Ralph, I gave up with the coving tool and just adapted my parting tool.........it was a 8mm until I ground it down to a 3mm so I could follow your instructions!
the ideal size to start turning the lattice is 3mm because it is a small enough size not to break but in fact they can be turned in a number of sizes so experiment to find a size you are comfortable with.
I found when i started again i found my hands stiff so i needed to turn a bigger lattice to get my fingers nimble again.
I spent 3 hours grinding away at my grinder trying to flatten the sides of the diamond shaped chisel
I did try it before with the untouched chisel but found the gaps to big for the little 50mm bit of wood...........I will try with a different chisel next time.........always best to practise with different tools as you never now the outcome, do you!
Thanks guys.........I was quite stunned myself.........I had cut a few discs of Plum wood ready to be stuck in the MDF jig but, when starting it flew off with half the MDF stuck to it. I changed the jig to Pine and that worked a lot better.
All a learning curve...........and I'm enjoying it too thanks to Ralph