Andrew
thanks for that diagram I see what you mean now
i have done a little work today but not completed the component yet as I need a new endmill to recess the front part
i managed to use the broken one for milling it out
john
they. Look a bit heavy to be honest I may have to make something from alu shouldn't be that difficult if I take my time
I will get hold of a t cut slotter and hopefully if it's machined accurately enough it should just slide on the rail
we will see !