Centroid T400 for lathe and gear head speed selection

[cncsnw]

The advice to install a separate ground rod through the floor adjacent to any CNC machine is outdated, and by my understanding is a bad idea.

You do want to make sure you have a solid ground back to your electrical panel: preferably via a 4th wire, not just via metallic conduit.

I don't believe there is any need to replace the Heidenhain encoders on the handwheels, but if the existing twisted-pair cable is not shielded, it would be a good idea to pull new cables for them.

Check your VFD configuration to see if you have a period of DC injection braking enabled as the spindle stops. I don't usually use DC injection braking, and I have seen one case where it very consistently induced errors on nearby wiring (false transitions on a limit switch input to the PLC, in that case).

[Marty_Escarcega]

The advice to install a separate ground rod through the floor adjacent to any CNC machine is outdated, and by my understanding is a bad idea.

You do want to make sure you have a solid ground back to your electrical panel: preferably via a 4th wire, not just via metallic conduit.

I don't believe there is any need to replace the Heidenhain encoders on the handwheels, but if the existing twisted-pair cable is not shielded, it would be a good idea to pull new cables for them.

Check your VFD configuration to see if you have a period of DC injection braking enabled as the spindle stops. I don't usually use DC injection braking, and I have seen one case where it very consistently induced errors on nearby wiring (false transitions on a limit switch input to the PLC, in that case).

Thanks for the thoughts and suggestion. It does have a braking resistor and it does brake the spindle. I will check that out and report back what I find...going to work a little on the machine this morning. Busy weekend with family stuff going on.
Marty

[Marty_Escarcega]

I disabled the deceleration in the TECO VFD. I think it helped somewhat but the axis encoder errors still exist. I took a close look at the X & Z encoder cables, they are shielded, not with the foil type shield, they have a braided wire shield that wraps the internal wires. There is a remote operators panel (see attachment) I check it and its shield was not grounded. I decided to disconnect this panel from the AIO DC to eliminate all possibilities.

While I did record what wires went to where on the AIO DC, one is obvious, Estop switch was wired in series with the rest of the control I removed it and completed the Estop circuit as it came from Centroid.
The other 3 buttons, went to Inputs 7, 8 & 12. Which lead me to find information on how I can find out what these inputs (and other configurable outputs are assigned) not much information in the installation guide that I can find other that they are configurable. What functions are they assigned to, and do they require a hi or low input. Either I have to disable these inputs or jumper them because I can't home the machine right now.

I am creating a pinout and wiring chart for the remote operator panel and where it connects to the AIO DC, but I do need to know how to look up and configure the configurable I/O.
Thanks again!

Marty

[Marty_Escarcega]

Happy Day! While I appreciated everyone's recommendations, it simply was odd to me that the moment the VFD was commanded on I got the axis quad encoder error trip, or when I was lucky enough to have the spindle run, when it was commanded off, I got the axis quad error trip. So, fortunately, I had another TECO 7.5hp VFD (this was an FM100) from an EMCOTURN 120 that is going to be refitted and I knew it worked. That machine had the Centroid T400S and I tested the machine prior to removing the control. I installed into the control cabinet of the EZ Path and guess what, no axis quad encoder trips.

I believe there maybe something wrong with the TECO CV7300, possibly noise going through one of its control lines back to the AIO DC. I wrote a program that commanded the spindle on, changed various speeds, commanded the spindle off with dwell times in between. No problem. I ran the VFD of single phase and then I tested with the American Rotary model AD phase converter suitable for CNC applications. Neither the TECO CV7300 nor the FM100 are rated for single phase input only. There is a coolant pump on the machine that is 3 phase. Lube pump is 120.

So, SO FAR SO GOOD.

Tomorrow brings another day. I will work on the gear box ratio parameter settings and do some more testing.

I'll report back tomorrow. I hope these results help someone else if in fact it was the VFD.

Marty

[cnctechml]

All of the inputs on the ALLIN1DC are configurable. They can be either 5VDC, 12VDC, or 24VDC inputs. They can also either be sinking or sourcing inputs. The inputs are tied in banks of 4. You can have inputs that are 24VDC sinking inputs as well as 24VDC sourcing inputs connected to the ALLIN1DC at the same time. The only thing is that if you have a 24VDC sinking input, the other 3 inputs on that bank also need to be 24VDC sinking inputs. This is all described in the ALLIN1DC manual.

As far as what each input is doing and what it controls, that is defined in the PLC program. Looking at your PLC program from the report that you previously attached, it shows that input 7 is defined as a RemoteFeedHold button, input 8 is defined as a RemoteCancel button, and input 12 is defined as a RemoteStart button. Attached is a copy of the CNC11 PLC programming manual in case you wish to customize your PLC program as well as a tech bulletin on compiling a PLC program. After a PLC program, xxxx.src, is created, you will need to compile it to create the mpu.plc file which is what the CNC11 software uses to see and control the I/O.

[Marty_Escarcega]

All of the inputs on the ALLIN1DC are configurable. They can be either 5VDC, 12VDC, or 24VDC inputs. They can also either be sinking or sourcing inputs. The inputs are tied in banks of 4. You can have inputs that are 24VDC sinking inputs as well as 24VDC sourcing inputs connected to the ALLIN1DC at the same time. The only thing is that if you have a 24VDC sinking input, the other 3 inputs on that bank also need to be 24VDC sinking inputs. This is all described in the ALLIN1DC manual.

