davidb wrote:The 'How to . . . ' I could do with concerns working out where the pivot points are meant to go. The rest is straightforward.

The spreadsheets are completely beyond me and I know this puts other people off CSB. How necessary are they? If I were to put a pivot half way between wheels with one at each end to match, would that be 'wrong' or mean it won't work? Can the placing of pivot points be simplified?

If you have a symmetrical wheelbase there is a simple rule of thumb. If the intermediate anchors half way between the axles, the outer anchors can be placed a distance 30% of the wheelbase beyond the outer axles. This relationship will hold true for any number of axles.

On a 6' x 6' wheelbase the distance between the axles and the outer anchors will be 8mm, for 7' x 7' it's 9.3mm and for 8' x 8' it's 10.7 mm (to the nearest 0.1mm)

On asymmetric wheelbases it is more complicated because there are many solutions that will give equal weights on the axles. However knowing of this rule of thumb gives you a starting point for using the spreadsheet. Enter in the the four anchor points as above, i.e. half way between the axles and 30% of each inter axle distance, and then adjust TWO of the anchors, either the two intermediate points or the two outer points, until you have a satisfactory solution.