mickoo

Western Thunderer
Peter, the rocker grate castings are/will be, available on demand ;)

Radius, cough, hurumph, well yes you see it's like this.......

Before I answer that it's probably important to step back a little, the generally accepted radius is 6 foot and models have been built to accomplish that, generally that means narrow frames, 26 mm or so over outside faces. How or where this radius was deemed the golden rule I don't know but it's something we're stuck with.

The W1 pushes the frame width out a little further to 28 mm over faces, 28.5 mm over rivets, that's not an issue, many large engines have already been built this wide and squeak through 6 foot curves. The original front end was a little tight so I've added a little more side control and beveled the outside cylinder a little more, the real engines are beveled here anyway so I wasn't overly stressed about doing it a little more.

The rear end is different, it's not the Cartazzi as it's closer to the rear axle than the standard Pacific, it's actually the trailing truck way out back. There are two areas where it is tight, the actual outside frame work is scale width as is the inside drag beam assembly. At the moment there's a radial slot in the trailing truck.

Trailing_01.jpg

It is inhibiting the amount of throw we currently have, I can widen that slot very easily in CAD, however, doing so presents two other issues, the inside of the wheel now impacts the centre drag beam and will short out, the other wheel will now rub against the inside of the outside frames, it won't short as the boss is touching, not the rim.

All of this wouldn't be a problem if Slaters wheels were the correct thickness, they're not, the rims and bosses are too fat, I think it's about 1 mm too much from memory.

The simple solution would be to skim the wheels, but it's not a practical solution so we have to compromise somewhere else. That's the bit that really really pi55es me off! I have to compromise because of someone else.

As it stands the W1 will just go around a 6 foot curve but there is a higher than acceptable risk of the rear end derailing. This leaves two choices:

Set the radius higher, not going to be popular with punters.

Widen the rear end frames (with correspondingly very narrow cab steps, which is what DJH did and it looks a pigs arse) and reduce the width of the centre drag beam. No one will notice the centre drag beam reduction but everyone will notice the frame width when the tender is coupled up, there will be a big offset between the two sets of steps and frames....not popular with punters.

As it stands, 6 foot is not a reliable commercial figure I'd commit to right now.

I need to get the injectors on and then run some detailed examinations to get accurate figures for minimum radius and then make a decision on where we go from there. I have my own personal views which probably should not be aired publicly :D
 

simond

Western Thunderer
Mick

No skin in this game as, lovely as it is, I don’t want one but...

Couldn’t you include a pair of narrower trailing wheels and axle in the kit?

Or maybe as an option for those who cannot machine their own?

Why is it “not a practical option”?

Does an S7 version manage 6’ too?

Best
Simon
 

mickoo

Western Thunderer
Simon, narrower wheels, yes but axle? Don't think so as that'll change the back to back surely.

By the nature of Slaters wheel construction if you take too much off the face....and that is where it needs to come from, then the rim will come off the plastic spoke insert. Slaters wheels have a recess inside from the rear so there is a thin flange at the front.

The boss is not a problem at all as we're using the MF 5/32" stub axles as opposed to the 3/16" grub screw ones, so you can take a heap off the boss really easily.

Narrowing the rear end inner drag box is also very easy in CAD, so easy you'd not even need a test build as the decrease in width has no impact on any other structure that it interfaces with, except the ash pan floor which is easily adjusted to suit.

Bespoke wheels is/was my third option in my dialogue above, but I edited it out, it's extra time, extra cost and quite frankly extra work to get over an issue caused by someone else.

I will try and skim these wheels and see how it goes, I've got a sacrificial set some where. That of course depends if we rigidly nail ourselves to 6' radius :D

I've not built a S7 version and there has been little interest in a S7 version to be honest. All the S7 guys I know would probably not even begin to try and get a W1 round a 6' curve in the first place so the debate is mute. If you model S7 you don't try and squeeze and elephant down a drain pipe :p you tailor your layout to suit or your stock to suit your layout; that seems to be part of the S7 way of doing things, well it certainly was when I was involved with Love Lane.

There's a couple of avenues to explore in the next few days, once the injectors are on I will know exactly how little space I have.
 

mickoo

Western Thunderer
Live steam injector, nice little project and the pipework isn't too complex, though I thought I heard CCU and his crew cruise past; so I'm going to leave the beast from below (exhaust injector) and cleaning up the live steam injector until tomorrow.

IMG_0633.jpg

IMG_0640.jpg

IMG_0641.jpg

And a quick clearance check.

IMG_0627.jpg

Furlongs of room, what was I ever worried about ;) Can't say the same for the step mind :eek: it does just clear though and in this game, just is more than enough.
 

mickoo

Western Thunderer
Okay, quick radius check.

Six foot curve, not reverse curves mind, if you want to be that daft you're on your own :p

Rear end clearance.

IMG_0647.jpg

Tight but not touching and due to the slot in the trailing truck almost impossible to touch, the inner (curve) wheel is also close to the step but far enough away for our purposes. The Cartazzi is well clear, but has another issue all of it's own in that it's not presenting the wheel to the rail correctly; I don't know why as the angles are copied from the 1:1.

It could be that the Cartazzi truck is too narrow (between bearings), this is the Alpha model one and not the production one which is a couple of mm wider, this would alter the arc and angle which may make the wheel present it's self better to the rail head. I'll whizz up the production one tomorrow and do the same check.

Front end.

