Model Engine Maker

Engines => Your Own Design => Topic started by: black85vette on February 09, 2013, 03:33:29 AM

Title: Another beginner engine - McCabe Runner redo
Post by: black85vette on February 09, 2013, 03:33:29 AM
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.
Title: Re: Another beginner engine - McCabe Runner redo
Post by: black85vette on February 09, 2013, 03:39:34 AM
A quick video;

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Title: Another beginner engine - McCabe Runner redo
Post by: ths on February 09, 2013, 06:51:15 AM
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.
Title: Re: Another beginner engine - McCabe Runner redo
Post by: zeeprogrammer on February 09, 2013, 12:12:08 PM
Nicely done Rick. That should inspire some newbies wanting to make their own engines.
Title: Re: Another beginner engine - McCabe Runner redo
Post by: b.lindsey on February 09, 2013, 12:54:12 PM
Very nice Rick!! I agree with Zee, would make a very nice first engine.

Bill
Title: Re: Another beginner engine - McCabe Runner redo
Post by: Don1966 on February 09, 2013, 02:51:27 PM
That's what I call simplified, very nice Rick and a great first engine project.

Don
Title: Re: Another beginner engine - McCabe Runner redo
Post by: black85vette on February 09, 2013, 09:34:03 PM
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.
Title: Re: Another beginner engine - McCabe Runner redo
Post by: black85vette on February 12, 2013, 08:11:27 PM
Here are the basic dimensions for this engine.
Title: Re: Another beginner engine - McCabe Runner redo
Post by: Tin Falcon on February 14, 2013, 12:29:16 AM
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