Engines > Your Own Design

Another beginner engine - McCabe Runner redo

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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;

IMG_5908 by black85vette, 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.

IMG_5909 by black85vette, 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.

IMG_5910 by black85vette, 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.

IMG_5912 by black85vette, 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.

IMG_5913 by black85vette, on Flickr

Here is the bell crank.   I made a brass pivot for it to ride on.   Then drilled / tapped holes at two corners.

IMG_5914 by black85vette, on Flickr

IMG_5915 by black85vette, 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.

A quick video;

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.

Nicely done Rick. That should inspire some newbies wanting to make their own engines.

Very nice Rick!! I agree with Zee, would make a very nice first engine.



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