"Bob La Londe" wrote:

I think I have a design for a Z-axis retrofit for it all worked out, and I
have a question or request for clarification from some of you guys who have
built, retrofit, or modified your own machines. Everybody says you need a
brake on the Z-axis if you use a ballscrew or it will backdrive. How much
force does it take to back drive? I know the answer is probably "it
depends", but I was looking for a more general answer.


I've worked on VMC's that used brakes and one that used a chain with pig iron for a
counter balance. See if a counter weight, simple as a pulley, cable and a balancing
weight will do. Oh, I was responsible for a waterjet cell that used an air counter
balance but it had a brake in case we lost air pressure.

Air cylinder and pressure regulator might be the easiest way to go. This isn't a danger
to life app like full sized machines.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller