[inertialabs]

I have a Bridgeport VMC 760 with a DX 32 controller and Siemens drives. I recently purchased the machine from a shop down the street and I had the chance to see it run before I bought it Everything seemed fine and in good working order. I have the mill powered up and running fine with everything but the spindle. If I put in a spindle command over 2000 RPM I get an alarm that reads
" MSG 05:15:21n PM Axis Drive Fault " The interesting thing is that if I bump up the spindle rate 200 RPM at a time I can get it up to 6K RPM. So to me it seems like the current draw spikes and trips the alarm with too big of an increase. I found the settable breaker in the cabinet and clicked it up to 25 amps but I am pretty sure it is not blowing. I also put a AC clamp meter on the 3 legs of the spindle drive and got equal readings around 8 amps while spinning at any speed and 24 max increasing RPM. That is what I learned today, I am not sure what to do next and I would surely appreciate any suggestions. Thanks

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Reason Bradley

[gus]

I wonder if there is a difference in voltage from one shop to the other, causing a too high current reading in your shop

[gridley51]

Could be like Gus says.Try increasing the ramp up time to see if it stops faulting.
Mark.

[inertialabs]

Hello Gus, Chipsweeper

Thank you for your insight, The answer to your question is definitely yes the old shop had Y and we have Delta from a CNC Rotary phase converter then going through a Capacitor bank then to the machine.

Voltage to Ground
Leg 1 119
Leg 2 125
Leg 3 240

Voltage between legs

245
250
270

This voltage does not sound great but all the other axis drives seem to be working perfectly, witch supports your RPM ramp theory.

I like the sound of increasing the ramp up time that sounds like a smoking gun to me, The only problem is I am not sure how to increase the time. Any suggestions on how to achieve that are welcome



Thank you both for you help

Reason Bradley

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Reason Bradley
[email protected]
415-596-3946

[gridley51]

First of all set the breaker back to its original setting,it`s there for protection.
I`m not familiar with that control,what model of Siemens drive do you have?
Mark.

[gus]

Woa, phase converter, that is the tipoff. Can't generate the same torque with that. You are going to have problems of some sort I think no matter what

[inertialabs]

Thank you I will set the breaker back immediatly, The controll is a siemens Semodrive 611

[inertialabs]

Yes I know they are not ideal, But it is a rotary type 30 HP CNC Balanced motor as you see it is barely in the 10 Pecrent range but I am currently running another Kitamura mill and a lathe off of them with no trouble, Is the voltage the concern or the lack of amperage ?

[machintek]

If you really need to have a phase converter, you need a digital one.
Obviously, there is not enough watts (area beneath the curve) to accel this mass in the given period of time.
Although there are tuning cards on the axis drives, you do not see any on the spindle drive. it is all done in parameters.
Also the Bridgeport installation sheets specify that you need balanced power.
There is a matching transformer on the bottom of the electrical cabinet but not for a rotary phase converter.

George

[inertialabs]

Any Idea of how you change the parameters of the acceleration curve ?

[machintek]

I have a list of parameters that are changed when installing a new spindle drive. i do not remember if i have a list of descriptions of these parameters. Next time in the office, I will check.

George

[gridley51]

Be very careful with the 611 drive.Some of the early servo controllers fitted to machines do not have phase loss protection.If a phase goes down while power is applied to the 611 it will blow.I have one here on a retrofitted Warner Swasey I bought.Put the main panel isolator on one day,powered the machine up,it came up,the lights flickered and it died.Found a fault in the main disconnecter,replaced it,powered up and got one of the bigger bangs I had heard in a long time came from the drive.Called up Siemens and explained what had happened,the guy asked "has a phase gone while power was on the drive?"
Yes."well you have lost the drive,you will have to return it to us for repair"
You can now buy a little box to add to the drive that senses the power going and shuts it down before damage is done.
So I have estimates of $2000-$2500 to repair this but it could be repaired and a mains failure occur the next day and bang it`s gone again.Other thing I don`t like about them is dc link voltage of 660 volts.Fatal stuff if you get caught by that.
If you have an email address I can post you pdf`s for the drive if George can`t find his.
Mark.

[inertialabs]

Wow that sounds like a big bummer, I have always found it is extremely hard to get all of the magic black smoke back into the circuits after you let it out. I sure would appreciate the break down on setting the parameters for the machine. As I said before it seems like the next logical step to try before I get into replacing things.

My email is

[email protected]

Thank you

--
Reason Bradley
[email protected]
415-596-3946

[inertialabs]

I appreciate your advise here, I just got back to Chip Sweeper about this as well. I don't want to simultaneously ask for the parameters from both of you but it sounds like you two are in contact with each other so I will thank you both and watch for an email.

Thanks again

Reason

[machintek]

Attached should be a note I received from Bridgeport in 1996 which lists the parameters Bridgeport was concerned with and what they are and do.
Use the list at your own peril.

George

[inertialabs]

Thanks for the parameters, I fired up the machine and I went into the parameter section and all of the parameters seemed to be very different than what was on the sheet, I am curious as to model machine you have ?

[machintek]

These are NOT the parameters in the BMDC (bmdcprms.sys). These are in the spindle drive. The one with the LCD display and the P and + and - keys inside the electrical cabinet.
I do not have a machine. I have worked on Bridgeports for 25 years. This sheet came from my stash of notes.

George

[inertialabs]

Ok I am a rookie, I get it now.

The parameter page you sent me makes allot more sense now, I went into the cabinet turned on the machine and pushed the P button and scrolled to the PAR 16 and logged the setting which was P 016.1 Then I pushed the + Key and increased the # to P 016.6 and gave a command of 3K RPM and the spindle spun up with no alarm. Then I tried 6 K and it worked perfectly. So I backed the # down to P 016.3 and tried it all over and it still worked perfectly. Would you recommend reducing the # until it fails and then increase it 1 digit or do you have some recommended method of calibration ?

Thanks a million George

I feel like I am getting closer to having a machine that runs

Reason

[machintek]

I do not have that list with me so I do not know what those parameters do. But, they were figured out by an engineer. We never played with them except to change a machine from 4000 RPM to 6000 rpm and then we had the changes given to us. The only parameter we played with was that for the "drift" or balance. This so with an M19 the spindle would be stationary. Any changes you make are temporary unless you tell the drive to store them.

George

[inertialabs]

Well I guess the other approach is to put a real heavy tool into the spindle and just run the thin and see how it does.

From what you are telling me I now need to figure out how to get the new parameter to stay in the controller. It is starting to look like I am going to need another manual for the Siemens drive end of this thing, I will look into that today.

George, Let me just say thank you again for you insight and help here I really appreciate it .

Reason