# Potty Finger Engine



## SBWHART (Apr 4, 2010)

Hi Chaps

This is a slight diversion from my Loco build but I've been wanting to build a finger engine for some time and kept my eys open for ideas that would add a bit of interest to the build. I saw thread on her where the chap added some engine turning to a horizontal engine that looked real nice this set the little grey cells going. :scratch:. Then on one of my scouting trips to the scrappy I spotted these







The scrap man saw scrap I saw flywheels.

First job clean up one of those discs






Then grind up a form tool out of a broken cutter, to use as a flycutter.






Then set my indexer over 5 deg, and mount a chunk of 2 3/4" dia ally in the chuck, that ally is way too long but I didn't want to cut it down and wast material as I'm planning on using it on another job.






This is the set up for flycutting flutes across the face with that formed flycutter. Th angle plate is to support the bar against the push from the cutter.






And this is the result 36 flutes across the face of the bar.






And this is what it will look like as a fly wheel hub.






Have fun

Stew



View attachment Potty Finger Engine Sh1-Model.pdf


View attachment Potty Finger Engine Sht 2-Model.pdf


View attachment Potty Finger Engine  Sht 3-Model.pdf


View attachment Potty finger Engine Sht 4-Model.pdf


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## zeeprogrammer (Apr 4, 2010)

Very neat. I'm going to enjoy this one too.


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## SBWHART (Apr 5, 2010)

Thanks Zee

Doing that flutting worked out better then I expecting, it just takes quite a while to go the circle (45 min) I did it in two cuts:- 2mm rougher and a 0.25 finisher.

Got a bit more done this morning.

Part off from the bar stock if you tried parting off this thickness in one go you'd end up in trouble, best way is to do it in steps so you keep the groove twice the width of the tool, then for the last bit just adjust the cut so that your bringing the disc to thickness.






And her's the first disc stuck in the rim with high strength loctite.






Looking good :thumbup:

Have fun

Stew

PS added sht 5 of drawing 

View attachment Potty Finger Engine Sht 5-Model.pdf


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## doubletop (Apr 5, 2010)

Yet another example of the value of this website. A practical demonstration of how to do something that I wouldn't have known where to start.

Thanks


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## Deanofid (Apr 5, 2010)

That's neat, Stew. Rosette flywheels.

Dean


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## Troutsqueezer (Apr 5, 2010)

doubletop  said:
			
		

> Yet another example of the value of this website. A practical demonstration of how to do something that I wouldn't have known where to start.
> 
> Thanks



I'm looking at the setup picture and I still don't know where to start. :big: Of course, I'm still a skeeter winger...

-T


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## SBWHART (Apr 6, 2010)

Finished off the disc for the other side, and loctited it in position.

One bit of kit I've found very handy especially for getting things clean for gluing etc is one of those elcheapo ultrasonic cleaners, I use it far more than I thought I would.






And here's both side of the fly wheel, I've got to bore it out for the bearing but I'm still waiting for them to come in from Hong Kong, and drill and tap for the crank pin.






That seems to have worked out great.

Cheers

Stew


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## SAM in LA (Apr 6, 2010)

SBWHART  said:
			
		

> And here's both side of the fly wheel, I've got to bore it out for the bearing but I'm still waiting for them to come in from Hong Kong, and drill and tap for the crank pin.
> That seems to have worked out great.
> Cheers
> Stew


Stew,
Your flywheels look awesome. I may have to try and steal your idea for my next build. I'll be watching your build closely.
SAM


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## cobra428 (Apr 6, 2010)

Stew, for a second there.....I though you where making turbine blades. Nice idea, looks great!

Tony


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## SBWHART (Apr 6, 2010)

Sam/Tony thanks for your kind comments

Tony:- I guess it will look like a turbine when its spinning, never thought of that,

Cheers

Stew


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## SBWHART (Apr 7, 2010)

More progress this time on the columb, turned a length of ally down to 15mm diameter than transfered it over to the mill and in the indexer with a 3/16 ball ended slot drill put 12 flutes up it.






Then gripping it lightly in a collet face, drilled and tap both ends M3






Milled a little square base up:- sorry no pics.

Then in the lathe by eye shaped up the roundels drilled 3mm and part off.






And this is what the columb will look like.






I want the engine to look like the Temple of Afinger the Greak Godess of Engines 

Have fun

Stew


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## SBWHART (Apr 7, 2010)

A bit off topic

Good crop of frog spawn this year.






OK Stole a few more shop hours and got stuck into the the columb cap.

First op on the lathe.






