Sam builds a mamod (was building pioneer)

[Lner fan Sam]

Another question guys.

I have decided to use the original boiler. It will be operated up to 26psi. I have a top up valve that is for use for boilers at 40psi. Can I still use this top up valve in the original boiler. (its threaded to 1/4 BSF)

Thanks in advance for the help Sam

[dougrail]

Hi Sam,

Fraid not, in short.

For some reason, the standard boilers and superboilers [IPE, DS, RWM, PPS, (Chaney?)] have different threads. In short, a 26psi SV for brass boilers won't work on a copper superboiler as made by the above, nor wil one of the above's 40+psi SV's work on a brass boiler loco.

One thing one has to consider when they consider just how far they want to upgrade and spend.

[DLRdan]

IF they are the same thread you can use it Sam but if not they are not hard to make, I've got it down to 25 mins

[Lner fan Sam]

Thanks doug and dan!!

I did try it in the boiler insert and it did fit but was rather tight (then again mss think that painting THREADS is good build quality)

Why mss why????

[dougrail]

Apparently one can make a standard Mamod 'nub' 12psi SV work akin to a 25psi SV by messing with the spring. Not 100% on it but believe it doable.

Dan, as an offtopic, very quickly, if you can make water topups in 25mins, may I ask how long it took to make the custom domes NarrowM and I have?

[DolwyddelanLightRail]

For some reason, the standard boilers and superboilers [IPE, DS, RWM, PPS, (Chaney?)] have different threads.

There is a reason for it...

*Insert image of someone accidentally fitting 40psi safety valve into 26psi boiler...*

[dougrail]

For some reason, the standard boilers and superboilers [IPE, DS, RWM, PPS, (Chaney?)] have different threads.

There is a reason for it...

*Insert image of someone accidentally fitting 40psi safety valve into 26psi boiler...*

Exactly that. But surely the sight glass window might blow first?

Regardless...yea, let's not go there.

[DLRdan]

Dan, as an offtopic, very quickly, if you can make water topups in 25mins, may I ask how long it took to make the custom domes NarrowM and I have?

Some where between 3 and 4 hours, probably 4 if you include the time to re-set the lathe.

[Chris Cairns]

The original question from Sam was could he fit a 1/4" BSF water top up valve into his MSS boiler, not a high pressure safety valve.

The answer is Yes as the Mamod SL/MSS boiler inserts are threaded 1/4" x 26 BSF. Some of these have not been cut very well by Mamod/MSS or your after market manufacturer so you may need to use a 1/4" x 26 BSF tap in the boiler insert. I had to do that to the boiler inserts of an SL1K.

It is also possible to adjust the pressure setting of a standard Mamod/MSS 1 Bar safety valve by compressing the spring more (Tony Bird did it on the Unofficial Mamod Forum on Page 2 of this Topic - http://modelsteam.myfreeforum.org/ftopi ... asc-15.php ). Another quick method is to fit a second 'O' ring under the top of the safety valve which effectively compresses the spring more.

The current Mamod now do a standard 40 PSI safety valve for their locomotives, as fitted to the Mark II, Saddle Tank & Brunel locomotives.

As to why the after market high pressure replacement boilers have a different thread size I think that one has been lost in history. It is my question for RWM & Dream Steam at Peterborough. The current Mamod locomotives have a sight glass plastic yet operate at 40 PSI, and I have a Mike Chaney replacement boiler where one insert is 1/4" x 26 BSF for the water top up valve, but the other is 1/4" x 40 ME for his safety valve which is also not adjustable. IP Engineering did a 1/4" x 26 BSF 25 PSI safety valve for the Mamod/MSS's but it could be adjusted higher towards 40 PSI.

Sam as you are now using the MSS boiler at a higher pressure with a gas burner I would recommend that you strengthen up the solder around the boiler bottom fitting, as I detailed in my MSS kit build instructions. It is soft soldered so cannot be silver soldered instead.

IP Engineering had a wise warning with their safety valve instructions - Please note that the boiler or any part connected to it must be capable of withstanding the increased pressure achieved by fitting this valve.

Some modellers have reported a hydraulic pressure test on a Standard Mamod boiler, where the sight glass developed a leak at 120lb/sqin, sealing again at when the pressure was reduced to 60lb. This would appear to indicate that the boiler is quite safe for use at 25lb/sqin, and possibly up to 40lb.

