Reply To: Co-ordinate positioning for circle of holes (not all equally spaced)

[JasonBModerator @jasonb]

The title is decieving as the holes are actually equally spaced, it is just a case of picking which ones you want to drill. Not realising this and giving a misleading title may have lead people astray and the theorist should have worked out that they are equally spaced. They are equally spaced in a 127 hole pattern that is spread over three diameters due to the fact they would overlap if all placed on one.

The OPs opening post said “There are a number of PCD calculators out there, however these all assume that the number of holes are all equally spaced.” However as mine and Martins examples show if you use an equal spacing of 127 and just pick the ones that don’t overlap then all these PCD calculators and a DRO and CAD will give what is needed based on equal spacing.

The practical man looks and sees that they are equal and uses the simplest methods to draw the part  and use the simplest way to arrive at the coordinates CAM. Or if you don’t need a drawing then the online PCD calculators are ideal

Computers are not difficult it is assessing the problem and then making best use of a computer to give the required results in this case the co-ordinates for the plate shown with it’s EQUALLY SPACED holes.

As for the maths, taking the outer ring you could say the 63 holes have 62 EQUAL spaces and a remainder. The middle row also has 62 EQUAL spaces and a remainder. The inner ring is the remainder. That is primary school maths.

This is done with the first PCD calculation that google threw up. results are not really any different to the spreadsheet produced on the first page. Just the first two of the three diameters to give the idea

Also works for the prime number example, does your easygraph image also produce the co-ordinates?