Hi John, Just a comment on linear glass scales.
Acu-rite does make the ENC250 series in the lengths up to 6 m. with a resolution of 5 um. Really on the edge if you want to control to 0.0005". Using a 2.5 um resolution scale would be better. No idea of price but the SENC150 series goes for ~$2500 at 10'. They do need to be very well supported and aligned. I must say that they are nice if you have a truly zero backlash system. I can't imagine that linear motors will be any less expensive by the foot. Protecting the ways will be an interesting project in itself. Good luck on your project. Dave On Sep 29, 2007, at 1:12 PM, John Laessig wrote: > What I like about linear motors is the non-contact, low > maintenance, no > backlash, high speed, and high accuracy. It may be overkill, but I > like > that. The extra speed may be useful for thin soft materials and > reducing > slew time when cutting lots of holes. The extra accuracy may be > helpful in > doing just a little better than typical waterjets. > The main problem with waterjets is the water and the fine mist of > abrasives that travels into the bellows. Other problem are > inaccuracies in > the width of the cut (kerf) due to abrasive flow, speed changes, > cutting > head offset above the material (usually about 1/16 inch), and > vibration of > the table and part. Add it all up and you are soon wishing for no > backlash > and infinite accuracy from your motion system just to gain some > sanity. > Since I don't want a 16ft ballscrew or belt drive system on the > long > y-axis I am designing, I think a rack and pinion would be my next best > option. I don't want to take a chance that this would wear out > quickly and > start showing backlash. Does anyone know what the difference in price > between a high accuracy rack and pinion and a low accuracy linear > motor > would be (+/-.0005 inches or better)? If I had enough incentive, it > wouldn’t > be too late to reconsider a cheaper drive system with adequate specs. > John > > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> Stuart Stevenson >> Sent: Saturday, September 29, 2007 10:14 AM >> To: [email protected] >> Subject: Re: [Emc-users] linear motors with EMC >> >> Why would you use liinear motors on a waterjet? The speed >> and accuracy needed would allow you to use a much less >> expensive drive system. >> I ask this to educate myself. I have never used a >> waterjet. I am sure I don't know and understand the waterjet gotchas. >> I understand doing it because you want to. >> thanks >> Stuart >> >> -------------------------------------------------------------- >> ----------- >> This SF.net email is sponsored by: Microsoft Defy all >> challenges. Microsoft(R) Visual Studio 2005. >> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.5.488 / Virus Database: 269.13.33/1036 - Release >> Date: 9/28/2007 3:40 PM >> >> > > No virus found in this outgoing message. > Checked by AVG Free Edition. > Version: 7.5.488 / Virus Database: 269.13.33/1036 - Release Date: > 9/28/2007 > 3:40 PM > > > > ---------------------------------------------------------------------- > --- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2005. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
