Experience with brushless air-cooled spindles?

I’m looking at spindles. In the short term, I’m hoping that the replacement power supply I am buying for my air-cooled brushed DC spindle gets me going, but in the longer run I probably want a better spindle. This router is for cutting wood and occasional plastic; rarely aluminum (for new plates, such as if I cut-it-forward) so I don’t see a reason to add the weight for water-cooled.

  • I see some spindles with only two wires advertised as brushless, which I assume means that they have an ESC built into the motor. Are these intended to be a drop-in replacement for brushed spindles, without the brushes? Do they have downsides relative to brushed spindles they replace? Since they are essentially three-phase AC motors, do they tend to have smoother torque and a better cut?
  • I see some brushless spindles with only three wires and no hall sensor. Is back-EMF sensing good enough for normal CNC router usage, so no real need for hall sensor if I’m cutting wood and plastic? It has to be synchronous to work at all, so my guess is that for this use hall sensor is unnecessary.
  • I see some brushless spindles with integrated hall sensors that use five sense wires as well as three power wires to connect to the controller. How sensitive to noise are these sense wires typically?

Can’t be of much help with DC spindles, I run 2 VFD driven spindles, one is air cooled 1.5kw and the other is a water cooled 1.5kW Noise difference really is not that much when the tooling is actually in the material, the water cooled is much quieter when just spinning. Unfortunately the OX Z axis can not handle the weight of the spindle without upgrading the Nema23 stepper to a high torque one.

I wish it were single-start lead screw instead of 4-start, then it would not back drive either. I do have the same stepper for Z as I do for X and (2) Y, so maybe it would work anyway!

What air-cooled 1.5kw spindle do you have?

This is the one I suse:

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Do you use a 1.5kw VFD or do you get an oversized unit like a 2.2kw?

Have you had good experience buying from banggood?

I used a 1.5kW VFD. And I have had a great experience with Banggood. Over 400 orders from them and very few defective products, which they reshipped or refunded without delay.

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I thought I had somewhat over-provisioned power in my shop with two separate 20A circuits down that wall with two outlets on each circuit every 4-5 feet. Now I regret not running extra wire for 240V in that wall. I guess I’ll have to see how hard it is to go fishing and pull another line…

This VFD is less expensive than I would have expected.

That’s $87 in yank dollars. And $160 for the spindle, makes $247 together. That’s less than some of the “BLDC” solutions I found for 800W, and BLDC is… basically the same as a three-phase AC motor.

What is the run-out like on that spindle, by the way?

Nothing really measurable, however I only work with wood. I think you will have more error based on the Vslot/wheels combo than anything the spindle will generate.

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I would never use a DC spindle anymore. We had one on the Optimum BF20 CNC Mill in our FabLab and the motor burned twice because of too much load. Replaced it with 3 phase motor and VFD.

I you search an easy and light spindle, I can recommend the Kress/AMB 1050 FME Spindles:

We have one of these on our Stepcraft 840 CNC router.