RE: [CAD_CAM_EDM_DRO] BALLSCREWS QUESTION

Ron,

Why would a 8:1 or 10:1 need to be a 2 step reduction? Is it to reduce
belt friction (more belt wrap on the large gear) or is it a moment of
inertia concern (large diameter gear = geometrically larger I). I'm
guessing the latter but just looking for confirmation.

Regards,

Adrien

-----Original Message-----
From: R Rogers [mailto:rogersmach@...]
Sent: Monday, January 24, 2005 2:10 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] BALLSCREWS QUESTION



Manel.

You can use those with a higher reduction between the screw and the
servo. Typically, there is a 2 or3:1 reduction with a .200 or 5mm per
revolution screw. You would need approximately 4 times that reduction to
retain the servo resolution per rev. I would go with like an 8-10:1
reduction then use a 200 or 250 quadrature encoder and a Gecko320. The
reduction would undoubtedly need to be a two stage arrangement. Two
belts running in parallel, each one with a 4 or 5:1 reduction. The belt
on the servo could be half the size of the belt on the screw. Lets see,
20 mm/8:1 reduction=2.5mm traverse per servo rev. 2.5mm/1000 servo
counts per rev (250 encoder quadrature)=.0025mm traverse per pulse step.
1mm/.0025 =400 steps per unit in perhaps Mach2 "motor tuning" menu to
calibrate the axies. This represents units selected as millimeters.
This is basically the same as a mill with 2000 steps per unit in inch
units having a .200" lead ballscrew. .0001" traverse per step. 8:1
reduction, Gecko320 and a 250 count encoder 1000 steps per rev. would
work well.

Ron


mfmiranda <mfmiranda@...> wrote:



I'm older to this list but this is my first question to the forum.
I'm looking at putting together my own CNC mill. I already have two
superb 40" german x/y linear assemblies and the servo motors (54V, 7A,
3000 RPM), everything saved from junk. I intend to use Gecko 340 and
Mach2.

The question I have regards to the TPIs of my ballscrews -they are 20mm
- (0.8") - per revolution. This seems very large to my purpose.

I would like to know if some of you kind folk would take a moment to
figure the way I can use it with a minimum of acurracy, say 0,01mm,
using belt reduction, I guess.

Thanks very much,

Manel Miranda
Braga, Portugal









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@... davemucha@...
[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


Yahoo! Groups Links









[Non-text portions of this message have been removed]



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@... davemucha@...
[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


Yahoo! Groups Links









-----------------------------------------
The information contained in this transmission may contain privileged and confidential information and is intended only for the use of the person(s) named above. If you are not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, any review, dissemination, distribution or duplication of this communication is strictly prohibited. If you are not the intended recipient, please contact the sender immediately by reply e-mail and destroy all copies of the original message. Please note that we do not accept account orders and/or instructions by e-mail, and therefore will not be responsible for carrying out such orders and/or instructions.
If you, as the intended recipient of this message, the purpose of which is to inform and update our clients, prospects and consultants of developments relating to our services and products, would not like to receive further e-mail correspondence from the sender, please "reply" to the sender indicating your wishes. In the U.S.: 1345 Avenue of the Americas, New York, NY 10105.