RE: Z velocity

["Eric Keller" <eek105-at-psu.edu>]

My BP cnc has a 2:1 reduction on the quill, and I think that the ballscrew
is 5tpi.  This is factory stock.

 Don't forget that the AC servomotor is going to have a large number of
positions that it can hold accurately for each revolution.

Eric


-----Original Message-----
From: emc-at-nist.gov [emc-at-nist.gov]On Behalf Of Richard
Sent: Friday, November 22, 2002 2:44 PM
To: Multiple recipients of list
Subject: Z velocity



Hi,

I'm CNC'ing a knee mill with a 56" x 10" (36" x 18" travel)
table and 18" knee travel, 5" quill travel. I'm planning on
around 200IPM for the table but haven't a clue how to gear the z
axis quill.

I'm working on bracketry to hold the 0.2" pitch ballscrew and
pulleys & belts. I'm using AC Servo motors and drives and have
one of around 3.5Nm(500oz in) constant stall / 25Nm(3500 oz in)
abs max peak reserved for the Quill drive. Current thinking is
double HTD pully reduction of 127/30 and 72/30 giving 0.5mm (20
thou) quill movement per motor rev and a max quill speed of
25mm/sec (~1"sec).

I've no idea what the norm is for home conversions. How do those
figures sound?. I guess the mill is similar to a large
Bridgeport. It's a Beaver MKII.

--
Best regards,
 Richard