of the cylinder is providing a small “assist.” I have not corrected this issue as of yet. I am thinking of making a gasket to seal around the piston rod and prevent the air leakage. On the better built commercially made double-acting engines the piston rod is passed through a nut that is holding a “gland” in place (usually an o-ring) which provides an adequate seal to prevent air leakage.

I will likely coat the piston rod with a Teflon based oil and then apply a bead of silicon chalk around where it enters the cylinder to form a gasket that hopefully will stick to the steel washer and not stick to the brass tubing that is sleeving the machine screw and prevent any leakage.

 

[The_Paso_Kid]

I did not build this engine. My grandfather and I happened to see it listed for sale on eBay and he had to have it. Alberto Salas who lives is Spain made it. It is another example of what can be accomplished using off-the shelf parts and a little ingenuity.