Messages

6951

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 06:14:49 PM »

Hi All,
I had problems with my spindle stalling. Its a 24000 rpm VFD driven unit and I was trying to use it to drive 6mm endmills  cutting
steel. The problem is that high speed spindles have so little torque. Consequently you could only take the lightest of cuts and if
you over did it or your Gcode called for a plunge or similar temporary overload the spindle would stall. With the tool stalled but still
engaged in the material the XY movement would snap the tool no problems, my wee mill has near 500kg of thrust, 6mm endmills
don't stand a chance.
For this reason I monitor the VFD for excessive difference between commanded speed and actual speed to Estop in the event of a stall.
It works mostly, the VFD can take some milliseconds to signal a stall and so an Estop may occur too late to save the tool.

I have since made a servo driven spindle with 6.5Nm rated torque and solved the whole problem of stalls. Now I have enuf torque
to 'twist' smallish (less than 8mm) endmills off like a carrot!

Craig

6952

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 04:44:03 PM »

Hi All,
garylucas has a great idea. The circuit as I've drawn it may well give Tarak problems when he tries to enable Mach at startup.
A Reset button like garylucas mentions would solve it.

I had in mind a software setup where the drive/drives were not monitored for faults until either Mach was enabled or was actually
machining, a complicated way of doing what garylucas suggests.

Craig

6953

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 08:28:42 AM »

Hi,
after talking about putting in a diode to be on the safe side I bloody well forgot to put it in there!

Craig

6954

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 07:42:47 AM »

Hi,
hopefully this makes a bit more sense.

Craig

6955

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 07:25:08 AM »

Hi,
I can't see any spec for it either. I do see that the upper board logic supply needs be capable of 0.1A. Clearly the outputs are logic level,
I wouldn't consider asking an output to sink more than 5mA, the risk of blowing it up is too high.

The Estop terminal on my BoB is logic high by virtue of 5V being applied through the series of normally closed contacts of my limit switches
to the Estop terminal with a 5k resistor from the same terminal to earth. Thus with all contacts closed 5V is applied directly to the pin, when
one or more contacts are open the 5V continuity is lost and the 5k resistor pulls the pin logic low and Estops Mach. If I were to hook the output
pin of a servo drive such as your TK 10 to the Estop in addition to the limit switch circuit it would fail. The 5V of the limit switch circuit would
attempt to hold servo drive pin high even when the pin was trying to go logic low, it would try to sink a lot of current and fail and damage the drive.

You'll need to introduce some resistance in the 5V supply to your limit switch string. If you put 5K in there with the limits all closed logic high would
only be 2.5V by virtue of the voltage divider formed by the 5k resistance to earth at the Estop pin, such a low logic high could render your Estop
noise sensitive. If you reduce the series resistance to 1k then the current to be sunk by the servo pin would be 5mA and yet have a logic high of
4V, acceptable. I would in addition put a diode in series with the servo pin so that if in fact its voltage goes higher, 12V say, it cannot blow your
Estop pin of you BoB if as in my case your BoB is a 5V device.

Craig

6956

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 04, 2017, 04:35:46 AM »

Hi,
I would've thought that if your Z axis servo faults you want to immediately go to Estop to protect the tool and/or work piece.

I don't know how your Estop is wired but if its like mine logic low represents fault/emergency stop. Thus could you hook the output
pin to your Estop circuit. Depending on the current that could be delivered by your existing Estop circuit you may have to protect
or otherwise buffer your pin. Does the manual tell you how much current the pin can sink?

Do you have many inputs to spare? I know that you're talking about a fault on the Z axis but ideally you would monitor both X and Y
as well. I would combine those inputs to one 'servo fault' signal and interface that one signal with your Estop. The reason I'd adopt
that strategy is so that a servo drive which is yet to be enabled at power-up does not prevent you from enabling Mach. At power up
you need to enable Mach but if a disabled servo prevents you and you can't enable the servo until Mach is enabled you can't do anything!

Craig

6957

General Mach Discussion / Re: Servo drive tripping, mach3 stays online.

« on: June 03, 2017, 11:57:38 PM »

Hi,
not familiar with your particular drive but drives I have all have a 'fault' output which can be monitored by Mach and
Estop on fault. Have a close look at your manual to see if indeed your drive is equipped with such an output.

Craig

6958

Mach4 General Discussion / Re: KX3 and Mach4 compatability

« on: June 02, 2017, 11:27:00 PM »

Hi,
I think you could use Mach4. My suggestion would be to use one of the Mach4 capable external motion controllers which plug into your PC with
USB and connect to your machine with a DB25 plug. With such a device you could use Mach3 or Mach4, your choice.

The only thing which determines whether an external controller can run Mach4 is if the manufacturer has got around to writing the software
plugin required to 'translate Mach4 to device output'. At this time there aren't many but the ones who have made the effort have been around
a long time and produce really solid products.

Try searching:
Warp9
PMDX
CNCdrive
PoKeys
VitalSystems
CSlabs

Probably not an exhaustive list but certainly every name on it is respected by CNCers.

Craig

6959

General Mach Discussion / Re: add relays to Break out board schematics

« on: June 02, 2017, 05:40:24 AM »

Hi,
just been dealing with a spotwelder/dent puller at work based on triac control of a transformer of low ouiput voltage but very high
current. Had to repair the control PCB and it turns out the 'solid state relay, SSR' was faulty. Bought a new one popped it in and away it went.
Bought it for $3.27 NZD, about $2.50 US so hardly breaks the bank. Has input sensitivity of 1mA with output capacity in the tens of mA and on
state resistance of 25Ohm AC and 3 ohm DC. Very useful and sensitive enuf to make your design task a little easier.

Check it out...LH1540....6 pin DIL IC

Craig

6960

General Mach Discussion / Re: Question about lost steps and CPU cycles...

« on: June 02, 2017, 05:26:42 AM »

Hi,
neither would be a mistake, both manufacturers have been around since the get-go of external controllers, both are good.

To my knowledge the UC100 has a Mach4 plugin whereas the UC300 and UC400 does not. Likewise the Ethernet SmoothStepper has a
Mach4 plugin but the USB SmoothStepper does not. Both companies have stated that they wish eventually all their products be Mach4
capable. Given the much greater IO capability of the ESS relative to the UC100 and have for my purposes the mandatory Mach4 plugin
leans me to favour the ESS.

Craig