Re: [CAD_CAM_EDM_DRO] Lead screws - made more accurate

Hi Doug

A web page on the cam correction of leadscrew pitch is still up...
follow the cnc links on the engineering page.

I used this primarily to match a pair of gear syncronized tandem screws.
Software correction is certainly easier for single screws if the controller
has that functionality.

The method is by no means new, but it can pretty much correct screw
pitch errors to any desired accuracy as long as the system is backlash free.
It was used to create some of the first truly accurate screw-cutting lathes
early in the industrial revolution around 1820 or so.

Les

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
http://www.alltel.net/~leswatts/shop.html
Surplus cnc for sale:
http://www.alltel.net/~leswatts/forsale.html

----- Original Message -----
From: "Doug Fortune" <pentam@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, May 16, 2003 1:23 AM
Subject: [CAD_CAM_EDM_DRO] Lead screws - made more accurate


> Don Rogers wrote:
>
> > Now, we are talking about lead screw accuracy, how do we get 0.001" per
> > foot accuracy when the best lead screw we have is 0.006" per foot? And
how
> > did we come up with one that accurate when a machine that accurate
didn't
> > exist yet?
>
> The machine doesn't have to be accurate, if you can calibrate
> the machine, then apply corrections.
>
> I believe Les Watts described on this list a year ago, a method
> of 'mechanically' correcting a leadscrew (ballscrew or acme) by:
>
> - determining the error (in fractions of a leadscrew-turn)
> - machining the counter-correction into a linear cam
> - a follower follows the spindle along the axis (along the cam)
> and the cam torques the nut appropriately (which applies the
correction).
>
> Of course its far easier these days just to apply the correction
> in software (conceivably even using hardware store all-thread and
> getting reasonable accuracy).
>
> I believe EMC/Linux can do this, I'm just waiting for the idea to catch
> on in the other interpreter packages.
>
> Doug Fortune
> http://www.cncKITS.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/
>
>
>