Question No. 1

Hi all in the group, I'm planning to build a small home workshop cnc
mill, lots of questions to come but where possible I'll try to find
answers on previous posts (so many) I've been following the recent
posts on limit switches & would like some clarification on what is
required on each axis, I think I need a hard limit switch at each end
of travel to switch off stepper power in the event of an "H bridge"
failure, (this would require a full program restart) inside these I
would need a switch at such a position that the axis could decelerate
from rapid to stop without tripping the hard limits (program able to
continue) I think that these can be software switches in the program,
also at one end of the movement I would require a hard switch for
home position (needs to be very repeatable). Am I close or way off
the track? I have some "Omron" photo electric limit switches type No.
EE-SX308-P1 (no data yet) which have a LED & photo diode in a plastic
mount such that an opaque vane can be inserted between them, may be
suitable for home switches & perhaps the vane could have a mechanical
advantage of 4 to 1 or such to improve their accuracy. Any comments
greatly appreciated. Also what cnc program should I look at to begin
with, & is something available on the net that I could start
with, "Dancad" perhaps? Thanks in advance, I hope I don,t ask too
many stupid or obvious questions, Ian Sutherland.