Spindle, VFD and sensor recommendation

[ian]

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

[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.

[JAZZCNC]

Ok here's my tuppence which is very much like Doddy's thou I'm reasonably sure I'm safe to say I've got a lot more experience of these spindles than Doddy or just about anyone on this forum as I've literally fitted 100's to the machines I build over 15+ yrs.

The Chinese 2.2Kw WC spindles with Huanyang Vfd's is pretty much rock solid in a Hobby environment, I have fitted dozens to machines working in business environments working 12hr, 6day weeks that are cutting none stop and only to change tools or sheets. Some of these are over 10yrs old and still going strong. My own machine which cuts exclusively aluminum is over 6yrs old and on short jobs(20-30mins), I don't even turn on the water, that's how robust they are. The WC side isn't critical unless your cutting long jobs at high RPM.

I can honestly say I've had less than 10 faulty units out of maybe 300+ sets over a 15yr period and out of those most arrive DOA and it's always the VFD. The Huanyang Vfd's have got better over the years and I wouldn't hesitate to buy one. Paying high bucks for a VFD doesn't always guarantee reliability and I have a very expensive ABB drive here to prove this as it died less than 3yr old for no apparent reason I can see, I didn't abuse it or miss wire. Just didn't start one day.!!

Regards Air or WC then it's a funny one. Air-cooled is ok provided you have a good electric Fan which can be controlled and monitored. The cheap spindles like what you have shown are rubbish and will overheat if run for any lengthy jobs, the duty cycle is very low on the cheap offerings. The high-end spindles are perfectly fine and while they make slightly more noise than WC it's not a massive difference.
However, I'd always choose WC over Air because of the duty cycle, WC doesn't really have a duty cycle and you can run them continuously for days without any issues, again I have customers who run 3D jobs that take 18-24hrs without stopping.!

It's a similar thing with the Inductive proximity SW, don't waste money on expensive SW as the cheap proximity SW is more than good enough. For less than 1 moderate brand name SW you'll get all the SW for the machine plus a spare set. Again I've fit 100's, no actually 1000's over a 15yr period and I have very few fails in comparison to how many I've fit.



Somewhere on Youtube several yrs ago I did a little test showing how accurate and repeatable the cheap Chinese SW is, check it out you'll be surprised.