Then onto the indexer for milling the flats, and drilling and tapping M3 blind






Then back onto the lathe to part off






A quick clean up and a polish, and this is where it fits






Cheers

Stew


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## Blogwitch (Apr 7, 2010)

Coming along very nicely Stew. I hope to see it in the flesh soon.

I don't suppose this one will need any magic dust, it looks magic as it is.

While rooting about today, I found an old sketch I did, for working out the conrod and finger treadle length on an horizontal finger engine. I suppose it could also be used for a vertical one such as yours, using a flat treadle rather than a right angled one.

The dimensions are rather critical for getting a good free running working engine with no mechanical locking up, and I hope you don't mind, but I will pop it in here as this is the only current finger engine build.

John


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## SBWHART (Apr 7, 2010)

Thanks John no problem at all

I remembered you saying the lengths were critical, so I kept the lengths the same as in the NAMES engine I've based it on, so I hope I don,t have any problems, if I do I'll bring it round to the master.

Working in a design office I learnt the hard way the importance of recognising critical features.

Cheers

Stew


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## arnoldb (Apr 7, 2010)

Good going Stew; some very interesting techniques. I filed those for future reference!

John thank you as well; that drawing with the ratios will come in very handy. I have to make some "paper weights" as gifts soon.

Kind regards, Arnold


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## Deanofid (Apr 7, 2010)

Nice looking column, Stew. You do nice work, Mister.

Dean


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## zeeprogrammer (Apr 7, 2010)

That's beautiful work.

And thanks for the happy news about frog spawn. First sign you know.


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## SBWHART (Apr 9, 2010)

Thanks Guys

Zee yep frog spawn is a first sign of spring, saw my first Swallow of the year last week also so I think summer is finally on its way.

Hacked the base out today from some ally jig plate.






Then squared it up and mill around the edge with a 1/4" ball slot drill.






The roller bearing arrived to day from Hong Cong £6.50 for 10 including postage:- don't know how they do it :scratch:

So that I can fit in the crank pin they are only 7mm dia by 2.5 thick I was planning to assy 2 to the shaft but ended up assembling 3

Her's the assembly so far.






IIt runs nice and free, but with a slight wobble I intended to drill the fly wheel for the bearing with the next size down letter drill so that the bearing were a tight fit but when It came to do the job I forgot and ended up sticking a 7mm :bang: drill through it resulting in a slack fit from the bearing so I had to glue them in place, that where the wobble came from I think.

And I'm not quite sure about the proportions of the base I may hack a bit more off it,

Have fun

Stew


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## cobra428 (Apr 9, 2010)

SBWHART
Man are you pushing the bling factor up to the Nth degree. I can't wait to see how much more bling you have up your sleeve

Tony


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## SAM in LA (Apr 9, 2010)

Awesome
 :bow: :bow:


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## ariz (Apr 9, 2010)

great looking flywheel and column Stew, Afinger would be proud of you :bow:


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## Hilmar (Apr 9, 2010)

Stew
     << One bit of kit I've found very handy especially for getting things clean for gluing etc is
 one of those elcheapo ultrasonic cleaners >>

Stew where did you get it from and how cheap ??
Hilmar


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## Blogwitch (Apr 10, 2010)

I can answer that for you Hilmar, because I picked it up for Stew while he was on holiday.

We have a small German supermarket called Lidl who have special buys twice a week, and I picked them up for just under 20 squid each (about 30 bucks)

http://www.lidl.co.uk/cps/rde/xchg/lidl_uk/hs.xsl/offerdate.htm?offerdate=9478

Unfortunately they are no longer available fom there, but you can buy them from lots of places at something a little more than we paid.

http://www.machine-dro.co.uk/index.php?target=categories&category_id=29

Bogs


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## SBWHART (Apr 10, 2010)

Thanks to John I dropped on a real handy bit of kit at a good price, you can use just plain water or add just a drop of washing up liquid, a chap on another site recommends a drop of jewelry cleaning fluid.

Their great for cleaning glasses and false teeth but thats something I've not tried :big:

Hope this helps

Stew


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## Blogwitch (Apr 10, 2010)

Stew,

You must remember to take your teeth out and glasses off before trying to clean them, otherwise you will end up blowing lots of bubbles. ;D


John


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## SBWHART (Apr 10, 2010)

Bogstandard  said:
			
		

> Stew,
> 
> You must remember to take your teeth out and glasses off before trying to clean them, otherwise you will end up blowing lots of bubbles. ;D
> 
> ...




