DP of gears, whats it all mean?

[John S]

Width and pitch of leadscrew have nothing to do with whether the gears will fit.
That's all down to the DP and whether they have the numbers of teeth you require.

.

[irving2008]

No I realise that John, but it does have a bearing on whether the gear set is useful for cutting standard threads... if i can't make meaningful trains with the pitch of leadscrew then there's no point in buying them.