Will it affect the main .cpr project?
I like having lots of backups while I’m working, but after the day’s work is done and I save the project, I don’t really need the .bak files to use up unnecessary disk space. Will anything go wrong if I delete them all routinely?
No. They are fully self contained. When you can’t load your cpr next day you may wish you’d kept them though.
I read that as ‘er on the side of caution’
Perhaps keep the last couple of .bak files and lose the rest…
In the Cubase Prefefences you can set the maximum amount of .bak files saved.
Regards. 
Indeed… and I like it to be set high because I back up every minute or so while working… But I want to clean up once I’m finished. Perhaps as John said it would be wise to keep the last few .bak files and delete the rest.
With the size of modern HDDs the .bak files don’t really use much space. Is it really worth your time & effort to clean up hundreds of Project folders only to end up with 2% more free disk space than you had before? It’s the audio files that eat up your disk space.
Be great if Steinberg just put the .bak files into a subfolder called e.g. backups! To keep our top level project folders tidy…
Mike.
+1
+1
Although I suspect they don’t because I think a .bak file is the same as a .cpr file with a different extension on the name, so they’d need to reside in the same folder so they’ll find the audio files, track pictures, etc. in the expected locations.
Caution! Just check and double check that you don’t accidentally include a .cpr file in your selection when deleting multiple files. I did that once and lost critical edits that I couldn’t reproduce.
I actually create a folder called Development then I copy all old CPR and BAK files into there. I never delete things, but this subfolder keeps the place tidy.
Mike.
Just a friendly reminder. 
We should all be performing regular OS level backups of any data that is important to us.
Thanks all for great suggestions and tips
It would be so nice if Cubendo just did this on it’s own. I have used Hazel for years to move this over. I think possibly that it doesn’t cause as much pain for Windows users who open up projects from Cubase/Nuendo because all of those extra unneeded files do not show. On a Mac from the Finder just like Windows in the Explorer shows all the files but also opening from Cubendo shows all these bak up flies and such an eye clutter.
The thing is moving the .bak file to a folder would break the path that is inside the .bak file.
A .bak file is just a .cpr with a renamed extension.
Easy to try, create a backup folder move a .bak file there, rename the extension to .cpr and try to load it.
Cubase can’t find the /audio folder as it is now in …/audio or whatever your OS denotes one level back.
It could be done if Cubase would write full paths to the files, but I fear that could get messy when the projects media files resides in multiple folders, as they perfectly well can be.
Personally I don’t care that much, as I limit the .bak files to 10, and change the project version number frequently, letting Cubase ad a 01 02 03 etc. at the end of the project. (Well i Save my first copy with a 01 at the end, the zero prevents the OS sorting to get messy). When I am finished for the day, I use the backup function in Cubase to move the project to a new folder again with a version number in the folder name, to indicate what is new and old. The old folder gets archived to a NAS, that runs a backup to another NAS every night.
I’m not saying everyone should be doing it this way, I started doing it this way over 15 years ago, and it works for me.
If anything can get automated in a particular workflow, like backups ,do it.
Even better make a plan on how you want to keep your files safe, print it out and hang it somewhere in view as a reminder.
I wish I had more discipline back in the day when we used real to real, those tapes have now turned to dust, before anyone got the idea to digitize them.
Sorry went a little OT here 
Thanks for your reply. Yeah, it would take some more programming on Steinberg’s part to always check in the backup folder and check if there is a .bak file that is newer and then warns you and then prompt you to save to the root folder.
Pro Tools back in version 5 use to save full paths and 5.1 they started saving and identifying files by unique identifiers and makes it find files more accurate (something most DAW’s haven’t duplicated unfortunately yet) and using relative paths.
That is interesting so do you end up with a ton of duplicated audio files as you work on a project over the course of a week? I have three backups for session, full hard drive clone, then another I do every 6 months (for catastrophic issues like a virus or deleting files I didn’t realize I had deleted until months later), and a third for TimeMachine for ID10T that does delta updates so I can go back if needed.
I do delete a lot of old incarnations of the songs.
But also I am contemplating making a video of the “creation of a song” from first mix to the final result.
Some start with 2 people in a room jamming along with 2 guitars and end up as mostly piano and orchestra based rock songs.
I do weekly incremental disk image backups for everything else, well except my sample drive.
That of cause decided to die on me, not to long ago.
I
peakae Thanks for the post and info.
Hi, I’ve stupidly deleted a lot of bak files in the last few days on a couple of songs not knowing it was going to get rid of my project altogether.Is there a way to retrieve them?
Any help would be awesome. Thanks.