The impact of tubing sizes

[Cyprio]

I tried that approach and it is somewhat problematic as the screw down ring is specifically made for a specific size tube. I did get it to work, but I had to use a lathe to get the nuts ID opened up.

Hmmm... i guess that's what i need to do with my fittings to get them to close fully.

10mm OD compression fittings with 10 mm nut, using Tygon 1/4" ID, 3/8"OD:





I think Alphacool produce an 11mm nut. Maybe that will help?