Hi cncfreakcncfrea,
that looks like a mighty nice spindle, ATC as well, bet it costs a bomb! You may have noticed 800Hz inverters are as rare as 'rocking
horse s...t' and also like to cost a bomb.
To be honest I don't care what you cut 'the slower the speed the greater the torque required'.
To take my spindle for instance 750W at 24000 rpm, its good, plenty of grunt for a small motor. The same spindle slowed down to
6000 rpm is only 187W, scarcely enuf grunt to get out of its own way. I make a lot of circuit boards and for those it goes great and
does a nice job on aluminium too. But when it comes to steel or larger diameter tools torque is king.
By comparison to a decent sized high speed spindle which is still capable of good torque down low suddenly servos don't seem quite
so expensive. Providing spindle and bearings with tool holder adds to the cost certainly but if you make them yourself well....
A 1kW Delta servo AND drive for about $650 (AliExpress) is pretty good buying.
I really wanted about 10Nm torque at up to 3000rpm. The servo I found does 12Nm and short duration overload of 48Nm. I'm hoping
to spin 16mm tools in steel at an engagement ratio of 25%, ie serious grunt for a benchtop mill. The servo itself is quite old, think
manufactured in '94, it looks brand new. Downside is it has an 8 pole resolver, old school stuff, simple and reliable and easily enuf
rotational accuracy for rigid tapping. Resolver capable drives are few and far between. Could change it to an encoder.
Electronics is my thing so I thought I'll make one. Easier said than done of course but I've proved its not impossible. Using a Texas
Instruments TMS320F 28069M micro on one of their Launchpad boards. $50 gets you the micro, isolated JTAG all pinned out and ready
to go. 32bit @90Mhz,single cycle floating point, all the peripherals you could possibly eat, free to use IDE and libraries. Had to learn C
to write the code, learn about field oriented control. Coded up and working well including my resolver-to-digital. Working on the inverter now.
Using Texas Instruments ISO5500 isolated drivers with de-satSD/UVLO and all the fruity bits, $5 each to drive 500V 50A MOSFETS @ $15 each.
Using heavy copper (420um copper layer cf standard PCB 35um) board. Rated output 14A per phase, 30sec overload 28A, momentary overload
48A. Input current (rated) 27A @230V.
I've got NSK 7204P4 matched angular contact bearings and a genuine 'you beaut' Regofix (Swiss made, real shiny!) ER20 spindle and a full
set of Jones&Shipman collets.
All up about $1000. Not finished yet but its coming along. I've put serious thought and effort into it.
Craig