Author Topic: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.  (Read 49327 times)

Offline pgp001

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Well I suppose its about time to let you into the workshop and see what progress has been made. I warn you now I am desperately slow and easily distracted. My problem as always is my desire to make or buy more tools.
At the moment my mind is a bit pre-occupied with a certain small jig borer that I just might be obtaining, but thats another story.

Just a bit of background so you know how I got to the stage I am at now.

Agnes was originally situated at Washpit mill in Holmfirth Yorkshire, she ran the mill for many years until retirement and was eventually relocated to the Markham Grange Steam Museum at Doncaster, luckily for me still in Yorkshire.

My late father knew the engine tenter Herbert White very well and visited him on many occasions at Washpit mill to watch Agnes in action, she was always his favourite engine. He discovered that Peter Southworth was also an admirer and was researching and building a pair of models of the engine, so back in the mid 1980's my dad approached Peter to see if he could buy some castings for Agnes.
All Peter had left after building his own two models was an incomplete set of castings that were intended as spares if anything went wrong, so my dad bought those along with a few original P&W drawings.
Peter apparently never made any scale drawings that we know of other than working sketches, and the patterns had already been given to a friend to burn (YES BURN) on his wood burning stove, so it was take what is available and make the best of it.

Moving forwards a few years, my dad made a good start on machining the main engine castings, the flywheel was a substitute from another engine in the Southworth range, but was 1" too small in diameter and not wide enough either. Even worse it was nothing like the original eight segment flywheel on the full size Agnes as it was of the type made in two halves. But that was all there was available so that is what the model had fitted.

Dad was much the same as me in that he had lots of other projects on the go at any one time, in this case it was a pair of 3" scale models of a Burrell road locomotive called "Dalesman"

Then the worst thing happened, dad was diagnosed with a rare and incurable lung disease that pretty much put paid to any heavy workshop activities in a fairly short space of time, and to cut the story a bit shorter he decided to part with the models whilst he was still able to deal with potential buyers himself. So all the models and "most" of his workshop went to new homes. I was lucky enough to eventually inherit his new Myford Super 7, and the  Alexander Master Toolmaker milling machine which you will see plenty of very soon.

Move forward thirteen years, one day I am wondering what has happened to Agnes in the intervening years, so I make an effort to track down the owner, only to discover he had not laid a  finger on her, she was exactly like the day my dad last saw her.
After some very tricky negotiations I managed to buy her back again and this is where the story really starts.









More to follow soon. Here is a clue
Phil


Online steamer

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Beautiful Phil!.....is the main casting a casting? or a fabrication?

Dave
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Damned ijjit!

Offline ths

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Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.
« Reply #2 on: June 29, 2013, 02:11:35 AM »
I really look forward to seeing and hearing more about this.

Hugh.

Online steamer

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Beautiful Phil!.....is the main casting a casting? or a fabrication?

Dave

Never mind!.....note to self to read all of it first....sorry

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online Jo

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So Phil what have you done about drawings for her? Did your Dad redraw her? Or have you?

To put her in perspective can you let us know the size of this model?

Jo
Enjoyment is more important than achievement.

Offline MuellerNick

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Quote
Here is a clue


That's the pattern for a new segmented flywheel.  :)


That engine looks really nice! Very promising so far.
Is the paint a very dark blue or a black?


Nick

Offline pgp001

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The bedplate is made in three castings exactly as per full size, the overall length of the base board is 36" and the currently fitted flywheel is 11" diameter.
My dad did make his own working sketches for some of the parts you see, but in the main it has been made by scaling down the original P&W drawings that still exist for Agnes. Luckily I have full size drawings for most of the main castings and valve gear parts.

I have been corresponding with Bradford Industrial Museum, and they may have found a couple more that I do not have.
However, I am doing a full set of scale drawings in Solidworks 3D just for my own use and to make sure it all fits together.

The colour of the castings is black at the moment, but I am considering whether I should paint in the colour scheme it is now, ie burgundy.





The pattern is indeed for the flywheel segment, more of that in the next installment.

Phil

Offline b.lindsey

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Lovely engine Phil, both in full and model scale. I am quite interested in how the segmented flywheel will be done too.

Bill

Offline pgp001

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This is the stage I have got to with the Solidworks 3D assembly of Agnes (See PDF file attached below)

When Peter Southworth built his two models of Agnes, it was never his intention to add this model to his range of commercially available castings, remember I told you how he had passed on the patterns to a friend with instructions to burn them. I think that showed fairly clearly that there were no additional models planned.

At this stage I must publicly thank Bob Potter, Bob took over Southworth models when Peter died and has been an enormous help in compiling information about Agnes. It was Bob who discovered that Peters wood burning friend had not actually burnt the patterns after all, but put them in his loft and never told anyone. Bob did some negotiations on my behalf and I have now taken over as custodian of the full set of Agnes patterns, and they are currently stored safely in my loft.
Peters wishes will be honoured and no additional engines will be built using the patterns, but I will arrange to display them along with my model when it is finished, giving full credit to Peter for making them.

Prior to me becoming custodian of the patterns it was agreed that I could have a set of flywheel segments cast in order to correct the one on my model, so that is what I have done and I am sure both Peter and my dad would have approved.

The pattern you have already seen was sent to a foundry in the West Midlands, and I had nine segments cast from it, I got one extra done in case of any mishaps, so far all has gone well. It took a while to figure out a method of machining them all so they formed a perfect circle when bolted together, each one had to be exactly the same.

These are the castings.



The first job was to remove most of the lump left over from pouring the casting.



The problem with these is how on earth do you hold them whilst maching them, I decided that the second operation would be to machine the side faces to give some sort of flat datum to work from, so I made this hold down bridge to wedge into the casting so I could clamp it to the mill table. This was the first of quite a few special bits of tooling  :)



I used an carbide inserted cutter to face off both sides of each segment so they were all the same width, these faces will ultimately be finish machined in the lathe when the flywheel is almost built up.



There was no way I could fathom to hold these in a vice and be able to machine the angles at either end with any sort of repeatability, so I designed a holding fixture for this job. I had a lump of aluminium under the bench which was just about right luckily.



So let the swarf begin.



Until a few evenings later I ended up with this.



Can anyone guess how I intended to use this ?

Phil

Offline Maryak

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Beautiful engine Phil,

The thing that has me intrigued with the flywheel is how the spokes are held to the centre boss. The GA has some axial circles on the boss so I am wondering are the spokes pinned axially so that the bolts spokes to rim line up?

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline Dave Otto

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What a nice engine.

Both of them; the full sized one and the model. I'm looking forward to watching this project progress.

Dave

Offline vcutajar

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Fascinating.  This is going to be a super flywheel when finished.  Following along Phil.

Vince

Offline FLG

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damm these casting are beautiful!  :o you got a very detailed and interesting proyect there, I will be following with lots of interest

good luck!

Saludos

Online Jo

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I am assuming that the flywheel segments sit in the U of the aluminium jig and the grub screws give you some sort of levelling adjustment. But  :noidea: once the segment is in the jig you can't get at them to adjust them.

Looks like a good quality pour  :ThumbsUp: Did you get some spares cast at the same time?

Jo
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Offline MuellerNick

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Quote
The thing that has me intrigued with the flywheel is how the spokes are held to the centre boss.


If you look at the pictures, you see that the hub is a disk with radial bores for the spokes. The spokes are pushed into these bores and held (radially) by wedges.


Interesting construction of the flywheel!


Why wasn't the in-gate for the casting placed on the outer circumference or one of the two sides? In Germany, we do signal (to the foundry) places for gates etc. by a yellow hatching.


Nick