radius help?

[jayme smith]

I wanted to know if the combination of three 18" curves, a short 18" curve section, and two 15" curves can make an half circle ans stay under 34" in width. I'm getting back into HO scale and I'm converting my N scale table to HO.

[jonathan]

Jayme,

If memory serves, it will take three 18" radius sections and three 15" radius sections to make a half circle.  Of course the half circle will not be symmetrical, but both ends will be parallel.  The diameter will be 33" from track center.  It would be symmetrical if you alternated between 15" rad. and 18" rad. pieces in a predetermined order.

By 'short' curve section, did you mean a half or one third piece?  That threw me off.

Regards,

Jonathan

[jayme smith]

thank you Johnathan.

you've cleared up some of my troubles. what I'm trying to do is have three 18" curves, with one on each end going into the curve. and in the middle of the curve having one 18" with a 1/3 section of 18" connected together. and between those three to have two 15" curves. I'm not to worried about it being a "perfect" circular curve. I'm a little limited on the space. I know that the 18" wouldn't work all the way, I'm trying to off center it just a little.

[Doneldon]

jayme-

Keep in mind that the ruling curve will be 15", not 18" or the average of the
two (16.6"). This will severely limit what kinds of locomotives and rolling stock
you can use.
                                -- D

[jayme smith]

I know. I'm going to be running a yard style layout with tank engines and box cars, and basic freight train rolling stock. So the radius isn't was I'm worried about. 

[jonathan]

I'm a little weird about this sort of thing.  Just to keep things even I would cut one 18" curve in half.  Then you have 1 1/2 18" curves on either end, leaving the three 15" pieces for the middle.  Brilliant!

Like I said, I'm weird about that sort of thing.  This way would also lend the 18" pieces as sort of a crude easement for the 15" pieces.

Just a thought

Regards,

Jonathan

[jayme smith]

Great idea Johnathan. thanks for the help. just what I wanted to do. After doing N scale for a few years I think my mind had forgotten all the HO scale stuff. Thanks again.

[Len]

You don't have to cut any track sections. Both the 18in and 15in full curve sections have 30 degree arcs.

Which means you can use one 18in section, four 15in sections, and another 18in section to create a slightly squashed half circle of track. The 18in sections would be your transition curves from the straight tracks into the tighter 15in curves. The center track to center track distance of the open end of the half loop will be around 30-3/4in.

Len