Chris Cairns.

Edited to include updated URL & reference.

[Lner fan Sam]

Thanks Chris, but for safety reasons I am using meths for firing.

James converted me at narrow gauge north

[Chris Cairns]

Sam, the advice about that boiler bottom fitting equally applies to a meths burner as the middle burner tube is very close to that fitting. I put a 3 wick burner in my MSS Saddle Tank and that fitting ended up leaking despite keeping proper water levels. Took me 2 goes to get it soldered up steam tight.

I trust that you will take care with your wick height. Unlike James's fireball Britomart your MSS boiler has a plastic sight glass which will melt if your meths burner flames get too close. I've already highlighted a possible blow back problem with the deflectors fitted to these burners ( http://gardenrails.myfreeforum.org/about6231.html ), and if you look at another recent Mamod that James has apparently advised on you can clearly see that the burner is already badly affecting the cab front - http://modelsteam.myfreeforum.org/The_N ... 61034.html

For an example of a meths melted sight glass experience see Page 2 of this Topic - http://gardenrails.myfreeforum.org/about86.html

Chris Cairns.

[Narrow Minded]

First rate info and superb presentation again Chris!
I'm really miffed that I won't be at Peterborough since I'd really like to shake your hand!

[Peter L]

How would go about stenghtening that tube. I'm planning a similar conversion and am following this thread with interest.

[Chris Cairns]

Peter if you scroll down to my 8th posting on this Topic you will see some photos and a diagram explaining this problem - http://gardenrails.myfreeforum.org/Buil ... t6201.html

If you are starting with a paint stripped boiler it is easier and I take the opportunity to solder around the top boiler inserts as well, then use a file or some fine wet & dry sandpaper to clean up the excess solder.

If you are doing it on a new boiler then remove as much paint around the tube end as you desire, then roughen up the bare brass surface with some sandpaper, applying flux and heat up, then use a silver bearing plumbers soft solder (not silver solder) around the tube end. Clean up the excess solder with a file or some fine wet & dry sandpaper, and you will need to open up the bottom slot in the front face of the combustion chamber so you can push the soldered tube end through.

Hope the above instructions make sense.

Chris Cairns.

[Lner fan Sam]

I will be fitting a incab regulator so will need to plug that hole. What would you do guys?

[Peter L]

Peter if you scroll down to my 8th posting on this Topic you will see some photos and a diagram explaining this problem - http://gardenrails.myfreeforum.org/Buil ... t6201.html

If you are starting with a paint stripped boiler it is easier and I take the opportunity to solder around the top boiler inserts as well, then use a file or some fine wet & dry sandpaper to clean up the excess solder.

If you are doing it on a new boiler then remove as much paint around the tube end as you desire, then roughen up the bare brass surface with some sandpaper, applying flux and heat up, then use a silver bearing plumbers soft solder (not silver solder) around the tube end. Clean up the excess solder with a file or some fine wet & dry sandpaper, and you will need to open up the bottom slot in the front face of the combustion chamber so you can push the soldered tube end through.

Hope the above instructions make sense.

Chris Cairns.

Thanks Chris!

[Chris Cairns]

I will be fitting a incab regulator so will need to plug that hole. What would you do guys?

Sam if you look at the Dream Steam 'Steam Regulator Kit' (zoom the photos) you will see they provide a plug which has an 'O' ring on one side (to go into the top of the tube), and you use the standard spring to hold this plug down against the inside of the steam dome.

http://www.dreamsteam.co.uk/mss-mamod-u ... r-kit.html

When PPS sold these regulator kits he did not supply that plug which caused problems for those trying to convert their loco. RWM is still awaiting new stock - wonder if he will include a suitable plug.

Chris Cairns.

[Lner fan Sam]

Could you provide soon photos of the spring assembly in the dome please Chris.

[Chris Cairns]

Sam it is Item 29 in the MSS instructions. The late Peter Longfils diagram explains it all.



So instead of the 'O' ring (Item 13) & brass washer (Item 52) you would put the plug into the tube and put the spring (Item 29) on top of the plug then fit the Steam Dome (Item 31).

Chris Cairns.

[DolwyddelanLightRail]

If you want Sam I have Brit's old steam pipe plug that I don't need anymore?