Re: Counterbalancing & Rong-Fu RF-45 Project
Posted by
Roland Friestad
on 2000-07-12 06:39:55 UTC
Time to stick my oar in the water again
COUNTERBALANCING - I've done some work with counterbalancing, including
several different approaches - What I would suggest, particularly for
something like a Bridgeport knee, is a couple of inexpensive air cylinders,
one mounted on each side of the knee - They should be connected in parallel
to an air reservoir that is quite large compared to the volume of the
cylinders - This allows the stroke of the knee to not affect the force
applied by the cylinders over significant travels - The air reservoir should
be supplied by a pressure regulator that you can set depending upon the
table load - My experience however has indicated that there is a certain
amount of "stick-slip" with the Bridgeport (or any other similar machine) if
the knee screw is not replaced with a ball screw - I doubt that you will
achieve any higher speeds with this approach unless your motor is already
close to stalling out
RONG-FU RF-45 RETROFIT - I said that I would have photos and info ready
about now on this project but ran into a little snag - My customer wanted 2"
more travel on the Y-axis than was available on the stock machine so after
making the required modifications to the frame the ball screws I had planned
to use were too short - New ones are on order and will be here in about 2
weeks - I haven't forgotten about those of you who have expressed an
interest in this project and will make info available "real soon now"
Roland Friestad
COUNTERBALANCING - I've done some work with counterbalancing, including
several different approaches - What I would suggest, particularly for
something like a Bridgeport knee, is a couple of inexpensive air cylinders,
one mounted on each side of the knee - They should be connected in parallel
to an air reservoir that is quite large compared to the volume of the
cylinders - This allows the stroke of the knee to not affect the force
applied by the cylinders over significant travels - The air reservoir should
be supplied by a pressure regulator that you can set depending upon the
table load - My experience however has indicated that there is a certain
amount of "stick-slip" with the Bridgeport (or any other similar machine) if
the knee screw is not replaced with a ball screw - I doubt that you will
achieve any higher speeds with this approach unless your motor is already
close to stalling out
RONG-FU RF-45 RETROFIT - I said that I would have photos and info ready
about now on this project but ran into a little snag - My customer wanted 2"
more travel on the Y-axis than was available on the stock machine so after
making the required modifications to the frame the ball screws I had planned
to use were too short - New ones are on order and will be here in about 2
weeks - I haven't forgotten about those of you who have expressed an
interest in this project and will make info available "real soon now"
Roland Friestad