Silver soldering mamod loco's?

[Leicester Thumper]

Hi all,

 

about to embark on a project where I will be building a mamod loco, however, one thing i seem to have hit (whilst thinking) is that my 40watt soldering iron won't be powerful to silver solder?

 

as we know, mamods can get extremely hot, hence why silver solder has to be used or the normal solder will just melt???

 

so will i need a more pwerful iron? or is there a composition of solder that will hold under extreme steaming heat which is not silver solder???

 

if no, then i need to spend more money on another soldering iron.... again... (i broke dad's last month!!!)

[Guest baldrick25]

In my experience, silver solder needs a 'flame' type heater to get hot enough. For small work , these pencil-flame butane powered things work effectively ( take care not to overheat the workjob though, only takes a few seconds) or for bigger stuff , and a boiler sounds like that, a butane gas blowlamp will be needed. Take care as well that localised heat can leave the workjob distorted permanently.

 

Maybe I'm misunderstanding just what it is you are doing, but normal tin/lead solder doesn't sound quite strong enough for a pressure vessel, ie a boiler. Solder , I was always taught is not glue, and don't use it as such. A sound mechanical joint is needed first , and solder is just an electrical connection or small-gap sealer.

[Leicester Thumper]

the loco is O gauge, similar to those found in mamod train sets, everything needs soldering so all pipework and the dome.

 

the Dome covers a large hole in the boiler at the top in order to allow the water to go down the reinforced pipe to the cylinders.

 

the boilers are only small.

 

so maybe a gas powered pencil would do?

[ozzyo]

the Dome covers a large hole in the boiler at the top in order to allow the water to go down the reinforced pipe to the cylinders.

 

the boilers are only small.

 

 

 

If the water goes down to the cylinders, I don't think you know enough about steam locos to work on the boiler. Sorry.

 

 

IIRC the Mamods work at about 25psi that pressure will have increased the boiling point of water to about 125 deg. so normal solder at approx 188 deg.is not far off melting point and will be in the elastic state or not far off, and another thing to think of if a joint goes the boiler WILL try and empty All of its content out of what may start out as a small hole but it can increase in size very rapidly. The water will turn to steam instantly. If you work out the internal size of the boiler in square inches, all of them are pressed to 25psi. and all of that will try to escape from any hole in one go.

 

Google boiler explosions, it will open your eyes.

 

If in doubt DONT do it.

 

Sorry if I sound to be doubting your ability, but steam can kill, even in these small boilers.

 

OzzyO.

[Leicester Thumper]

D'oh, i meant in order t stop the water going down!!!

 

(long shift at work + tiredness = fail)

 

I know what you mean, but I have had mamods since I was 9 years old, and operated them every year since, it's just that until now, I have never had the opportunity/confidence to repair/build them myself, I know what you mean, i just needed to know what type of solder to use and what type of pencil/gun to use.

[bertiedog]

I am not treading on others advice here, I am sure it is sound and offered in good faith, but I am a trained boiler tester for Model Locomotive and boat boilers, and able to offer certification for small capacity model Boilers.

 

Before doing any work on even a low pressure boiler like a Mamod, you have to know precisely what you are doing, and exactly why.

 

The Mamod boiler, if in sound non leaking condition, is usually a very safe boiler, they run at about 15 PSI or so, and give very little trouble. They do deteriorate with age and hard water, but usually leak before they blow up.!

 

If you are after adding new steam pipes etc, they really should best be added to the existing copper pipes, with brass screw compression unions to suit the existing piping sizes, usually 1/8th external.

 

These unions are available from all good model engineering suppliers, and are soldered on with soft solder to attach the sealing rings, ( Yes, I know they are compression, but solder adds a bit of security), and then the nipples are screwed home with a touch of PTFE tape, or sealing compound, to seal completly.

 

The Mamod boilers themselves are made of a good grade of quality brass, and are soft soldered together with a high melting point soft solder (Pewter grade), not silver solder.

 

The reason for this is that silver soldering brass sheet risks burning up the zinc content, and rendering the brass brittle, or even porous,if wildly overheated.

 

This is the reason that brass fittings are not used on any boilers in direct contact with heat, or soldering by brazing, or silver solder, bronze is used instead. It is called de-zincing, and is dangerous on larger boilers.

