Re: [CAD_CAM_EDM_DRO] Measuring backlash more accurately?

You're not resetting your zero point during the milling process are you,
say to run a subroutine, and then going back to original zero for the main?


At 01:47 PM 2/16/03 -0800, you wrote:

>I have been fighting a problem on the gantry mill. The Y axis seems to
>"drift" so that over the course of macining a contoured part (say 10 depth
>passes of outline and internal pockets) it has moved 20 thou or so. For a
>part that has 30-thou walls, this has created great frustration.
>
>After completely rewiring the controller box, fully separating signal from
>power grounds, minimizing wire runs, twisting pairs, etc. I made another
>trial run this morning, with no help.
>
>I realized that the backlash settings might not be right. (That's about
>the only thing left...) I had measured the backlash on each axis by the
>conventional method (move + increment, zero indicator, move + increment
>again and then - increment and write down the reading) but after a program
>that has maybe 100 Y moves, it seems to me that I need a more accurate way
>of measuring the backlash.
>
>Is there a way to cycle the axis so the backlash accumulates? I could then
>run the cycle 10 or 50 or 100 times and divide the resulting accumulated
>backlash by the number of cycles. I can't think of a cycle though, that
>just doesn't run back and forth in the backlash window.
>
>The only other thing I could think of is to input a backlash value that I
>know is wrong, and run the machine back and forth and see how it "drifts",
>tweak the backlash value, run it some more and repeat until it doesn't
>drift.
>
>I have a Starett "Last Word" indicator with half-thou graduations. I can
>estimate to maybe one-tenth but maybe more reliably to 2-tenths.
>
>Any advice?
>
>Thanks!
>
>Randy
>
>Randy Gordon-Gilmore ,----.___________ ______________ _________________
>ProtoTrains // = = === == || == == == = || == == == = == =|
>Rio Vista, CA, USA /-O==O------------o==o------------o==o-----------o==o-'
>zephyrus@... http://www.prototrains.com
>
>Addresses:
>FAQ: http://www.ktmarketing.com/faq.html
>FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
>Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
>Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
>List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,

timg@...

>Moderator: pentam@... indigo_red@... [Moderators]
>URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
>OFF Topic POSTS: General Machining
>If you wish to post on unlimited OT subjects goto:

aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.

>http://www.metalworking.com/news_servers.html
>
>http://groups.yahoo.com/group/jobshophomeshop I consider this to be a

sister site to the CCED group, as many of the same members are there, for
OT subjects, that are not allowed on the CCED list.

>
>NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.

DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........

>bill
>List Mom
>List Owner
>
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>

Regards, Hoyt McKagen


Anti-virus request: Please do not add this email addy to address books
Belfab CNC - http://www.freeyellow.com/members/belfab/belfab.html
US Best MC - http://www.freeyellow.com/members/batwings/best.html
Camping/Caving - http://www.freeyellow.com/members/batwings/caving.html
Hac a hac que haec, hoc, hoc, patui