Ray,L can you post a photo of the gas springs you mounted on the knee? Id like to see exactly where you put them.
I have continued to work with my new AC servo on the knee. I have run it up and down very smoothly many times, but every once in a while it will hang and fault the motor going DOWN. I have also heard a bit of a growl, or chatter going down. I suspect I have a gib problem. I think it may be shifting slightly and acting as a wedge.
Eliminating the gears and driving the screw directly works very well. The crank shaft came out through the side in a bolt on casting, so I simply removed that and have a nice access hole into the knee. I was able to get the motor inside the knee casting. with a short belt to the screw. Mechanically it looks very neat, almost like it was designed that way.
Ron,
Some bad cell-phone pictures below. I placed the gas springs next to the dovetails. I thought a lot about the merits of putting them there, or alongside the pedestal, and decided this was best, to avoid the problem you seem to be having. I figured this was more likely to keep the dovetails moving smoothly.
Mine does make more noise coming down than going up. Up is actually pretty quiet. On the way down, I get a small amount of "clunking" that I believe is the knee lagging slightly, then dropping. The noise, I believe, comes from the bevel gears as the small amount of backlash opens and closes. I haven't had a chance yet to really get to the bottom of it, but I don't think it's anything to be too concerned about. And it also happens only at high speed (above ~50 IPM).
Regards,
Ray L.