MOK Standard 4 2-6-0 in S7

[richard carr]

Adrian

I bought some tufnal from Direct Plastics, it's not the best quality certainly not as good as Alan Harris used to supply.

Richard

 

[Silverystreaks]

Steve

I'm contemplating purchasing a MOK 9F kit at some time and should I do so it will be my first foray in constructing a kit made up entirely of Nickle silver etches rather than Brass.

Its a metal I have not worked with apart from chassis / valvegear and I wondered how different it is to work on compared to Etched brass especially when it comes to bending shaping the material.... which the Ivatt 4 has plenty of.

I do recall way back in my 80's 4mm days I scratch built a coal rail tender body for a Wills A3 and also replacement deflectors for an A1 but a whole 7mm kit is an entirely different challenge.

Regards
Bob

 

[mickoo]

Granted Nickel Silver is a stronger material but if designed correctly and the right thickness used, should be no harder than brass to bend.

The big plus is that is solders vastly easier and doesn't go green from the flux and best of all stays clean.

I develop and work solely in NS now, the only time I'll use brass is if it's some one elses work or the original parts are in brass, example, window or splasher beading.

There's marginal difference in cost and what little extra is far outweighed by it's cleanliness and ease of soldering.

Building O gauge on line safety flux works exceptionally well with NS and has no shelf life; so I've just stocked up on another two bottles for the future.

MD

 

[SteveB]

Hi Bob

I can’t really give you a comparison between brass and nickel silver because I’ve only ever worked with the latter. All I can say is that my first attempt at kit building was one of MOK’s Std 4 tanks and I was pleased with the results.

Nickel Silver tends to be a bit springy and needs a bit of ‘over rolling’ when forming the smokeboxes and boiler barrels, but I can’t imagine that brass would be much easier as I suspect its probably supplied in quite a hard state.

I personally, don’t think you would have anything to worry about. I have one of his 9F’s to do, and although I haven’t started it yet, it would seem to be a very high quality kit.

Regards

Steve

 

[markjj]

If I had my choice Bob it would be nickel silver every time. Unfortunately it carries a high premium with many suppliers and they often won't touch it now. Until you have built a nickel silver kit I doubt you will realise how much different it is.

 

[Silverystreaks]

Mick, Steve and Mark thank you, your replies were immensely helpful. I have always fancied doing a 7mm MOK kit and I've thus far held back on the other 9f kits that are available
My only experience of MOK was their Class 40 released way back in 1984/5 and which to me remains to be the best looking Class 40 in 4mm and one of the few items in that scale that I retained after moving up to 7mm.

Thanks again

Regards
Bob

 

[SimonT]

Bob,
I am just coming to the end of building the BR1G tender for my 9F. It is astonishingly good in design made better by the use of NS. I loath brass and even had three 42XX etched in NS by DA before he stopped doing NS. Crisp folds, easy soldering, no tarnishing, paint adheres better.
Simon

 

[richard carr]

Bob

I can only agree with Simon's comments, nickel silver is much much nicer to work with than brass.

Richard

 

[Mr Grumpy]

Whilst I’m waiting for loco etches, I thought I might as well get on with the rest of the tender. If the tender is anything to go by, then this will be a very enjoyable build. I thought the Std 4 Tank was good, but this is better. Having only built MOK kits so far, I think I’m going to ‘come back down to earth with a bump’ when I try another manufacturer! In my collection of kits to build, I do have one of Dave’s 9F’s and a Finney7 WC, so it’ll be a while yet.

The instructions in the kit are a bit daunting but quite straight forward. The whitemetal sides were soldered on (as recommended in the instructions) with 145deg solder with the iron set at around 300 deg. The whitemetal is such a large heat sink, it worked fine, although I must admit, I was quite nervous about it to start with.

I was fortunate to see Scanlons thread on his build of the 2-6-0, so I was aware that I shouldn’t fit the water pick up and that there were missing rivets on the back.

Incidentally, can anyone advise me about what they did with the Water Scoop Handle? I assume, they wouldn’t have fitted it, but what would they have done? I’ve looked at Scanlons photos. It’s difficult to make out, but it looks like the handle boss was there, just not the handle itself, can anyone help please?

Its actually a shame about not having to fit the Water Scoop. The castings supplied are really nice.

