Hello all.

Excuse me for my bad english.
I just have my BP 1 CNC and before i want to run in with a PC and Mach 3 control i want it to run nice and smoothly.
Now my Y-axis moves very nice. My X-axis only moves in little steps. When i hold the move button i can hear the motor running but the table won't move. I found a bad main transistor behind the heat sink for that axis so i guess i can solve that problem by replacing the bad transistor.
A different story is the Z-axis. It has the same problem. It can move in little steps. But when i hold the move button, it moves a little bit, then makes some noise and after that i can hear the motor running but it isn't moving anymore.
I also checked the four main transistors for that one but they all seems to be good. Next i've checked the controlboard which is fitted on the door with the black heat sink. I measured a lot on that one and it seems to be good. What can i check now? I really think it's a electrical problem.
Hope someone can help me.

Regards,

Bart

Flush the Z axis with a hydro carbon based solvent. Then re-oil with Mobil Vactra number 2 way oil (or a type 68). This may help.
If an axis does not have enough power to the motor(bad connection somewhere, a washer or screw dropped onto the terminal strip below those transistors, low voltage, shorted transistor, excessive friction) the motor cannot keep up with the command and falls behind enough to get attracted to the coil behind it instead of the coil in front of it. Thus the motor oscillates between poles and emits a whine like it is running but is not.
Check current. The ACC board is adjusted to 8.0 amps with the axis in a static state. This is in the maintenance manual.

George

George,

I don't have the maintenance manual so I don't know what's in it. Can you give me some more detailed information about what i should do. I don't think i have to flush or re-oil the spindle because when it moves up and down it goes very smootly and it looks really nice. I just can't keep it moving, so i thinks it's typically a electrical issue.
What you descibe about the motor is what mine does i think. It seems like it's running but probably it isn't

Bart

George.

What do you exactly mean with the things i should do with the acc board. I don't really understand it (sorry for my bad english) And i don't have the manual you reffered to.
I already flushed the spindle axis and the thread eventough they looked very good. I checked all the transistors, diodes and fuses. They were all good. Maybe it's because the acceleration is to high but ifso I don't understand why the X and Y axis doesn't have the same problem.

Bart

Press in emergency stop (to turn drives off).
Remove the DC fuse for the Z axis (fuse 14?).
Attach a meter than can measure 10 amps DC in place of the fuse.
Pull out emergency stop and turn drives on.
Drives should be pulling 8 amps. If not, turn the bottom multi turn potentiometer
until it does.
At this point I step the Z down and watch the current. Any variations means that a transistor or some other part of the circuit may be screwed up.
I usually at this point try a rapid move but you cannot. In rapid, the current should drop to 2 amps or just a little bit more.
Turn drives off before removing meter or you will blow a transistor.
Put fuse back in.
Attach meter between fuse 14 and ground set to DC volts. Turn drives on and again step it. Voltage should be in the 9 volt DC range and should remain the same as you step it. If not, again, you may have a problem.
Next I measure the voltage drop across the fuse to make sure the connection has no resistance.
You can compare your results with the other 2 axis. All three are individual circuits.
You need a manual.

George

George,

I did the measuring of the amps. I measured 8.75 ADC.
You said it should be 8, is this to much then?
What do you mean with the bottom multi turn potentiometer?
And where is it? maybe a picture of it should do a good job because sometimes i got some little problem understanding it.
I really hope this is the problem so i can fix it, then every problem is solved and the real retrofitting can start!

Bart

The ACC has 3 multi turn potentiometers.
From top to bottom, they are X, Y, and Z.
8.75 amps is too much. The manual calls for 8 amps.
Since I have not worked on one in years, I cannot provide a picture.

George

Ok but to be honest i don't really know what you mean with the ACC.
I know where the ACC board is but there's noting i can adjust on it.
Is it in the same cabinet where the fuses are?
Thanks for helping me.

