Spindle, VFD and sensor recommendation

[Doddy]

Hi Doddy

Thanks for the reply.

I'm not sure what you mena when you say the "overspending the drive by 50% compared to the spindle" - does this mean the VFD is overpowered for the spindle?

The reason for the air-cooled options was to keep the set-up simpler to options I am a bit more comfortable with. I wasn't aware that the water-cooled version operated with less noise - since the machine will be used a lot in my home office for protyping, that can be a big advantage (although I intend to also build sound insulated enclosure). It seems that it is possible to get some complete kits so I will look into it. What size/volume is your system?

I will mostly cut small enclosures (45mm - 75mm) from hard engineering plastics of ± 12 - 20mm thickness. I need a set-up that can work continuously at speed with good spped/feed rates and DoC and intended to get a 2.2KW spindle - the CNC is primarily for work purposes to get a job done - although I won't really need end mills larger that 1/2'. I just want to be able to machine comfortably.

Thanks

My bad... I meant to say "overspecc'ing" (I sometimes wonder about auto-correct). My point is that you can find spindles and VFDs bundles that are matched - a 2.2kW VFD with a 2.2kW spindle. Actually the cost difference is typically much less pronounced than the difference in power between VFD and spindle. But, why specify a VFD that is designed for a larger spindle than you aim to buy? Do you have a 20A supply available for this?

I can understand the attraction of air-cooled - it is notionally simpler... but I wouldn't overthink the complexity of water cooling - kiddies are building water-cooled gaming rigs, plenty of kits around. Unless you're putting the spindle under a large sustained load you'd probably get away without the cooling (not a recommendation!, just an observation).

What size is mine?, I have two milling machines (rather than the possibly more popular routers) - the skeleton of an old Starmill 80kg, working volume about 150mmx100mmx200mm, actual footprint more like 800mmx600mmx500mm), which has the 2.2kW WC spindle. The second, a 130kg SX2.7 converted to CNC - working volume around 500mmx180mmx400mm, practical footprint around 1200mmx600mmx800mm, with - ironically - a much smaller 800W servo spindle which max's out around 2krpm - which is used for cutting steel and alloys. Previously I had a router - a Marchant Dice machine as mentioned earlier - work area was something like 300x200x200mm, weighing in around 30kg - which couldn't butter toast, let alone cut it. Don't get fooled into thinking that the spindle is the heart of the machine - look at the rigidity of the machine - that will define the limits of what it can cut, and at what speeds. My experience with routers was a poor introduction, driven by a poor choice. I predict you'll get advice from others here to treat kits with caution, you'd be sensible to listen - and by all means challenge - that advice.

If your build volume is truly as constrained as you say, a mill may be more appropriate than a router - but that's a decision that only you can make.