I need to know exactly where to locate the top edge of the upper wheel assembly horizontal support arm and mark that off on the vertical support. For that we need to measure the distance between the shaft or bearing centres plus allow for thickness of the tyres and then subtract from that figure enough slack clearance to allow the blade to slip onto the wheels.

To measure the centres the blade needs to be mounted on the wheels, don’t want to fiddle with something that has very sharp teeth so as before I’ll use banding tape in place of the blade.

Wrapped the tape around the blade and held it on with cloths pegs

Slightly tensioned the tape, marked the ends and cut off the excess. Then wrapped the join with masking tape. Put the tape on the wheel and when I took up the slack it came apart – need a stronger joint.

Set it all up again and this time used super glue and then put on croc clamps – let it dry.|
Once again wrapped the joint with masking tape,

This time it held, was able to gently tension the tape so I could measure the centres – 71cm.

Made all the calculations and marked off the height on the vertical post.