Dave, Power is just torque times rpm. The motioneering software selected motors and displayed a torque curve showing the operating point was in the safe region.
Although I did not list it, the optimum motors were in the range of 600W or so rated cont power. This occurs at max cont torque and max rpm. At the 3 to 5 reduction the motor will only be going a few hundred rpm for the gantry speed I used. The power actually delivered will be only perhaps a tenth of what the selected motor is capable of. The voltage will similarly be much lower than rated. I know this may seem really sub optimal to use the motor this way, but we are trying to optimise cost- not motor power utilization or efficiency. The only mechanical load that really consumes real power is friction. That is very low in your proposed machine. What we need is FORCE to accelerate the moving mass... and in a regenrative servo system you actually get that back when you deccelerate....it pumps up the supply cap voltage. So it turns out that the software selected motors capable of the torque required can generate much more power if they were run at a high rpm. The smaller motors at the high ratios run at higher rpm, but they have to use more torque to fight their own rotor inertia. As you can see the software found NO practical motor that would give the selected machine performance above 20:1. Let's say you had a car that you wanted to be fast off the line. You can use smaller and smaller motors with more and more gearing to get the same torque. At some point the time to wind up the smaller motors to high rpm would actually be the limiting factor rather than the car's mass. Les Leslie M.Watts L M Watts Furniture Tiger Georgia (706) 212-0242 Main page: http://www.lmwatts.com Engineering: http://www.lmwatts.com/shop.html Cnc surplus for sale: http://www.lmwatts.com/forsale.html Carved signs: http://www.lmwatts.com/signwp.html -----Original Message----- From: turbulatordude [mailto:[EMAIL PROTECTED] Sent: Tuesday, December 28, 2004 2:19 AM To: [EMAIL PROTECTED] Subject: [CAD_CAM_EDM_DRO] Re: Plasma table gear reduction <snip> > 3) 3:1 reduction drive with 1" diam timing pulley > 250 in oz torque 0.1 oz in sec^2 rotor inertia <snip> > So with the numbers I used you can see that there is a sweet spot at about > 3:1 to 5:1 where the peak torque required is minimum and a reasonable and > typical > rotor inertia gives a good impedance match. > > This is not anywhere near the point where the motor delivers best power or > is > most efficient. It is simply the point of best economy for your design. > > > > > Leslie M.Watts > L M Watts Furniture > http://www.lmwatts.com Thanks Les, dumb question, but is that power into the drive ? or do you also divide the power by the ratio to get the motor power needed ? I see is that a 1,000 RPM motor is the place to start. that would offer something between 200 and 300 inch per minute rapids. Thanks for your efforts to guide me straight. Dave Addresses: FAQ: http://www.ktmarketing.com/faq.html FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ Post Messages: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [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 Addresses: FAQ: http://www.ktmarketing.com/faq.html FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/ Post Messages: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] Unsubscribe: [EMAIL PROTECTED] List owner: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED] Moderator: [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] [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 <*> To visit your group on the web, go to: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
