Sorry Gus for the delay but other forums and other tasks have been taking up much of my time.
First, a big thanks for the offer, but we have never been globe trotters and am now at an age where it is too late to start.
With regard to the points you have commented on, starting on the easier one, to discuss that is.
Making a dividing plate with a large number of holes, typically 100, if using the paper strip method there will be nominally lines spaced at 3mm if on a 100mm face plate. If making a low load, low speed gear the accuracy should be adequate, but of course the system becomes more suspect the greater the number of divisions to be made.
An alternative is to using the paper strip method, working out the X and Y coordinates for the holes and producing the division plate on the milling machine using the values can be cosidered. This should be more accurate.
Working out the values can be quite a task unless one is into using spread sheets or has a programable calculator.
If you have a particular large number to divide I could possibly work out the coordinates for you as I have it programmed and only takes a minute or so to set up and a split second for the results to appear. I could convey the results using another website that I use. For this do contact me using the contact page on my website.
My web page regarding holes on a PCD is here
http://www.homews.co.uk/page400.html
If wishing to screw cut a worm gear the resulting pitch/TPI will almost certainly be a complex number. Rather than go into detail here the subject is covered on my website here
http://www.homews.co.uk/page362.html
I have a page on my website that lists all the pitches possible using any of the combinations (over 66.000) using 13 Gears(I think that is the number) This is ideal for the complex values that are required when cutting a worm or metric threads on an imperial lathe. Also simple values where the user has only an incomplete set of changewheels. The pages are here
http://www.homews.co.uk/page28.html
Should anyone be reading this and learn of my website for the first time a good place to start is at the index for the metalworking section. This is here
http://www.homews.co.uk/page463.html
Hope this helps Gus.
Harold Hall