Here an alternative for Grandtline or Tichy BNW
http://www.scalehardware.com/simulated_hex__bolts.htm
Jacq
Two more sources:
http://www.microfasteners.com/index.cfm (http://www.microfasteners.com/index.cfm)
http://www.smallparts.com/ (http://www.smallparts.com/)
Mark Layton
Another source to consider is the J. L. Morris Company ? http://www.morris01550.com (http://www.morris01550.com).
They have an excellent range of products and tools available. I've used their 000-120 fasteners and taps in some of my loco work. Photo below shows a pair of their 000-120 flat head screws fastening a pedestal block on a 1:48 Kodama K-27.
Paul
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fwww.roughboy.net%2Fimgs%2FK27PedBlock.jpg&hash=1474e3b9baa236b47853cb77a9db7650dcd49ef0)