Bart

The swing out side door on control cabinet of BP Boss mill has 4 circuit boards. Three are step motor drive (SMD) boards. They are labeled SMD cards on lower left of card or board. Nothing on these cards is adjustable. The last card is ACC card. It has three trim pots for adjusting step motor current one for each axis. I recommend setting at 7.2 amps. The drive transistors have a heavy shock load when there is sudden decelaration in table move. This is when they usually blow. The spindle drive transistors usually blow on a cold day in shop or if the NSK ball screw becomes stiff. Also anything which causes quill tightness will blow transistor. I have images of the transistor drive block, the SMD and ACC cards. The ACC card has screwdriver at the trimpot for Y axis.
Frequently an underpowered transistor is used to replace what should be a 20 amp 600 volt transistor. These transistors are now expensive and may last 5 years or blow within minutes after replacement. Solution is to upgrade to Gecko type drive and eliminate BP components.
jh

http://community.webshots.com/album/562583810DfSqiK

Jholland,

Thanks that picture with that screwdriver really helped me. But unfortunately it didn't solved the problem. I even brought the current back to 7 amps but the motor still starts to oscillate like nothing has changed.
The X-axis sometimes had some problem with moving and that's over now. I brought that one back from 8.75 to 7.85 and now it runs without any problems.
Thanks!

Bart

Hello bartL
A few more tricks. Use pencil and mark each SMD card x,y,z. Substitute cards and see what happens to motion. Another trick. The ACC card may be turned upside down and placed back in socket. This switches x and z power control. If you do this you must use thin cardboard as insulator between ACC and SMD cards so components do not touch.
Tell us what happens.
jackson

Jackson,

I just tried both of your tricks but they both didn't help. It's still oscillating.

Bart

Bart
Now you will have to go to bottom on drive door. Cut off power. Remove SMD and ACC cards. There is a terminal block at bottom. The motor leads are from left z, y, x. You need to inspect all connections for metal chips, opens, shorts. If all looks ok lightly pull each wire to be sure of connection. Then along bottom row disconnect y and z axis wires. There are 6 wires per motor.. Terminal 5 always has 2 wires fitting in one screw connection. These are both labeled x5, y5, z5. You will connect z axis wires in proper sequence into y axis sockets. Since x and y axes are running ok, the drive electronics for these axes are good. If the step motor for z is bad, it will be bad on x and y power sockets. To cross verify, connect y axis step motor wires into z terminal sockets. If this motor runs ok then the z step motor is bad. This is double check. Next remove metal cap from z motor and verify that wires are ok and no burning of wires is present. Sometimes when step motor goes bad a burned winding can be seen or even smoke deposits.
Let me know result.
jackson

Jackson,
I just did what you suggested. And the Z-axis is still oscillating, even with the switched wires in the terminal block. I also removed the cap from the motor, but all the wires look really good. I can send you a picture if you want, but you have to send me a pesonal message with your e-mail adress.
I'm not happy with this cause i hoped nothing would be wrong with the motor. But is seems it does. Or there has to be something wrong in the driveline which makes the axis move real heavy.
thanks for your help, i really appreciate it.

Bart

Bart
Did you hook up y axis motor to z axis drive? This would definately tell if z motor is at fault.
jackson

Jackson,
Do you mean replace the Z motor by the Y motor? I want to try that but i didn't knew i could do that without any problems.
Bart

Bart
At bottom of swing out door where wires from step motors go into screw connector terminal block. The bottom cable wires from y motor must go into z sockets. Then power machine and move z. This will move y axis on knee. If everything works good the z axis drive is good. This means z step motor is likely bad.
jackson

I look at it this way. A lot of field service is done by probability. So how many bad stepping motors have I had in 26 years? Maybe 2.
How many other axis drive problems have I had on the stepping motor type Bridgeports? Maybe a 30 or so different problems on a few thousand service calls.
Do I believe the stepping motor is bad. I doubt it. I would be checking a lot of other items.
Most probable: Transistor
Also probable: bridge rectifier.
There are 3 seperate drives in this machine. They do share the 54VDC power for the ACC board. Compare the Z against the other 2 and where you measure a voltage difference gives you a clue as to where the problem is.

