Messages

41

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: July 12, 2016, 01:58:18 PM »

You could always fit a SSD if you're worried about hard disk life.

42

General Mach Discussion / Re: Novice to Mach3, may be asking too much??

« on: July 11, 2016, 05:13:33 PM »

I managed to get a better result with Velocity mode, however by the time I tried Torque mode, I was already getting good results with velocity mode.

In theory Torque mode should give better results, however everything has to be tuned well to achieve it or it won't work well, unlike velocity mode where you can usually get reasonable results even if things aren't tuned that well.

43

General Mach Discussion / Re: G82 Mach3 Lathe issue

« on: July 11, 2016, 05:06:48 PM »

I used to use the M830 macro, and the key was you had to use G-code files with line numbers, just like the example files show.
I think you might also of had to use .nc as the file suffix.
They certainly worked fine for me, but I was hand coding the files. I think it might be a bit more of a challenge trying to get a CAM post-processor to output the required code though.

44

General Mach Discussion / Re: Novice to Mach3, may be asking too much??

« on: July 09, 2016, 02:16:58 PM »

The documentation for the drives is listed in the bottom right corner of the page. It took me a while to find the links.

They're only amplifiers, so it's up to whatever controller you're using to take the encoder feedback and close the loop.

45

General Mach Discussion / Re: Novice to Mach3, may be asking too much??

« on: July 08, 2016, 03:58:08 PM »

Tacho feedback can pretty much be classed as obsolete technology.

With modern DSP (Digital Signal Processing) tech, an encoder can be used to provide the same information but far quicker and more accurately.

46

General Mach Discussion / Re: Bridgeport Knee Mill Conversion?

« on: July 05, 2016, 06:43:26 PM »

Ideally you want the drive to stop before removing power, however anything that relies on AC power to power it, should not have any issues with the power being cut cleanly.

The worst that should happen, is the drive enters fault mode when it detects the internal DC bus voltage has dropped below the minimum voltage.

Power being removed while the drive is under hard deceleration would be no different to the drive still being powered. If things decelerate too fast, with too much energy being dumped back in to the internal DC supply, the drive will fault out due to the internal DC bus voltage rising too high, at which point the drive will normally fault out and let the servo freewheel to a halt. This is where external braking resistors come in, as it allows the drive to dump more energy, and avoid triggering over voltage errors.

47

General Mach Discussion / Re: Which Control/Breakout Board

« on: July 05, 2016, 04:39:35 AM »

And in the UK you have http://diycnc.co.uk/ however they're designed around parallel ports.

It's also worth mentioning Emvio sell Ethernet Smooth Steppers in the uk - https://emvioeng.com/shop/cnc-and-automation/motion-control/ess-bundle/

48

General Mach Discussion / Re: Which Control/Breakout Board

« on: July 04, 2016, 07:10:29 PM »

Other Euro option would be the PoKeys57CNC board - https://www.poscope.com/pokeys-devices/PoKeys57CNC
I've never personally used one, but seems a very capable controller with good support.

49

General Mach Discussion / Re: CSMIO-IP/A and max velocity setting?

« on: July 02, 2016, 06:55:09 PM »

There are tuning parameters for the BST drives, however the descriptions/translation are pretty poor.
Pn153 up for Speed Control mode, and Pn188 up for Torque Control Mode.
Speed control mode is generally easier to setup, but Torque Control mode will give better performance if it can be set-up correctly (if you don't get it setup correctly, it'll give much worse and far more unstable performance than Speed Control mode).

Without an autotune function, you need to play with the settings manually, and you need to tune them while attached to the machine, as the extra load acts like a damper.


For comparison, my lathe holds within 6 counts on the Z axis, and 17 on the X-axis. The X-axis is a slant axis with a turret on it, so it's got a bit of an imbalance.
I ended up using speed control mode, as in torque control mode I came to the conclusion the internal filtering of the servo drive was causing too much of a delay to change of input voltage, as even with all filtering reduced to an absolute minimum, there was still a delay in the response plots (KFlop lets you plot position commands against encoder feedback, so you can see exactly what is happening).

50

General Mach Discussion / Re: Novice to Mach3, may be asking too much??

« on: July 02, 2016, 05:26:54 PM »

There are a few servo amps available for DC servo motors, however I'm having a complete mind blank as to the manufacturers!

Personally I'd say run what you have for now if it works, but plan for replacing later, unless you really need as much reliability as possible, in which case I'd look at swapping to AC servos.