DLT's SR Locos - Lord Nelson Craftsman Kit

[DLT]

Ok chaps, as you were....

That didn't work either, I couldn't drill them accurately enough as the drill wandered when it met the whitemetal/araldite joints.  I ended up back where I started with hollow cylinders.

So, its on to Plan C. (maybe this should have been plan B, or even A)  I'm making false cylinder fronts from brass, drilled (accurately this time) for the pistons and slidebars.   The Romford piston-sleeves have been soldered into them, and the fronts will be filed to shape to match the cylinders.  This way the whitemetal cylinders become purely cosmetic, and play no part in determining the accuracy.

 

 

 

 

Edited September 6, 2022 by DLT

[Tony Teague]

I am always stunned by your perseverance in the quest for accuracy!

A real lesson to us all.

Tony

[37Oban]

5 hours ago, DLT said:

Ok chaps, as you were....

That didn't work either, I couldn't drill them accurately enough as the drill wandered when it met the whitemetal/araldite joints.  I ended up back where I started with hollow cylinders.

So, its on to Plan C. (maybe this should have been plan B, or even A)  I'm making false cylinder fronts from brass, drilled (accurately this time) for the pistons and slidebars.   The Romford piston-sleeves have been soldered into them, and the fronts will be filed to shape to match the cylinders.  This way the whitemetal cylinders become purely cosmetic, and play no part in determining the accuracy.

 

 

Glad to know I'm not the only one to try and do something that looks easy, and fail, sometimes several times, before doing it the way I should have done in the first place!  I even make a memo to myself:  "Don't be fooled if you think it's going to be simple because it probably isn't!", but I keep forgetting to read it!

 

Roja

[DLT]

15 hours ago, Tony Teague said:

I am always stunned by your perseverance in the quest for accuracy!

A real lesson to us all.

Tony

 

Thanks Tony,

I'll usually try to eradicate what to me are glaring errors, but its just as much getting the thing to work properly and reliably at the same time.

 

11 hours ago, 37Oban said:

Glad to know I'm not the only one to try and do something that looks easy, and fail, sometimes several times, before doing it the way I should have done in the first place!  I even make a memo to myself:  "Don't be fooled if you think it's going to be simple because it probably isn't!", but I keep forgetting to read it!

Roja

 

Quite so Roja,

Even though I try to work out as much as I can beforehand, I still tend to crack and find things are more complicated than I thought.  You can't predict everything!

 

Cheersd, Dave.

[DLT]

Ok at last, this method is bearing fruit!  The "false front" to the cylinders seems to be the way to go.  It means you can control the alignment of the pistons with the sleeves and slidebars without having to machine/drill the whitemetal of the cylinders themselves with any degree of accuracy.

Anyway, here's how it all looks now.  You can see where the cylinders are whitemetal and/or solid Araldite.

 

 

 

 

And I'm very pleased to announce that it all seems to be working fine, everything sliding freely.

This is becoming one of the most complicated motion jobs I've ever done!  Which probably means I'm over-complicating it, something I normally do my best to avoid.

 

Cheers, Dave.

Edited September 6, 2022 by DLT

[N15class]

A nice solution to the problem. But I'm wondering if it would of been quicker to make new cylinders.

[DLT]

4 hours ago, N15class said:

A nice solution to the problem. But I'm wondering if it would of been quicker to make new cylinders.

Hi Peter,

Thanks for your thoughts.  I did consider new cylinders, but as the castings are fine both visually and dimensionally, that was unnecessary.  

I have in the past made new cylinders for a kit, but that was when the supplied castings were just misshapen, undersized blobs of whitemetal!

Not so this time.

Cheers, Dave..

[Jack P]

Dave, You're certainly doing a cracking job!

 

It's actually slightly re-assuring for me that its complicated for you. I thought maybe the reason I was finding the rest of the kit so hard was simply my inability to build kit, but maybe it was just a bit of a pig of a kit!

 

I really can't wait to see it all running!

[DLT]

Hi Jack,

As I've said before, what you have done with this model is excellent, as everyone commented at Taunton the other week.

Some issues with the valvegear stem from the slightly unusual prototype design, and the difficulty of accurately representing it.

You often end up with a trade-off between accuracy and working reliability, and I try to steer a middle course.

Cheers, Dave.

 

PS  I may need to take a short break from this project, while I get the narrow gauge stuff ready for the show in Littlehampton next weekend.

[Jack P]

Dave,

 

You, and others have been very kind about my work, its certainly humbling for a first kit building adventure! 

I understand what you mean, everything is bit of a compromise, I think your standards are higher than most, and it really doesn't look like much of a trade off!

 

No worries, there's hardly any time pressure here, (21/05/18 will mark one year since the start of the build), so please take your time, and thanks again for doing such a fantastic job!

