Author Topic: Potty Popcorn Engine (Read 110755 times)

sbwhart · « **on:** August 23, 2011, 09:37:11 AM »

This will be a long drawn out project as I plan to fit it in around work on my loco, there will be a good few weeks between each part so any one who wants to follow along and build an engine with me is more than welcome.

John showed me a drawing he had of a popcorn engine some time ago, and a few weeks ago I cam across a picture of a popcorn engine on the web, this got me doing a little research into them.

This is the type of popcorn engine I'm planning on modeling its a Dunbar Popcorn Engine, the model is going to be 1/3 scale so it can be made on small machinery, and i just had in my stash a lump of brass that would make a 1/3 scale flywheel.

All the engine pictures I've found are different the only thing that they all have in common is curved flywheel spokes.

So the flywheel is the first part I've made, the spokes don't have to be curved, but I liked the challenge of making a flywheel with curved spokes.

This is the only part drawn up so far, the remainder I'll get drawn up over the next couple of weeks and as i do each part I'll post the drawing for those who want to follow along.

So her we go.

This is the chunk of brass to make the flywheel a scrap yard find

First job gripping on the out side skim up the face and the OD to give two clean surfaces to work on.

Then gripping on the inside turn up the OD to size and skim the other face.

Then using some shim from a drinks can so you don't damage the OD finish off the bore and skim to width.

That the rim done

Next turn the hub down drill put a 5mm roughing drill down the middle.

Don't part the hub off you'll do that last when the spokes are fixed.

Transfer over to the mill and cross drill and tap 1/4 ME

To bend the spokes you need to make a bending jig.

The spokes are made from annealed 1/4 brass bar its important the brass is annealed, just heat it up to red heat for a minute or so and either quench or allow to cool.

The bend is done it two stages

Stage one

Stage two reverse bend around pegs.

Spokes done

Cut spokes off to length and thread a short length 1/4 ME and screw into hub with thread lock allow to cure.

Over onto the lathe with a sharp tool gently skim the spokes off to a nice tight fit in the rim.

Fix to rim with high strength loctite.

I'll let the loctite cure for a few days before I finish the flywheel off.

Stew

PTsideshow · « **Reply #1 on:** August 23, 2011, 10:52:09 AM »

Looks like you have a good start on it. Here are some photo's of a Dunbar popcorn wagon and one of the engines. It is Paul Newman's original wagon he used when he started the popcorn brand. A complete Dunbar are much more rare. this museum is a museum about popcorn since it is in the popcorn belt

Paul Newman's Dunbar

The Dunbar in place

Cretors engine

Another Cretor's engine

a Cretors horse wagon

a Cretors truck

A Cretors wagon

I have the casting kit for a ½ scale Cretors from Meyers Engine Works

Dunbar worked for Cretors and then left to start his own firm, One thing about both Dunbar and Cretors engines they didn't make the engines in house after a while they framed them out that is why there are so many slight variations in the engines as long as the bases. and the holes and piping lined up they where good to go.

In the Sept/Oct issue of Live Steam & Outdoor Railroading volume 45 their is an article on the Cretors engines by my friend Art Gaier.

One more minor item, they are not popcorn engines, they are peanut roaster drum turning engines. after they figured out a way to pop the popcorn as they improved the cooking equipment, they made drive gears, sprockets and chains to drive the popcorn popper stirring rod, so it wouldn't burn.

assorted engines

Model 2 wagon

Some of the advertising cuts form one of their catalogs

PTsideshow · « **Reply #2 on:** August 23, 2011, 11:05:25 AM »

And as an added bit of information. Under the books section I can recommend all of the books and booklet (reprints) of the catalog. Great stuff!

spuddevans · « **Reply #3 on:** August 23, 2011, 11:35:41 AM »

That looks like a nice project Stew, and I love the curved-spoke flywheel, something I want to try in a future build, so I'm taking note of how you assemble it

Tim

arnoldb · « **Reply #4 on:** August 23, 2011, 12:20:07 PM »

Good start Stew

Chair and popcorn pulled up for the build!

, Arnold

Stilldrillin · « **Reply #5 on:** August 23, 2011, 12:43:10 PM »

Very nicely done Stew!

Who needs castings, with your dexterity......

Off to a flier, as usual!

David D

doubleboost · « **Reply #6 on:** August 23, 2011, 03:32:38 PM »

Nicely done Stew

John

CallMeAl · « **Reply #7 on:** August 24, 2011, 12:23:47 AM »

Innovative construction ideas an fun looking engine to build. This will be fun to follow.

Al

NickG · « **Reply #8 on:** August 24, 2011, 06:33:21 PM »

Nice work Stew, will be watching!

sbwhart · « **Reply #9 on:** September 04, 2011, 08:00:52 AM »

I've bin slowly drawings up the engine in between working on my loco and a lot of other domestic duties that seem to be falling my way at the moment.

I've read that they had lubricators, but the photos i've seen with what look like lubricators are not configured in a way that would suggest that they used displacement lubricators, they appear to be some sort of drip feed into the steam inlet, is there anyone out their with any information on this they could pass on.

Thanks

Stew

Brass_Machine · « **Reply #10 on:** September 04, 2011, 09:33:46 PM »

That's all...

