7mm Dikitriki's Dark side: A WD 2-8-0

[Dog Star]

Centre right ( and just to whet Graham's appetite ) is a completed return crank which just needs a little tidying up.

Please do not upset the natives by offering tantalising glimpses! If the photo shows what you have achieved with the return crank then best "words and music" are a necessary contribution to feed and placate the members (can you hear the chairs scuffing on the lino in the rest room?)

regards, Graham

 

[Len Cattley]

Steph, yes and no, more detail shots but not Scots, they're all from Jubilee 'Bahamas' at NRM last month, many common parts if your doing a rebuilt Scot version, but your welcome to the lot if you think any of them will help, as is anyone here for that matter. Interesting, when poking under 'Bahamas' she's only a two legged donkey at the moment.

Surprised to see Richard note original Partiots had the same gear as Jubilees, one being Stanier and the other Fowler, I think Stanier produced his own style of gear, though much was probably taken from earlier designs and to all intent and purposes looks the same, but suspect there were subtle differences etc.

Hi Mick, would it be ok if I downloaded your photo's as I have a Rebuilt Scot to finish off and have little pics of the valve gear?

Len Cattley

 

[mickoo]

Len,

Of course you can, help yourself, hope they are of some use to you for finishing your Scot, some pictures of your model when you finish or even as you go along would be grand.

Kindest

 

[Len Cattley]

Hi Mick, will photo as I go but have to finish off some 4mm stuff first as SWMBO said she would throw them out if I don't do it by the end of the year .

Len

 

[iploffy]

Well I don't know Tricky has an anti dazzle cutting mat pattern copied off the Bismark

 

[alcazar]

Is that return crank 7mm? And are you using Scale Hardware? If so, what size?

 

[Dikitriki]

Is that return crank 7mm? And are you using Scale Hardware? If so, what size?

Hi

Yes, everything I do at the moment is 7mm. I haven't done any 4mm in 15 years or so.

I shall go through the construction of the return crank in a while (and I will say exactly what I did/used), but yes, I do use scale hardware components. There are 11 separate pieces in each return crank.

Richard

 

[Dikitriki]

More progress.....



Top is the crosshead (and just below it the new pin). If you refer back to the earlier pic of the dismantled valvegear, you will see that the gudgeon pin was represented by a simple nut and washer. I had some spare pins from DJB which better represent the castle nut, so I filed the old one off and drilled through for the new one.

Bottom far left is the shortened expansion link - shortened so it won't clout the top of the Gladiator bracket. Inside that is the other half tidied up and with the centre bearing hole drilled and a reprofiled link at the bottom. It's not right, the bottom link is a little small, but it's close enough, and the bearing hole will be in the right place.

On the right is the first part of the return crank. I filed a new one from scrap chassis etch, drilled holes at the same centres as the one provided in the kit and market it for the 4 securing nuts. You can see my drill wandered a bit - it's only a .45mm hole - but I shall 'drift' the holes to the correct positions by using a drill as a miller, and the holes will be oversize anyway so I will have wiggle room for final adjustment of the nuts. On the far right is a miniature top hat bearing. That will go through the crankpin hole at the bottom.

To be continued....

Richard

 

[Steph Dale]

On the right is the first part of the return crank. I filed a new one from scrap chassis etch, drilled holes at the same centres as the one provided in the kit and market it for the 4 securing nuts. You can see my drill wandered a bit - it's only a .45mm hole - but I shall 'drift' the holes to the correct positions by using a drill as a miller, and the holes will be oversize anyway so I will have wiggle room for final adjustment of the nuts. On the far right is a miniature top hat bearing. That will go through the crankpin hole at the bottom.

To be continued....

Richard

Thanks Richard - I've just sussed what's going on here (or maybe just worked out how I'll make it work!). Nice to know I'm not the only one who seems to get irritated by either the lack of chassis/motion detail or it being incorrect.

Some useful tricks there, which I shall apply to the Scot and City in due course...

Steph

 

[Dikitriki]

Return Crank part 2.....



Before doing anything further, I soldered the return crank shown in the last photo to a piece of half-etched nickel silver and cut out another, thin, return crank. This will form the outer layer. All holes except the crank pin hole were drilled through again. This is the piece on the right.

I then soldered the top hat bearing in from the back on the original crank with 60/40 solder, and filed the front flush.

The remaining components are Scale Hardware. The nuts are SMHN-07-B 0.7 hex nut with stud, and the washers are WASH-05-B o.5mm washer. They are tiny!

