[hmc710]

Hi Guys,
Been working on my BP / TNC145 x axis stutter issue and the machine had a position error today as the x axis was acting up. I stopped the mach and looked at the encoder again, tighten up wire connections and checked the motor brushes. Went to power up mach and went to REF the axis, but the main power to the drives will not come on. I know I read about this before, but a lengthy search has not helped. When I push the main power button on the control panel, the relay does not even click in. I've checked fuses, power, e-stop, oil reservior, etc. What am I missing?
Thanks,
Tim

[hmc710]

Last time this happened, I was on the z axis limit switch, but holding in the power button allowed me to come off it. Now there is no power so I am searching through my manuals for a wiring diagram.

CRT: The top line of my crt only shows the bottom half of the line. Can this be adjusted? Its awful hard to decipher what the message is.

Switched op modes and keyed in 84159. Software limits are inactive. Tried to power drives and still no go....

No wiring diagrams..... Opened up the cabinet and measured power and check fuses. Found OL3 and OL1 (no OL2...?) Shut power down and pushed OL3 and it reset, OL1 did not. Both OL have adj pots set at 6.7 Turned power back on and system powered up. Went back into auto (inch) mode and referenced axis. Z and Y ref fine. X started to move and shut down and now have X MEASURING SYSTEM DEFECTIVE error. I do have the back cover off the motor so I could check the encoder / tach wires.

Given my intermittent x axis stutter issue and the previous comments about cables and encoder, I'll see if I can trace the cable down and check it. Any comments or suggestions are welcome.
Thanks,

[machintek]

Swap X and Y motors. If problem follows the motor it will probably be the encoder. The control sees a problem with the x axis position loop.

George

[hmc710]

Hi George,
I'll give that a try. I am checking my positioning errors also. Z & Y were about .0060 ea, X is .0250. TNC145a says to adj to as close as 0 as possible. Is there a point that is too far out of range indicating another parameter / set up issue.

I also tried to check the Offset, but when I Ref the axis, the manual says that the XYZ is supposed to be "preset at "0" " then adj the offset to get as close to zero or oscillate around it. My values are x 534, y 235, z 89 so I'm trying to figure this all out.

I assume a motor issue would mean sending it out for repair, what about the encoder?

Thanks for the help and insight!

Tim

[hmc710]

Checking the wiring on x axis. Back of encoder goes to control CRT w/6 wires. Motor wiring goes to main control box and has a red and a black wire that looks like it comes from the encoder end of the motor to teminal strip at motor. Red & Blue wires come out of motor to control. This is a shielded cable. Shield is terminated at motor end. Blue is T1, Red is T2. Which set of wires is sending info to the control and is there a way to measure output? Is this a 0-10v output?

Wrote program to move x back and forth @ F999 and feedrate overide at 50% and measured output at motor T1 - T2 and teminal strip 40-41. Both measured at 3.4v and motor operation was not smooth. Now what?

Tried same procedure with overide at 100%. Had a wisp of smoke come from motor and hit E-Stop. Motor was not hot at all. Will pull the motor and see what it looks like on the bench. Its an SEM MT 30R4-58. Any source for these or repairs?

[gridley51]

X axis stutter can be a lot of things from dry slides,faulty bearings,faulty encoder/motor.
If the encoder is a gonner you`re in deep as these are expensive.Run at about £800 new which is about $1200-1300.
As I mentioned on another thread someone on Ebay UK is selling these motors complete with encoders for £500 which is about $750-800.
Put the cost of these encoders firmly at Bridgeports door as they were the ones that designed a machine with imperial pitch ballscrews.
Mark.

[hmc710]

Hi Gridley, thanks for the comments. Got the drive pully off the motor and pulled the housing off. Brush area is full of gunk. Downloaded the info from SEM on the motors on disassembly. Will try this and see what happens. Turned x axis by hand and it is very smooth in both directions. Hopefully it is just some crud buildup in the motor.

Cleaned out motor and reassembled. Powered up and Ref all axis. X was smooth as silk. Hopefully a step in the right direction. Thanks for all the input.

[Revolver]

Hi folks, I actually have the same motor and X axis does not give any coordinates back, but the motor still moves.. The bearing seems to have some slack and a little noise, could that be part of the problem?
I've read that the most common problem with these is that the windings fry and after that it seems that the encoder does not give any feedback, even if it still works. How would you diagnose which one is it?
I also took some pictures of the motor. Could some of you experts say if everything, like the windings dark purple colour looks allright? I don't know how they looked from factory..



And what is this gunk, is it for balancing?



And what about these bronze looking sticks?



I also measured the four brushes lenght, all had 9mm left. Is that still enough?

[gridley51]

"I actually have the same motor and X axis does not give any coordinates back, but the motor still moves"

If by that you mean the motor jogs and runs ok but you get no positional info from it.it means you have a problem with the encoder,cable or control.
The motor windings look ok to me but I`m only seeing a bit of them.
There is a pdf available for download from SEM`s website on maintenance of these motors and another one explaining how a motor can affect surface finish.

[Revolver]

If by that you mean the motor jogs and runs ok but you get no positional info from it.it means you have a problem with the encoder,cable or control.

I don't know if it run perfectly ok, I'd say it was a bit sluggish. But now that I replaced the worn brushes and the front bearing, the X position came alive!
Luckily there was nothing wrong with the encoder or the windings. :cheers:

Even though my old brushes had 7-9mm left, its was not enough since the spring pressure became too low. The new ones are 14mm. The new brushes are also equipped with a longer spring, I guess people at Sem have noticed this and improved it in the later revisions of the motor & spare parts.