Originally Posted by Adam0801 View Post
Ok so I have worked out the top plate is 10mm. Coil is 42mm.

So 42-10 = 32/2 = 16mm

Mark 16mm from to of coil and that Mark should sit flush with top of the top-plate??

Cheers Adam
fixed it for you. ▲

Set your coil position that way, but also make marks on the inside of the former. That way you can be absolutely sure it doesn't move when you put the spider on.