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cnc coolant motor not working

the spin doctor

Cast Iron
Joined
Jul 15, 2004
Location
oklahoma city, ok
I have a Nakamura Tome CNC lathe and the coolant stopped flowing. I cleaned the tank and checked to see if there was an obstruction and did not find any problem. I don't see any filters or screens on the inflow or outflow.

So today I took the motor off and a local motor repair shop tested it and said all was well. I put the pump back on the machine and tried again and still no coolant. The contactor is pulling in and all 3 legs have equal voltages. Does not make sense. Any ideas?

Thanks
 
Something jamming up the impeller?

I've seem pumps that seemed to work fine in the air, but as soon as they were submerged they didn't have enough power to run. Need to put a load on it on the test bench.
 
Lets back up 2 steps...

So when YOU put power to the motor, it doesn't spin.. When the motor doctor puts power to the motor,
it works fine....

The key here is "motor spinning".. or "motor not spinning"..

OR are you saying that when you put power to the pump, you don't get coolant????

2 totally different roads to go down here.. Do we have a pump problem, or do we have an
electrical problem.. And it all hinges on weather or not the pump is spinning when you
turn on the coolant.
 
When I turn on coolant with the pump installed in the machine, I don't get coolant. The pump is getting electricity. I can't tell if the pump motor is spinning. The motor doctor says the pump spins on the test bench when he puts power to it. He claims to have opened it up to see that the impeller is intact. I could open up the bottom of the assembly and turn it on to see if it spins?
 
No idea of the layout on this lathe, but it seems like once a year I have a coolant pump that no longer moves fluid... especially when it gets hot out and the last thing I want to do is get greasy and sticky with old coolant.

Sometimes I have an electrical problem with a relay inside the machine. Put go juice directly into the pump contacts and see if it makes coolant.

Sometimes the impeller is broken or gunked up. Motor turns, but no flow.

Sometimes the capacitor that starts the coolant pump has given up the ghost.

Sometimes the pump motor is smoked.

One year, long ago I was messing with the Mastercam post and changed the M08 output to an M09 accidentally... I thought the coolant pump was out until I actually read the code...

Work through it logically and the diagnosis usually isn't that hard. This fix might be painful.
 
When I turn on coolant with the pump installed in the machine, I don't get coolant. The pump is getting electricity. I can't tell if the pump motor is spinning. The motor doctor says the pump spins on the test bench when he puts power to it. He claims to have opened it up to see that the impeller is intact. I could open up the bottom of the assembly and turn it on to see if it spins?

I don't think you know if the pump is getting power. You said that the contactor is making and that there is power at the contactor. Also, do you mean at the top of the motor starter or at the machine disconnect?

What you have done so for according to your descriptions does not mean that there is power at the pump motor.

The motor starter also should have a a motor overload. Make sure that it is not off.

The first thing I would do is to check for continuity of the motor wires at the bottom of the contactor. Make sure to turn the power off first and check the resistance between legs. You should see somewhere around 2-20ohms resistance depending on the exact pump and all three should be relatively close in resistance.

The pump should be making a little bit of sound if it is running and a 60hz hum if it is locked or two phasing.
 
The first thing I would do is to check for continuity blah blah

The FIRST thing to do is figure out if the motor is spinning..

Quite honestly I would have figured out if the motor was spinning before I
brought it into a motor guy..

If you don't know if the motor is spinning (and therefore spinning the pump)..
You're just pissing up a rope... And have absolutely no direction to go in
to actually fix the problem.

**************************************


Have a friend that has the mechanical ability of a Kardashian...

His car wouldn't start one day.... Won't start.... Logical conclusion
is the starter (period, end of sentence)... The STARTER STARTS the car,
if the car won't START, its the STARTER...

Long story short, as I was under his car... I asked.. "why did you think
it was the starter?"...

Car wouldn't start, I need a starter...

"Well.. What did it do?"...

Well, it went wuh wuh wuuuhhh wwwwuuuuuhhhhhh wuuuuuuuuuhhhhhhhhh
click click click...

Battery.
 
The FIRST thing to do is figure out if the motor is spinning..

Quite honestly I would have figured out if the motor was spinning before I
brought it into a motor guy..

If you don't know if the motor is spinning (and therefore spinning the pump)..
You're just pissing up a rope... And have absolutely no direction to go in
to actually fix the problem.

Yep the motor is spinning and there are proper voltages at the motor so apparently the pumping
action is the problem, nothing electrical. The motor is so smooth that it barely makes a vibration
and no noise but there is a sight window on the top.

Thanks, at least I have a path to follow now!
 
We have a machine that if there is no coolant actually in the pump to start with it just won't start pumping.
Have you tried priming it?
Just disconnect one of the hoses that go into the pump, pour coolant into it till the pump fills then try again.
 
Yep the motor is spinning and there are proper voltages at the motor so apparently the pumping
action is the problem, nothing electrical. The motor is so smooth that it barely makes a vibration
and no noise but there is a sight window on the top.

Thanks, at least I have a path to follow now!

Ok so now that we know that it is spinning at least is it running the correct direction, which it probably is since it was working and hopefully is connected up the same as before, which is checked by looking at the sight window.

Next IF you believe what the motor guy said is true I wonder if he checked if he can stop the impeller independently from the motor... Could have a sheared pin/key that as soon as it is under load the impeller does not spin even though the motor does. First thing I would have checked right after checking if it is actually spinning.

Next check if all your coolant being pumped is not just pumping straight back into the tank because of a messed up hose.

