Any Question Answered

[Geordie Exile]

I'm blessed with a loft that will allow me a circular layout some 7.0m x 5.5m (ish).  The thought of a DMU trundling endlessly around a loop while I play with a specific bit of the layout pleases me no end.  However, does a loop of 25m mean that the resistance of the rails, or the 1.5mm cable I'm planning to use as a bus, will reduce the current so much that at the furthest point from the DC controller the said DMU will simply grind to a halt?  I know that DCC will give me a higher voltage, but I'm trying to avoid the expense and complexities of DCC.

[Nick Mitchell]

6 hours ago, Velocemitch said:

What are people using for primer on etched kits etc, top coat would be enamel.

ive tried an aerosol from my car resto collection, but I think the spray is a bit course for models. I seem to recal a discussion about certain aerosol brands, but not sure where. I could use my airbrush, but again not sure who’s paint.

 

Traditionally I have used Precision 2-pack etching primer, sprayed from a single action airbrush, and following Ian Rathbone's advice of thinning it with cellulose.

Like the little girl with the curl, when its good, its very very good, but when its bad it's horrid!

 

Recently I tried UPOL Acid8 from a spray can (bought in Halfords), and am happy with the results. I'm not convinced it is quite as smooth as the Precision primer at its best, and spraying from a can always feels more fraught somehow - especially outside when the wind always seems to know what I'm about to do and comes from nowhere!!

[Mallard60022]

4 hours ago, Geordie Exile said:

I'm blessed with a loft that will allow me a circular layout some 7.0m x 5.5m (ish).  The thought of a DMU trundling endlessly around a loop while I play with a specific bit of the layout pleases me no end.  However, does a loop of 25m mean that the resistance of the rails, or the 1.5mm cable I'm planning to use as a bus, will reduce the current so much that at the furthest point from the DC controller the said DMU will simply grind to a halt?  I know that DCC will give me a higher voltage, but I'm trying to avoid the expense and complexities of DCC.

I used Mains Copper wiring for my Power BUS 24 x 10 roundy roundy with some 4 track parts and a set of 7 storage sidings. One NCE supply with no booster and it can handle two running Loco's and a few others sat in various places. I  use a DC BUS for my Point Motor Power but they are all linked to the Track as are Two 6 inlet Frog Juicers.

No issues with power drop.

Phil

[martin580120]

I don't use enamels, well, much, so pinch of salt here - but I just use Vallejo or Army Painter airbrush primer - it's formulated for 28mm wargaming so is fairly good on the detail abs smooth finish.

 

Might be worth trying a Humbrol or Phoenix Precision or RailMatch black/grey/white enamel - either a spray or airbrush. Might take a couple of thin coats.

[Donw]

Voltage drop per amp per metre

 

1 sq mm   44mV

1.5 sqmm 29mV

2.5 sq mm 18mv

 

with a feed in the middle you would have no more than 5metres from the source  so at 1A 1.5mm cable 145mV however  a 2mm loco is more likely to be drawing 0.25A   so even if two locos running the draw would only be 0.5A

 

So i would suggest a voltage drop of say 75mV out of 12v would be negligeable . In fact the voltage may be less that that most of the time so say the loco is running on 7.5 volts ambling along 75mV  is a 1% drop between the middle where it gets full power and the extremes where it gets the 1% drop. Would you notice a 1% drop in speed?

 

Don

 

[bécasse]

You already have convincing replies on the voltage drop (or, more realistically, effective lack of resistance drop) on your proposed circular layout, but it might be worth adding one final statistic. The resistance of 1,5mm2 copper wire is all of 11,5 ohms per kilometre.

[Compound2632]

2 hours ago, bécasse said:

You already have convincing replies on the voltage drop (or, more realistically, effective lack of resistance drop) on your proposed circular layout, but it might be worth adding one final statistic. The resistance of 1,5mm2 copper wire is all of 11,5 ohms per kilometre.

 

Again, giving a voltage drop of 14 mV over 5 m at 0.25A .

[Velocemitch]

6 hours ago, martin580120 said:

I don't use enamels, well, much, so pinch of salt here - but I just use Vallejo or Army Painter airbrush primer - it's formulated for 28mm wargaming so is fairly good on the detail abs smooth finish.

 

Might be worth trying a Humbrol or Phoenix Precision or RailMatch black/grey/white enamel - either a spray or airbrush. Might take a couple of thin coats.

Thanks for all the replies, I’ve ordered some Phoenix etch primer and thinners, so will see how it pans out.