 

If the Mamod boiler is simply leaking from a seam, it should be cleaned out inside with a good kettle de-scaler, and then the outside cleaned with a stainless steel brush, a plumbers flux added to the repair,and soft solder of a high melt point added, the old fashioned Tinmans grade. A 60/40 solder could be used for pin hole repairs. It will usually need a small gas torch to get the required heat, or a very powerful electric iron.(150- 200watt).

Modern pure tin solder is quite all right for repairs, the lead free type of solder with a higher melt point.

 

Once Brass has been soft soldered, it cannot then be silver soldered, the lead contaminates the surface, and silver soldering cannot take to the metal properly.

 

Silver soldering is strictly a gas flame job at 600c or more, dull red red or more, and is done on new metal, and rarely brass, except where no further heat with be applied. Easy flo silver solder is the usual grade used a medium free flowing solder, used with Easy Flo flux.

 

So in all the Mamod is a safe, soft soldered boiler, at a suitably low pressure to meet the regulations for toy and model uses

 

The boilers should not be interfered with as far as the safety valve goes, the simple "Nail head" and rubber seal they use is quite sound, and blows at safe pressures, do not change it for a higher rated one.

 

Under no circumstances enlarge the burners or give them bigger capacity of fuel, the water level is designed to last longer than the fuel for safety!!!!!!

 

If you are into Boilers, Garden Railways, and making small boilers with silver solder, make the from copper, with appropriate thickness's and designs, then you can up rate the whole boiler to higher and more efficient pressures.

 

I can recommend reading Terry Walshaw, (Tubal Cain)'s books on boiler making, also Ken Harris and of course the articles and books by Curly Lawrence (LBSC) of the Model engineer magazine. There are also books by Henry Greenly, and many modern authors like Stan Bray.

 

If you have any queries about boilers please just ask, they are not a black art or mystery, they are very easy to make, once you know how.

 

A mistake though with higher pressures than the Mamod can have very serious consequences, be guided by the experts, they have learnt from others.

 

Stephen.

[Kempenfelt]

I've used butane in the past but now use an oxy propane combo, sold as a turbo torch, check out CUP Alloys. Practice first before you attempt something you wouldn't want to damage! You'll need some good flux and appropriate solder too! Keith (CUP Alloy's) can advise. Would be worth finding someone to show you how, it isn't particularly taxing to learn. As per Ozzyo's suggestion's be careful, you talking serious burns now if it goes wrong, not just a burn from a soldering iron!

 

Here's a few pic's of one of my first soldering attempts. It's a 5" 21t hopper chassis and is taking place in my mates living room! He's got a missus now so all soldering now banished to the garage! This is by know means the ideal starting point but within most people's limits with practice and a bit of care!

 

 

 

 

I strongly advise googles btw and a bucket of water just in case!

 

Cheers

 

Paul

[Leicester Thumper]

i have seen someone who modified a mamod engine to have a tender containing a larger gas burner to give a longer running time, but what he cleverly did was put a pipe from the top front left of the cab down into the top of the boiler where he could get a syringe pop it in the top of the cab and squirt a load of water in one every ten minutes.

 

anyway....

 

yes, the only problem i have with the piping situation is, I also wanted to put the accelerator (or what have you) in the cab which means either routing a pipe from the dome to the cab or creating a new pipe elsewhere??? or shall i stay to the K.I.S.S. principle? (Keep It Simple, Stupid!)

 

EDIT: I am always conscious about safety, googles and eyeprotection will be worn at all times. and when the weather is nice the work takes place outside on hardstanding granite/concreted areas (on our property of course!!! although the church car park may be interesting )

[Kempenfelt]

Just read Bertiedog's response and very sound advice it is too! I didn't think about the boiler being brass or soft soldered, do take Bertiedog's advise on this! I have experienced the results of de-zincification, quite alarming when its on a blowdown valve for a 5" loco boiler!

 

As mentioned above, it really is worth getting advice from someone who has proven prior knowledge, ideallly from your local model engineering club!

 

Cheers

 

Paul

[Leicester Thumper]

Don't worry the advice has been safely saved on my computer!!!