Bugger that's what I've bin doing wrong.

 Rof} Rof} Rof} Rof}

Stew


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## hobby (Apr 10, 2010)

Very nice work on your project,

The flywheel looks great,does that have to be a real tight press fit, using a arbor press, or is it hand pressed in with the glue holding it firmly?

The column is a work of art in itself. th_wav

Good naration on your build thread.


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## SBWHART (Apr 10, 2010)

Hi Hobby

Thanks for your comments

Its just a nice hand push fit with high strength loctite, I tried shrink and hard press fit on a similar fly wheel on another engine build but I've found the loctite method far simpler and just as effective.


Cheers

Stew


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## SBWHART (Apr 12, 2010)

Thanks Guys

Finish with the ally work and on with the brass levers.

These were to be fabricated just like the column and silver soldered together the fluting was done in the same way on the indexer but using a 1/8" ball cutter, the lever was also squared up and the centres drilled in the indexer.












I used some square brass section and the rest of the bits were just simple turning jobs

Here's the trunnion being turned up






And her is the parts ready for silver soldering together











And these are the bits after soldering and a bit of time in the pickle and a rub down, I'm quite a messy silver solderer so I'm quite happy with the result






And how things are looking.






Cheers

Stew


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## Blogwitch (Apr 12, 2010)

If the Greeks had finger engines Stew, I'm sure they would look just like you are making.

I think it is called classic Greek design.

Bogs


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## zeeprogrammer (Apr 12, 2010)

That's looking real sharp.
I hope I can do half..quarter...I'll take 1 percent!...of the soldering job you did.


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## Deanofid (Apr 12, 2010)

Looking mighty fine, Stew. This is surely going to be a dandy thing.
That soldering job looks good in the pic. I don't see any globbys!

Dean


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## SBWHART (Apr 13, 2010)

Thanks Guys:-

I think Afinger was looking after me when I did that soldering ;D I usually end up with gobs of solder all over the place.

Not many pics for this post 

But forgot to take my camera into the shop, and there wasn't anything really that interesting going on. 

I finished off drilling the levers and made the bearing blocks and did quite a bit of fitting and fettling to get everything turning over.

So this is it I need to give the bearing blocks a bit of bling and give it all a polish just to finish it off but it works great so when its had its polish I'll post the obligatory Video.






Have fun

Stew


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## arnoldb (Apr 13, 2010)

Stew, I *love* it ;D ! - Thm: Great job and really unique!

Kind regards, Arnold


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## SBWHART (Apr 15, 2010)

Thanks Arnold

Ok you've seen the drawings you've followed the build now the Movie

[ame]http://www.youtube.com/watch?v=M4UzHkv5kic[/ame]

That was a nice quickie build now I relay must get on an build that boiler for my Loco.

Have fun

Stew


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## Blogwitch (Apr 15, 2010)

Stew woke me up from my beauty sleep this afternoon, just to show me this great little engine.

And what a stunner it is in real life. The vid doesn't do it justice.

But I should mention one thing, all the time Stew was sitting talking to me, he was pumping away at this thing without even having to think about it. 

Methinks he has turned into a finger engine nut, just like most of us who have built one.

Nice one Stew.


Bogs


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## rake60 (Apr 15, 2010)

Very nicely done Stew! :bow:

Rick


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## Foozer (Apr 15, 2010)

Now that would keep the Grandkid busy, now to see if i can even build one.

You make it look so easy


Robert


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## Tin Falcon (Apr 15, 2010)

That is a piece of art Stew
Tin


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## mklotz (Apr 15, 2010)

It's a beautiful engine, Stew, but for the sake of all us non-British English speakers, find a different name for it! "Potty finger" brings up images I really don't think you want associated with your fine craftsmanship.


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## arnoldb (Apr 15, 2010)

:big: :big: Thank you Stew !. Another couple of builds just moved up the list - ;D
I need to give some people paper weights, and you just showed an excellent way to do it :bow:
Kind regards, Arnold


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## Deanofid (Apr 15, 2010)

Why are these so much fun to watch? That's a question for the ages.
It _is_ fun though, and a very pretty piece too. Nice work, Stew!

Dean


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## SBWHART (Apr 16, 2010)

Thanks again Guys:-

It was a nice little project with some interesting machining and I'm really pleased with the result.

I take your point with the name Marv, it never entered my head that it could have a different meaning around the world:- boy this language thing is complicated, its sitting on the computer desk so that it can be gently spun whilst thinking.

I suppose it could be called a:- Thinking Engine. 

Cheers

Stew


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