thank you very much !!
Am i right in seeing that it is the square brackets that I have to use?
regarding the groove tool - I am using a groove tool to do the whole job.
the groove tool i am using will cut left, right and front. this is ok with plastic
because it plastic material is soft so there is little sideways pressure required,
certainly not enough to bend the shaft of the groove tool.
many thanks and wishing you many happy hours of making chips
regards fred