[Geordie Exile]

16 hours ago, Mallard60022 said:

I used Mains Copper wiring for my Power BUS 24 x 10 roundy roundy with some 4 track parts and a set of 7 storage sidings. One NCE supply with no booster and it can handle two running Loco's and a few others sat in various places. I  use a DC BUS for my Point Motor Power but they are all linked to the Track as are Two 6 inlet Frog Juicers.

No issues with power drop.

Phil

 

14 hours ago, Donw said:

Voltage drop per amp per metre

 

1 sq mm   44mV

1.5 sqmm 29mV

2.5 sq mm 18mv

 

with a feed in the middle you would have no more than 5metres from the source  so at 1A 1.5mm cable 145mV however  a 2mm loco is more likely to be drawing 0.25A   so even if two locos running the draw would only be 0.5A

 

So i would suggest a voltage drop of say 75mV out of 12v would be negligeable . In fact the voltage may be less that that most of the time so say the loco is running on 7.5 volts ambling along 75mV  is a 1% drop between the middle where it gets full power and the extremes where it gets the 1% drop. Would you notice a 1% drop in speed?

 

Don

 

 

12 hours ago, bécasse said:

You already have convincing replies on the voltage drop (or, more realistically, effective lack of resistance drop) on your proposed circular layout, but it might be worth adding one final statistic. The resistance of 1,5mm2 copper wire is all of 11,5 ohms per kilometre.

 

10 hours ago, Compound2632 said:

 

Again, giving a voltage drop of 14 mV over 5 m at 0.25A .

 

Fantastic, thank you all.  I'll drop this off my list of things that concern me, and go back to worrying about turnout operation, frog juicing, track bed composition, automatic decoupling etc etc etc 😁

 

Richard

[1965Nick]

I’m sure everyone will have their opinion or a different solution. But would you recommend to attach white metal castings to etched nickel silver? 
In a larger scale I would have soldered using a low melt solder or an epoxy resin like Araldite. 

[Valentin]

Every component (mostly white metal and brass, but also a small N/S bit) on this little Shay was put together using low-melt solder (70 C).

 

 

[Klaus ojo]

Valentin,

a really nice model and nice work! Thanks for showing

 

Please allow some questions:

There wouldn´t move any rods or pistons, would there?

Do you know the composition of the 70° solder?

 And is it brittle? (The Rose Metal I have is very brittle, appox. 100°C melting temp., contains Pb,Bi,Sn) My own attempts in soldering whitemetal were not so convincing until now...

 

The most common sources of the 70° solder do not tell much about composition but they should do so.

AFAIC there are mainly 3 alloys in that temperature range: Woods Metal is containing lead and cadmium  and the 2 other candidates are Indium alloys which are rather dear and so unlikely to be used (or explicitely would have been advertised therefore: for the 50g bar this is 10 quid for the Indium alone at sourcing )

The SDS I´ve found:  https://belmontmetals.com/wp-content/uploads/2017/09/SDS-Bi-Low-Melting-Alloys-1.pdf    (It´s the cadmium I´m concerned, not the lead.)

So precautionally keep your hands and desk clean .

 

cheers

Klaus

Edited February 9 by Klaus ojo
link repaired / 2 In alloys

[Chris Higgs]

19 hours ago, 1965Nick said:

I’m sure everyone will have their opinion or a different solution. But would you recommend to attach white metal castings to etched nickel silver? 
In a larger scale I would have soldered using a low melt solder or an epoxy resin like Araldite. 

 

A tip I have seen for soldering whitemetal to nickel silver is to tin the metal with normal solder, then solder the part on with the low-melt stuff.

 

But to be honest in 2mm I would glue, probably with a gel cyano.

 

Chris 

[1965Nick]

Thanks Chris, I’ve tinned nickel silver before and then soldered white metal castings to it using low melt but the space on your mk1 underframe kits to solder in gas cylinders and voltage controllers is way too small to get a hot soldering iron tip in. Cyano gel it is. 

[Valentin]

On 09/02/2024 at 08:24, Klaus ojo said:

[...]

There wouldn´t move any rods or pistons, would there?

Do you know the composition of the 70° solder?

 And is it brittle? (The Rose Metal I have is very brittle, appox. 100°C melting temp., contains Pb,Bi,Sn) My own attempts in soldering whitemetal were not so convincing until now...

 

[...]

So precautionally keep your hands and desk clean .

 

Hello Klaus,

 

I am afraid I am far from being such a good modeller to have any moving parts on a Shay in the 2mm scale. Apart from the PowerMAX motor and the wheels, the only moving parts are the bogies.