As far as what each input is doing and what it controls, that is defined in the PLC program. Looking at your PLC program from the report that you previously attached, it shows that input 7 is defined as a RemoteFeedHold button, input 8 is defined as a RemoteCancel button, and input 12 is defined as a RemoteStart button. Attached is a copy of the CNC11 PLC programming manual in case you wish to customize your PLC program as well as a tech bulletin on compiling a PLC program. After a PLC program, xxxx.src, is created, you will need to compile it to create the mpu.plc file which is what the CNC11 software uses to see and control the I/O.

Great. The inputs all correlate to the buttons on the remote operator panel, verified after identifying each wire through the CPC behind the panel.

Thanks for the information on where to find the I/O and the docs about the PLC and compiling. More reading to do.

This morning shows consistent operation. No more axis quad errors. Further, I was able to tune the 0-10vdc analog spindle output. I also was able to set the parameters for the medium and low gear ranges. They are within 20-30rpm of the called S value now. Also cleaned up the control cabinet. (Picture attached). I'm waiting on some DB-9 hoods to replace those that are missing. I want to work with the accel/deceleration parameter settings in the vfd. I may reinstall the braking resistor, with such a large chuck, it will be good to try and slow it down rather than coasting for so long.
Marty

[cnckeith]

nice..
yeah.. i run dc injection braking with no issues on the machines i update with new controls that don't have a mechanical braking system, its nice to have the spindle stop quickly.

[cncsnw]

Keith,

Do you mean DC injection braking, or do you mean dynamic braking (ramp-to-stop)? They are different things.

[Marty_Escarcega]

Thought I would post a follow up (and video clip) on how things are going. So far, no more axis encoder quad errors. Control seems to be running fine. Yesterday and today, I reterminated the Spindle and X/Z handwheel encoder DB 9 connectors at the control. X had a loose wire. Probably from pulling on the wires since it had no hood. I have an AMP crimp tool and prefer to strip and crimp rather than fight solder cups. Also helpful if you poke a pin in the wrong hole, I have the extraction tool to pull the pin. :-) So all that is cleaned up, wiring is pretty secured and dressed, all but one "extra" hole in the cabinet is plugged. I am working on tuning the VFD for DC injection braking and deceleration times. The chuck is large and with the gear train, the spindle takes a while to come to a stop. So a little shorter decel time will be helpful I think.

[cncsnw]

If you want to ramp to a stop somewhat quickly, then you want "dynamic braking" or "regenerative braking".

Dynamic braking means that the VFD ramps the output frequency (3-phase AC output waves) down from the running frequency to a minimum near 0Hz. In doing so, it absorbs energy from the motor, which it dumps to an externally-connected braking resistor as needed in order to keep its bus voltage within limits.

"DC injection braking" is used for final stop and brief position holding. In DC injection braking, the VFD puts a fixed DC current through the windings. This has the effect of holding the rotor in one position (presumably one of six possible positions, for a 4-pole 3-phase motor). Left on indefinitely, that will cause the motor to overheat, so DC braking is only applied for a few seconds, to bring the motor to a full stop.

DC injection braking is usually not necessary, but it does help bring the spindle to a quicker final stop.

[Marty_Escarcega]

If you want to ramp to a stop somewhat quickly, then you want "dynamic braking" or "regenerative braking".

Dynamic braking means that the VFD ramps the output frequency (3-phase AC output waves) down from the running frequency to a minimum near 0Hz. In doing so, it absorbs energy from the motor, which it dumps to an externally-connected braking resistor as needed in order to keep its bus voltage within limits.

"DC injection braking" is used for final stop and brief position holding. In DC injection braking, the VFD puts a fixed DC current through the windings. This has the effect of holding the rotor in one position (presumably one of six possible positions, for a 4-pole 3-phase motor). Left on indefinitely, that will cause the motor to overheat, so DC braking is only applied for a few seconds, to bring the motor to a full stop.

DC injection braking is usually not necessary, but it does help bring the spindle to a quicker final stop.

Struggling a bit with this now. Don't need DC injection braking, want the TECO FM100 to decelerate in a given period of time. Though when I command the m5, the gearbox makes a hideous noise. Having lunch right now and reading more on the TECO FM100 parameters. I find Dynamic Braking FN48 and DC Braking FN53. Its a bit confusing and not so clear in the manual....

Marty

[Marty_Escarcega]

OK, I figured out the combination
Using 3000rpm, the max speed of the lathe (no chuck and likely only this RPM for collet work)
This combo seems to work on the TECO FM100
Acceleration time; 2.0 seconds
Deceleration time: 6.0 seconds
DC Injection braking programmed to come in at 10HZ
Percentage of DC injection: 10%
DC Injection time: 2.0 seconds

So the machine decelerates towards 0HZ from commanded speed in 6.0 seconds, when the VFD hits 10HZ, 10% DC injection is applied for 2 seconds and then releases.

Without DC injection, there is a bit of a "jerk" at the very end, like the headstock is loaded, then unloaded and then loaded. Which can't be good for the gear train. Using the DC injection puts the brakes on and does not allow the "jerk" to occur.

Any comments on the process?


Marty