Richard

 

[Dikitriki]

Return Crank Part 3....



I've now soldered the nuts and washers to the front of the thicker part of the return crank and enlarged the holes in the half-etched front piece so it sits nicely on the rear piece, and the washers are in the holes.

The must-not-forget part comes next - tapping the bush for the crank pin 12BA.

Richard

 

[Steph Dale]

Return Crank Part 3....
The must-not-forget part comes next - tapping the bush for the crank pin 12BA.

Richard

Erm, shouldn't that be 10BA? Slater's crankpin buches are 12BA clearance for the screws they provide...
I'm assuming you're advocating the use of threaded bushes and 10BA crankpins?

Steph

 

[Christian]

Yes, very clever Richard

 

[Dikitriki]

Return Cranks, final part.

In this case, I did mean 12BA. I am happy to use the Slater's 12 BA crank pins, though I do sometimes use 10BA, even mixing and matching on the same loco. In this case, as a rebuild, I am having to use the original builder's bespoke crank pin bearings. The holes in the coupling and connecting rods are large - a Slater's crank pin bearing drops through - and the bespoke bearings were 12BA clearance, and too long for me to tap all the way through 10BA, so I am keeping to 12BA.

You will have worked out, of course, that this method can be adapted to anything - tapped 10BA, soldered directly to crank pin caps a la Mundy or Harris.

Anyway, final pics of the day - the completed return cranks...








A sigh of relief that they worked well, but a fair bit of careful work.

Richard

 

[adrian]

Very nicely done - I too shall be copying this method. What thickness was the thin top shim?

 

[alcazar]

Very nice. Have you ever had to do one with a pinch nut and square ended shaft?

Also: you drilled it 0.45mm, the bolts were 0.7mm(??) and the washers 0.5mm?

I assume the 0.7mm refers to the HEAD of the bolt, what does the 0.5mm refer to?

 

[Steph Dale]

Thanks for the clarification Richard, that makes perfect sense to me now.

And will be plagiarised mercilessly...

Steph

 

[Dikitriki]

One thing I forgot to say. Before soldering the top shim to the return crank, I put a little marker ink on the return crank around the threaded bush to stop any solder contaminating the threads.

Very nicely done - I too shall be copying this method. What thickness was the thin top shim?

0.165mm

Very nice. Have you ever had to do one with a pinch nut and square ended shaft?

No - and I wouldn't know what one of those looked like!

Also: you drilled it 0.45mm, the bolts were 0.7mm(??) and the washers 0.5mm?

Yes, the bolt heads are 0.7mm. The holes in the washers are 0.5mm, the outside diameter approx 1mm. Funny way of describing them really.

I assume the 0.7mm refers to the HEAD of the bolt, what does the 0.5mm refer to?

I must admit I was looking at the return cranks last night and wondering whether it was really worth it - it's about 2 1/2 hours work per crank. You can hardly see that the bolts are hex with the naked eye, and the photos posted are about 10 x full size.

In the end, I came to the conclusion it was worth it - because I can, because it stretches my ability, but most importantly, because that's what the real things looked like, and that's what we're trying to reproduce. I do think that my kitchen table efforts are a bit amateur compared to the techniques some of you lot use though!

Cheers

Richard

 

[7mmMick]

Very nice indeed Richard. If you have a similar mindset to myself when I'm pondering whether to carry out some detail work I always end up carrying it out rather than not as in the past I haven't and i'm never truly happy with the finished result. Even when the piece is finished and people offer compliments in my mind I always know the compromise and it gets to me. Oh dear I appear to have beared a little of my OCD personality !! Ok quietly off to the back of the class whence I came,

ATB Mick

 

[adrian]

0.165mm

Cheers - 6-1/2 thou in Christian units!

alcazar said: ↑

Very nice. Have you ever had to do one with a pinch nut and square ended shaft?​

​

No - and I wouldn't know what one of those looked like!​

I presume he meant the LNER style return cranks.

On the "Standard" 4 tank some were built with the LNER style return crank and some with the LMS style 4 bolt return crank. Guess which version is in the MOK kit and which style is on the loco I chose to model? Hence my interest in what you have done so effectively.

I must admit I was looking at the return cranks last night and wondering whether it was really worth it.
<snip>
I do think that my kitchen table efforts are a bit amateur compared to the techniques some of you lot use though!

Yes it was worth it and nothing amateur about it, does it matter how it was achieved when you get results like that?