The basic rule of thumb is a 1:2 ratio, radius of build plate : arm length.
So if you have 6 inch radius the arm length will be best at 12 inches
This allows for the largest build volume and will achieve the most circular of build areas, as this ratio veers away from the 1:2 ratio in either aspect the more triangular the build area becomes
The overall height simply needs to be the arm length plus the size of the build volume you want so if you want a build area of a basic cylinder shape with a 6" radius base and a 15" height then your height would be the 15" plus the 12" for the arm plus any added height to accommodate the base you want so with 6"added for to be the base area you would have an overall length of 33" vertical support pieces, if the pieces go through the base entirely(not compensating for height loss due to addition of brackets and parts required for stabilty)
I currently am constructing one that is fairly large
9" radius
18" arms
66" vertical support(extruded aluminum tslot)
with a 8" base might be 6" not sure yet
so I will have base on the 8" base a build (based on a cylindrical build area)
V = π * r^2 * h
or V = 3.14 * 81 * (66-18-8)
or V = 3.14 * 81 * 40
or V = 10173 cubic inches
not quite circular so a bit less
So if you have 6 inch radius the arm length will be best at 12 inches
This allows for the largest build volume and will achieve the most circular of build areas, as this ratio veers away from the 1:2 ratio in either aspect the more triangular the build area becomes
The overall height simply needs to be the arm length plus the size of the build volume you want so if you want a build area of a basic cylinder shape with a 6" radius base and a 15" height then your height would be the 15" plus the 12" for the arm plus any added height to accommodate the base you want so with 6"added for to be the base area you would have an overall length of 33" vertical support pieces, if the pieces go through the base entirely(not compensating for height loss due to addition of brackets and parts required for stabilty)
I currently am constructing one that is fairly large
9" radius
18" arms
66" vertical support(extruded aluminum tslot)
with a 8" base might be 6" not sure yet
so I will have base on the 8" base a build (based on a cylindrical build area)
V = π * r^2 * h
or V = 3.14 * 81 * (66-18-8)
or V = 3.14 * 81 * 40
or V = 10173 cubic inches
not quite circular so a bit less