Don Young’s ‘Doncaster’

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Hi Phil

PTFE does work, I know of a number of fellow model engineers who use PTFE successfully, some say that the valves leak a little until heated up to seal but not all. I guess that depends on how tight a fit you make them, if the slot is wide enough it should take up most expansion sideways rather than tighter in the bore.

The other option used is to fit 'O' rings under the PTFE rings to push them against the bore, I guess there are many ways to skin a cat… I have PTFE piston rings on my Heilan Lassie, those are the main rings though, she's slide valve. The glands for Doncaster's piston valves are screwed and those have O rings, this is how Don drew them so not something that I've changed.

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

afternoon guys, a few more images dug out, some 'between the frames' action..

first, an overview showing the state of play as she is today. Getting busy but a long way to go yet

Close up of the twin vacuum cylinders, there are also an identical two on the tender..

overhead view showing the crank, you can also see one of the return cranks fitted and the two steam sander boxes in place.

the inside connecting rod is different from the one drawn by Don, Don's has the later (IIRC 1947) reinforced cap that has the added ridge around the back. this was added after play was discovered during service. i have followed the earlier type with no ridged back, learning from this I have increased the depth of the cap for extra strength.

a close up of the big end showing no ridge…

a picture for reference showing the later 1947 type cap, this is the connecting rod for the new build P2.

Lastly, the 3 cylinders ready for fitting to the frames

regards

Pete

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

An interesting part of the model is the 'Spencer' design sprung buffers for the A1/3, the A4's were different, one of the few component differences in the design.

The first picture shows what's involved component-wise for just one buffer, needless to say, these were not a 5-minute build.

You would have noted in the picture above that there are a number of rubber and steel discs in two sizes, these make up the damper, there are no springs in the 'Spenser double-action sprung buffer.

This next picture shows the smaller discs which make up the damper for the buffer head, they are a tight fit within the buffer housing which in itself was an interesting thing to make.

Here we see the buffer stock, the double action is achieved when the weaker discs on the buffer head giving way first. The buffer head will retract/depress until it hits the sliding step in the shank which then compresses the larger discs held within the buffer stock. Both sets of discs are spaced, rubber, steel, rubber, etc as seen in the previous picture

This is pretty much identical to full size and works very well.

Lastly, a picture to show both buffers fitted…

Please forgive the 'Photobucket' watermarks, this is a leftover from when they played their tricks in demanding silly money for what was a free hosting site. I do have all of the originals, just haven't got around to changing them over yet.

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

coming back to the present, the stainless steel cylinder cover plates have now been fitted as are their working relief valves, they just require a final polish to finish. The next job is fitting the valve guides, their crossheads fitted to the spindles and then assembled. I may leave the Flourosint bobbins off until the rest of the motion is complete and ready for timing.

regards

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

morning all, hope everyone is having a good weekend… I have been working on fitting the Gresley 2:1 conjugated valve gear of late, this is very much a dry test fit to check that things are as they should be. I have to say that getting to some of the valve guide nuts is a challenge, I'll make up some proper tools to make this an easier task while in service. everything is very dusty in the photos, lots of tidying up is required in this area on completion.

Here's a picture of the rear R/H valve guide

A rear top view to show the various 2:1 gear components which very much follows the prototype with a few additions to aid maintenance. As can be seen, it's getting very busy between the frames and I have a long way to go yet.

Last picture to show the R/H connecting link with its oil cup pin, this has a small reservoir in the top which feeds oil to the bronze bush. Note the mudguard on this side is currently missing, I'll refit this soon. I'm beginning to hate the macro lens on my new phone, it picks up far too much detail which is invisible to the naked eye…

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

good evening all…. I'm hoping to put the model on static display at my club this coming weekend. Doing this involves a fair bit of work in not only making the model more presentable but also the time in putting everything back together. As these stages will probably be of more interest than some of the other recent updates I'll post pictures as she comes back together. two for tonight, as can be seen the running boards are back and I have to say the new coat of paint is a massive improvement to last time. I have painted the splashers Doncaster green but alas won't be able to line them before the weekend. i was planning on attaching the brass trim which I'd do before the lining anyway as they give a good guide for the lining. Unfortunately, at the time of discovering that 4472 still had her brass trim in 1938, I ordered extra laser-cut trim without paying much attention to how the parts were to be assembled. The trim fits under the outer shell and thus is not wide enough to use for the brass trim fitted over the inner trim. No big deal, I'll sort this in due course. I have fitted the splashers anyway. Tomorrow I have a hundred or so 10 BA bolts to fit and various other parts, I'll also take a look at the boiler and temporarily fitting the smokebox to it, note the saddle has already been fitted. The lining on the valance is a little heavy, I shall deal with that another time once it's fully cured. I'll hopefully post more pictures tomorrow.

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Morning all.. this isn't today's planned pictures.. this was in response to a couple of questions from a fellow ME down under and I thought others may be thinking the same thing, so I've copied/pasted my reply to here.

Don's design is more or less a true miniature of full size, both in looks/design and in how the various parts work, the lubricators are an example which I'll cover at the end with some pictures. Due to the complexity of this model and my limited time in this world I have tried to build it where I don't need to keep taking things apart, or at least to greatly reduce this. If I had got her to the running stage without first making all of the brake and sanding gear it would have made things much more time-consuming. As an example, the gravity sanders had to be done before the cylinders and their slide bars were fitted, it made sense to also make all of the rod linkages to the cab at the same time and test. The same goes for the steam sanders, vacuum brakes etc. This has a knock-on effect, such as the cab needed to be at least made to a basic stage which it currently is. there are so many parts (all working) to the model that it gets a little bewildering sometimes. I would love to have it running on air, I am getting closer but still have a fair bit to do first, the lubricator drive arm and connecting rods being such an item.

