Re: Re: Brushless Servo

Raynor Johnston wrote:

> From: "Raynor Johnston" <rhj-rbj@...>
>
> Yes Jon... absolutely right with closer inspection it's dca is 2.1 amps so I
> guess not a lot of use for too much.
>
> On this list i think people have mentioned that the older large central
> computer processors are a source of quality motors suitable for axis drives.
> The suggestion was that the tape drives..the sort that drive those big tape
> reels on the vertical face of the processor...so beloved in 'Hollywoods
> James Bond mad prof control rooms ilk' are quality servos or steppers. Can
> anyone expand on that are there any names that have those ie. IBM
> models......etc. so I can take a look about here and are they steppers or
> servos?

All high-speed tape drives use servo motors, as they are delivering high
torque peaks, and also need high speed, especially on rewind.
The best motors are found in tape drives where the tape reel hubs are
mounted directly on the motor shaft, with no belt drive. These are
optimized for lower speed, higher torque, ideal for leadscrew drive.
Any tape drive of 45 IPS start/stop speed is a candidate, and 75 IPS
is even better. Digital sold a large number of TU77 and TU78 drives,
which were really Pertec T1000 drives under the Digital label. These
were 125 IPS, start/stop.
Another good drive is the CDC 'keystone', models 92181 and 92185,
also sold as the Digital TU80 and TU81. These were 75 IPS streaming
drives, with some very nice Ametek motors. There were hundreds
of thousands of these made, under many different vendor's labels.

I don't know specific IBM models, but I got some real nice shunt
motors from a Fujitsu clone tape drive, that would be emulating
an IBM 3420-series tape drive.

All the above are BRUSH motors, not brushless. They are easier
to work with.

Jon