NAMES Finger Engine Improved

[kquiggle]

I recently built the vertical finger engine from the NAMES plans available on the Internet (see picture below). It worked, but I found it very finicky to keep going. As others have noted, the NAMES design of this engine is far from ideal, so I did a few experiments to see if I could improve performance.

To make a long story short, I found that simply increasing the crank radius from 0.250" to 0.350" made a big difference. I made some other improvements as well, primarily putting a significant counterweight in the crank design. I experimented with other changes, like changing the connecting rod length, but such changes also require redesign of the lever, etc. Simply changing the crank design, however, can be done without changing anything else.

For those interested, I have posted a build log and revised plans which include other minor improvements at the link below (alternatively, if you are building from the NAMES plans, do yourself a favor and change the crank radius!).

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/build---finger-engine

 

[deverett]

Nicely done.

For anyone wanting advice on designing a finger engine, Blogwich (remember him?!) posted a couple of sketches showing the relationship between the various levers. The sketches shown do refer to a horizontal model, but I'm sure they will be just as valid on a vertical engine.

http://www.homemodelenginemachinist.com/showthread.php?t=8249&highlight=finger+engine&page=2 Reply 13.

Dave
The Emerald Isle

 

[kquiggle]

I saw those sketches, and played around a bit with converting the diagram for use with a vertical finger engine. However, if I applied the ratios to the NAMES engine it required essentially a complete redesign.

I also have a question about that sketch - hopefully someone reading this can answer it: What is the theoretical basis for this? Can anyone cite a more detailed discussion of this topic, which explains why these are the optimal ratios?

 

[kquiggle]

Since I already made up the drawings for my own use, I thought I may as well add them to my write-up. Basically all I have done is convert the rough sketch previously posted by "blogwich" into a clean drawing, and added some illustrations to help clarify.

You can download the drawings for both vertical and horizontal finger engines at the link already cited:

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/build---finger-engine

Below is one of the drawings, by way of example:

 

[deverett]

Bill Reichart had plans for his 'Thumb fun Engine'. http://www.billreichart.com/images/thumbfunengine_lrg.jpg

Blogwich's design sketches closely resembles Bill's and I expect he copied or perhaps modified Bill's dimensions for his own satisfaction.

Dave
The Emerald Isle

 

[Blogwitch]

Dave,
Far from it, I worked out the ratios all by myself. It didn't make my brain cells hurt too much.
I did it because so many people were having trouble working things out to give a nice smooth action. If you follow the ratios I give, the finger engine should run smoothly and in either direction.
Where people go wrong is that they don't get the centres lined up correctly, that causes the used finger to go different distances up and down and so the brain can't get correct information to have a smooth co-ordination.
I have Bob's plans here, but didn't purchase them until after I designed the throws, and in fact Bills engines, although nice, just aren't quite balanced enough for me.

This is a pair I made directly from my formula.

[ame]https://www.youtube.com/watch?v=ezOawsPXMns&list=UUbmnXOvtxx1wUp4fFjFLsfA[/ame]

And a special, made again to my formala, but upright this time, and even after all these years, after drying out, it still works perfectly.

[ame]https://www.youtube.com/watch?v=kxk4_pTyRug&list=UUbmnXOvtxx1wUp4fFjFLsfA[/ame]

John

 

[deverett]

John

Good to see you back here again.

I wasn't doubting your ability; it was just that your sketches looked like a squared-off version of Bill's model. Thanks for putting the record straight.

Two flywheels make the engines easier to run, which corroborates John's statement on the video that the larger flywheel engine runs more easily.

Dave
The Emerald Isle

 

[kquiggle]

Blogwich -

Hope you don't mind that I re-did your sketch as a drawing. I am hoping you can provide a bit more background on your statement (which I don't doubt) that these are the correct theoretical ratios.

P.S.

Love the engines you made. How did you make the bearings run so smoothly?

 

[Blogwitch]

Dave,
I have been here most of the time, just you haven't seen me.

K,

You do with drawings whatever you want. I just put things up in the hope it will help someone.
Bearings - each standard on the crank has two flanged bearings inside.
The wooden one just has a bit of brass tubing.
I must have made well over a dozen of these engines and given them all away as gifts, just like my engine collection, except for four or five of my early ones, they have all gone to new homes as gifts.

John

 

[bob shutt]

I never did get mine to work correctly. changing from .250 to .350 is working much better. Thanks