BP Knee air lift assist?

[DennisCNC]

I have a BTC mill and it has what I think is a air rotation assist motor on the knee ballscrew, is this correct? Does it need air pressure all the time or only when moving the knee?
I put some air in the hose that goes to the knee base, then oil and air came out. Does it need oil also or is it oil that built up from the ballscrew lube supply?

[machintek]

This was an air assist that was full time. It was set to 40 PSI for a bare table. It was increased 5 PSI for every 100 pounds of mass put on the table.
I had a case (S2NC) where a knee went up but not down. Sure enough, there was 80 PSI on the regulator for the knee and the stepping motor could not move it down, only up. It also helps the knee to stop instread of continuing down.

George

[DennisCNC]

Thank you very much for the info!!!!

Do you happen to know approx torque for the steppers on this machine?
They are big nema 42's but from my testing they don't seem to have much torque.

[colin1544]

Hello dennis the one I had many years ago was the same as yours but as far as I am aware they were only built with D C servos not Steppers. Cheers Colin

[machintek]

I gave an example of a machine that had steppers. I remember seeing drive boards for the BTC2 and I believe they also use steppers.

George