Author Topic: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.  (Read 59619 times)

Offline b.lindsey

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Phil, I am playing catch-up again on this build but its incredible. The gears and tiles all look great (whichever way you decide to orient them), but that flywheel is fantastic...so much detail. Still watching even if quietly.

Bill

Offline pgp001

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Re: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.
« Reply #76 on: October 28, 2015, 01:16:02 PM »
Crikey, I had not realised how long it was since I posted an update on Agnes.

The truth is, there is no update  :ThumbsDown: In fact I have not actually made anything in the workshop for exactly a year now.

I decided last October to have another go at learning to "play" Acoustic Guitar, as opposed to "playing with" it from time to time.
The trouble is, I don't have enough time to devote to everything at once, I started taking (and paying for) guitar lessons, so I have spent all my spare time over the last year sat practicing and learning.
I will not be forming a band any time soon, but my wife has suggested that when I retire I could go stand on a street corner and do some busking  :lolb:

Anyway, the last bit of news on Agnes was that I took the part finished flywheel to our annual Bradford club exhibition last December, and won a rather large silver trophy for best unfinished model.

The next job on the flywheel is turning the rim to size and producing the rope grooves on the outer diameter, the trouble was my lathe runs a tad too fast and Iwas afraid of spoiling the job with chatter marks etc.
So last weekend I have bitten the bullet and bought a new three phase motor and fitted a spare inverter I had been saving. The lathe will now run at a suitable speed for the job so I have no excuses not to start making some swarf again.
One thing I am not really looking forward to is cutting the 200 internal gear teeth for the barring engine one at a time with the slotting head.

I think I might have mentioned a couple of years ago that I am a bit slow  ;D

Phil

Offline Alan Haisley

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Re: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.
« Reply #77 on: October 28, 2015, 05:37:05 PM »
Phil,
At least you can get away with showing the first couple and last couple of gears being made.  :Jester:
Alan

Offline ths

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Re: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.
« Reply #78 on: October 30, 2015, 09:25:38 PM »
Slowhand? Hugh.

Offline pgp001

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Here is the latest update on progress, yes I have actually made some !!
I will keep the words to a minimum and let the photo's explain.............Any questions just ask.

Phil

Since the last installment, the flywheel in its part finished state won me a big silver cup at the Bradford Model Engineering Society annual exhibition.
After I brought it home from there it was totally stripped down again to allow the inside face of the eight main segments to be fettled up a bit with some filler and smoothed off ready for painting. Then it was put back together for the last time for the final machining operations to add the 200 teeth for the barring engine ring gear, and the 18 grooves for the rope drive on the outside face.

Here it is having the crank side face machined, this will be a datum face later on.





Now the outside diameter is being cleaned up true for the first time in the lathe, this will also be a datum and still needs another finishing cut later on.



The segment joints need to be relieved in the area where the barring ring gear is to be fitted.



This shows the blanks for the eight segments laid out on my flywheel drawing to make sure they will fit OK.



The gear blank segments are clamped in place and then drilled for countersunk screws to hold them to the flywheel.





Obviously two screws is not enough, so I ended up with five in each.



Then mill away the bulk of the material to get it round inside.



Then round outside.



Then back onto the lathe to face the thickness to size and finish the inside diameter to size ready for its teeth.



To save the single point gear tooth cutter having to remove too much metal. I drilled some of the tooth away first, this meant 200 indexes on the rotary table. You do not need any interuptions while doing this.





Then swap the high speed head for the slotting head.



And start another 200 indexes to cut each individual tooth. I made a dead stop on the Y Axis so I could not go too deep by accident.



Boy did I breathe a sigh of relief when I got to this point.  :ThumbsUp:



Then it went back in the lathe to finish the outside diameter for the final time, I have fitted an inverter so I can run the lathe down to about 10 rpm, the final pass on a slow feed took about half an hour.



Note the big lumps of lead to stop the overhanging tool chattering.



Once the outside diameter was finished the 18 rope grooves were added, I made a special form tool for this as the grooves are tapered with a radius in the bottom but start off with parallel sides as per the original drawings.





And finally the finished result, I say finished but the countersunk screws will be filled over prior to painting, I do not agree with being able to see modern fasteners on models of old engines.







My main objective was to make the flywheel as true to prototype as possible, the biggest fear I had was that you would be able to see the joints between the eight segments, so I have been a bit paranoid about making sure everything was checked and double checked along the way. I am very pleased with the way it has turned out and I can put that worry behind me.

I think I might make the barring engine next, see you in a year or so  ;D

« Last Edit: April 08, 2016, 06:12:48 PM by pgp001 »

Offline Roger B

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Glad to see you back on this  :ThumbsUp:  :ThumbsUp: I'm looking forward to seeing how you cut the gear  :headscratch:
Best regards

Roger

Offline pgp001

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Roger go back and have another look, I added more photo's in the last few minutes.

Phil

P.S.

Can anyone guess how many separate bits of metal including fasteners are in that flywheel ?

Offline Roger B

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Thank you  :ThumbsUp: Looking at the pieces in each spoke I would think 5-600 in total  ::)
Best regards

Roger

Offline Don1966

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Phil that work is jaw dropping. It is well thought out and executed and the results speak for itself. Awesome mate.......... :praise2:

Don.  :wine1:

Offline Tennessee Whiskey

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I'm gobsmacked,  simply beautiful  :ThumbsUp: :ThumbsUp:.

Cletus

Offline joe d

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Phil

This was worth the wait :ThumbsUp: :ThumbsUp:

Joe

Offline Jasonb

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I know how many  ;) but won't spoil the game for others. Very nice Phil and gfood to see what you have been upto over the winter.

J

Offline vcutajar

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Very beautiful.  That is a project on it's own.  Good thing you are not going to cover the inside of the flywheel with wood.

Vince

Offline crueby

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Magnificent job on the flywheel! Clever way to do the wedge ends.

Offline pgp001

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I know how many  ;) but won't spoil the game for others. Very nice Phil and gfood to see what you have been upto over the winter.

J

Jason

I have had a re-count, and I think the figure you have will be wrong anyway.

As for "over the winter", the additional work you see here has been done over the last ten evenings. I had set an un-offical target of finishing the flywheel before I was 60.
So I have done with a day to spare.  :old:

Phil