IMG_0649.jpg

The cut out chamfer in the cylinder rear (as does the real engine, A4's and A3's are the same and rarely modeled) is doing it's job and clearing the trailing bogie wheel. The Alpha model was slightly smaller (to scale) and intermittently touched, the trick was to alter the angle of the cut out by moving the point by the splasher up 1 mm and the point by the drain cock out by 1 mm. A compromise I was happy to facilitate.

The drain pipes on the other side had a lot of spare room, easily a couple of mm so no concern there.

Overall view of test set up.

IMG_0650.jpg

The meter says it all, pushing it back and forth and twisting it aggressively showed no change to the meter.

So, six foot curves it is then :thumbs:
 

P A D

Western Thunderer
Looks good chaps.

Nothing to do with the kit, but the front driving wheel screw seems to be counter sunk very deeply into the wheel boss. Is it a faulty wheel or just an artifact of the image?

Cheers,
Peter
 

mickoo

Western Thunderer
I slipped with the lathe :p cant remember why I was deepening the counter sink but it's now a sacrificial test wheel and serves that purpose just fine until I can remember to order a new one.
 

simond

Western Thunderer
Mick,

sorry, missed a comma and an "an"; I intended what I said to mean "narrower wheels, and an axle". I wasn't recommending an on-the-hoof revision of the Guild standards :)

Anyway, looks like it's not an issue, which is good.

As a bonus, I might take the idea of a subtle reduction in wheel width to resolve the inteference on the trailing axle of my 2nd hand Duchess which is a hybrid of a Gladiator kit and Premier chassis, and which just seems to trip over on 1750mm curves. (just over 5'8, on the basis that if it'll do that, it'll never have a problem on 6' laid "a bit tight")

cheers
Simon
 

mickoo

Western Thunderer
Apparently they do the LNER 3' 2" wheels which might help the clearance problems.
Len, I can't see them on their site (slaters) I'm afraid, but I suspect they are 3/16" axles and we need 5/32" axles. Changing the design to accommodate the larger axles will require the trailing truck to be enlarged to hold the bigger top hat bearings and that will have an impact on other areas and clearances.

As it stands it will go around a six foot curve but not much tighter (if at all) and it will need springing accordingly.

Personally I fail to fathom why you'd build an engine this big with this much detail and then try and force it around Xmas tree curves, but then I'm probably alone in those thoughts.

The design criteria was six foot radius (right or wrong) and it achieves that, job done :cool:.
 

mickoo

Western Thunderer
Mick,

sorry, missed a comma and an "an"; I intended what I said to mean "narrower wheels, and an axle". I wasn't recommending an on-the-hoof revision of the Guild standards :)

Anyway, looks like it's not an issue, which is good.

As a bonus, I might take the idea of a subtle reduction in wheel width to resolve the inteference on the trailing axle of my 2nd hand Duchess which is a hybrid of a Gladiator kit and Premier chassis, and which just seems to trip over on 1750mm curves. (just over 5'8, on the basis that if it'll do that, it'll never have a problem on 6' laid "a bit tight")

cheers
Simon
The Princess Coronation is another of those engines with a long radial arc at the rear end, boxed in by outside frames. I've got a Finney7 one to build shortly so will then have first hand experience of that little issue myself ;):D
 

Len Cattley

Western Thunderer
Len, I can't see them on their site (slaters) I'm afraid, but I suspect they are 3/16" axles and we need 5/32" axles. Changing the design to accommodate the larger axles will require the trailing truck to be enlarged to hold the bigger top hat bearings and that will have an impact on other areas and clearances.

Hi Mick, they are on the Scalesevern group site under members scale Severn stores. I don't know what size the axle's are but maybe they could make them 5/32" to fit the Finny7 W1.

Len
 

simond

Western Thunderer
It probably sounds like anathema to many of an engineering persuasion, but I reckon a 3/16” axle on a pony truck would run in bearings made from the thickness of the etched n/s for several hundred real miles with next to no wear, given an occasional smear of grease / drop of oil.

There’s almost no load, and more or less 5 square mm to support it, assuming 20 thou material.

Might avoid the need for extra bearings, and the space they would need.

Best
Simon
 

mickoo

Western Thunderer
Ahh I see, I'm not a member of S7 so cannot see them :D.

Realistically I cannot force buyers to join S7 to buy one set of wheels. They can of course...if they choose to, modify the trailing truck to fit S7 wheels, if they encounter clearance problems by running through less than six foot curves, that is their choice but I will not force it upon them.

If they want to go outside of the recommend operating radius then they're on there own, but it is nice to know there is another option available for those that wish to go that way :thumbs:.

Simon, I get the idea, but which ever option/change I choose, requires a change to the etches and I'm right out of energy to make any more changes ;) There's actually a significant amount of spring load on the rear trailing truck; due to the lateral force from the long wheel base there is a tendency for the rear truck to derail or tilt so it needs a strong downward pressure to remain level.

Right, back to the beast from below :headbang:
 

P A D

Western Thunderer
It probably sounds like anathema to many of an engineering persuasion, but I reckon a 3/16” axle on a pony truck would run in bearings made from the thickness of the etched n/s for several hundred real miles with next to no wear, given an occasional smear of grease / drop of oil.

That's what I did on the A4 as I prefer to use the normal Slaters wheels with 3/16 axles, although I doubled up the bearing surfaces with spare etchings. But as Mick says, buyers won't be running a W1 around Christmas tree curves will they? Maybe the one in Trafalgar Square. :)
 
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