George

Jackson,
I already tried to switch the wires from the Z into the Y sockets. But that didn't help. No i'm just back from switching the whole motor from the Y to the Z position. That's didn't work either. SO thank god it isn't a bad motor.

Machinetek,
Where do i have to measure those voltages?

Bart

Bart
You likely have blown drive transistor in drive block. These transistors are located above and behind drive cards. Z axis transistor block is usually the top one. Each block has 4 transistors. Usually only one is bad. Now go back to index in this forum and read all posts from last few days. From me and moderator. I have many pics and explanations about transistors and repair. Before you power up after repair be sure all wires are in original position. I will check later.
jackson

Jackson,
Those were the first I've checked. They were all good. I only had a bad one on the X-axis block. I replaced that one and that really helped. But those from the Z-axis were good so i don't know what else it can be.
Bart

I can think of two other test to make.

1. With drives unenabled ( machine power off even better.) can you turn the Z indicator wheel freely?

2 Swamp SMD boards

Thanks,
Darek

Bart
How are you checking transistors? You have to take axis transistor block out of machine to properly test. Blown or short transistor is most likely problem. Remove transistor block take readings, and let us know.

Good advice from Hillbilly also.

jackson

Darek,
With the machine power off, i can turn the timing belt by hand pretty easy and the axis is going up and down.
What do you mean with swamp SMD boards?

Jackson,
I removed the transistors from the heat sink and measured them in every direction with the diode tester on my DMM. They were all good.

Bart

The SMD boards are on the back heat sink panel in front of the power transistors. There is one SMD board for each axis. There is one ACC board that contains a chopper circuit for each axis power supply, hence the three trimpots.

Darek

Darek,
I already checked those SMD and ACC board. I even assembled the ACC board upside down, to gide the Z-axis power trough the X-axis powerline on the ACC board.
To check the SMD boards I switched them by a board from another, nothing changed so those boards seems to be good.

Bart

Bart
You are working very hard to find problem. One more try. Please take transistor block from y axis and mount in z axis location. Then hook up Z wires and power up. Tell us what happens.
jackson

Jackson,
Yes i'm trying hard to solve this problem. I want my machine to run perfect.
I just switched the transistorblock from X and Z axis but that didn't helped. The X-axis is still running well and the Z axis isn't. So i'm pretty sure now the transistorblock isn't the problem.

Thanks,

Bart

Bart
I am out of helpful thoughts. George-Machintek-perhaps can resolve this puzzlement.
I notice you have Hardinge HXL. I have one also and will soon put new control on. I will let you know how this goes.
jackson

Jackson,
Maybe the only way to solve the problem is to reduce acceleration with the mach3 control. Or maybe it's because of a mechanical problem, wrong lubrication or whatever.
Great you have a HXL too, i almost thought I was the only one. I would really like some help when I start with that project because I haven't got a clue how to do it. I searched for some information on the internet and it seems it's not as easy as the bridgeport mill.
Is it possible to send me information about it if you got it by e-mail?
I really appreciate your help!

Thanks,
Bart

Bart,

A couple of questions:

1. Do you have the drive schematics?

2. Have you tested for the 8amp drive current on each axis?

Thanks, Darek

The answer may not be simple. In 26 years of fixing these, I have seen quite a few strange things. One customer lost a screw on the transistor terminal strip and replaced it with one of a length that would hold the wire and ground it at the same time to the metal beneath it. Others leave off the insulators. I had a BOSS 6 that had a bad opto coupler on the ZDI sending the pulses to the SMD which created a situation that it would misposition. It may be a bad full wave bridge rectifier. Have you ever replaced one of these? It is a devil of a thing to get to. I had one machine that had a open 14 gauge wire from T2 to the bridge rectifier. This does not move. How did it go open?

My point is that at some point it is cost effective to get a GOOD service engineer in there to diagnose and fix it. Especially if it not something high up on the possibility list.

George

Darek,
I don't have the drive schematics.
Yes I've checked the current on all three axis and set them up to 7.8Amps. I also measured the volts and they were all between 9.1 and 9.4 VDC so that seems to be good too.

