Rolling a nickel silver boiler - how?

[Mol_PMB]

I've treated myself to a 7mm scale etched loco kit for Christmas, a Kitson 0-6-0T from 88d models.

I'm fairly experienced with etched kits but I normally build wagons or diesel locos.

The kit looks nicely designed and good quality, and all the etchings are nickel silver.

 

A flat piece of 0.3mm nickel silver is provided for the boiler, 0.3mm thick. At the firebox end it narrows so that a slot remains at the bottom for the motor to go into.

Looking at the disc formers provided, the boiler is 32mm outside diameter and around 100mm long.

Now I know from experience that nickel silver is very springy and much harder to curve smoothly than brass. Have I got a hope in hell of shaping this flat sheet into a tube? I don't have any rolling bars.

 

Apart from a couple of small holes on it to locate the dome and safey valves, there is no other detail on the boiler etch. So I'm wondering whether it's better to just buy a length of brass tube, which is available in 1.25" or 32mm OD.

For example I found this with a quick google: https://brasstubes.co.uk/product/32mm-brass-tube-new/

 

Any thoughts or advice would be welcome.

 

Cheers,

Mol

Edited December 21, 2021 by Mol_PMB
One letter typo

[Scottish Modeller]

Hi Mol,

 

There is a topic on here already

 

 

Without rolling bars - you will struggle......

 

Is there a club near you - ask if they have some

 

Are there other modellers near you - ask them

 

If you are close to me - I have a set that will take the size you are trying to roll.

 

Thanks

Phil H

[Mol_PMB]

Hi Phil,

 

Many thanks for the link, I'd done a search of the forum but for some reason that didn't come up.

Thanks also for the kind offer of asistance, sadly I'm nowhere near you but I will ask other local modellers that I know.

 

Cheers,

Mol

[Nig H]

2 hours ago, Mol_PMB said:

I've treated myself to a 7mm scale etched loco kit for Christmas, a Kitson 0-6-0T from 88ds models.

I'm fairly experienced with etched kits but I normally build wagons or diesel locos.

The kit looks nicely designed and good quality, and all the etchings are nickel silver.

 

A flat piece of 0.3mm nickel silver is provided for the boiler, 0.3mm thick. At the firebox end it narrows so that a slot remains at the bottom for the motor to go into.

Looking at the disc formers provided, the boiler is 32mm outside diameter and around 100mm long.

Now I know from experience that nickel silver is very springy and much harder to curve smoothly than brass. Have I got a hope in hell of shaping this flat sheet into a tube? I don't have any rolling bars.

 

Apart from a couple of small holes on it to locate the dome and safey valves, there is no other detail on the boiler etch. So I'm wondering whether it's better to just buy a length of brass tube, which is available in 1.25" or 32mm OD.

For example I found this with a quick google: https://brasstubes.co.uk/product/32mm-brass-tube-new/

 

Any thoughts or advice would be welcome.

 

Cheers,

Mol

You could try this technique.

 

Feed the sheet between two lengths of tube or rod and rotate them against the sheet to pull it through. The diameter of the rods governs the diameter you end up with. Practice on a bit of the scrap etch first to get the technique. The photos show me bending some 0,125mm nickel silver so 0.3mm might be harder to do but maybe worth a try.

 

 

 

 

I usually use a length of plain tube inside the nickel silver overlay so I bend the overlay to a smaller radius than the tube. The overlay is then a tight fit on the tube and the two can be soldered together more easily. You can force one end out a bit for taper boilers, and use a ring of larger diameter tube on the other tube at the big end.

 

Nigel Hunt

 

 

[Mol_PMB]

Thanks Nigel, great photos to illustrate the method! I'll try it with a bit of scrap.

I suspect that may work on a narrowish strip like the smokebox wrapper which will be very helpful to me, it may be a struggle with a 4" long boiler barrel of thicker material.

Cheers,

Mol

[ngtrains.com]

Mol,

next time your at Blodge go see Warren in Minffordd for a masterclass on boiler forming.

