chmod the shared folder on
machine-1 to whatever you want it to be.
If all the users on any client machine (or at least those that actually write to the share) have their
umask values set to 002, you should not - in theory - need to do anything else.
However, if you cannot be sure of the
umask values of the client machines, you might want to add a default ACL to the shared folder before creating any sub-folders. To do that, make sure the filesystem on the server
machine-1 that actually contains the shared folder has ACL support enabled, and do this:
setfacl -m d:u::rwx,d:g::rwx,d:o::rx /shared/folder/on/machine-1
As a result,
getfacl /shared/folder/on/machine-1 should now return:
# file: /shared/folder/on/machine-1
# owner: <username of folder owner>
# group: <group name>
The last three lines describe the permissions automatically applied for any sub-folders and files created to this folder from this point on. Regular files will have the execute permission automatically omitted, unless the program creating the file specifically indicates it wants to create an executable file.