EZ2 McCabe Runner revisited

[black85vette]

I had read a number of posts mentioning the McCabe Runner as a good first build so I went over and had a look. Liked some things and didn't like some things so I thought I would take the concept but run it through the EZ engine process. First was the valve. The Runner uses a piston which has a drawback. During exhaust the engine has to push against the full force of the air pressure

In staying with the original concept I kept the materials to a minimum, tools to a minimum and used fairly simple machining. I used .75" square aluminum stock for the cylinder/valve block, the upright for the flywheel/shaft, and the mount for the bell crank. It can be built using only 4-40 screws so you just need one tap. The valve and the flywheel shaft are .25" so a reamer for that and a .5" for the piston is all you need.

I am just getting through the initial proof of concept and just have working drawings (slightly better than COC but not by much). ;D It runs fine and I have taken it down to about 3-4lbs. I have already got it to run on lung power with just a minimum run in time.

Not much in the way of build pictures because there is not much to it.

 

[Deanofid]

That's a fun one to watch, Vette.

Dean

 

[rake60]

I have to make a confession here Vette.

I see videos first, pictures second and text last.
When I watched the video I was thinking.
"Damn, that looks like a variation of Prof.Nial McCabe's Runner."
The I looked at the pictures and thought,
It HAS to be a variation of Prof. Nial McCabe's Runner."

And THEN I read the text... :

Nice build! Thm:

Side Note To Prof. McCabe:
Your students may find this usefull.
Feel free to use it as you see fit.

Thanks for the Post Vette!

Rick

 

[Swarf Rat]

Vette, I appreciate your effort to simplify engine fabrication. I'm scrounging up some materials and mentally working through the build process for your EZ. These engines are simple enough for me to envision success while having enough parts and features to pose a challenge - a perfect mix.

 

[zeeprogrammer]

Nice idea and excellent choice Rick.
That'll be a winner.

 

[black85vette]

Swarf Rat; Thanks for the comments. That is encouraging because it is exactly what I had in mind when I started the first EZ. I will finish up finalizing everything and then post some plans for this one along with some photos and notes on how to build it.

Zee; Thanks!

 

[SAM in LA]

Nice build.

I'm curious to how the valve works.

Looking forward to seeing more details.

SAM

 

[black85vette]

Sam;

Here you go. The valve is a .25" round rod. It cut away on one end to half its diameter for the exhaust side and has a .125" hole though it near the middle for the air supply to pass to the cylinder during the power stroke.

Look at the attached drawing. I think it does a good job of showing how it works.

Could somebody tell me the name of this valve. I have used it several times and don't know what it is called. :shrug:

 

[SAM in LA]

B85V,

Clever valve.

I believe it would be considered a spool valve.

Much like what is used in hydraulic/pneumatic systems.

SAM

 

[black85vette]

As a point of comparison here is the valve configuration of the McCabe runner as originally designed.

 

[SAM in LA]

As a point of comparison here is the valve configuration of the McCabe runner as originally designed.

The piston is also known as a spool. Hyd/Pneu spool valves can have many different ports and even orifices between the spool groove or recesses to bleed pressure off to additional ports.

SAM

 

[ksouers]

BV,
That's a nice variation on the McCabe Runner! Thanks for sharing it.
Early on I played around with my own variations of it just for fun and learning. They are great platforms to experiment with.

 

[substandard]

I now understand what you meant about the valve having to move against the air pressure. Your design is a better, should make the engine run better also.

 

[black85vette]

.............. Your design is a better, should make the engine run better also.

Thanks, but it is not my design. I first saw it in a build that Brian did. It is more efficient and the engine only needs a little air and a single flywheel is plenty.

Tonight I moved the bell crank away from the cylinder a bit, changed its ratio, and moved the pivot on the flywheel from .375" to .25" to reduce the stroke on the valve side. This gives a little more room for the valve linkage and makes things smoother. Engine now runs on less lung power. No huffing and puffing. ;D My pressure gauge does not even register, so I am guessing 2 lbs.

I will do a set of drawings now with the dimensions I ended up with and post some build pics.

 

[Swarf Rat]

I think your improved valve design for the EZ2 is especially interesting. I've been studying the plans for EZ and rearranging the components in order to figure out the "why" behind your design decisions. I had a difficult time understanding the valve timing until I decided to pass the exhaust gasses out the back side and move the input passage inline with the passage to the cylinder. Then the light came on, the timing is exactly the same as a simple wobbler. My reconfiguration of the EZ valve looks identical to your drawings here in this thread. That convinced me I am beginning to understand some of this stuff.

Keep up the good work

 

[black85vette]

Then the light came on, the timing is exactly the same as a simple wobbler. My reconfiguration of the EZ valve looks identical to your drawings here in this thread. That convinced me I am beginning to understand some of this stuff.

No real rocket science here. These are all pretty basic valves. Certainly not the best designs but easy to understand and build. Designing these engines got me to do the same thing as you; get in and understand why and how they work so I can use them in other ways. Its good to hear you are enjoying learning from them.

Can you post something about your redesign of the valve?

 

[Swarf Rat]

Can you post something about your redesign of the valve?

.... "my redesign of the valve". Let me answer like a politician. I mentally worked through the build process for the EZ engine and decided I had a reasonable expectation of success. I don't have any of the specified stock on hand nor the proper size reamers. There was also something about the visual aspect of the staggered cylinder and valve block from the top view perspective that "just didn't look right to me". I found a scrap of 17/32 thick plexiglass and a 5/16 reamer that would be appropriate for the cylinder. I would need to make a D reamer for the spool valve. I think that would work well - 3/16 dia brass rod would ream its own bore and become the spool.

Since I was scaling down the engine, rearranging the parts to suit my visual preference seemed like a reasonable next step. I couldn't figure out why all the cuts were needed in the original spool valve design. I also wanted to move the input air supply connection in line with the passage to the cylinder since I was hoping to make the cylinder bore and valve bore both in the same block of material. With my new arrangement, the valve timing became obvious to me and I think the exhaust cycle is slightly less restrictive this way. At least in my imagination, all the parts line up for a functional engine and I can get the components from the scrap of plexiglass I have.

I'm still working on one design feature and I think I may be close to a solution for it. I want to make an eccentric to operate the valve and I want to locate it between the frame and the flywheel.

So, I don't intend to follow the EZ design "to the letter", but follow the spirit of the concept and use the build process as a learning opportunity.

The plexiglass is residue from years ago when I tried to make "Lucy" from plans I found on the web. That build was such a disaster that I lost interest in engines. My machining capability has improved over the years and I thought another engine attempt would make a good winter project. The Fizz Wizz engine was a challenge, but it finally went together and now it runs better than I originally imagined. The information I found on this forum contributed significantly to my building success, and I think I may have caught the engine building fever from yall.

There's one other design criteria I have in mind for my version of the EZ. Grandson has his 5th birthday this Spring and I thought this would make a great gift for him. It would be especially cool if the engine could run using a common aquarium air pump.

I'll start a build thread when I start construction. I have other projects at a higher priority right now.

 

[black85vette]

I'll start a build thread when I start construction. I have other projects at a higher priority right now.

Great. I'll look forward to seeing what you come up with.

 

[black85vette]

Edit:

Moved pictures and drawings to a folder in the uploads section to save space.

 

[black85vette]

Here is a video of it after some clean up but no bling or paint.

[ame=http://www.youtube.com/watch?v=trOFys9OB1Q]http://www.youtube.com/watch?v=trOFys9OB1Q[/ame]