Re: Narrow gauge wheel profiles
- If centering difficult on 3/4 jaw chuck then mounting just wheel on a faceplate to turn the boss might be a better option?
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I would like to add my thanks to Roy for his wise words and fully
agree that his standards do work, and see no reason to change them. My
main interest in this is to prove one way or another whether the
Romford/Markits wheels with the 14mm axles are compatible with these
standards. So far it is clear the old 'standard' profile wheels
definitely are not.
I have now obtained some Romford/Markits RP25 wheels which I intend to
use one of these days to rebuild my 20 year old Wrightlines Baldwin
(the current plastic centred wheels are inclined to slip on the axles).
Having assembled these wheels with the 14mm axles exactly as is, i.e.
with no fettling, I have measured the back to back as a fraction below
12.6mm (my guess is around 12.57 +/- 0.01). This is just slightly
wider than our standards of 12.40 12.50mm. The flanges are certainly
quite fine and look to be very similar to the RCL wheels.
This suggests to me that the wheels would benefit from a slight skim
of the boss at the back. However, I agree with the suggestions that
this can be simply achieved by rubbing down* the back of just ONE of
the wheels until it is flush with the back of the tread. From my
measurements this would indicate that about 0.20mm would be removed
which brings us down to 12.40 (or a fraction less) so it is probably
best not to overdo it.
(*my preference would be to use wet & dry used wet on a known flat
surface e.g. mirror)
Having said that, the wheel set as is seemed to run well through point
work and ran freely on it's own for several yards down a slight
incline - this included a reverse curve. A better test would be to
make up a simple 4 wheel chassis and propel it via a loco, but I am
not sure when I'll be able to get around to it.
My conclusion is that the RP25 wheels with 14mm axles can be made to
work with a bit of simple fettling and can therefore be recommended.
I would welcome further comments from others. Furthermore please
consider whether this should be made as a formal recommendation to the
7mmNGA to pass on to manufacturers. Adrian if you have been
following this have you anything further to add?