Delta Rods length and print area volume

Hi folks,

I've a real quick question that are made me crazy and I would like to understand because I'm intent do update my kossel printer (anycubic kit) and also want to build my own kossel with a larger print area but that isnt for now.

Basically my anycubic plus have a heatbed of 230x230 and the rods lenght are 267mm long, my question is how the rods lenght influence the print area (circumference of bed)? I mean I want to add a magnetic rods with diferent length its possible? What is the theory behind?

That is because a guy in a forum have made the update for magnetic rods with the length of 255mm for the rods and magnetic ball and he claim that just update the values of rods in the firmeware that is possible? that printer will mantain the same print volume? how we can calculate this?

Edited 1 time(s). Last edit at 08/06/2018 12:14PM by masterviana.

Perhaps the lost horizontal volume is made up by the increased vertical volume. Can you live with the decreased horizontal volume?

p.s. There are online delta calculators that will give you accurate print areas and volumes.

Edited 1 time(s). Last edit at 08/06/2018 12:30PM by etfrench.

Well i'll prefer mantain the same print volume, but if is for losing something I'll prefer lose some vertical volume, could you explain the teoriry that relat the rods lenght and the build volume? especial horizontal volume

A rule of thumb is:

 printable radius = rod length x cos(20°)

The 20° rule is based on the achieveable angles of rod ends. Magnetic ballstuds usually have a bigger angle, but the steppers have a hard time to maintain constant effector speed then.

Reprap.org has lots of info on designing deltas. Start here.