 

The 70° low-melt solder I purchased from Carr's many years ago. It's similar to this one, only it's not a wire, but a bar. It's not brittle at all, I use it by cutting with a scalpel small bits which I then attach to the joint with tweezers before soldering.

 

As for glueing parts together with CA... I never had any success - I admire those who can put kits together by gluing them. My advantage is probably that I've been using a soldering iron sice I was 8.

 

Edited February 10 by Valentin

[nick_bastable]

On 09/02/2024 at 08:24, Klaus ojo said:

Valentin,

a really nice model and nice work! Thanks for showing

 

Please allow some questions:

There wouldn´t move any rods or pistons, would there?

Do you know the composition of the 70° solder?

 And is it brittle? (The Rose Metal I have is very brittle, appox. 100°C melting temp., contains Pb,Bi,Sn) My own attempts in soldering whitemetal were not so convincing until now...

 

The most common sources of the 70° solder do not tell much about composition but they should do so.

AFAIC there are mainly 3 alloys in that temperature range: Woods Metal is containing lead and cadmium  and the 2 other candidates are Indium alloys which are rather dear and so unlikely to be used (or explicitely would have been advertised therefore: for the 50g bar this is 10 quid for the Indium alone at sourcing )

The SDS I´ve found:  https://belmontmetals.com/wp-content/uploads/2017/09/SDS-Bi-Low-Melting-Alloys-1.pdf    (It´s the cadmium I´m concerned, not the lead.)

So precautionally keep your hands and desk clean .

 

cheers

Klaus

Klaus

 

this works for me

 

https://www.langleymodels.co.uk/awd1/index.php?route=product/product&product_id=4643&search=solder

 

and I always wash after soldering filing etc

 

but use a dedicated tip on the Iron

 

 

Edited February 11 by nick_bastable
more info

[Doncaster Green]

I am just in the process of preparing my first set of Mk 6 wheels and I noticed that the crankpins are a much easier fit than the Mk 5 - little need for any real persuasion for them to slide in!  At the moment I have retained them using Loctite 603, is this strong enough or should I be looking at using some form of cyano.

 

John

[Smalltrainsgreatpains]

I guess the finish on a model is all down to personal preference.

What do you all use in regards to varnishes and sealers, acrylic, enamels?

[Caley Jim]

I finish locos and coaches with Ronseal clear acrylic satin varnish. For wagons I use matt paints. 

 

Jim

[richbrummitt]

 

19 hours ago, Smalltrainsgreatpains said:

I guess the finish on a model is all down to personal preference.

What do you all use in regards to varnishes and sealers, acrylic, enamels?

Citadel; because I can buy it locally, it doesn’t have an odour, covers well and it can be thinned/cleaned with water.

[richbrummitt]

22 hours ago, Doncaster Green said:

I am just in the process of preparing my first set of Mk 6 wheels and I noticed that the crankpins are a much easier fit than the Mk 5 - little need for any real persuasion for them to slide in!  At the moment I have retained them using Loctite 603, is this strong enough or should I be looking at using some form of cyano.

 

John

I believe 603 should out perform cyano in this application. 

[John Brenchley]

Can I ask any road or bridge engineers if they can tell me where the rail height is likely to be as it goes over the bridge in the below picture of the Pixon Lane bridge in Tavistock please.  Unfortunately, I haven't got any pictures at rail level. Track was lifted 40 years before this picture but it looks from the left as if it might have been roughly at the level of the stone course above the white line.

Also, can I confirm that the clearance of 12' 3'' is measured to the point below each of the vertical white lines, not the top of the arch.

Thanks

John

[2mm Andy]

Hi John,

 

You are correct - it is likely that the underside of the railway sleepers would be at the level of the stone course you mentioned. The attached sketch from some old British Rail notes might be of use, although it's not to scale.

 

You are right about the headroom - the signed headroom is that available between the white 'goalposts'. In practice it will be a few inches more than that displayed.

 

Andy (bridge engineer)

 

[Donw]

Agreed with Andy but depending on the period modelled  the road level may have risen slightly if the road originally was unmade. Nowadays with taller vehicles more effort is made to keep the maximum clearance possible.

 

Don

[John Brenchley]

Thanks Andy and Don

Very useful diagram thanks Andy

I'm just completing the woodwork for the next baseboard for my model of Tavistock so want to lay a road surface as well as the track supports so need to get the vertical heights correct.

Best wishes

John