yes Zymrgy that is exactly what i meant
very very very ... nice machine btw, i would like to have one in my garage just as fixittt has
and also i agree with hara, make some calculations and the extra fins remove them because they could only be restring the flow of the water.
You need just a little bit more than 2mm of fins or 2mm of fins on each side of the core, ie, if the core is 10x10mm, then 14x14mm of fins would be enough