Next it might not be a self priming pump and it could have picked up some air. Look for a grub screw on the pump itself somewhere that seems like it just blocks off a port/hole. With the pump running slowly loosen it till a bit of fluid comes out and see if that helps.

I don't mean to sound like a dick but these are all pretty basic things that should be checked.
 
Which type of pump is this?

The kind that sits down in the tank?

Or the kind that is outside the tank?

My lathe has the type that is outside the tank.. It has to create a vacuum to
pull from the tank, even though its low enough that coolant should just flow
into it anyways...

Anyways.. There is a seal on the pump shaft, if the seal goes... You got nothing..
The seal was less than $20, but the shaft is all mucked up around the seal, so
it kept eating them.. I said screw it and tossed a pump I had hanging around right
into the tank...

Just another idea or possibility.

Edit: another thought.

Next check if all your coolant being pumped is not just pumping straight back into the tank because of a messed up hose.

Many moons ago, had a lathe that over fairly short period of time lost coolant pressure...

First thing in the morning, when you fired it up, it had great pressure, over the next few minutes
the pressure would drop and drop and drop until NOTHING was coming out...

Half hour later.. A little dribble, and back to nothing.

Let her sit 4 hours... Good pressure to start and then back to nothing..

Turns out the inner liner of the coolant hose coming from the pump got a pin hole in it..
The coolant would be pushed out of the inner liner and end up in between the inner and outer
liner, and it would eventually crush the inner liner so that no coolant could pass.

That was a weird one to figure out..
 
Many moons ago, had a lathe that over fairly short period of time lost coolant pressure...

First thing in the morning, when you fired it up, it had great pressure, over the next few minutes
the pressure would drop and drop and drop until NOTHING was coming out...

Half hour later.. A little dribble, and back to nothing.

Let her sit 4 hours... Good pressure to start and then back to nothing..

Turns out the inner liner of the coolant hose coming from the pump got a pin hole in it..
The coolant would be pushed out of the inner liner and end up in between the inner and outer
liner, and it would eventually crush the inner liner so that no coolant could pass.

That was a weird one to figure out..

Oh wow... being a machine tool fitter/machinist by trade I have seen quite a few interesting things but never that! I think once I had figured it out I probably would have cleaned my tools, packed it all up and just gone home till I didn't feel as stupid anymore.
 
Makes sense, I will give it a try at lunchtime. Thanks

The motor repairman said the impeller was fine. Could be a leak on the plastic intake hose so I will check that too.
Makes no sense why it stopped pumping in the first place...
 
It is an external pump. I can't believe it needs to be primed but will give that a try. Will look for any leaks on the intake side that could be sucking air. Will look for the screw on the side too. Thanks everyone!
 
One last thing... on one of my machines I spent better part of a day F-ing around with the pump. Pulling my hair out. Grab the part number off the pump and type it into google. Amazon comes up with the exact pump for sale for less than $200, overnight shipping for $8.00 more.

The old pump made a satisfying noise when it hit the bottom of the dumpster.
 
If the pump is not working, I will certainly take the advice to find another on line. However I just climbed under it again and found that the back of the tank is not filling. I found that there was not enough coolant to get to the intake! The upper reservoir is filled and not flowing so there is an internal obstruction. At least now there seems to be a reason. I will go though the terrible process of cleaning it all out plus remove the rear panel in case there is a filter there that I can't see or find anything about in the docs. I feel close to a resolution but have to get dirty in the interim. Thanks again!
 
The horrible reality that I have read about concerning coolant reservoirs is upon me. My big lathe has underneath its entire cast body, a 40 gallon coolant tank integrated and almost impossible to reach to clean. Crummy engineering is all I can say. There is no possible method to get it clean. There must be 30 years of goo formed in every nook and cranny. Even with a power washer, there is just no access to the far reaches of the chamber. At this point I can only hope to flush it out and go with dirty coolant. I have a fantastic pump driven by compressed air so I plan to plumb it onto the drain plug hole and then begin powerwashing while the dirty fluid is being pumped into a large tank for later disposal. So messy but paying someone else to do it would be very expensive at $150/hour from the local tool repair company.

As far as the pump goes, it is just not pumping anymore. There is no obstruction and the motor is running. At this point I will give one more try tomorrow to see if the impeller portion can be repaired then if not, order a new pump. It is a beautiful machine worth the trouble but it is lots of trouble when something goes wrong...
 
The horrible reality that I have read about concerning coolant reservoirs is upon me. My big lathe has underneath its entire cast body, a 40 gallon coolant tank integrated and almost impossible to reach to clean. Crummy engineering is all I can say. There is no possible method to get it clean. There must be 30 years of goo formed in every nook and cranny. Even with a power washer, there is just no access to the far reaches of the chamber. At this point I can only hope to flush it out and go with dirty coolant. I have a fantastic pump driven by compressed air so I plan to plumb it onto the drain plug hole and then begin powerwashing while the dirty fluid is being pumped into a large tank for later disposal. So messy but paying someone else to do it would be very expensive at $150/hour from the local tool repair company.

As far as the pump goes, it is just not pumping anymore. There is no obstruction and the motor is running. At this point I will give one more try tomorrow to see if the impeller portion can be repaired then if not, order a new pump. It is a beautiful machine worth the trouble but it is lots of trouble when something goes wrong...

There is a very good chance that the coolant pump is air locked.

What happens is that you have coolant in the line to the machine somewhere. This prevents the coolant from entering the coolant pump especially since this is an external pump. Sort of like losing prime.

Blow some air into the coolant line in the machine and get the line open. Make sure that there is enough coolant to fill both tanks properly. Should be good to go then.
 








 
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