Back EMF is a problem. You may need a much higher voltage like as much as 10 X to get 10X higher speed unless the drive can do field weakening. But with a PM motor you cant field weaken much - you are fighting the PMs field. I think only around 20% might be practical.
John Figie On Wed, Oct 3, 2018, 7:00 AM Roland Jollivet <roland.jolli...@gmail.com> wrote: > On Wed, 3 Oct 2018 at 11:32, andy pugh <bodge...@gmail.com> wrote: > > > On Wed, 3 Oct 2018 at 06:49, Roland Jollivet <roland.jolli...@gmail.com> > > wrote: > > > > > If only the speed was a lot higher, it would be an awesome spindle > motor > > > for rigid tapping. > > > > How much did you pay for it? > > What do you imagine would happen if you ran it faster? > > > > You could always gear it up. Maybe have a 1:1 ratio for tapping and a > > speed-up for normal milling. > > Either one toothed belt and two sets of (carefully chosen) pulleys or > > two permanently-engaged toothed belts with a peg to engage the > > high-speed ratio and an over-running clutch on the low-speed one: > > This one can do 85Nm: > > > > > https://simplybearings.co.uk/shop/p152524/CSK25PP-25mm-Sprag-Clutch-One-Way-Bearing-with-Internal-&-External-Keyways-25x52x15mm/product_info.html > > -- > > atp > > > > > I probably paid about $10 for it, as scrap metal, from a CAT scan machine. > I remember the scrap yard guys rolling their eyes as I carried it out of > there. Junk collector.... > > I don't know if it could run faster with the correct drive. Maybe back EMF > would be a problem? I would like 7000 RPM, but I don't think a 10:1 setup > is practical. > And surely it's rated 700RPM for a reason. I doubt the magnets are going to > fly apart, so what would that reason be? > > The irony is that I've just got myself a scrapped CNC mill with a missing > spindle drive motor, that's why my attention was back on that motor. > This is a LinuxCNC candidate so I will document/blog the re-build. > > The over-drive arrangement would work, but maybe better suited to my lathe. > Direct drive for threading, then step-up to ~ 2000RPM max for turning. > > > > > > > > <https://lists.sourceforge.net/lists/listinfo/emc-users> > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