[DLT]

Gulp!  Just realising that its been a month since I did anything on this project.

However, the (highly successful) 40th Anniversary celebrations of The 7mm Narrow Gauge Association (in which I was heavily involved) are now behind us, and I can return to paused projects.  Top of the list is finishing the N15X, so there should be some progress on here shortly.

Cheers, Dave.

[DLT]

Ok, one-pace forward, two-paces back time!

I'm looking at the front end of the valvegear, in particular the Union-Link and the Combining-Lever.  That is the horizontal rod below the slidebars, and the vertical rod it links to.  They should both be the same length, about 9mm.  However, the kit parts are not; one is 10mm, the other 7mm.  I think I can get away with using the 10mm for the combining lever, as it has to be cranked and that will reduce its apparent length, and I will make new union links to suit.  So not insurmountable.

Cheers, Dave.

PS  Photo is a crop from the Russell book.

 

 

Edited September 6, 2022 by DLT

[Michael Edge]

You can't see all of the combining lever in that photo, there's more of it behind the footplate angle but I can't see how it connects to the valve spindle.

[DLT]

Thanks Mike,

I can't work out exactly where the valve-spindle is.  Looking at the shape of the cylinders, I think it may be inboard and driven by a linkage that we can't see.

Cheers, Dave.

[Denbridge]

2 hours ago, DLT said:

Thanks Mike,

I can't work out exactly where the valve-spindle is.  Looking at the shape of the cylinders, I think it may be inboard and driven by a linkage that we can't see.

Cheers, Dave.

Yes. The valve chests on these were between the frames. Ive just tried to find my copy of Bert Perrymans book on the Remembrance, which has works drawings, but its vanished. I'll have another look later.

[LN850]

Perhaps these will help.

I also have an extract from the Pipe & Rod drawing, but it wouldn't fit in this post.

I can send in another post if it would help.

 

Mike

Extract_from_N15X_frame_drawing.pdf

[Michael Edge]

That's still not very clear, must be some sort of rocker but it's hard to see the pivot point. Are these outside admission piston valves? The return crank is back set.

[DLT]

Hi Mike,

Just had another look, here is a crop from the drawing in Russell's book, which appears to show a rocking lever (visible on the GA) but I still can't work out how it would work!

 

 

 

Edited September 6, 2022 by DLT

[gz3xzf]

1 hour ago, DLT said:

Hi Mike,

Just had another look, here is a crop from the drawing in Russell's book, which appears to show a rocking lever (visible on the GA) but I still can't work out how it would work!

 

 

 

 

Hi Dave, that explains it, I spent sometime yesterday looking at the drawings that LN850 posted and couldn't make out exactly how it worked, but that is much clearer. Normally the valve rod would be connected to the top (in this case) of the combination lever to operate the valve above the cylinder; what the designer has done here is connected that to a 1:1 lever with the pivot going through the frames, bringing the movement back down parallel to the cylinder centre line where the valve is beside the cylinder inside the frames.

 

I hope that make sense?

Edited June 20, 2019 by gz3xzf

[DLT]

Hi Bryan,

Yes, that makes sense.  I couldn't work out where anything was pivoted.

Not that it makes a lot of difference on the model, but I do like to know where everything goes and why, it makes the modelling so much easier.

Thanks very much, Dave.

Edited June 20, 2019 by DLT

[DLT]

I've made some progress on the model at last.  All the valvegear parts are now built and riveted together.  Next job is to blacken it all, and assemble it on the loco.

I'll post some photos later.

Cheers, Dave.

[N15class]

The combination lever is attached to short lever on the shaft through the frames where another short lever on the shaft drops down and is attached to the valve rod. Much the same as GWR  do but in reverse.

[DLT]

The right-hand crosshead (the replacement Romford/Markits product) with the etched droplink and combination lever from the kit added, plus the new union-link joining them together.

 

 

The left-hand side, with all the various valve-gear bits hanging in place.  Getting somewhere at last!

 

 

Cheers, Dave.

Edited September 6, 2022 by DLT

[LN850]

1 hour ago, N15class said:

The combination lever is attached to short lever on the shaft through the frames where another short lever on the shaft drops down and is attached to the valve rod. Much the same as GWR  do but in reverse.

 

Agreed. The shaft is fairly substantial, 4" dia. It is held by two bearings, the one on the outside is part of the bracket supporting the front of the top slidebar, that between the frames is held in a bracket attached to the frames using some of the same bolts as the outside bracket, clearly identified by dotted lines on the side view of the frame drawing.

 

The valve rod is attached to the drop down lever by a short rod.

 

Mike

[Jack P]

Dave, 

 

That looks faaaaaaaantastic, you are a true craftsman. I can't wait to see it all in motion! Please don't worry too much about the finish on the wheels or the body - I've decided to strip it when it arrives and repaint/re-line the thing.