In article ,
Ignoramus24647 wrote:

On 2010-12-29, DoN. Nichols wrote:
On 2010-12-28, Ignoramus24647 wrote:
A couple of days ago, I started working on getting my 4th axis rotary
table to work.

http://igor.chudov.com/projects/Brid...-2-CNC-Mill/24
-Troyke-Rotary-Table-U12PNC/

I mounted it on the milling table a while ago and started integrating
it on Sunday or thereabouts. Constantly being interrupted by the
family, of course.

For feedback, it has a separate tachometer and a "resolver". This
resolver has six leads, two for rotor excitation and two for stator.

http://igor.chudov.com/manuals/Harow...300-F10-10.pdf

I would use Jon's resolver to encoder converter board:

http://pico-systems.com/resolver.html

Hmm ... the resolver has specs at 400 Hz (aircraft use) and at
2.5 KHz -- but the board seems to want to talk at 10 KHz. Any certainty
that this one will handle the 10 KHz frequency?

I have NO idea, this is a good question. I wondered about the same thing.

Yesterday I had a revelation and changed my mind. I decided that an
extra week spent on doing things the right way would be time well
spent. I decided to replace the terminal strip on the rotary table
to accommodate completely isolated stators, add a connection for home
switch, etc.

So I ripped everything apart again and will use a 12 lead cable, with
every lead pair shielded individually.

Hmm ... I would instead put each of the secondary windings from
the resolver in a separate shielded twisted pair instead of individual
leads shielded. Better common mode rejection.

Yes, this is what I tried to say, every pair is shielded.

1) 6 wires (3 pairs) for the resolver
2) 2 wires for the tachometer
3) 2 wires for home switch
4) (possibly) 2 wires for limit switch.

Best of luck,
DoN.


thanks.

Any thoughts on this excitation frequency?

Whatever the resolver wants. The datasheet provided above says 400 Hz
through 2500 Hz. I bet it is not critical within that range, but 10 KHz
is too high. I would ask Pico. Much more important to accuracy than
excitation frequency is good shielding.

Joe Gwinn