View attachment 64338
View attachment 64339
The holes in the coal space will be for my tender speaker. I came across an interesting article regarding speakers and sound. I’ve mentioned it before in a previous post.

www.youtube.com/watch?v=j4kgLeDltxg

Well worth a look. I carried out some trials myself as I didn’t really believe that a speaker would actually be better when it’s not mounted in an enclosure, but it’s all true.

Regards


Steve

Hi Steve,
This is a fascinating and absorbing thread with some top quality information flowing both ways
Thanks for the speaker installation link, that is really interesting
Also, that tender looks superb! I'm really struggling to hold back on my 9f, but feel I still need more experience to be able to do it justice Hopefully @SimonT will post some photos of his build (any chance of some photos of the tender please Simon? I also have the BR1G)

 

[SteveB]

Well, that was quick. I emailed the dxf files to PPD on 20th Feb and the etch was delivered to me this morning. I took Mickoo’s advice and asked them to sandwich the etch between two pieces of hardboard. It arrived in perfect condition.



The 76xxx items all look good but I think I’ll need to redo the 8F Tender sides. The problem is the size of the etched rivets, they’re really too small. What I hadn’t made enough allowance for was the amount of ‘over etching’ thats done. An item that’s 100mm long will be shrunk by around 0.1mm but so will a 0.4 dia rivet. In fact it looks like the rivets were over etched even more. Probably caused by the entire top surface being etched away. The rivets are still there, but only just. I probably should do some test pieces to see what actually is produced.

The material is 0.45mm thick NS and I had drawn the rivets at 0.4mm, I think 0.5 would have been better. I had also made a mistake with the beading around the tender side. For some reason, I had stupidly put the beading on the rear vertical edge as well! Easy enough to correct, but with the rivet issue, it make sense to do the whole lot again. Still, it means that I can crack on with the 76xxx whilst I get another etch done.

I’m reminded of the saying, “he who never makes a mistake never makes anything”. I must have made an awful lot of thing then!

I’ve been getting on with the rest of the tender.



It wants a good clean, but I’m pleased with how it’s gone together. Still a few bits to go on. I haven’t bothered documenting the build, because it’s been very straight forward. The only error I found was that a small half etch recess had been put on the wrong side for the front steps. Easy enough to correct, but given MOK’s previous performance and reputation, it took a fair time for me to accept that it was an error with the etch rather than my own.

Now all the weight is in the tender, I’ll be able to test out the suspension and ride height. That’s the next main job. I've also finished a few of the 3D files for the replacement castings. I'll post a few images, later on.


Regards


Steve

 

[SteveB]

I spoke with Dave Sharp today, and he’s quite happy for any new etch or castings to convert the 76xxx to S7 to be made available through the ScaleSeven Group. It’s still early days yet but I’ll email the Trade Liaison and Stores people to make them aware and to see if they want to proceed with them.

In the meantime, I’ve started with some of the 3D files. I’ve drawn the cylinders as well, even though these wouldn’t be too difficult to alter. It’ll be interesting to see how they come out.


I've still got the weighshaft brackets and an injector bracket to do.

Regards

Steve

 

[SteveB]

The tender is just about finished, although theres still a few things to do. I’ve been playing around with different gauge piano wire for the CSB. I’ve been quite surprised how much difference even a 0.001” change in diameter can make. I’ve settled on quite a soft spring of 0.016” (0.4mm). It seems to work quite well going up and down my 6’ test track but it’s quite easy to change, if necessary, when I can try it out properly.





The missing rivets on the side of the water tank is not where I've slipped with a file! They were actually missing on 76026. I don't know why. All other photos I've seen of BR2 tenders show them. Anyone know why 76026 was different? I assume they were just countersunk rather than snap head.

I’ve started doing the loco frames. The frames as supplied have a rigid front axle. The photo below shows how I used my chassis jig to, hopefully, ensure correct spacing. You’ll see a small ‘bridge’ linking the two sides of the hornblock. This is just to help keep the two sides vertical until soldered.


The completed frames.



The chassis went together quite well, although I did get a couple of the tab spacings wrong, I’ll correct these, so any future etch will be okay. The frame spacer at the front end of the chassis is quite different to the MOK one, as I intend to fit a small speaker.




My skills must be improving a bit, each of the spring castings were threaded 12BA so the springs themselves, can be removed and I didn’t break a single tap.

I’ve finished the 3D solids for all the ‘changed’ castings and I’ve got a price from Shapeways for producing them in brass. After I picked myself off the floor (very expensive) I sent the files to a more conventional caster for a comparative quote. I suspect this will be dearer because rubber moulds will also have to be made, but it’ll be cheaper for any subsequent batch. I’ll publish the prices when I get the second quote.

