Mamod SL2 / SL3 Refurb/Restoration

A very popular starting point for Live Steam. With their low cost comes a number of problems which can be discussed here
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dougrail
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Post by dougrail » Sat Jan 12, 2013 12:37 am

I just use stove paint on a smokebox, bit thin but well wearing. :)

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Spule 4
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Post by Spule 4 » Sat Jan 12, 2013 5:09 am

Dichloromethane did not take the original Mamod SL3 paint off the smokebox, but did off of the SLK1 very quickly.

Both were repainted with high temp BBQ flat black rattle can spray.

On the SL3 smokebox it is doing well, it is coming off the edges on the SLK1 however.
Garrett

"Some say that Mamods have problems.  Whatever. I view them as opportunities for improvement."

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Chris Cairns
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Post by Chris Cairns » Sat Jan 12, 2013 2:58 pm

it is coming off the edges on the SL1K however.
Which is what has happened to my repainted smoke box above.

Chris Cairns.

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Post by WWLR » Mon Jan 14, 2013 10:12 am

Didn't have much time to work on the project over the weekend (DIY and decorating time) but with a bit of a rearrange in the garage I have liberated the lathe from the surrounding clutter and had a go at making up an adaptor to attach the pressure gauge for testing the boiler.

I found a short length of 7/16” hex brass in the odds and ends box and turned down about 8mm of one end and threaded it 1/4” BSF to use in either of the small top connections. Going well, I thought, until I tried it in the front boiler connection, it had gone in about a turn and the ferrule detached itself from the boiler! I now have a half finished adapter spinning round in the top of the boiler.
Don't you just love it when a project is coming together – not!

Possible options:

1) Throw it down the garden and order a new boiler from DS. - a bit over dramatic and defeatist!

2) Try re-soldering the ferrule with the adaptor stuck in it. - possible

3) Try to super glue the ferrule in place in order to unscrew the adapter and then remove, clean up, and re-solder the ferrule – don't know how well super glue takes to solder.

Any ideas anyone?

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Post by Narrow Minded » Mon Jan 14, 2013 10:20 am

Possibly "tack solder" the ferrule to remove the adaptor rather than super glue?
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Chris Cairns
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Post by Chris Cairns » Mon Jan 14, 2013 10:27 am

Scrap the paint away around the offending ferrule/insert and roughen up the surface. Apply some flux. Heat the flux up then gently melt in a small bead of soft solder around the ferrule/insert. Let everything cool down plenty then see if your adaptor will come out.

I had problems with a leaking whistle on my SL3 and eventually the insert went loose on that boiler. Turned out that the whistle and insert had not been cut accurately at 1/4" x 26BSF so I now have a 1/4" x 26BSF Tap in my tool box to clean out any offending inserts.

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Post by WWLR » Mon Jan 14, 2013 1:33 pm

Hi

Thanks for the advice.

I think the front connection may have been stressed a little already. If you look at the close up of the safety valve in place you can see that it isn't sitting straight compared to the steam dome.

Image

I carefully put a 5/16" BSF tap down each of the small ferrules to make sure they were clean and they seemed OK. It may be that my die is cutting a bit oversize but I was only using light finger pressure when inserting the adapter.

Just out of interest what size is the steam dome thread? It looks to me like 12mm x 1mm.

Regards

Will

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Chris Cairns
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Post by Chris Cairns » Mon Jan 14, 2013 2:38 pm

Will,

Yes it looks like your front boiler insert has been bent out of place at some point. Once you get your adaptor sorted out a little bit of heat and pulling there will help set it back again.

I do not know the correct thread size for the steam dome insert but I've just posted the question over on the 16mm NGM Yahoo group so I'll keep you advised.

Chris Cairns.

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Chris Cairns
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Post by Chris Cairns » Thu Jan 17, 2013 7:18 pm

Will,

Finally got the answer from the 16mm NGM Yahoo group, and you are right - it is M12 x 1.

Seems strange to use different standards for thread sizes - BSF & Metric.

