#emc-devel | Logs for 2007-10-02

[00:00:12] <LawrenceG> they were a little touchy to get good quadrature waveforms
[00:00:17] <jmkasunich__> I've thought about using some kind of magnetic sensors to detect the teeth on the spindle gear (inside the headstock)
[00:00:58] <LawrenceG> I havent had the headstock apart... what is in there? mine rattles a lot
[00:01:24] <jmkasunich__> a gear on the spindle
[00:01:31] <jmkasunich__> an idler shaft with two gears
[00:01:49] <jmkasunich__> and the shaft that comes out in the "belt box" to drive the threading/power feed geartrain
[00:01:52] <LawrenceG> ok for the power feeds (not used on cnc)
[00:01:56] <jmkasunich__> right
[00:02:23] <LawrenceG> that gear would be a nice place
[00:03:04] <jmkasunich__> I have no idea how many teeth it has
[00:03:10] <jmkasunich__> other than "not all that many"
[00:03:19] <jmkasunich__> it would be a fairly coarse encoder
[00:03:38] <LawrenceG> add a piece of ketstock for an index pulse
[00:03:50] <jmkasunich__> I hadn't even thought about the index
[00:04:25] <LawrenceG> thats easier to get.... maybe something on the drive pulleu
[00:05:22] <LawrenceG> my encoder is 360 counts/rev.... and rpm pyvcp meter shows +-rpms
[00:05:35] <jmkasunich__> handy
[00:07:25] <LawrenceG> I was fighting with a hal config for the lathe.... it seems to want x,y,z config settings.... and I just redirected the x,z pulses to the right parallel port pins
[00:08:11] <jmkasunich__> emc doesn't deal gracefully with non-sequential axes
[00:09:08] <LawrenceG> but at least everything is working in the right direction (jogs, moves etc)... now to figure out threading
[00:09:35] <LawrenceG> I have no idea how to setup to cut an M10 thread for a drawbar
[00:09:49] <LawrenceG> a smop!
[00:10:50] <LawrenceG> just need to figure out what the key diameters are
[00:12:18] <jmkasunich__> get out the thread wires ;-)
[00:13:44] <LawrenceG> next project is some 10-24 thumb screws for my pcb hold-downs
[00:13:59] <jmkasunich__> male threads?
[00:14:08] <jmkasunich__> (on the thumbscrews)
[00:14:32] <skunkworks> * skunkworks yells vacumm table!
[00:14:35] <LawrenceG> yup..... chance to try knurling, threadcutting and cutoof tool
[00:15:24] <LawrenceG> lets see at $70/hr... I figure they should be worth a fortune
[00:15:34] <jmkasunich__> I cheat for things like that
[00:15:49] <jmkasunich__> drill, tap (female thread), then screw in and locktite a socket set screw
[00:16:10] <jmkasunich__> gives me a grade 8 or so quality steel thread
[00:17:32] <LawrenceG> my tabletop is 3/16 lexan... I dont thing grade 8 is necessary, but it may be faster to knurl some stock and cut off some knowbs and do what you suggested
[00:17:59] <LawrenceG> whew... my fingers must be broken today
[00:19:51] <SWPadnos> hmmm. given that brass knurled thumbscrews, 10-24 (1/3-1") are betwen $0.50 and $0.72, I'm not positive about the economics of making them yourself :)
[00:20:02] <SWPadnos> err - 3/8 to 1", that is
[00:20:53] <LawrenceG> I definately wont have a market selling them to china!
[00:21:01] <SWPadnos> or to McMaster ;)
[00:21:40] <LawrenceG> now how many do I have to make to justify having this shoptask?
[00:21:50] <SWPadnos> 43557, at least
[00:25:00] <fenn> LawrenceG: can you use link-belts?
[00:25:14] <fenn> on your shoptask-lathe
[00:26:19] <LawrenceG> yes.. that would be an idea.... I can move the belts fine, its just when I have to replace it, I will have to move the encoder pickups
[00:26:55] <fenn> they are supposed to be better anyway, and only cost about 3x as much
[00:27:03] <LawrenceG> I am still using the orignal belts from 1995, but they are cheap crap
[00:28:12] <LawrenceG> I would like to find a 1.5hp 3phase 220 motor.... I have a VFD that mould make a nice spindle driver
[00:28:46] <LawrenceG> some of the servo motors are approaching that size
[19:38:37] <cradek> I think "tool setter" is not pending - it works fine
[19:39:30] <cradek> mach, turbocnc, deskcnc can probably do thread milling (helixes). I doubt any of them can do rigid tapping.
[19:40:40] <skunkworks_> I was wondering why mach couldn't rigid tapping as it does lathe threading.. THen I remembered you have to reverse the spindle..
[19:41:14] <skunkworks_> and follow back out
[19:42:10] <cradek> yeah, 1ppr only works if you assume the spindle never changes speed
[19:42:19] <cradek> reversing ... is a speed change
[19:43:01] <skunkworks_> right
[19:43:48] <cradek> I hear with a 3ph motor you can just smack it from fwd to reverse - I'm scared to try it on my mill though
[19:44:07] <cradek> (in theory I could rigid tap that way)
[19:44:46] <SWPadnos> I think you get very big screams from the supply wires if you try to "thwack" a 3-phase motor into reverse
[19:45:10] <cradek> yeah I was concerned about nuking my phase converter
[19:45:21] <SWPadnos> you might end up reversing your phase converter ;)
[19:45:21] <cradek> startup sounds a bit hard on it already
[19:45:25] <cradek> haha