Thanks, Jamie;

In Len's post on this he quotes 9+1/16" (9.0625") rather than 9" as the diameter of the No.6 Outfit ring-gear; Roberto says he counted 290 teeth on his, and 290 divided by 9.0625 = 32, the DP of the gear, which is exactly what you'd expect. (Roberto: there is no rounding error - you need to measure from half-way up a tooth on one side of the gear to half-way up the tooth directly opposite, ie on the other side - not between the tops or bottoms of the teeth. Why? Think about two gears in mesh.........).

Adding this 1/16" (the tooth depth) to the ring-gear dimensions given in your post we get diameters of 12+1/16" and 20+1/16", which translates to 386 and 642 teeth respectively. Jamie, could you possibly confirm this (by measurement, as above, rather than by counting teeth - which would take forever)?

And does anyone know the Constants (ie as quoted by Len for the No.6 Outfit) for the No.8 Outfit and No.10 and No.16 cameras?

Or any of the above information for the No.5 and No.6 cameras (which use 48 DP gears), ie ring-gear specs, pressure angle (likely also 14+1/2 degrees) and Constants?

The reason I'm asking for this information is that I'm compiling an Excel spreadsheet to show the pinion gears required for each camera based on the distance between the RNP and Film plane, ie if you know the exact position of the RNP for any lens, and know which camera you're using(!), by measuring the distance between the RNP and film plane for any focussed image you can simply look up the required pinion on the table.

So far this looks OK; once I've finished testing it on my No.8 I'll make the table freely available for others to test, particularly on other Cirkut models.

Of course if anyone thinks this is impossible, please let me know why - you could save me a lot of work!

Cheers to all; Dave