[Kempenfelt]

Also, careful of using hard standing, slabs etc. My very first soldering fail was because I used a slab instead of a ceramic hearth. Even just a minute amount of water in the material will boil and in my case caused the slab to crack, propelling the job (which would have 600oC + across the room! Not good!

 

Cheers again

 

Paul

 

 

[Leicester Thumper]

Also, careful of using hard standing, slabs etc. My very first soldering fail was because I used a slab instead of a ceramic hearth. Even just a minute amount of water in the material will boil and in my case caused the slab to crack, propelling the job (which would have 600oC + across the room! Not good!

 

Cheers again

 

Paul

 

 

 

ahh yes.... I forgot about the oxygen bubbles in the slabs/concrete......

 

thanks!

[bertiedog]

Typical copper boiler, for a DeWinton vertical boilered 040 in 16mm scale, internally fired by butane, and rated at 100PSI, running at 80PSI, 4 inches tall, 1.7 inch diameter, all solver soldered, with bronze or nickel silver fittings.

Stephen.

[bertiedog]

I should mention the other maker, Wilesco from Germany, who were soft soldered, but changed to silver soldering at some point on certain models.

 

I am pretty certain most older Mamod's are all soft solder, but there is a chance others exist in silver solder, mainly modern production, which does continue in a small way from the new owners and current parts makers.

 

The visually simular Japanese Saito boilers are brass and silver soldered, and very high quality indeed, but again are lower pressure units, although some are rated at 30PSI, and in my own opinion require strengthening stays to be added to the ends, an east task that makes them super safe.

 

Mamod use a domed end or a dished end to provide strength, but again through screwed 1/8th bronze stays can be added to improve the safety.

To qualify a point, Mamod need no insurance or certification for normal uses, straight from the box. They are Toys and Models of approved design, and safe for normal use.

 

A model boat club, or a model railway club, may insist on a test or examination , and a certificate or insurance for public running of boilers of any type.

 

Model Engineering Clubs like the Southern Federation do not issue certificates for such small "toy type" boilers, not out of malice!!!!,..... but the tests for larger boilers would be the wrong standards to apply, far too rigorous.

 

So modify the boiler with care, seek advice adding pipes etc., to the structure of the Mamod, either the stationary or the Locomotive type.

 

With any Mamod system a very good idea is to provide a break in the supply pipe and sleeve it with a piece of silicon fuel pipe. the push fit will hold normal pressures, but leak should it rise on a failure of the safety valve.

 

You can also use silicon piping to do any steam joints, but it does look a bit odd! To neaten a copper pipe to copper pipe joint with a silicon sleeve, add electrical heat shrink black sleeving, the heat shrinks it to a perfect fit. Do not use near the boiler, but a bit further down the pipe. The heat exhaust from the burner would be too much for the plastic.

 

Also in passing never use silicon piping to transport gas to burners, this is highly dangerous as the Butane attacks the silicon. Copper or brass is 100% safe.

 

If you have the Garden Railway Mamod, they are excellent runners but need a few mods to improve them, and NUMBER ONE is to use real steam oil, a medium grade, not the grease!! Maidstone Model Engineering supply suitable stuff, it does work fine, with a startling improvement in running.

 

All normal mineral oils turn to soap in steam engines, and gum up the engine when cold, and do not lubricate properly. If the oil is too thick, add a dash of paraffin to thin it a touch, it melts with the heat anyway.

 

hope this helps,

Stephen. . .

[Leicester Thumper]

thank you very much Stephen!

[Happy Hippo]

I concur with all Stephen (Bertie Dog) has to say about boilers/fittings and the various typs of soldering.

 

If you do need parts for locos there are a number of companies that have 'Mamod' upgrades. These vary from replacement gaskets and 'O' rings all the way through to spirit burners and proper silver soldered boilers capable of working at 40 psi.

 

Try:

 

www.pps-steam-models.co.uk (no commercial interest)

 

Stephen has already mentioned building and modifying boilers, and we have been fortunate in this country that the main leads in boiler safety has been the model engineering federations and the smaller associations that use live steam, rather than a government department with no knowledge or experience of the subject. There have been a number of subtle changes to the rules and regs (EU compliance) concerning the size at which boilers require initial and then subsequent certification. I was suprised how big a boiler can now be before mandatory certification is required. (we needn't go into the calculations here)

 

However, that does not negate you from ensuring your boiler is safe to use, which involves a hydraulic test.

