@Dave Siff I've dabbled in 5ths tuning but not a committed to it guy. So pardon for having my 10cents worth about those string gauges. If your happy with the lowest and highest string gauges, than a useful calculation to find the ratio between those two strings and apply it to have the remaining inner string gauges be in that ratio relationship is to
'Divide the smallest gauge by the largest gauge
and raise that to the power of 1 divided number the number of inner spaces bewteen the strings.'
So the equation for your 5 stringer would be
.020/.110=0.1818. Raise that to the power of 1 divided by 4. This gives a ratio of 0.6529. You can apply it from the largest gauge to each subsequent gauge by multiplying gauge by the ratio. Or start from the smallest gauge and multiply by the reciprocal of the ratio. In this case 1.531. Now applying that ratio to each string from smallest to largest by multiplying by 1.531 yields with rounding
F#3/.020
B2/.030
E2/.046
A1/.071
D1/.110
Obviously the exact gauge as given is not always possible for every string and one has to choose the closest gauge available in the brand and type of string desired. You can see that your 60 gauge and 85 gauge for E2 and A1 are a big departure from the ratio. A 45 sounds about right. Think of it as how E2 is on a guitar. Your .020 is common for G3 on a guitar and is a good fit for slightly downtuning without increasing the gauge in this case. Your .035 B doesn't depart from the ratio much. So prob not worth changing. So that leaves the 085 A1 string. You say you like that gauge. Nonetheless if you wanna do the ratio thing, swapping it out with an 070 is the go.
In summary. 3 of your gauges could stay in place. And replace the A and E with .070 and .045 gauges respectively.
