Denford Senior 3C CNC Mill - (spurious?) E-Stop

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DMIOM
Posts: 17
Joined: Thu 05 Mar , 2009 9:33 am

Denford Senior 3C CNC Mill - (spurious?) E-Stop

Post by DMIOM » Sun 15 Mar , 2009 20:18 pm

Denford Senior 3C CNC Mill / Heidenhain TNC155B control - (spurious?) E-Stop

On power-up, it has a permanent E-Stop on screen.

Have powered up on the rear mains switch and then released the E-Stop button and then after mem test etc. and CE have pressed the green machine power on and and IF I HOLD THE GREEN RESET / POWER ON BUTTON IN, I can then press the start cycle and traverse the reference marks etc.; and can even go into programming mode - provided I hold the green button in all the time. The control does seem to be aware it is 3-axis and doesn't seem to be looking for 4th. axis e.g. only 3 DROs shown on screen). Its not the red E-stop either, and the machine isn't on any of the limit switches. Whilst holding the green button I can use the MDI to give it a move command in any of X Y or Z and all those work OK - but if I add an M03 or M04 the spindle doesn't start either.

Believe the front-panel EStop is OK as even when I hold the green On/Reset in, the control senses and responds to the front-panel red E-Stop being pressed.

Don't think its a stuck limit switch, as (a) it will reference OK, and (b) if I jog manually it will stop at the extremities of each axis and show Limit X+ etc. on the VDU; and when I jog away again, I can CE the Limit message. Have checked all the fuses and reseated them, also re-seated the relays and even tried transposing relays all to no avail. Have opened the back of the TNC enclosure and unplugged / re-seated all of the connectors therein.

Is there some extra trick with this machine? ( am slightly familiar with TNC155 from elsewhere so don't think its the TNC, its something on the machine).

When I received the machine it had a set of generic TNC155 manuals, but nothing machine specific - does anyone have the Denford specifics manuals? or schematics?

cheers / Dave
Last edited by DMIOM on Thu 19 Mar , 2009 13:28 pm, edited 1 time in total.

Martin
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Post by Martin » Sun 15 Mar , 2009 22:06 pm

The limits you are seeing on the VDU are software limits set in the control. It sounds more likely that one of the axis limit overide switches is faulty.

Can you inspect the switches to check that none are stuck in? Otherwise you will have to meet at each switvh in the back of the machine.

DMIOM
Posts: 17
Joined: Thu 05 Mar , 2009 9:33 am

Post by DMIOM » Wed 18 Mar , 2009 13:34 pm

Thanks Martin - understand now that the limits seen on-screen are soft.

I've pulled the guards off and physically inspected each switch; they all appear intact and un-contaminated, the roller arms are all free and clear of the operating button, and all have an audible snap. The only ones I been able to prove are the reference ones and can manually fool the homing process by depressing the relevant axis reference switch.

Unfortunately, as the Burgess switches have captive tails and no accessible contacts, the only way to test them would be to cut the loom open, and I would rather not do that yet.

I'm assuming that the normally-closed red&yellow from each limit switch is commoned up (series-ed?) in the loom - can't easily spot a multiplicity of them in the back cabinet?; and by the time it goes up and from the column out through the arm to the TNC, it is (I think) in a multicore signal cable. I'm also wondering though if there are any other signals integrated into the external E-Stop loop - floats? temperatures? spindle VFD?

I could try to find the overall external E-stop where it goes into the TNC, but I would rather not defeat the E-Stop circuitry without knowing what I'm defeating!

What I think I could really do with is a schematic .... Have read through the scans of the Drawing Index book that has been kindly uploaded and found what looks promising - is there any way I could get a scan or a copy of them? (book page 327 - schematics for 3C - A3 400 074 - 081, 085, 119-122 )

thanks / Dave

DMIOM
Posts: 17
Joined: Thu 05 Mar , 2009 9:33 am

Post by DMIOM » Thu 19 Mar , 2009 13:30 pm

Have made some more headway.

Firstly, after having perused the downloaded Drawing Index, it clicked that there were similar numbers on the machine and the manufacturing data plate is in fact engraved "Wiring Diagrams A3 400 074-082"

Found the limit switch connections in the junction box on the knee and in the spindle housing - appears correct continuity all through; tracked them back in the multicores to rear cabinet and then followed E-Stop through the rear cabinet and the operator reset button thence to the TNC - all possible because the loom had been so diligently numbered when it was manufactured!

Having found all the limit switches and confirmed loop continuity out from the cabinet and back again, the only other item I can find that is in series with the external E-Stop loop is the fault relay on the Jaguar Cub VC150 VFD (although I can't be certain if the float switch on the Bijur pump is connected anywhere). Defeating the rear cabinet interlock so I can keep the door open, I have momentarily seen the VFD fault LED illuminated - so (after waiting for it to discharge!) I have opened the VFD and pulled the E-Stop loop off the VFD fault relays N/O contacts and jumpered it so the VFD relay is no longer in series - and the E-Stop issue then disappears! - however the spindle still doesn't run - so it looks like VFD was keeping the E-Stop loop open. With the VFD fault output bypassed, as soon as an M03 or M04 is executed, the VFD faults.

Have checked the motor - it turns freely, DC resistance app. 5 ohms across all three sides of the delta - so I suspect its the VFD. Have searched online but can't find a manual for the Cub VC150 (and it has different pinouts to the 'VFD manual clips' in the downloads section here) - so does anyone know where I can find a manual / fault-finding guide for the Jaguar Cub VC150 ?

Dave

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