16mm NGM Peterborough Show 2014 - the Mamod Chapter

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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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Tue Apr 29, 2014 7:07 pm

Just for info, here's how my Brunel looks at the moment:

Image

and

Image

Dunno what will happen in 30 days as that's when my free trial period with imageshack expires.


Mike

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Chris Cairns
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Post by Chris Cairns » Tue Apr 29, 2014 11:05 pm

steamyjim wrote:It appears the piston rod is somewhat shorter
I guess both a change in length of the piston rod plus the slip eccentric could be used, but would this not affect the timing?

Mike,

Interesting to see you have re-orientated the boiler. As mine is fitted with the earlier version of axles & bearing retainers it would be a more expensive option to fit new frames, gearing, etc. Do you happen to know what size the banjo bolt for the pressure gauge is? My workshop/kitchen is already too full so I'd need to make space before getting my Brunel out of storage. Just wondering if it is the standard Mamod 1/4" x 28 BSF as that would make fitting a pressure gauge to the Thomas Telford a good possibility.

Chris Cairns.

Bill/Rubery
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Post by Bill/Rubery » Wed Apr 30, 2014 12:03 am

Today I have been putting new buffer beams plus buffers on my Brunel. While doing this I had a good look at the underside. If the new gearing has two cogs on the one shaft that would?? possibly mean that a bigger cut-out is needed at the footplate. It is simple to drill out the pop?? riveting and cut the footplate to accommodate this new gearing. I noticed that in the report about the 16mm show that Mamod was selling off the last of the 'old' models?? (i.e. like mine!) so they could start selling the new model. As I said before, this is a model in progress, I seem to have paid for a model that had not been finished properly hence this mark 2.....
Regards, Bill/Rubery

www.amalgamatedconserves.org.uk

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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Wed Apr 30, 2014 8:00 am

Interesting to see you have re-orientated the boiler.
I altered the displacement lubricator to stop it using all its oil in the first 5 minutes, so rotating the boiler made connecting the steam pipe a bit easier (my pipe bender only does really gentle curves). It also meant the pressure gauge wasn't hanging out on one side.

Just wondering if it is the standard Mamod 1/4" x 28 BSF as that would make fitting a pressure gauge to the Thomas Telford a good possibility.
Yes, mine has the same thread as the safety valve and water filler so fitting a pressure gauge to a TT should be relatively easy.

If the new gearing has two cogs on the one shaft that would?? possibly mean that a bigger cut-out is needed at the footplate. It is simple to drill out the pop?? riveting and cut the footplate to accommodate this new gearing.
That's basically what I did when I regeared my Brunel. However I don't think Mamod have quite gone down that route. If you look at the photos I posted yesterday you'll see the cog on the flywheel shaft has very few teeth (in fact its from Meccano) and it drives a new thin cog (that's the one I cut myself) on the layshaft. Then the original Mamod layshaft cog drives the main axle cog.

I don't know for sure but I believe Mamod have retained the same size cog on the flywheel shaft. They can't make the cog on the main axle any bigger otherwise it would hit things on the track. So the only way I can see them altering the gearing would be to move the position of the other two shafts, particularly the layshaft, in relation to the main axle. I'll have a good look when I visit next week and take a few pictures.

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