Water cooled spindle?
 

A fellow on the shopbot forum is offering some 3hp water cooled spindles. The spindles are made in China, have a 3phase inverter, and use E20 collets. They do rpms up to 24K. I believe they are DC, but I'll have to verify that.

THe price is about $1000. I'll need to add a bracket and a potentiometer to control speed manually. Probably some sort of water resevoir as well.

The guy says these are made in an ISO 9000 factory, and use NSK double bearings.

I'll mount this to my modified Shopbot PR. It has a very stiff aluminum extrusion gantry and bishop wisecarver rails/wheels.

Any issues to worry about with this sort of spindle? I don't mind a Chinese brand or make, as long as the runout and longevity is better than my Porter Cable.

Anyway, somebody tell me what I need to be considering to make a good decision here.

Thanks Gerald for an EXCELLENT forum!

Wayne
White Salmon, WA

Hi wayne,

look here
http://www.mechmate.com/forums/showthread.php?t=915

is it any one of these?

RGDS
Irfan

Aside from bearing quality issues, and the quality (concentricity, smooth thread finish) of the ER20 spindle nose, I would be concerned about the inverter's quality. That inverter may be electrically noisy and cause interference back to the control system.

A follow up question if I may. The seller says the controller is a 3 phase one, but that he can wire it to run single phase. Will there be any loss in power if the controller is used this way? As I understand it, the controller sends a varying voltage to the motor, and the motor itself is 3 phase. If the motor is 3 phase but running on single phase, won't this reduce the motor's efficiency and possibly generate more heat?

I use a Porter Cable router now, and am limited by its power. I can't cut ply goods or lumber in a single pass. I expect the spindle will let me cut most sheet goods in a single pass. I also expect it to be considerably quieter. At any rate, the choice for me is between the Porter Cable and a $1000 spindle, not a 5hp spindle.

Thanks as always for your help. I know I'm not a MechMate builder yet, but I very much appreciate the base of knowledge here.

Wayne

The controller takes incoming AC power, converts it to DC, converts it again to very high frequency AC (this is what can cause interference), converts that again to a 3-phase AC output of a fixed voltage (400V?) where you choose the frequency. The spindle wants a fixed voltage (400V?) 3-phase input, and your changing of the frequency makes the spindle run at different speeds.

The spindle is a rather dumb electrical motor - its behaviour is determined by what the controller throws at it. You can see that the controller has a complicated set of conversions to do. A poor quality controller makes a poor signal (eg. misshaped sine wave, too low voltage, unbalanced phases) and these things can make the motor hot, even without much load on the spindle.

Most brands of controller can be given a single-phase supply instead of the 3-phase, but then it is accepted that they will produce less power. (there are a few exceptions).

I somehow don't believe that 3HP spindle setup is going to give you happy single pass cutting of boards, unless you can verify it with someone who is already doing it . . . . . on single-phase . . . . . . for more than a few weeks already.

Gerald, you're right about a 3-hp spindle being on the light side for one-pass cutting. My 3-hp Colombo can cut in one pass, but it does it using all the power that it has. That leads to quick heat build up. I like to keep the bearing temperature at 120 F. Although I don't really get concerned until the bearings get to 130 F. When they reach 135 F, I shut down for a while. The spindle is rated at 140 F, but I'm reading from the outside with an Infared thermometer. I really have no real idea how hot the actual bearings get, so I stay on the low side.

One other factor about cutting one-pass is hold-down. My two Fein vacuums can't reliably hold most pieces when I do one-pass cutting. (I'm at 4,500 feet altitude, which is a big factor for these little vacuums.)

A 3-hp spindle is great for two or three pass cutting. I've run mine for hours on end in the heat of the summer without a problem, but one-pass cutting would require a larger spindle.

Hi Wayne,

If I may ask, what vendor are you referring too ?

I know a few there is a few selling those but I found one that sells those type of Chinese water cooled spindles offering some up to 5HP. Have a look, here’s the link.
Hope this can help your decision !
Amicalement, Robert ;)

Great info
 

Thanks Gerald and all. I'll do some more pondering about this. I was really expecting to be able to cut reliably in a single pass. I also have some concern about noise. I've had static problems in the past, so I understand noise is not a good thing.

I'm going to check the 5hp water cooled units at the link you gave, Robert M..

Any worries with water cooled in general?

Wayne