CNC 6040 VFD/Spindle problem...

[m_thread]

Hi

I bought a CNC 6040 a couple of weeks ago and i have some serious problems.

The machine and the controller for the stepper motors works ok. I have tried it out with Mach3 and it seems to function correctly. The build quality of the 'thing' is ok, not great, but its a robust piece of equipment.

My problem is that I cant get the spindle motor to function. I have programmed the VFD that came with the 0.8 kW water cooled spindle according to the instructions from the seller:

PD013 = 8 (factory reset)
PD005 = 400 Hz
PD004 = 400 Hz
PD003 = 400 Hz

The first time i started the motor ran for about 2 mins, with the water cooling running, then i stopped it as it seemed to be working.

Now when i press start on the VFDs control panel the motor jerks, runs maybe a turn or two and then the VFD trips with E.O.C.A (over-current).

I have checked and measured the cables for shortcuts and bad connections but they are ok.
I have tried to measure the resistance of the windings in the motor but i dont know what values are ok. If I measure between any two of the three windings i get next to 0 ohms ( maybe 3-5 ). Is this ok, or is it a sign that the motor is broken?

I have an ongoing discussion with the seller about the spindle problem ( and some other issues with missing cables and wrong sized collets ), but the seller acts a bit evasive and asks me to produce some sort of evidence of what is wrong. The seller told me to bring the VFD to someone who could check if it is broken. But i dont know of anyone who could do that.

I have even made a short movie clip and sent that to the seller since he says that all text is machine translated to chinese and that they have to see movies or pictures describing what the problem is.

Does anyone here have any advise on how to find out what the root cause of the problem is?

Edit: Personally I think the motor is broken. But how would I prove that it is the motor and not the VFD?

Many thanks
/Fredrik

[Al_The_Man]

A low reading of a few ohms is normal for a AC induction motor, have you tried a start command with the motor disconnected?
If it goes into O.C. in this mode it usually indicates a shorted solid state power device.
Al.

[m_thread]

Thanks Al.
I feel a bit stupid not having thought about that obvious test myself

/F

[m_thread]

Ok, I just tested the VFD with the spidle motor disconnected at the motor end of the cable.
When pressing start the VFD display starts to show acceleration ( increasing revolution ) and continues to increase the speed until it reaches 400. Pressing stop gently decreases speed until it reaches 0.

Is this the proof i need to convince the seller that it is the motor that i broken?

/F

[aarggh]

Have you tried disconnecting the control lines from the spindle to the controller, and just powering and controlling up the spindle directly from the vfd since? Effectivley bypassing any relays, etc.

Also, my unit had a similar problem, it turned out to be some swarf from the mounting holes in the controller case shorting some pins!

The spindle should happily run for hours when testing it without any coolant when not under any load.

Another problem my one had was that the parallel cable that came with it, was shielded at both ends, and noise was feeding back into the control circuitry making it go haywire. Changing the cable also helped as the unit had numerous earthing problems, and the multiple earths was not helping at all in the end.

cheers,
Ian

[m_thread]

Hi Ian

Thanks for your advise but I am running my spindle without any connection to the controller. Just the vfd connected to the spindle.

I am currently uploading some more video proof to photobucket. I will update this post when it is done.

/F

[comandojon]

I would see if you can't find the acceleration curve in the Vfd manual, that might be the cause of your problem, I had an over current fault on my new spindle when I had the curve programmed wrong. Do you have the Vfd manual? More than likely it's on the web someplace.

I had a similar problem with my original 2.2 kw watercooled spindle. It failed with the same error after the first time it was used hard. Of course that was outside of the warranty period so I was on my own to deal with it.

What's curious about yours is it failed so early on. Even if I hooked the old spindle up today it would run fine until it got to between 70-80 degrees f. Then show the over current.

I am not sure how you can truly test either the Vfd or the spindle without a second one of each. I know it is frustrating. I went the cheap route and just replaced both with new Chinese Vfd and air cooled 3kw spindle.

Just to see the result I installed the new Vfd while the machine had the old spindle still on it. Programmed it to match the acceleration curve of the 2.2kw motor, and had the same issue.

It sounds to me like the spindle is blame, do you know anyone else that has a Vfd / spindle set up you could try the spindle on?

I am sorry for your frustration, I went through it to with a US importer of a similar machine.

In the end I had to deal with the issue myself. On these machines you will learn lots about how they work. They do work you just have to work the bugs out of them.

If they won't replace the spindle you have a few options.
Go the eBay route , it's cheap but quality is questionable
You would get a new spindle and Vfd for a few $ US

Go with a better spindle from columbo, I have another thread on here where on of the other people on this site is a legitimate US dealer. A spindle and Vfd set up that small would be pretty affordable.
This option would be the best.

Wait for china to possibly send you a new one.

If you have to buy it , go bigger on the power, a spindle that is .8 kw can be overloaded pretty easily.

I hope I was a help. If you need the columbo dealers info,I can find it for you.

I hope your day gets better. I am off to see the eclipse.

Jon

[m_thread]

Thanks for all your wisdom Jon.

Today I spent some time trying to produce some evidence of my problems.
I ended up with two new videos which i sent to the seller.



And



And Jon, yes my day actually got better later on
/F

[aarggh]

Had a look at the videos, with the collet size that is normal, one of the first things you'll need to do is buy a set of ER11 collets, as the set of cutters they supply are all usually small shank, but generally you do get a 1/8th and a 1/4 collet with the spindle. Maybe this seller just doesn't supply the 1/8th, or they forgot it?

Out of curiosity, have you tried removing the spindle from the machine chassis and just powering it up on laying it on a towel or something so it's electrically isolated from the machine, assuming it doesn't have an earth wire inside the connector from the vfd to the spindle that is? I say this in case there is a form of digital grounding or earthing not properly implimented, and the spindle may be completing a path and introducing noise inappropriately?

From all i've seen here and with my machines, crappy mains and digital ground or earthing, or the lack thereof is the biggest problem with these units, even with my large unit the earth lead was cut off!

cheers,
Ian

[jallitt]

Also... check the spindle cable and make sure pins 1,2 and 3 are connected to the 3 phases from the VFD - they may have wired the cable incorrectly and now you have the earths figured out for the rest of the machine one phase may be shorting to ground.

If pin 4 is connected it should be to ground and I'd recommend cutting it to see if it helps.

I have 2 chinese machines and one had no shielding on the VFD cable and it produced enough EM interference to take out the wired ethernet. The other one arrived with no ground connected in the power socket and 110 volts floating between the chassis of the machine and the PC ground. I'm glad I checked and tied everything to ground before rewiring it for mach3.