Next step will be to make a set of axleboxes so I can get a rolling chassis with coupling rods.

Regards

Steve

 

[adrian]

That is an impressive/professional modification to the kit. The CSB fulcrum points look like they have been soldered on, were you not tempted to etch them in the frames to fold up? Or were you still experimenting with their position?

Adrian

 

[SteveB]

Hi Adrian

Thank you for your compliment. The frames are as supplied from MOK, I just had new etches done for the spacers. I've actually copied the fulcrum positions from your notes on the 2-6-4T as the wheel centers are the same.

Regards

Steve

 

[SteveB]

One of the most important lessons I’ve learnt in life is to manage people’s expectations. If something has gone wrong, make it sound worse and then when reality is known then the bad news can become good! I know it doesn’t work for every situation, but there’s quite a few were it would be appropriate. The reason for waffling on, is that I thought the price from Shapeways was expensive, well I’ve just had a price from a well known model railway supplier and there price makes Shapeways look like bargain of the century!

Here’s what I’m trying to get made.



The price from Shapeways to produce them in bronze from the 3D files is 220 Euros. The price from the well known UK model railway supplier is £700 just to get to the stage that waxes could be produced. I’m sure that there would be a big difference in terms of the quality of the parts, but even so............

The large part of the cost from Shapeways is for the two cylinders, so the smaller parts would appear to be quite reasonable. Depending of course on what the quality of their castings is like. There’s only one way to know, so I placed an order with them today. I chose to order the cylinders as well, even though I could quite easily modify the MOK ones, just to get a better understanding of Shapeways capabilities. I will post some photos, when they’re delivered. They may all end up in the bin. We’ll see.

The reason why I specified bronze rather than brass is that there was no difference in price and based on experience gained from doing other LWC for Steam Traction World, the casting definition always seems better when bronze is used. Our castings are quite a bit bigger though, so maybe, that makes a difference.

I’m told by Shapeways that delivery should be expected by the end of the month, so at least their service levels are quite good.

Regards

Steve

 

[adrian]

The reason why I specified bronze rather than brass is that there was no difference in price and based on experience gained from doing other LWC for Steam Traction World, the casting definition always seems better when bronze is used. Our castings are quite a bit bigger though, so maybe, that makes a difference.

Thanks for posting - always interested to see developments like this. I've always considered bronze was harder and more brittle than brass, so I'd be interested to see how you get on with tapping the various attachment points. Personally I'd have chosen brass for being easier to tap and solder.

 

[SteveB]

Hi Adrian

Drawn bronze is a nightmare to drill and tap, even worse than copper. Cast bronze though, is normally okay. I must admit, I've never soft soldered bronze but I wouldn't have thought there would be much difference to brass. Perhaps I'll live to regret my decision.

Regards

Steve

 

[Brian McKenzie]

Steve,

The one time I asked for 'raw bronze' castings, they arrived as 'polished bronze' in error! The finish of the free replacements was unsatisfactory. In Shapeways language, "raw bronze displays a subtle marbling effect". There might be time to change your order to raw brass - should you wish (recommended).
Did you check to see what waxes only cost? I am slightly suspicious that some Shapeways waxes may be made at coarser layer thickness levels - when they also get to do the metal casting. Buying waxes only gives you more downstream options.

-Brian

> One of the most important lessons I’ve learnt in life is to manage people’s expectations.
> If something has gone wrong, make it sound worse and then when reality is known then
> the bad news can become good!

 

[SteveB]

Hi Brian

Thanks for the advise. I've just tried to change it and my order is shown as 'in production'. I think the way Shapeways operate, is actually quite good, but it could be much better. Perhaps by being able to select resolution, orientation etc and miss the rumbling stage would be good. Anyway, we'll see what turns up. I am looking at this as very much a learning exercise.

Regards

Steve

 

[SteveB]

Did you check to see what waxes only cost? I am slightly suspicious that some Shapeways waxes may be made at coarser layer thickness levels - when they also get to do the metal casting. Buying waxes only gives you more downstream options.

I've just looked at the wax costs and they're around 70% of the overall cost. Have you found anyone in the UK that would use these waxes? When I enquired a few weeks ago, I couldn't find any caster prepared to use them. It would probably be the best option as I could work on the waxes before sending them off.

Regards

Steve