 

If you are into small steam locos and perhaps want to get out into the garden, then join the 16mm Association:

 

www.16mm.org.uk

 

They have a wealth of knowledge and a network of local groups that would be of great assistance. All the local groups have boiler test facilities.

 

Regards

 

Richard

[bertiedog]

Just to clarify, the lack of a test only applies to unmodified Mamod items, that are used as designed by the maker, and covered by the Approval Certification scheme the makers follow.

 

I would not consider adding pipes to existing pipes a modification requiring a hydraulic test, and would only test a modified boiler barrel.

 

However a club inspector would require a test steaming in their presence, and must test the safety valve truly works on a Mamod at the running pressure of about 15 PSI max.

 

I would not like to subject a thin brass boiler like a Mamod to a full hydraulic test, the stress may harden the brass, distort the ends or barrel, and lead to other failures. Two, to two and one half would take the boiler to 45/50 PSI, and I would not like to subject a Brass Mamod to this much pressure.(and never pressure test with air, only water to the brim).

Old Vintage brass boilers should be tested, but only to just above the working pressure, no more than +20 %, and only be operated with a fully tested safety valve known to leak at working pressure.

 

Original Victorian or Edwardian etc., safety valves should not be used, replace with a commercial or home made tested design for actual steaming.

 

All home made boilers, both brass and copper, would be tested and inspected for the materials used, with receipts or identification of materials including the type of silver solder used.

 

16mm RTR like Roundhouse, come with a Certificate, but the Associations and Clubs may insist on a re-test to establish the unit on the records of the Club for public demonstrations. You can use such items at home without restrictions at all.

 

Stephen.

[Coombe Barton]

It may be worth you contacting the Leicester Society of Model Engineers - http://www.lsme.org.uk/ - they will ahve the necessary contacts for testing, at least.

 

They have a public running session on May 1st-2nd in Abbey Park, according to their website.

[woodsman]

Hello All

 

I'm new to this forum and a newbie Mamod restorer.

I have an SE1 which I have owned since I was a young lad.

The water level plug was lost and the housing damaged, so I have replaced it with an insert and new plug supplied by Manor Models.

I soldered this (see pics) using a small butane torch and electrical solder.

Reading the contributions here, I think this may be unsafe.

 

I would be greatlul if anyone can advise me.

[bertiedog]

Indeed it may be unsafe, it all depends on the mechanical strength of the joint, did the replacement screw into place?

Or did it simply drop into place in the hole and was soldered?

• If simply soldered in to a hole it might get too hot if the water ran dry, unlikely with the original burner, quite frankly..
• If screwed in to a thread, and sealed with solder, then all is OK, as the same degree of heat would not reduce the mechanical strength, only allow a weep of steam at pressure.

So in both cases you are basically safe, but only if the original burner is used, with meths or the fuel tablets.

The pressure remains low, about 15 lbs at most, and Mamods valves usually blow at far lower than that.

Make sure the valve is clean and operating, that the water level is correct, and NEVER just add more fuel to a half empty boiler, one water load equals one fuel load for safety.

 

Hope this helps,

Stephen.

[bertiedog]

Generally soft solder can be used as a caulk to a sound joint, with the basic strength provided by the joint mechanics, screwing, overlap fit, riveting, flanges, all of which work against pressure on their own, the solder just acts as a final seal.

 

Pressure results from a temperature, and at a pressure a certain temperature has to be achieve to maintain the pressure, a boiler is far hotter than boiling water. The temepearature at which soft solder fails is reached easily in larger boilers, but even there soft solder is trusted as a caulking agent to sound joints.

 

With all toy units like Mamod and earlier German units , the pressure is very low, one bar or so max, and the temperature the solder fails at is not reached, but not when a boiler is dry, and the heat is still applied, at that point it may well fail.

 

But the Mamod uses simple fuel to get around this, meths trays or fuel tablets that will not get that hot in normal use. there is a large margin of safety.

 

So as long as no extra heat or a different safety valve are fitted, then all will be OK to repair with soft solder.

