Water cooled spindle

Questions/answers/discussion about initial setup of your CNC Shark

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Re: Water cooled spindle

Postby GuyDamato » Thu Jul 12, 2018 9:43 am

In reference to the Water Cooled Spindle: (I just received my water cool spindle) Is there a "cleaner" way then using a 5 gallon bucket. Does a lot of dust get in the bucket?

Also, the hoses...., is there a clean way of having them run to my water supply so they do not get "hung" up?

thanks in advance...

Guy
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Re: Water cooled spindle

Postby Rando » Thu Jul 12, 2018 11:28 am

GuyDamato wrote:In reference to the Water Cooled Spindle: (I just received my water cool spindle) Is there a "cleaner" way then using a 5 gallon bucket. Does a lot of dust get in the bucket?

Also, the hoses...., is there a clean way of having them run to my water supply so they do not get "hung" up?

thanks in advance...

Guy


I use a 3Ga boat gasoline tank. The fuel outlet goes to an RV lavatory (self-turn on) pump, to a 90-degree ball valve, then through the spindle motor. The returning fluid goes into either the open filler-cap hole, or if you're like me, you'd drill and tap a hole for a fitting the flexible tube connects to. That way no dust gets in, and it could be knocked off the shelf it's on and not leak. We have earthquakes here in WA :D. Also, I keep it on the same vertical height as the spindle, to avoid siphoning either way, and thus less load on the lavatory pump. I run all my spindle-related wires and hoses UP to a sprung holder so that as little of that weight is added to the already-sagging gantry.

Most people use water. I used anti-freeze, 3:1 with water, though theoretically I'm going to eventually regret it. Apparently it's not good on seals (are there seals in these?) and water actually carries away more heat per unit volume of fluid. Sigh, yeah, whatever....originally my 3Ga gas tank was kept in the freezer, so the cooling fluid was a nice cold 38-40F at the spindle. Not going to do that with mere water through a 12-foot tube (my freezer was a bit away). Runout was low, but also low bearing life due to limited grease movement. So now instead, the fluid is at room temp, and rarely moves beyond that even on long hard cuts in aluminum, so I'm going to say the 3Ga tank, filled to about 70%, is "enough".

Smaller units I'm seeing these days are using a much smaller heat exchanger pump-type thing.

But yes, dust and dirt can foul the aquarium pump, if not the inlet filter, if you leave the reservoir uncovered. If you use a sealed tank, be sure to include an air-break where the fluid comes back into the reservoir. That will let you have a sealed system so no leaks in or out, without having to worry so much about hydraulic fluid-flow issues.

Just to keep track of things, I stick a beer homebrew thermometer (flexible self-adhesive strip with LCD-material showing temps) on the side of the spindle. That way I can pretty easily see if the temperature is getting out of hand.

Currently what I'm hearing is that the spindles want to be "warm" in the 80-90F range, but avoid getting over much 130F (not C!). If it stays in that range, the bearings will work and last longer due to improved lubrication flow, the heat-load into the cooling reservoir will be small enough to avoid thermal runaway in the system, and life will be good and quiet for some time.

One final note. All systems have resonant frequencies. You'll often find that a certain spindle RPM will be a lot louder than others. Sometimes adjusting the RPM out of whatever resonant mode it's gotten into with the rest of the machine will make it not only quieter, but eliminate chatter in harder cuts.

Anyway, cheers, hope that helps!

Regards,

Thom


P.S. Ask me how I convinced the pump to be turned on when the spindle's VFD is set to "run" mode. Hint: a setting change and a small form-C relay is all it took; no additional components besides wires. Now no need to make sure to turn the pump on. When it's needed, it's turned on. :ugeek:
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Re: Water cooled spindle

Postby GuyDamato » Thu Jul 12, 2018 12:12 pm

Hey Thom,

Thank you for all the valuable info. You really went above and beyond.

I will take your advice, and keep the water at room temperature, use water not 3:1 anti freeze.

I like the idea of the gas can, but then I would need to get a different pump. I will think about this one....Might just use the bucket with the lid for now and make and drill fittings in the bucket so no dust gets in. I do have an aquarium pump in the garage, I could use that on the gas can.