Yes, the boiler will be fed by two injectors, there are no handpumps or axle pumps on this model. There will, however, be a backup water feed method. The boiler will be filled via an electric HP 12v pump. Not only will this fill the boiler from empty pretty quickly but it will also be an emergency method of replenishing the water if both injectors fail, the pump will be capable of overcoming 130 PSI which gives a good safety margin against the working boiler pressure of 100 PSI.

Finally the lubricators and whether any provision has already been made for them, You'll be happy to learn the answer is yes, I'll post a few pictures to show where we are and how things will work.

First up is a picture of where the forward lubricator sits, I have placed one of Adam's superb castings to give a general idea of how it will look. This will be a fully working lubricator, I'll work out the internal design later. This sits exactly where it does on the prototype and will be connected to the valve gear in the same way. A few things to point out, the front lubricator sits very close to the gravity sander linkage, also in this picture, you can see the 10 BA CSK screws which are practical, all the others are sealed, this makes future maintenance much easier although still a lot of work if needed to remove the running boards etc. These particular screws will be changed for newly painted items on final assembly. bTW this particular lubricator will feed the 3 cylinders, as per full size

Next is the rear lubricator position, this one will feed the 3 main driving axle boxes, their axles and horns, again, as per full size. The slot to the front is for the operating arm to drop down through to connect to the rod linkage below. Also of note here is the close proximity of the steam sander filler neck, I secure its lid later, it's already made.

Lastly, a close up of the spigot that's part of the R/H expansion link shaft, the drive arm will fit this spigot and have two connecting rods from it to the two lubricators fore and aft of this position.

Hope that answers all questions…

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Today's progress on reassembly ready for the weekend..

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Reassembly continues.. only one photo worth showing today but it does mean another tick in a box. After having a great day at the club, after returning home I found a couple of hours tonight to do a little more. I had to remove the upper running boards as I had forgotten to screw the saddle down, it's a pretty tight fit anyway but playing safe I have fitted a couple of screws on either side for peace of mind. After replacing the boards I then fitted the main steam pipe covers, as with most of the other reassembled parts I have only used a few screws.. no point in a total screw down as it's all got to come off again. I also paid a little more attention to the cab, I thought it would be a nice touch to give the roof a coat of satin black, it will be redone properly when I finish the cab (lots of detail work to be done there still) but it adds a little definition to the cab rather than just grey all over. Things are looking promising for Saturday, the weather is a concern as although the motion has been oiled the model is far from protected from the elements. George the organiser for this year has kindly offered to find a place for the model up at the station where it will be under cover. The added bonus to this idea is that it won't get covered in ash like in previous years from sitting in the steam bay all day…
with this, in mind I may take the display track to sit it on, we shall see.
So jobs lefty to do tomorrow, fit the cab and connect the two cab levers to their various cables/rods, clean the tender (not touch for a few years and very dusty) touch in a few gloss black marks on the wheel centre's and lastly give the entire model a clean…I think that's everything…

Photo for tonight is to show the main steam pipe cover fitted, I have, of course, chosen the R/H side with the ejector elbow for added interest.

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Good afternoon guys.. well, the loco is now ready for tomorrow, and on a plus note, the weather now looks much better than had been threatened, there's even some sun so should be able to get some properly lit photos. I have taken some photos with the tender sharing the stand, a good test of its strength if nothing else.
The last photo in this group shows the loco hoisted by its lifting rig ready to be lowered onto its traveling board. I have done this a good few times now but still get nervous at this stage, rightly so as each time the model is getting heavier. I would guess her to be approx 200lbs now, perhaps a little more. You may recall that when weighed on the scales without her boiler and other parts missing she weighed in at 148lb, the boiler must be at least 50 lbs, I suspect more as she's more heavily built than the drawing, ie, larger tubes and thicker upper tubeplate sections etc, plus all the extra bronze bushes. Having said that the lifting rig will handle more than twice that weight but it doesn't stop me from getting a little twitchy…

And another video to bore you all…” src=”https://storage.proboards.com/forum/images/smiley/smiley.png” />

**LINK**

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

A few photos from yesterday's club event, managed to take these during the short breaks between the rain when the sun did show itself…

A short (poor quality) video to show that gravity sanders do work in 5 " even if the sand has been in the boxes for many months and when out in weather that was at times dreadful and very, very wet/damp. Please excuse the short commentary… I shouldn't have tried to stand up while talking these days… I forget sometimes..lol

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

Evening all.. things are still progressing nicely with 4472, Today sees the combination levers close to completion. Once I have removed the boiler and running boards I'll be able to fit them properly, for now, I have only tried them in place to check all is as it should be…The lever is only wedged in the general position here to check that everything aligns as it should, when it's fitted properly I'll file down the bearing that sits in the crosshead a little further so that it swings freely without any sign of it rocking.

regards

Pete

[Peter Seymour-HowellParticipant @peterseymour-howell39349]

union links done and test fitted, next up will be the motion pins to fit them properly

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