Bart

That is good, but I also step the axis to make sure it does not change as the transistors turn on and off. This also means the bridge rectifier is good.
Then try .010 inch movement then .1 inch movement, the continuous.
Worse going up or going down?
Where is override pot set to?
Try a MDI move with a slow feedrate.

George

George,
I've never replaced a bridge rectifier, what is it? Maybe i should just wait untill I got my computer fixed on it so i can adjust the acceleration. Somebody else with the same machine told me that could be the problem. With the control now i don't really know how i can adjust it, it's always going full speed.
All the bolts in de transistor strip are original.
I'll do the measuring with the steps and see what happens. I'll give you the results.

Thanks,
Bart

The default state is G0 (rapid)
You have to turn the spindle on (have it in MDI), type in G91G1 Z-1.0F100, enter.

This should do an incremental move in the negative direction of 1 inch at 10 inches per minute. You can turn the feedrate down and up to see where it stalls.

Why do you need a computer?
Basic commands can be put in as above.

There are test points and adjustment pots on the ZCK for adjusting feed rates and maximum rapid. What is needed is a meter.

George

George I want a computer on it so i can run it with mach3.
I don't know any commands on the Boss control. The only thing i know is how to move the 3 axis.
Hope I can put in the code you gave me.
How can I turn up and down the feedrate?

Thanks,
Bart

George,
I've just measured the Amps while stepping the Z-axis.
It reads 7.8A when I do nothing. When I do a little step it reads 7.75 a really short time. When i do a larger step 0.1 it reads around 7A for a second.
But when I hold it in JOG position the value is going down and when the motor stalls (oscillates) it reads 5.14A. I think that's really low but I don't know what is allowed.
I also typed the code exacly as you wrote it in your post. While the axis was moving I turned the feedrate but I could turn it to the highest position and the motor didn't stall.

Bart

Glad you found the feedrate pot. This proves that it can move slow but not rapid.
This is a funny system. When in rapid the counter EMF generated in the motor impedes the current and on a good motor it will drop to just more than 2 amps. At the same time the voltage goes up to 60 V.
Keep typing the mini program in changing direction (+/-) and the feed rate go up by a value of 50. 150 is 15 IPM, 200 is 20 IPM etc.
Lets see how fast it can go before it stalls.
What is the AC voltage at T2, the transformer in the back, top, 3rd and 6th wires from the left?

George

George,
I tried to speed up the IPM's with the mini program and with the feedrate pot completely open.
Is there a maximum of IPM's? I tried it up to program G91G1 Z-1.0F5000
so that should be 500IPM but I had the idea after a certain value it didn't go faster anymore? Is that right? I couldn't get him that far he would stall, so in one way that's a good sign I guess.

Thanks,
Bart

I believe the maximum is 200IPM. Maybe it needed to be freed up?
Will it now work in rapid?

George

George,
At 200IPM it worked fine. What do you mean with freed up? I don't understand that word, sorry!
It still doesn't work in rapid, but then it moves way faster.

Bart

There is a possibility that there may be a problem with the ZCK clock card but that would effect all 3 axis.
Without being there, it is hard to figure out.
Freed up means that working it, it may work with less friction.

George

George,
I already thought it could be because off too much friction. When I bought the machine they put a lot off grease on all blank steel to provide it from resting while shipping the machine to the Netherlands. I took that off the spindle before trying it but maybe not enough. I already tried too wipe it clean with PTFE spray but that didn't worked. Do you have any suggestions?

Thanks,
Bart

I have had cases where people used the wrong oil but I flushed the ball screw and quill with Kerosene, and then re-oiled it. On your side of the pond, maybe try naphtha? Some solvent that will flush anything out.

George

George,

What exactly do you mean with the ball screw? I know what usual ball screws are but I don't think you meant those ones.
Maybe I should try to clean it with Kerosene, but what exactly should I clean?
The trapezium thread? Or the quill? Or maybe something else?

Thanks,
Bart