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Post by spooner » Thu Jan 17, 2013 8:21 pm

My theory for thread difference is the safety valve and whistle were taken from [the stationary engines] a old design and the dome was a new design?
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Post by Spule 4 » Thu Jan 17, 2013 11:53 pm

Chris Cairns:79440 wrote:Will,

Finally got the answer from the 16mm NGM Yahoo group, and you are right - it is M12 x 1.

Seems strange to use different standards for thread sizes - BSF & Metric.

Chris Cairns.
Sounds like a late 1970s US built Chevrolet or AMC!
Garrett

"Some say that Mamods have problems.  Whatever. I view them as opportunities for improvement."

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Post by WWLR » Fri Jan 18, 2013 11:19 am

Chris

Thanks for confirming the thread size. I was wondering about the size in case I wanted to make a modified steam dome. I’ve got a M12 x 1 tap but obviously couldn’t screw it into the boiler fitting with the internal pipe in place.

I think Ian (spooner) is right about the new/old mix of parts. I’ve been making some CAD drawings of the loco components while it’s in pieces and it’s all metric so far, but it makes sense of Mamod to keep the safety valve and whistle compatible with their other steam products.

Boiler Update:

I managed to re-solder the ferrule and get my part-finished adapter out. I tightened up the 1/4” BSF split die and ran it down the thread again and now it’s a looser fit in the boiler. I will finish the adapter and the pressure gauge connection when it’s a bit warmer in the garage – it’s only a few degrees above freezing in there and it’s still snowing outside.

I will probably have another go at soldering the front connection. Any suggestions on how you stop the ferrule dropping in to the boiler when the solder melts? I did the temporary repair with the boiler on end but it would be easier to work on with it in its normal orientation.

Regards

Will

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Post by WWLR » Mon Jan 21, 2013 1:44 pm

Still too cold to do much restoration work in the garage, but I have been sorting through the very nice selection of goodies that Greg (Narrow Minded) put together for me at a very reasonable price.

Image

This has provided me with a number of items that were missing/broken on my original loco purchase:

Cab back and retaining spring
Meths burner
Selection of buffer plates and assorted buffer/couplings

Additional items include:

Dead leg displacement lubricator, steam pipe, curved tip syringe
Spare cab front
Small oval brass '1' number plates

I had been trying to decide on whether to go with a meths burner or try a gas one, but speaking as someone who's parents had the foresight to buy me a Mamod/Meccano stationary engine while I was still at junior school, the great smell of meths, oil and steam should bring back some pleasant memories!

I am very impressed with the support I have received from the forum members in the short time I have been here. You are a great source of knowledge and inspiration.

Many thanks

Will

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Chris Cairns
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Post by Chris Cairns » Mon Jan 21, 2013 6:48 pm

Will,

I find using wood stove fire rope makes great wick material for meths burners. It has a ceramic content which means once it has burnt a few times the ceramic part tends to seal around the top of the burner tubes which means no meths leaking when the loco falls over. Works well in my runaway Bowman locomotives.

Not many Forum members use the Dead leg lubricator, with many changing these for Displacement lubricators instead (not sure if this is just for looks). As long as you prime the steam pipe that enters the dead leg lubricator every time that you fill the lubricator then I find they work every time - I use a syringe to push steam oil into the steam pipe. However how much oil is used per run does vary from loco to loco. I've recently found some good info on the dead leg lubricator from Mike Chaney (the original designer of the Mamod one, which IP Eng & Dream Steam have copied) which I need to edit. You will also need to solder the steam pipe into the dead leg lubricator to get the best steam tight seal.

Chris Cairns.

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DolwyddelanLightRail
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Post by DolwyddelanLightRail » Mon Jan 21, 2013 7:15 pm

Dead leg's seem to be a black art. Britomarts one has always worked since the first time it was steamed with it, I haven't had to prime the steam pipe every time like you have mentioned above though. The only thing I have noticed recently is that it has been going through oil a lot more than it used to.

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