I've just invested in a 120g external drive but I'm not sure I'm using it correctly.
I'm saving the project to the external but all the render files etc. are remaining on the mac drive. If I delete the files from the mac everything on the external goes 'off line'. What am I doing wrong?
Laymans terms please.
Regards all.

David,
(small, but important detail): What editing software are you using on your Mac?

FCP3

OK. I'll head you in the right direction. You need to change the settings in your System Settings to point to your external drive.

The menu steps:
Final Cut Pro >> System Settings >> "Scratch Disks" tab.

Thanks Ken, I think I see where you're comming from.
Regards david

Many thanks Ken, everything works a dream.
Regards David

there are two basic approaches to use. you can keep all your render files and such in one area and never change that so if you use, for instance, an external drive you can set it to keep all your captured files, render files, etc. on your external in a particular folder. Or you can create a new folder for each project and put your files in that new folder each time. However you MUST remember to reset your preferences for that folder each time you change the project you are working on. FCP will assume you are continuing to work on the same project you were on last time so if you go from working on project A with it's folder on Drive1 to working on project B, it will put captured stuff into the project A folder on Drive1 unless you tell it to change.
I wish FCP would be smart enough to remember where you told it you wanted the files from this or that project to go.