Mamod Copper Boiler Sight Glass mounting

alan2525 · 04-02-2008

I'm currently working on building a little 16mm scale loco using mamod cylinders and burner.

I wanted to build my own silver soldered copper boiler, however there's one part of the boiler I'm unsure about and thats the fitting of the sight glass for the water level.

This picture shows the PPS Steam Models aftermarket boiler fitted to a little mamod loco:

The fitting of the sight glass seems a real Heath Robinson affair, I was trying to figure out if this could be done a little neater, without so much silver soldering and odd bits of pipe! It seems it could prove to be a little awkward to align all the bits whilst soldering it up.

Any ideas of how this is achieved on other small boilers?

I think this is the first time that Mamod and the word "Scale" have ever appeared together!

**Bunkerbarge** · 04-02-2008

This is the considerably neater unit fitted to a Hemmens Ribbersdale boiler and a spare one that I used on my feed tank.

alan2525 · 05-02-2008

Thats funny the sight glass fitted at an angle across the back of the boiler looks just the same as the sketch on the back of my envelope here!

I think it'll be considerably easier to just solder on the threaded bushes and use steam fittings rather than cobble up some nasty looking bits of old tube!

Where do you buy those little steam fittings? And can the sight glass be purchased in various lengths and is the glass 5mm diameter?

Lots of questions!

Alan

**Bunkerbarge** · 05-02-2008

To be honest I think most of the boiler manufacturers will sell you a sight glass assembly complete with a length of glass tube. You can cut them to size very carefully with a dremel to fit exactly your own needs.

I would give John Hemmens a ring, Maccsteam, PPS Steam Models, Historic Steam Models etc but start off with this outfit here:

Current Range

The tube OD is obviously designed to fit the unions so I have no idea what it's size is.

I agree with soldering on the threaded bushes but use silver solder as you need the strength and heat resistance for the job.

Don't forget all this will then have to be pressure tested and certificated when you have finished before you will be able to use it in public or obtain insurance via a club.

bogstandard · 05-02-2008

For setting up the sight glass unions get a piece of rod the same size as the glass, and use that until everything is finished. Only at the very end put the glass in. Don't ask how I know. But about three tubes later !!!!!

John

BTW, all the boiler regs were changed in spring 2007. If you are below the 3 bar/litre rule you don't need certification and the insurance companies will accept it. The only people not accepting the ruling is the M.P.B.A.
If you want a breakdown I can post it for you.

alan2525 · 05-02-2008

I was thinking of using a length of rod to align the top and bottom fittings of the sight glass. I do prefer the idea of an angled sight glass though, threded into elbows theaded into bushes on top and bottom of the boiler alongside the fitting for the regulator. That way I could get it to fit reasonably closely to the back of the boiler.

Bogstandard - I thought I recognised you from the Mamod forum! Do you have any locos or are you into stationaries or traction engines?

Regards,

Alan

bogstandard · 05-02-2008

Alan,

None, I just help out with a bit of model engineering on there. You know the sort of thing, easy ways to make an inline luber, things that help out a group of enthusiasts.
I design and make my own engines, all sorts, just what takes my fancy.

John

alan2525 · 05-02-2008

I can see how people get into the whole live steam thing! Those brass steam fittings look really nice! I've ordered the sight glass and from there I can get a closer look at mounting to my boiler!

Then it's a case of turning the bushes for the inserts and flanging the ends. I'm planning on using the gas and air brazing hearth at work to do my silver soldering so I'll have a bit of a practice on making a few little stationary engine pot boilers first!

bogstandard · 05-02-2008

Alan,
Just a little note, boiler bushes should be out of phos. bronze, not brass. Also check the thread on the fittings, usually at this size they are either 1/4" x 32tpi or 1/4" x 40 M.E. threads.

John

alan2525 · 05-02-2008

I've been doing some research and already have a length of Bronze rod on order along with a selection of 1/4" ME 40TPI Taps!

Whats the best way of making the threaded connections steam tight? For example the IP Engineering Steam Regulator has a Tee piece which threads into an insert in the the boiler.