Model Engine Maker
Engines => Your Own Design => Topic started by: black85vette on February 09, 2013, 03:33:29 AM
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Took the same approach to this engine as I did with Elmer's Standby. Reduce the materials required, simplify the build, and use minimal tools. For this one I scaled it up a bit and used the same main material; .75" x 2" aluminum bar. From that we get the cylinder, main shaft support, flywheel, support for the bell crank, the bell crank, and main crank. Here are the pieces;
(http://farm9.staticflickr.com/8242/8457692642_1a181c3229_z.jpg) (http://www.flickr.com/photos/17576549@N05/8457692642/)
IMG_5908 (http://www.flickr.com/photos/17576549@N05/8457692642/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
The cylinder is .5" drilled 1.375" deep. Piston is .5" long and stroke will be .75". Behind the cylinder is a .25" hole cross drilled. This will house the valve.
(http://farm9.staticflickr.com/8523/8456592315_9207148981_z.jpg) (http://www.flickr.com/photos/17576549@N05/8456592315/)
IMG_5909 (http://www.flickr.com/photos/17576549@N05/8456592315/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
From the rear of the cylinder a .125" hole is drilled all the way through to the cylinder. The air supply will connect here.
(http://farm9.staticflickr.com/8248/8456592177_e368f3f959_z.jpg) (http://www.flickr.com/photos/17576549@N05/8456592177/)
IMG_5910 (http://www.flickr.com/photos/17576549@N05/8456592177/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
The valve is the main change I made to the original runner design. The original had a piston valve that had to push against the air pressure to work. Instead I brought the air supply in the rear and used a hole in the valve to control the air inlet. I made a flat on the end of the valve that is .5" long and .050" deep. This is the exhaust port. On the other end of the valve is a flat that is rotated 90 degrees for the linkage and tapped for a screw to attach the link arm.
(http://farm9.staticflickr.com/8230/8457691798_40c8221507_z.jpg) (http://www.flickr.com/photos/17576549@N05/8457691798/)
IMG_5912 (http://www.flickr.com/photos/17576549@N05/8457691798/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
I took a little different approach to the link for the bell crank. This link has the ends 90 degrees apart and it has to move in two different planes. In the past I have used a .25" round rod and just drill it with the ends rotated 90 degrees. I have seen a flat piece used and twisted in the middle to get the holes aligned. In this case I decided to use some linkage from an RC helicopter rotor. These ball links are threaded and can pivot over a wide range. Plus the threaded rod that connects them makes it very easy to adjust the length.
(http://farm9.staticflickr.com/8531/8456591437_272140f624_z.jpg) (http://www.flickr.com/photos/17576549@N05/8456591437/)
IMG_5913 (http://www.flickr.com/photos/17576549@N05/8456591437/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
Here is the bell crank. I made a brass pivot for it to ride on. Then drilled / tapped holes at two corners.
(http://farm9.staticflickr.com/8097/8457691210_3d896de4d1_z.jpg) (http://www.flickr.com/photos/17576549@N05/8457691210/)
IMG_5914 (http://www.flickr.com/photos/17576549@N05/8457691210/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
(http://farm9.staticflickr.com/8512/8456590861_74158f625e_z.jpg) (http://www.flickr.com/photos/17576549@N05/8456590861/)
IMG_5915 (http://www.flickr.com/photos/17576549@N05/8456590861/) by black85vette (http://www.flickr.com/people/17576549@N05/), on Flickr
Flywheel and Piston are the same as the last engine so no need to show them.
There you have it. I have some drawings in process and will get something posted.
Also thinking about moving my original EZ Engine over to this same material / format.
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A quick video;
https://www.youtube.com/watch?v=F5ww6PjhFUw
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I like that! It looks as though it's madly shaking hands with itself. I like the changes you've made, it looks a more convincing engine than I recall the original plans showed.
Cheers, Hugh.
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Nicely done Rick. That should inspire some newbies wanting to make their own engines.
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Very nice Rick!! I agree with Zee, would make a very nice first engine.
Bill
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That's what I call simplified, very nice Rick and a great first engine project.
Don
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Thanks for all the comments!
A couple of things;
1. Does anyone know the name for this type of valve? I have used it a couple of times and don't know what to call it. If I get my third engine done there will be 3 engines that are very similar in construction but use 3 very different valve / timing methods.
2. These are just prototypes at this point. If you have a comment, idea or suggestion to make them even more beginner friendly post your thoughts. When I am comfortable with each I will do more of a step by step build instructions.
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Here are the basic dimensions for this engine.
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IMHO the McCabe runner is an excellent choice as a beginner engine. I have built a couple
(http://cdn.homemodelenginemachinist.com/images/2/5/thumb2_runner2.JPG)
Pretty simple as is my first one I used a piece of brass as a valve machined it bet it and stuck it in the valve plate. and made a valve rode from a piece of coat hanger. primitive but effective. I used a piece of square aluminum tube with hat bushings for the main bearing and a sqare piece of aluminum held with super glue to hold it to the base the bottom plate is drilled and tapped for a thread.
my second one is clear and see through.
(http://cdn.homemodelenginemachinist.com/images/2/5/thumb2_Claire_3a.JPG)
keep it simple looks like you are adding parts
I used a e clip and groove to hold the valve plate down on bothe versions the second one uses a piece of bycicle spoke for the valve rod.
Tin