[doilum]

Poverty old school uses a length of thick broom handle and a couple of jubilee clips. The broom handle  can be padded out with masking tape to the  required  diameter. Rolling on thick card helps to get started.  Try practicing on recycled tinplate.

Edited December 19, 2021 by doilum

[davknigh]

Annealing the metal first by heating it to dull red and allowing to cool slowly will help cut down the springiness. Test drive the technique with a few bits of scrap first.

 

HTH,

 

David

[Pebbles]

15 minutes ago, doilum said:

Poverty old school uses a length of thick broom handle and a couple of jubilee clips. The broom handle  can be padded out with masking tape to the  required  diameter. Rolling on thick card helps to get started.  Try practicing on recycled tinplate.

Tinplate is relatively easy to roll, if I have  it correct we are dealing with nickel silver, an altogether springier metal. You could try to anneal the nickel silver, but this can be a bit hit and miss. As you have already invested in a kit, don't agonise, just get a pair of rollers; they will always come in handy.  

[Mol_PMB]

Thanks all - lots of options including a very kind pm offering to lend me some rollers. 

Cheers,

Mol

[Scottish Modeller]

4 hours ago, davknigh said:

Annealing the metal first by heating it to dull red and allowing to cool slowly will help cut down the springiness. Test drive the technique with a few bits of scrap first.

 

HTH,

 

David

Hi all,

 

Nickel Silver work hardens with heat....

 

Phil H

[doilum]

10 hours ago, Scottish Modeller said:

Hi all,

 

Nickel Silver work hardens with heat....

 

Phil H

I Knew there was a reason not to anneal it!!

Back in the day I built a few locos from low volume / budget n/s kits. A short length of 25 mm round steel bar (scrap go kart axle) made an excellent rolling pin. Once the curve is established the jubilee clips do the rest. That said if I could have afforded one at the time, a set of rollers would have had plenty of use by now.

Edited December 20, 2021 by doilum

[Stephen Freeman]

Experience and reading tells me that Nickel Silver can indeed be annealed. Perhaps you didn't get it hot enough, cherry red and don't quench. Of course you may then end up with it too soft, then you will need to heat it up again , quench and hope. I remember having to do it on wrappers for a cylinder casing on a Perserverence chassis kit for a 4mm Star, so know it works. Like Brass it does work harden though.

 

I do recall at one Guildex seeing Malcolm Mitchell on his stand using nothing more than a cloth, bar and his thigh to roll a brass boiler, I've always needed a set of proper rollers though.

Edited December 20, 2021 by Stephen Freeman

[Jol Wilkinson]

3 hours ago, Stephen Freeman said:

Experience and reading tells me that Nickel Silver can indeed be annealed. Perhaps you didn't get it hot enough, cherry red and don't quench. Of course you may then end up with it too soft, then you will need to heat it up again , quench and hope. I remember having to do it on wrappers for a cylinder casing on a Perserverence chassis kit for a 4mm Star, so know it works. Like Brass it does work harden though.

 

I do recall at one Guildex seeing Malcolm Mitchell on his stand using nothing more than a cloth, bar and his thigh to roll a brass boiler, I've always needed a set of proper rollers though.

Nickel silver needs to be 600 -700 degree to anneal (cherry red) according to an internet search.

 

John at London Road Models anneals the n/s boilers for his kits, then rolls them with GW rollers. Kit suppliers should provide boiler ready rolled as it is beyond most modellers capability unless that have a rolling mill.

 

Martin Finney also used to demonstrate rolling his kit boilers at shows, usually on the floor with a bar of ome sort and some track underlay foam. That is probably okay with short sections for taper boilers but not for longer parallel boilers.

[doilum]

8 hours ago, Jol Wilkinson said:

Nickel silver needs to be 600 -700 degree to anneal (cherry red) according to an internet search.

 

John at London Road Models anneals the n/s boilers for his kits, then rolls them with GW rollers. Kit suppliers should provide boiler ready rolled as it is beyond most modellers capability unless that have a rolling mill.