Eric

*oh yeah, gonna be watching!

sbwhart · « **Reply #11 on:** September 20, 2011, 06:31:42 AM »

Well I had a desaster on my Loco work I chipped a chunk out of the wheel flange its totaly US, this realy pissed me off I've consigned the loco under the bench whilst i get over my sulk, I'll just have to buy a new wheel.

In the mean time I decided to get on and do a bit on this.

Her's the assy drg

I was planning to fabiricate the cylinder in three parts but then I found I chunk of 1 1/2" square brass left over from the loc chimney, I realised that I could make the cylinder in one peice from this.

So marked it out and set it up in the four jaw.

Drilled and reamed the bore out 1/2" then turned a mandrell up for it to fit on.

With this in the spin-indexer milled the cylinder to shape.

Then milled the steam ports

So that I ended up with this

Cylinder covers

One thing a beginner struggles with is lack of kit for drilling holes on a pitch circle.

Well if you have one of those digital protractors you can use it to acuratly mark out the holes.

With the bar in the lathe
First put a small centre into the bar then using a pair of deviders mark the circle in the end of the bar.

Then zero the protractor up on the bed of the lathe, put the protractor on the chuck jaw, rotate to get it zero, then mark across the bar with a scribbing block, rotate the chuck until the protractor is showing 90 deg mark across again, job done.

Centre pop and drill holes

I decided that I would like something fancy on the cover, so with the chuck mounted on the spin indexer and with a vee shape fly cutter form a star in the end.

That doesn't look bad.

Stew

Bernd · « **Reply #12 on:** September 20, 2011, 08:47:47 AM »

Stew,

Realy like the looks of that star.

Bernd

madjackghengis · « **Reply #13 on:** September 20, 2011, 11:08:15 AM »

That's a really good start on an interesting flywheel, I really like your down and dirty method of indexing, with that electronic level, it ought to be dead on, and good for repeatability. I'm looking forward to seeing it completed, even if it is between building another.

Cheers, mad jack

arnoldb · « **Reply #14 on:** September 20, 2011, 11:18:27 AM »

Quote

That doesn't look bad.

Definitely not! - in fact, it looks great - good going Stew

Sorry to hear about the loco wheel - that's a real bummer...

, Arnold

raynerd · « **Reply #15 on:** September 20, 2011, 01:47:48 PM »

That star looks super Stew, infact, it has given me an idea!

Chris

sbwhart · « **Reply #16 on:** September 20, 2011, 02:05:22 PM »

Quote

Realy like the looks of that star.

Quote

That star looks super Stew, infact, it has given me an idea!

I thought I was doing a flower

Stew

Bluechip · « **Reply #17 on:** September 20, 2011, 02:29:17 PM »

Hi Stew

Keep 'em quiet ...

Tell them it's an Aster ..

BC

Rob.Wilson · « **Reply #18 on:** September 20, 2011, 03:22:49 PM »

Hi Stew

Looks like this is going to be another master piece of engineering/design ,,,,,,

,,,,,, great drawing

The star is non to shabby too

Rob

NickG · « **Reply #19 on:** September 20, 2011, 03:53:43 PM »

Star is great Stew

I also like the method for indexing holes, I have always struggled with that, on my flame licker I ended up having to elongate holes with a needle file, very messy! I have a rotary table now so should have no excuse but I don't have a chuck that'll go on it yet! I do have the same angle gauge as you though, never thought of using that, cheers!

sbwhart · « **Reply #20 on:** September 20, 2011, 04:06:49 PM »

Quote from: sbwhart on September 20, 2011, 02:05:22 PM

Quote
Realy like the looks of that star.

Quote
That star looks super Stew, infact, it has given me an idea!

I thought I was doing a flower

/quote]

Quote
The star is non to shabby too

Its not a star its a bloody Aster

Thanks for you comments chaps

Stew

saw · « **Reply #21 on:** September 20, 2011, 05:21:45 PM »

A nice projet you have here, I will be folow this with great intresst

sbwhart · « **Reply #22 on:** September 23, 2011, 12:37:38 PM »

Got on with making the valve chest, this was fabricated and silver soldered, I used some hex bar fly cut down to size.

The bits for soldering I losely pined together with 1/16" brazing rod

And soldered together

I squared the fabricarion up as you would a casting, then centre drilled for the valve rod position, and set it up in the four jaw with a wobble bar

Drilled it through 3mm then drilled and tapped 1/4* 32*8mm deep

Marked out for the bolt holes drilled these through 3mm then used the chest as a jig to spot through and drill and tap the cylinder, and drill the cover 3mm.

Slide valve milled a bit of brass to size and milled the vlave pocket in the base flipped it over and milled the cross slot for the rod and cross bar.

These are the bit for assy.

Slide valve in the chest.

That valve cover is just calling out for something.

saw · « **Reply #23 on:** September 23, 2011, 01:18:47 PM »

Looking good, nice work.

Bluechip · « **Reply #24 on:** September 23, 2011, 02:47:43 PM »

Hi Stew

What did you do to get the silver solder to run into the joints ?? If anything ..

Did you flatten some or does it just run in?

What was the grade ?

BC

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Author Topic: Potty Popcorn Engine (Read 110755 times)

Rob.Wilson