I plan an Indian tea depot with dual narrow gauge (NG) and Indian broad gauge (BG) track beside a warehouse. My main OO9 railway will deliver tea in operational wagon trains and then it will be imagined that broad gauge (5' 6" scaling to 22 mm) wagons take it away. The tracks will diverge a little bit away from the warehouse - the NG continuing straight and the BG curving away. I'm choosing to interlace the tracks, meaning beside tghe warehouse there will be one NG rail (NG1), then one BG rail (BG1), then one NG rail (NG2), and then one BG rail (BG2), because the narrow gauge wagons need to be closer to the warehouse. (This will avoid points with moving parts.) I will hand-lay the broad gauge track with code 80 22m gauge track to match Peco OO9 track for height and so on.
I will need just one frog where the curving BG1 rail nearest the warehouse crosses the NG2 rail farthest from the warehouse. I haven't worked out the angle yet - it will depend on the curving BG track radius and the separation of the parallel rails - but that will be straightforward. There are no electrical issues - I won't be running anything on the BG rails so the BG1 can be in electrical contact with NG2. (NG1 and BG2 will be uninvolved.) But of course the NG flanges and the imaginary BG flanges have to be able to traverse the frog.
@B.Meldon or others, how can I buy, 3D print, scratch build, or steal (from existing points?) such a frog?
If my understanding is correct, this will be a regular frog, ignoring the curved nature of BG1. The type found in a standard point should suffice.
If you do not intend to use any BG stock, or the BG stock will all have fine scale wheel flanges I would just use the electrofrog section from a Peco 009 point or an N gauge point. (18 inch radius may be best.)
Lay all the track with the same rail, so that will be the same as you have for the NG, ie Peco code 80.
If you mix the rail section then you will have issues with rail head heights.
I needed to run SG with bigger flanges on my duel gauge so I used code 100 for all the dual gauge track, but this required some pre-planning of the 009 that needed to be lifted slightly and the SG that needed to be lowered slightly in both cases over about 6 to 12 inches of track to avoid any obvious slope.
If the broad gauge purely cosmetic and the 009 track carries straight on then there is no operational reason to include a working frog, just to give the appearance of a frog being present.
If Dutton Bay's diagram is correct then a straight piece of 009 track could be laid and the BG placed in the appropriate positions. (I'm guessing PCB sleepers or similar will be used.)
The frog gap could be hinted at by filing, grinding or sawing through the head of the rail and perhaps a bit of the web in much the same way as cosmetic rail joins are made for appearances sake or to give a "clickity clack" effect.
That would keep the 009 track in gauge and if the BG is off gauge but still looks OK it doesn't matter.
The BG side of frog nose doesn't even need to be soldered to the 009 track, just filed and stuck down to look like it joins. Likewise the wings of the frog.
(Cannibalising a section of an N gauge or 009 point as suggested by Brian might be the quicker option though, so long as the 009 closure rail can be spliced into the running rail. I think you will need to start with a large radius point because the curved running rail (BG1) has to tighten up its curve in order to stay clear of the 009 running rail (NG1)).
Thank you 'duttonbay', Brian, and Graeme. First of all I'm glad I got my point (ha ha HA) across. Secondly, thank you all for your responses. I think I'll cannibalize a large-radius OO9 point, but I'm impressed by Graeme's alternate solution. (Yes, Brian, I thought about rail heights and will use OO9 code 80 rail for the broad gauge.)
By the way S gauge (22.48 mm) is just about spot-on for Indian gauge in our scale, and I experimented with some in my aborted layout in Ukraine, but at 1:64 scale the track I acquired was too high to look right. Of course in reality the broad gauge would probably have heavier rail - I assume it does where the Darjeeling Himalayan Railway intersects Indian gauge track at New Jalpaiguri - but I definitely want to keep my rail heights consistent.