 

What you should not do is apply a gas torch as a heat source, or a different type of safety valve,and home made valves must be tested to ensure they blow as intended.

 

Stephen.

[bertiedog]

It may be worth you contacting the Leicester Society of Model Engineers - http://www.lsme.org.uk/ - they will ahve the necessary contacts for testing, at least.

 

They have a public running session on May 1st-2nd in Abbey Park, according to their website.

 

Regrettably some Model Engineer boiler testers will not test Mamod or small boilers below a certain capacity, as the rules that Societies use, like The Southern Federation, do not allow such tests to result in a certificate.

However most testers will give a nominal test and inspection , but without any certification or guarantee.

 

Mamod are usually non certified as such, or self tested units, so bear this in mind seeking help with testing.

As long as used as intended they are safe, it is modifications that may be more troublesome.

 

I have known testers who are distinctly unfriendly about any requests to tests, so be warned!!!!! approach this with not so much a request for a test, but to seek advice on running the Mamod safely.

 

Stephen.

[Donw]

No one seems to have mentioned that the Mamod back plate is part plastic so you can see if there is any water in it. I have two Mamods one has been fitted with a external gas burner which Tom Cooper used to sell. It works a treat but you do have to make sure there is enough water.

There is no legal requirement for these small boilers to have regular boiler tests but ALL boilers should be tested on construction or after repairs failure to do so would be negligent. Most 16mm groups would not allow one to be used unless it was checked which any competent repairer would do. IN fact the biggest danger is not an explosion, these boilers are too small, but a small fracture could release steam or very hot water under pressure which is not good for your skin and even less good for your eyes. It amazes me to see otherwise sensible people peering over an engine whilst raising steam you never know just when the safty valve will blow off. Ideally if you want to experiment with Mamods join your nearest 16mm group. You will enjoy the chance of running on others layouts. Meet people some of whom are probably experienced engineers and the group should have access to boiler test equipment.

I am looking forward to fitting a coal fired boiler to an edrig chassis, the boiler came whith a conversion kit, it's properly designed built and tested not cheap but I can have a lot of fun putting it together. Building your own really needs quite a bit of experience.

Don

[bertiedog]

The older Mamod have no window, Wilesco do, and some of the later Mamod boilers, especially the road vehicles.

But the basic principles should followed, one charge of water, one fuel load. In 16mm locos adding water is done, with a syringe as a pump, and extended fuel capacity is used, but you must know what the basics are before adding to the capabilities of the units.

Gas burners can be added to Mamod 16mm, but it needs other alterations, and really a new boiler to get the very best from them.

Other more advanced types like Roundhouse can be kept in steam indefinitely with pumps and gas re-fills. Same applies to Model Boat steamers.

 

Stephen.

[woodsman]

Generally soft solder can be used as a caulk to a sound joint, with the basic strength provided by the joint mechanics, screwing, overlap fit, riveting, flanges, all of which work against pressure on their own, the solder just acts as a final seal.

 

Pressure results from a temperature, and at a pressure a certain temperature has to be achieve to maintain the pressure, a boiler is far hotter than boiling water. The temepearature at which soft solder fails is reached easily in larger boilers, but even there soft solder is trusted as a caulking agent to sound joints.

 

With all toy units like Mamod and earlier German units , the pressure is very low, one bar or so max, and the temperature the solder fails at is not reached, but not when a boiler is dry, and the heat is still applied, at that point it may well fail.

 

But the Mamod uses simple fuel to get around this, meths trays or fuel tablets that will not get that hot in normal use. there is a large margin of safety.

 

So as long as no extra heat or a different safety valve are fitted, then all will be OK to repair with soft solder.

 

What you should not do is apply a gas torch as a heat source, or a different type of safety valve,and home made valves must be tested to ensure they blow as intended.

 

Stephen.

 

Thanks a lot Steven for your really fast response.

I have had the engine running at really slow speed and the joint remains dry.

The solder I used was Draper Expert and the joint was just a tight push in.

Once again, I'm grateful for your reassurance.

Incidentally, the cap on the 3 burner unit is a replacement and I found that the breather hole was too large

resulting in an overflow of fuel which caught alight and needed fast action to put it out.

I have soldered this over and drilled it with a smaller diameter hole which seems to have fixed the problem..