DropLit Assembly Guide
You want to only thread the rod in a short amount – it should only be slightly above the nut
inside the Anti-Backlash Nut Carrier as shown in Fig. 5-42.
Insert the small compression spring between the two uprights in the Anti-Backlash Nut Carrier.
Now insert an M5 nut between the uprights and use it to
compress the spring about 3/16” of an inch.
Thread the M5 rod up until it engages the M5 nut above
the spring and then continue to thread it until you've got
about 2” of rod above the Anti-Backlash Nut Carrier.
I'd like to take just a second and
explain what this whole Anti-Backlash thing
is all about. We're essentially capturing the
M5 rod between two fixed points and using a
spring to keep tension on those fixed points.
See a nut will have a little “give” to it in
order to allow it to easily thread on to a screw
or rod. This is a great feature in a fastener,
but an absolutely rotten thing to have if you're
using these things to precisely move a
platform or carriage. What happens is that
when the threaded rod changes direction, no motion will result for some small percentage of the
rotation because the rod is going to take up the “slack” in the nut. If the rotation is small enough, the
carriage won't move at all because the motion did nothing but take up that extra room. By having the
Anti-Backlash nut installed, that slack is removed by the spring. The nuts capturing the rod are
ALWAYS in contact with the threads because the upper nut is pressing against the upper face of the
thread and the lower nut is pressing against the lower face of the thread, so a direction change will
result in instant motion of the attached carriage. Ok, now that you understand why that's being done,
let's get the Z-Axis rod connected to the stepper motor!
51
Fig. 5-43: Spring installed.
Fig. 5-44: Rod captured in Anti-Backlash Nut.
