[Samba] Samba Share Help Needed

[Ben]

Hi,

I have the following directory shared for the user "pcbadmin". He/she 
can mount and read/write without any difficulty:

[pcbdata]
    comment = PCB Design Files
    path = /home/pcbadmin/pcbdata
    valid users = pcbadmin
    public = no
    writable = yes

Question: How can I make the same directory only readable by the rest of 
the users ?

TIA, Ben