 

Martin Finney also used to demonstrate rolling his kit boilers at shows, usually on the floor with a bar of ome sort and some track underlay foam. That is probably okay with short sections for taper boilers but not for longer parallel boilers.

The question is, would you pay an extra ten or fifteen pounds for a pre rolled boiler? Having known a couple of budget kit manufacturers profit margins are slim on what is a hobby time enterprise. There is not only the time involved but the possible implications for packaging costs. Anyway boilers are the easy bit, wait until you try saddle tanks!!

[Michael Edge]

On 20/12/2021 at 00:02, Scottish Modeller said:

Hi all,

 

Nickel Silver work hardens with heat....

 

Phil H

No, heating softens it - working it (i.e. rolling it) hardens it again, so it might need repeated annealing. Nickel silver really doesn't roll very well which is why I rarely use it for boilers, brass is much easier to work with.

[Mol_PMB]

Thanks for all the info. In the end I have decided to replace the boiler with a length of brass tube, which has cost me about £15 on ebay. 

I suspect that even with rolling bars it would be a challenge to get something truly round and even from that piece of nickel silver, especially since there is no extra material provided at the edges. 

The brass tube will also be more robust (thicker wall thickness) and I can drill it for details such as washout plugs (not provided for in the kit) without fear of denting it. 

I haven’t actually started the kit yet, but will do in the next few days. I’ll probably do a built thread. 

[Jol Wilkinson]

10 hours ago, doilum said:

The question is, would you pay an extra ten or fifteen pounds for a pre rolled boiler? Having known a couple of budget kit manufacturers profit margins are slim on what is a hobby time enterprise. There is not only the time involved but the possible implications for packaging costs. Anyway boilers are the easy bit, wait until you try saddle tanks!!

 

Would it add £10 - £15  to the cost of a kit? If the alternative is a piece of tube at £15 and  which would be ideally should be turned to length, then rolling an etched boiler seems sensible for the kit manufacturer. Might the extra sales promoted by removing possibly the hardest part of the kit assembly for most modellers make it worth absorbing some production cost? Packaging cost (in 4mm at least) is something of a red herring unless you want to flatpack the kit which, if castings are included, is a poor solution anyway.

 

As for saddle tanks, agreed.  Which is why London Road Models supply cast resin tanks in their LNWR and L&Y saddle tank kits.

 

[doilum]

Whilst there is some merit in brass tube, most flat boilers come with the boiler bands pre etched and all the handrail knob holes started. If I had to rank the difficulty of tasks I would place the accurate  marking out and drilling on a curved surface way above rolling out the boiler. One scratch building wheeze I have deployed is to use a slightly undersize tube wrapped in a thin brass outer layer. This makes the attachment of boiler bands easier with the heat sink removed.

[Mol_PMB]

In this case, there are no pre-etched boiler bands. Indeed there are no boiler bands provided at all, despite the real loco having them. The loco does not have boiler-mounted handrails. There are a selection of washout plugs but again these are not provided for in the kit. 

The only features in the blank intended to be rolled into a boiler are holes marking the position of dome and safety valves. My prototype has different safety valves anyway!

 

for marking out tube I have had success by doing the marking out on a flat piece of paper which is then taped round the boiler and the marks spotted through. There can be a bit of iteration but it works fairly well. 

[Jol Wilkinson]

Boiler bands were generally 1/8" thick, about .04mm in 4mm and .07mm in 7mm.

 

.012" brass, the norm for 4mm etched kits is .3mm, .015" is .4mm and .018" is .46mm. So etched or even half etched boiler bands are too thick. Transfers or thin adhesive tape is a better way.

[LaScala]

I have built 2 88D kits and had few difficulties with boiler rolling. The broomstick and phone book routine works well and I didn’t anneal. I did use clamps and found the formers needed a subtle shave to get a good seam.

I think the first action to resolve this could have been to give Mike Morris a ring as he is a helpful fellow.

The big advantage of n/s is how terrific it is to solder.

Boiler bands should be almost invisible so the half etched option always looks way too heavy imo. 
Good luck with the build.