Bridgeport Series I X-axis won't move

Dear All,

Hopefully someone can help me out here.
I've got a Series I machine which used to run very well untill it stopped moving the X-axis. When I try to move the table you'll see it trying to start moving but then the motors starts to windup imidiately. No I can't find what causes this failure. This is what I've already tried.

- Checked transistor plates.
- Checked all diodes on the side of cabinet
- Checked SMD-board by trying it on another axis.
- Checked the fuses related to this axis
- Checked motor connections
- Checked mechanical connection to the table.

This is where my knowledge stops so if there's somebody with suggestions about what I should try it would be great!

Thanks,
Bart

Nobody?

It really confuse me that everything seems to be all right. Today I thought I'd find the problem when I found a bad connection in the motor but after replacing it it was still acting the same way.

Any help would be appreciated!

Bart

Is this a servo or stepper machine?
What control?
Always start an enquiry by giving the model of the machine and the control.
There are a few Series 1 machines.

You're right.

The machine has the original steppers on it and used to be a Boss 5 machine which I retrofitted to a Mach 3 control.

Bart

Would it not make sense to ask on the Mach forum?

I'm pretty sure it's not a mach issue.
When you control the X-axis the machine seems to start moving but then the motor stalls direktly. And you can here it's still making noise but there's nothing moving.

It may not be a Mach issue,but,on the Mach forums there are hundreds of other guys who have done the same as you,with probably the same setup as you,so they know the problems.
People who work with machines in their standard form have not got a clue how you are controlling the drive or handling feedback,if any.
If the axis starts then stalls,have you checked for mechanical tightness?
Have you ran the motor disconnected mechanically from the machine.
Have you checked the drive is putting out what it should be?

I'm not even sure if mines a series1, but think it is...look under the right side of the x axis, can you see a kinda spiral cam on the ballscrew? if so its like mine, the ramp is the hardstop, its part of the ballnut. with the power off, you should be able to rotate the nut- mines got servos, so it moves pretty easily, think with steppers it will be kinda 'clicky' as the poles in the motor line up, but still, should be fairly easy to rotate.
if it dont want to turn, try loosening the ballscrew locknut on the other end of the table a couple turns, it will give you some backlash...see if the ballnut turns easily again in the backlash area. if it dont turn easy, your screw might be locked up- mine did this years ago.

I took the locknut off the end of the screw, pushed the table to the left to disengage the keyway, rotated the screw(and the ballnut/servo) around, sprayed some penetrating oil in it, kept rocking it back and forth, till it started to free up...ended up having to pull it out/reload it, but its still in there.

if with the loose locknut backlash, you can turn the servo easily, you might just have a tight slide/gib...I had to rescrape mine a bit, it had the typical 'loose in the center' condition, and would get sticky at the ends of the travel...its nice and smooth/snug full travel again now.

if the ballnut turns ok with the locknut and everything as-is, then its pointing to a dead drive phase or motor winding- I dont think thats the case though, as you stated it moves a little- just sounds to me more like mechanically stuck. if you are comfortable messing with the gibs, thats a easy way to get the slide load off it, but if the ballnut is locked up, you'll be in for some work...reloading one isnt difficult, just the first time you pour 100 ball bearings out of one, its kinda a 'oh-crap' moment...

my bridgeport was the first machine I messed with that the screw was stationary and the nut spun around it- my thrust bearings were fine, but fine chips had gotten in the nut, eventually locked up one of the ball circuits...cleaning, putting new balls in, cost like 20 bucks, not good as new, but still has preload, still smooth= good enough:)

I had just finished reloading a 6 circuit nut one day at work, was filling the tubes/greasing the ends, had already pulled my wire stops out of the nut...my buddy Rick walks up, 'hey Tim, hows it going?' and spun the nut...he didnt see the tubes were out, but his jaw about hit the floor as the balls spilled out...they were those little 1/8"ones too, like 300 of them in there...had to clear it all out, start again :(

Tim,

Thanks for your clear advise. If I got the oppurtunity I'll try to check this today since it makes me curious if this will be the problem.
With this machine I learned almost all issues are electrical issues so that's why I started looking at this. I've had the same problem on the Z-axis (tried to move but motor starts winding directly) and there one of the transistors was fried. So when starting at this issue I was pretty sure I already know what the problem was. Just an hour of work and I'll get it back working again. Too bad it wasn't.

Bart

Hi

sorry to drag up an old thread and wondered if you ever managed to get this sorted i am havin the exact same problem on a series 1 BP boss5


It has the superior motors. and no conversion still running BOSS
Y and Z fine, X you can hear the motor whining but doesnt move appears stalled.
Swaped over SMD cards to see if it made a difference, NONE
Turned upside down the ACC, No difference
at this point susspecting the motor, I wired (at motor) the Z drive wiring to the X drive motor and the motor moved perfectly, so it is not the motor.

ALL fused checked and changed to new.
All wiring checked for loose or broken.

Any Ideas or clues

Many Thanks

Hi again

to any that run into this problem and need to know a soloution that worked for me here goes.

After checking all the obvious as above and then all the wiring I assumed it must be an electronic fault on one of the boards or units, so I methodically went from section to section tracing every wire and junction though every board and unit.

I found a low resistance on wire 111 and again going over every point that went though and desoldering various diodes that are along the path of this wire thinking it was one of those shorted, I came to a unit fitted to the small door on the right hand side of the cabinet, this door open out to the rear of the machine. one of the transistors had failed and was short one way.

Tested the wiring forward of this point and all read OK on the meter, so swapped the unit with the Y unit, (it looks like a black heatsink with4 transistors on the rear) confident that nothing forward of the unit will blow the unit. and hey presto X was fully functional again.

The transistor was marked STA7018, this is not available any more, but the exact equivalent is the NTE165 which is available from RS in the US, part number 2508956973. £4.87 each plus £10 shipping so not too awfull to get sorted.

I have odered them (have to buy 2 minimum) and should be here in 10 Days. but it might help someone.

Many Thanks

Hello Pat-Uk,
Sorry I didn't came back to you earlier but it seems you already found the problem.
The transistors where one of the first things I checked since they where fried on another axis earlier.
On my machine I still haven't found the problem. I'm suspecting the motor itself more and more but I haven't had time to check it yet.