Terry
I'm not sure that a cutting disc is the best tool for cutting through what
is relatively thick brass.
The wear rate on the disc will be high and the particles from this with the
brass dust are not pleasant.
Even wearing safety goggles recently I found the particles were getting
behind them and could be felt on my eyes. Like getting caught in a
sandstorm. And this was simple trimming around a hole not a major
excavation.
I would persevere with a junior hacksaw with the boiler held firmly in a
vice. Use lead sheet to make soft grips. Don't use a blade purchased at B&Q
or similar; two or three strokes and the teeth are gone even in brass. Buy
from an engineering supplier.
Mark out the area you wish to remove, black felt tip and the line scribed
in that. Drill holes in the corners to terminate the cut. Cutting across the
diameter without marking the boiler beyond the cut will be difficult
whatever method used. Drill a series of holes close together and join them
up and then finish with a file. Use a new drill and centre pop the positions
so the drill point doesn't slip.
I suspect the brass will be at least half hard for its machining qualities
so drilling and sawing should be straightforward. If the brass produces very
fine individual pieces of swarf then this will confirm its hardness. Slivers
and spiral swarf will say it is softer brass and you will be stuck with
this.
Bob

-----Original Message-----
From: 7mm@... [mailto:7mm@...] On Behalf Of John
Shelley
Sent: 12 July 2009 08:53 AM
To: 7mm@...
Subject: Re: [7mm] O7 kits

Terry wrote:
> Hi John
>
> Just looked again more closely at the kit and have noticed that the name K
Dales appears after the O7 name,so does this indicate the earliest offering?
> You are right in that it does appear that the boiler is a brass
tube,starting about 1.25mm thick at the smokebox end,and this has a further
section of about 1.25mm thick tube over this to form the actual
smokebox.Behind this the boiler has been turned down,and then reduced yet
again to under 1mm, leaving strips untouched to represent the boiler
bands.It has been drilled for washout plugs,but not for chimney etc. I have
just realised that part of this will need to be cut away for the motor-what
would be the best way for this as it is quite a thickness to get through.
>
> Regards
> TerryR
>

Probably an original, although George Norton continued to use brass tube the
etched boilers and frames were introduced by London Road models.

As to how to make the cut out, Raymond's cutting disc is probably the way to
go, unless you fancy using plenty of elbow grease and a hacksaw.

If the idea of drilling all the holes doesn't appeal you could buy a boiler
etch from the current manufacturer. Who that is depends on the kit.

--
Cheers for now,

John, from St Ciers 33820, France



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