Hi Graeme,

My first thought was - Is there any set-up error. Has the problem always been there or has it crept in over time.

You make a great play on rigidity issues, but give us no info on the construction of the machine apart from C7 screws. Let's have some pictures of the machine and we might be able to suggest something.

I have a MD machine and it has rigidity issues (please no jokes here !). I found that the gantry rails (unsupported 16mm rods) were mounted on the twist (or had moved due to cutting forces). It took me a long time to realise why my squares came out as parallelograms, and you may have a similar problem.

Cheers,

Rob