TO BUILD ??

[Laurie_B]

Dec 12, 2008 16:31:26 GMT dscott said:

Now we have the good news that the 30" GWR locos will be covered by Poly Models, we can look forward to some lovely products to help us with this engine.

Do Saint cylinders also fit 51XX's?

David.

I do have a drawing of the mild steel fabrication but would have to build one to see if it would work.

Looking at copies of the Great Western Railway Journal;at the G.A. drawings for the 29xx and the 51xx classes,the cylinders look very similar,other than the cylinder bore for the 'Saint' is given as 18-1/2",whereas a figure of 18" is shown for the 51xx.
Otherwise,from what I can see,all the other major dimensions are the same.
The other point to consider is that the 51xx class had outside steam pipes,whereas the 'Saints' originally didn't.

[dscott]

On the cylinders, all we would have to do would be drill and fit the outside steampipes, the ones for the Saint being drilled from the inside and plugged.

David.

[ducatibob]

David,
I havmade the press tool and produced the joggle. It realy looks good however an awfulll lot of effort. Regarding the cylinders I am currently having a go at drawing them as well as learning Turbocad at the same time. Ideal for these cold nights. Say more about the Polly connection and when may we expect them to start producing castings.
Bob

[PeteT]

David,
Saint cylinders do not suit a prairie, apart from steam pipe issues, the saddle radius for the boiler is quite different. However as readers of Model Engineer may have noted, Pete Rich has drawn a large prairie and since this is based on Swindon drawings, there is likely to be a lot in common with Trevor Shortland's design. Churchward had the right idea with standardisation in 1903, horizontal cylinders and a foundry pattern which could be made to suit different locos by using different saddle parts. In model engineering, the cylinder which we developed in collaboration with Neville Evans for Penrhos Grange has been very successful and much of the motivation for that came from the obvious difficulties both in the foundry and in the workshop to produce the true scale Churchward style cylinder. We plan in the near future to produce a hall and modified hall cylinder to suit Neville Evans other designs and it may be that cylinders to suit other standard GWR classes such as the 28 will be derived.

Pete T

[ducatibob]

I have designed and am part way through building a fabricated set of cylinders for my 51XXX. Looks good at the moment but time will tell. Anyone wanting information I would be pleased to pass on.

[ducatibob]

David,
I forgot to report on the side frame joggle. I produced a press tool and was very satisfied with the result. I made the frames our of black steel sheet and after all holes and slots were cut there was no appreciable movement so would recommend to others.
Regards,
Bob

[dscott]

I had to look after the metal work shop this morning due to a workmate being stuck in the snow, so I gave my joggle press tool a go,
cold almost then with some heat perfect.

Saw a lovely model being built by our Chairman, inspiring engine complete to chassis and boiler.

David.

[ducatibob]

Ureka I have manufactured a set of fabricated cylinders. It has only taken me about 150 hours and 1000 cups of tea, nevertheless I think I am there.

[alanetm]

This thread started with an "any problem question". I have got to the stage of a rolling chassis with side and connecting rods and cylinders (pistons and valves) fitted and I am now in the process of making the valve gear.

The only problem I came upon was that the connecting rod strikes the lower slide bar. Initially I thought I had made something to a wrong measurement but all checked out OK. So the only solution was to put a clearance radius on the lower slide bar. I was unhappy about doing this until I saw the photo of Shortlands own loco when it was sold and it has a clearance machined into the lower slide. This is not shown on the drawings! The way the clearance has been done on Shortlands loco is better than my radiused clearance as his is a tapered slot to suit the width of the connecting rod which leaved the impression that the lower slide bar is still finished off square.

[ducatibob]

Aug 2, 2006 18:42:31 GMT starspider said:

Hi I am thinking of building a prairie to trevors drawings for my next project, wondering about any major problems etc.
so your comments welcome good or bad

[ducatibob]

I started a prairie before xmas. It is a very detailed model and test of engineering skills however when complete will give major satisfaction providing it is built right. The big issue is the cost of catings from reeves particularly the cylinder/valve blocks. I have fabricated mine and they look OK. happy to share the drawings if wanted.

[alanetm]

OK piston valves this time..... I found using cast iron rings that the they did not seal (on air) as I would have liked. This is because the ring is quite deep and therefore is not truly round when gapped (making your own) and then the pressure on the walls is too great to get smooth movement if they are forced back to a round state when in the bore.