The water pump connected to the spindle??? don't you have to turn on the spindle manually before running your gcode? or do you have that tied into the controller??

I like the idea of the Thermometer on the spindle.

How did you run your water tubes? do you have them tie wrapped to the Gantry in any way?

thank you sooo much for all the information !!!!

Guy
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Re: Water cooled spindle

Postby Kevink18 » Thu Jul 12, 2018 6:46 pm

it would be very easy to use a relay plugged into controller to start spindle when you start G-Code.
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Re: Water cooled spindle

Postby Rando » Thu Jul 12, 2018 7:06 pm

Kevink18 wrote:it would be very easy to use a relay plugged into controller to start spindle when you start G-Code.


I've been using just that setup with the controller-enabled coolant for a while, and I can tell you from experience that having
the automatic-enable be at that point in "the system" is the exact wrong place to put it.

When you have the CNC controller turn on the coolant pump, that means that the coolant is only flowing when a program is
running. Not a good idea when you've just finished a multi-hour long run, the coolant is hot, the spindle is hot, and the program just
ends. Because the spindle RPM isn't being controlled by that same controller, the spindle will keep running, leading to bearing burnout.
Stepping away for even just a few minutes at the end could lead to catastrophe with overheated bearings if the coolant pump gets
turned off by the controller, but the speed isn't cut.

No, it needs to be that the coolant pump turns on automatically whenever it's possible for the spindle to move under power at all.

That way, after that hot run finishes, you turn the spindle speed down to zero (never turn it OFF before turning it down and letting it stop; takes
WAY longer if you turn it off first, and the VFD is made to brake the motor to the degree it can) and then leave the "Run" mode enabled.
That way the coolant will keep circulating, even though the spindle has stopped.

But, to do this requires multiple configuration changes (or at least verified) inside the VFD itself, and it requires adding a relay between
a specific pull-up voltage output from the VFD to one of it's Open-Collector outputs (configured to output the signal, under the right
condition).

The relay Normally-Open contacts are then wired in parallel with any pump-enable switch you might already have added. In
my case, it's a lot safer because it's a 12VDC RV lavatory pump, not a 120VAC aquarium pump, so I can use normal low-voltage wiring
to that relay. Depending on the pump, the relay needs to be able to handle that AC and inductive load (use 0.7x the rated DC load).

That way, you can use the original switch, or just let it turn itself on and off. But, one way's for sure, if that spindle is turning,
the pump WILL be on. That's a level of failsafe you'll NEVER get from any NWA controller-driven solution.

When you're moving into more-advanced uses, you find that being able to spin the spindle at low RPMs, say <1K, is needed to warm
the spindle up on a cold morning (a few minutes of warm up will save you many hours of lifetime), or to use an edge-finder
(electronic or mechanical, they all expect to be spinning), or to measure bit runout. My point is, in all those cases, you still
want coolant to flow, even if you're not running a program.

Hope that clarifies the real-use needs a bit.

Cheers!

Thom
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Re: Water cooled spindle

Postby Rando » Thu Jul 12, 2018 10:14 pm

GuyDamato wrote:Hey Thom,

Thank you for all the valuable info. You really went above and beyond.

I will take your advice, and keep the water at room temperature, use water not 3:1 anti freeze.

I like the idea of the gas can, but then I would need to get a different pump. I will think about this one....Might just use the bucket with the lid for now and make and drill fittings in the bucket so no dust gets in. I do have an aquarium pump in the garage, I could use that on the gas can.

The water pump connected to the spindle??? don't you have to turn on the spindle manually before running your gcode? or do you have that tied into the controller??

I like the idea of the Thermometer on the spindle.

How did you run your water tubes? do you have them tie wrapped to the Gantry in any way?

thank you sooo much for all the information !!!!

Guy


Hi Guy,

That's a good idea. I was going to say use a bucket with a lid, but a) you'd have to modify the lid, and b) the only lids I'd use would be screw-on cool sealed ones, and ONE was more than the gas tank :D. And, who wants to injure a perfectly good sealing bucket lid? You and I both know how hard THOSE are to keep around the house!

