Messages

431

General Mach Discussion / Re: What is a charge pump?

« on: January 07, 2012, 01:36:01 PM »

The Mach3 charge pump was never intended as a safety feature, and should NOT be counted on as part of a safety circuit.  It's original intent was to simply disable the drive motors, spindle controls, etc. during boot-up, and before Mach3 was running.  Without it, there is a tendency for some systems to turn on during PC boot-up.  The charge pump prevents that.  However, since the charge pump output from Mach3 is software controlled, there are MANY ways in which Mach3 and/or Windows can crash and leave the charge pump running, so it cannot be counted on to reliably disable the machine under any conditions other that on boot-up.  Similarly, any well-designed E-Stop mechanism should function WITHOUT depending on Mach3 to do ANYTHING AT ALL.  This means both the charge pump circuit, and E-Stop switch(es), should act directly on the power supplies, typically though a power contactor, and NOT simply provide an input to Mach3, then depend on Mach3 to disable the drives/spindle/coolant.

Many BOBs (Break-Out Boards) have on-board charge-pump circuits, and E-Stop logic, that will directly force all BOB outputs to their inactive state whenever the Mach3 charge pump signal is not present, or the E-Stop switch is disabled.  I've used a number of the Homann Designs BOBs (www.homanndesigns.com) on my machines, and am very happy with them.  They're cheap (under $40), very well designed and built, and small (about 3"x5"), making them easy to mount almost anywhere.  The latest ones contain both E-Stop inputs and charge pumps circuits.  Peter Homann is also a regular on these forums, and always provides great support.

Regards,
Ray L.

432

General Mach Discussion / Re: Edits to M6End not being seen?

« on: January 03, 2012, 02:30:18 AM »

What is this M100 macro you keep mentioning?  I don't think it's a standard part of Mach3....

Regards,
Ray L.

433

General Mach Discussion / Re: Capability of 800W spindle

« on: December 31, 2011, 12:50:36 PM »

800W is over 1HP, which should be FAR more than you need for any kind of jewelry.

Regards,
Ray L.

434

General Mach Discussion / Re: False Estop detection

« on: December 30, 2011, 01:23:55 PM »

So did you get it resolved?

435

General Mach Discussion / Re: False Estop detection

« on: December 29, 2011, 03:30:45 PM »

Add stiff pull-up resistors (220 ohm) to +5V, and/or small capacitors (100pF) to ground on ALL switch inputs.  That should dramatically reduce their noise sensitivity.

Regards,
Ray L.

436

General Mach Discussion / Re: A couple of questions re servo's

« on: December 29, 2011, 09:34:50 AM »

I don't think you'd want to stack the toroids without some space (perhaps an inch?) between them.  Either file system should be fine.

Regards,
Ray L.

437

General Mach Discussion / Re: A couple of questions re servo's

« on: December 28, 2011, 09:07:32 PM »

Wiring 3-terminal regulators in parallel is not wise.  One will invariably be set to a slightly different voltage than the other, and end up doing most of the work.  The right way to do it is to build a high-current regulator using a pass transistor capable of handling the full load current.  An analog regulator will also be very inefficient, since 1/3 of the energy will be lost as heat in the regulator - you'll need some hefty heat sinks.  You'd really be FAR better off just getting a 24V supply.  Do you NEED the full 36V for the Z axis?  If youi don't need it to go to full rated RPM, run all the motors on 24V.  The only thing you'll lose is top-end speed on the Z axis will be reduced by 33%.

Regards,
Ray L.

438

General Mach Discussion / Re: A couple of questions re servo's

« on: December 28, 2011, 03:44:57 PM »

well my thinking is that rpm and volta\ge are linked and ive checked this ie at 2800 rpm on a gecko the motor is drawing 24 volt

The motor does not "draw" voltage.  Voltage is applied by the driver, at the power supply voltage, and that voltage induces current in the motor windings.  Most motor ratings are determined by thermal limitations.  What you measure with a voltmeter is an average value, but with a PWM drive, like a Gecko, it is the instantaneous values, which CANNOT be measured with a simple meter, that will get you into trouble.

Regards,
Ray L.

439

General Mach Discussion / Re: A couple of questions re servo's

« on: December 28, 2011, 02:16:37 PM »

No, I would guess that's probably not a smart thing to do.  The Gecko uses PWM, which means it is switching the full supply voltage on and off to control the RMS (average) current.  Running the Geckos at above rated voltage for the motors would not only leave open the possibility of cooking the motors if the Gecko fails, andI would think it would also be likely to result in the motors running hotter than they would if run within their ratings.  If you want to get a definitive answer, I would contact Gecko tech support directly.

Regards,
Ray L.

440

General Mach Discussion / Re: Missing steps! Upgraded my screw drive to R&P

« on: December 18, 2011, 11:47:00 AM »

You went from 8000 steps/inch to 1388 steps/inch, which means you will now need almost 6X the torque to get the same performance!  It is incredibly unlikely you had enough reserve torque before to be able to handle this, even at low speed.  Seems painfully obvious to me you need larger motors, which will likely also require better drivers.

Regards,
Ray L.