I have now fitted plain PTFE rings with no gap and they seal OK.

Now some say PTFE is not good at steam temperatures, some say it should be filled PTFE, and some swear by using it. It's a dilema. At least if I have to go back to cats rings I still have them.

[alanstepney]

For selection of material for O rings,
www.marcorubber.com/material_chart.htm

I prefer CI rings (in a CI bore) rather than O rings. To make them, follow the instructions given by Tubal Cain in his articles on the subject, (and as repeated in his book(s)).

[Andy Clark]

Apr 19, 2009 15:29:35 GMT alanetm said:

This thread started with an "any problem question". I have got to the stage of a rolling chassis with side and connecting rods and cylinders (pistons and valves) fitted and I am now in the process of making the valve gear.

The only problem I came upon was that the connecting rod strikes the lower slide bar. Initially I thought I had made something to a wrong measurement but all checked out OK. So the only solution was to put a clearance radius on the lower slide bar. I was unhappy about doing this until I saw the photo of Shortlands own loco when it was sold and it has a clearance machined into the lower slide. This is not shown on the drawings! The way the clearance has been done on Shortlands loco is better than my radiused clearance as his is a tapered slot to suit the width of the connecting rod which leaved the impression that the lower slide bar is still finished off square.

And the full size has the same clearance machined in the lower slide as can just be seen in this pic



Andy

[alanetm]

My prairie chassis has now run successfully on air. It needs 40 psi to really get going, below that it begins to struggle. Probably all a bit stiff at the moment. It runs on ballraces so the wheels are not just hanging in space.

The smoke box is now also done. Fitting the steam pipe covers is impossible if the drawing is followed (in MHO) so mine slide down from inside the smoke box and register in a fixed flange on the running board.

[Alan]

I also found the steam pipe covers of dubious usability, so i just slotted the back of them so i could easily fit them.
Cant tell the diffrence once they are on.

[alanetm]

An aspect I puzzled over was how to fit the lubricators. I did not fancy them sitting on the running boards.

I ended up fitting 1" square tanks with a hinged lid on the inside of the frames just behind the smoke box. The lid will lift sufficient to see that oil is being used and to refill with a pump action oil can. The oiler is driven from the inner ecentric with a rod bolted to the same fixing as the expansion link.

[Alan]

alanetm. Thats the way it says to do it on the drawing, and i have seen a couple like it but with purpose made tanks

[fostergp6nhp]

Aug 31, 2010 20:03:49 GMT alanetm said:

An aspect I puzzled over was how to fit the lubricators. I did not fancy them sitting on the running boards.

I ended up fitting 1" square tanks with a hinged lid on the inside of the frames just behind the smoke box. The lid will lift sufficient to see that oil is being used and to refill with a pump action oil can. The oiler is driven from the inner ecentric with a rod bolted to the same fixing as the expansion link.

From looking at the 5199 photo's post that is were the front sand boxes are on full size so you could use the sand box fillers to fill the oil tanks.

[taff]

Hello Laurie B, Ducatibob and everybody else,
I don't usually get involved with the correspondence in the forum's but the matters arrising about the "Prairie" cylinders have struck home with me. I have followed G.W.locomotive matters all of my life and when the Great Western Society decided that they were to go ahead with my ideas about converting a "Hall" class to a "Saint" the responsibility for the design of the new engine (Lady of Legend) was laid upon my shoulders. Part of the work was to produce the drawings for the new cylinders and this involved me in a great deal of research into this aspect of the new loco. Prior to my design for the cylinders we investgated possibilities of fitting cylinders from other loco's but found that due to the differences involved with the smokebox saddle it was impossible to utalise existing cylinders, hence the new drawings.
Regardeing what Peter Thomas has said in the forum I should point out that I am also a Model Engineer and concurrently with my work on the full size I have produced a design for the "Saint" class in 5" gauge from which any 30 inch stroke G.W. engine can be built and includes the cylinders in lost wax and which pattern can be altered to suit any size smokebox at any scale height. I have not yet made these cylinders available commercially as I am trying to find a foundry which will produce them at a reasonable price. The wax pattern involves welding together a large number of waxes and it takes me a week to produce six complete wax patterns. I have cast them myself but with my present state of health I cannot contemplate doing this again in the forseeable suture.
I think the best thing I can do now is switch over to lurking mode.

Pete Rich.