As for the coolant, yes, you're right: I use the VFD's front panel (mine disconnects, so is at the end of a 3m-long ethernet cable, up on the end of the Gantry...okay, clearly I need to post pictures) to enable the Run mode, which turns the pump on. Then I use the knob to adjust the RPMs. When it's up to speed sufficiently (I slowed down the ramp-up speed in the VFD settings), then I start the program running on the NWA CNC controller.

(Note, as the resident CNC nutcase :mrgreen: I also have something I call a "PilotFish": an Arduino-controlled automated power-strip where the "outlets" are located remotely, near the equipment under control, or alternatively are low-voltage circuits local to the machine area. The ten channels can be programmed through custom post-processor changes I made to the Vectric and BobCAD software, so whenever a toolpath runs, the proper other equipment gets turned on. For me, that's a blower, vacuum, shop-air compressor, lubricant mister (Kool-Mist), under-spindle lights, and even one for the spindle coolant. Essentially, I added 10 more control channels to their one Router-Enable signal going to the solid-state-relay inside the controller box. Each is under software control from the CAD/CAM program. The PilotFish listens to the router-enable signal, and detects special pulses to set channels to different modes. Each channel has a remote and a local set of relay channels, and can be pulsed (two modes), enabled, disabled, or turned on via "passthrough" of that NWA-controller router enable signal. Sneaky engineers!)

After I remember to come back now that's it's been done for 10 minutes, I return to a machine back in home position, with the spindle still going and the pump keeping it safe. I give myself a firm forehead-slap for missing the deadline to return, and turn the spindle down to zero. But, I leave the pump running by not turning off the VFD's Run mode. Works awesome. It's nice to look over at the lighted coolant-pump switch and see it's turned on even when it's not pressed down for manual coolant-enable. If for some reason I need to "Shut It Down!", there's a valve from the pump to the spindle, say if there's a coolant leak....just in case.

My tubes go up to the landlord's rafter's whether he likes it or not ;-). Photos below, finally!

20180712_194809.jpg
To reduce the weight-induced Z-axis sagging, I unload as much weight as feasible.


20180712_194922.jpg
Don't get me started on spindle associated wiring....

(IoT it Ain'T :shock: )

20180712_195016.jpg
Like the little fishies that follow sharks around, this is a PilotFish.


Regards,

Thom
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Re: Water cooled spindle

Postby GuyDamato » Fri Jul 13, 2018 7:04 am

Hello,

I really like your setup!!!

though your set up is a little out of my league for now, hopefully in time (lots of time) I can have a set up similar to yours.

thanks again for all the great info !!!!

Guy
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Re: Water cooled spindle

Postby Rando » Fri Jul 13, 2018 11:57 am

Thanks, Guy. If you're wondering what kind of things I make on a monstrosity like that, here's a shoot of some work:

_DSC0184.JPG
The stuff cuts like buttah! Do it right and you'll have zero problems.


And yeah, sometimes I perform horrible acts of carving on the dead relatives of the trees in the yard.....

20180709_191731.jpg


Cheers, and of course feel free to ask questions. It's not above-and-beyond, honestly; that's pretty normal for my
responses. I've had people who hate--and others who like me--both say "yeah, that #%$& never leaves anything out...."
When in the service of working through a complex subject that stymies many over time, including me at some point,
I'm okay if that's the worst insult they can come up with :D.

Thom
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Re: Water cooled spindle

Postby GuyDamato » Sat Jul 14, 2018 2:59 pm

I did not know you could CNC Aluminum on a shark...…that is soo cool !!!! must need special bits. looks like the sky is the limit, with some limitations...lol

this sounds like a silly question. how do I change bits on the water cooled spindle? there does not seem to be anything to "lock" the spindle while I unscrew the collet holder. Was there supposed to be a special tool???

thanks again

Guy
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Re: Water cooled spindle

Postby sharkcutup » Sat Jul 14, 2018 3:21 pm

this sounds like a silly question. how do I change bits on the water cooled spindle? there does not seem to be anything to "lock" the spindle while I unscrew the collet holder. Was there supposed to be a special tool???



13mm open end wrench on spindle shaft along with a 17mm box end wrench on the collet works just fine for me! :)


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