Messages

151

General Mach Discussion / Re: Using an Encoder for Jogging

« on: March 14, 2013, 02:32:34 AM »

A macropump is a macro that is started automatically when Mach3 starts up, and runs as long as Mach3 is running.  Look at the code I referred you to.  It shows how to implement a full pendant, with no "smarts" in the hardware at all - just switches and the MPG.

Regards,
Ray L.

152

General Mach Discussion / Re: Using an Encoder for Jogging

« on: March 14, 2013, 02:16:19 AM »

Got it.  Basically you need to have a smart board that will run small macros and send keyboard scan codes.

Well, if I keep this machine Mach when I finish it I won't waste another second with the MPG idea then.  I'll just throw in an arcade joy stick and a couple fire buttons for Z. 

No, I don't think you got it.  All you need is a Mach3 macro.

Regards,
Ray L.

153

General Mach Discussion / Re: Using an Encoder for Jogging

« on: March 13, 2013, 10:28:19 PM »

There are OEM codes for selecting which axis the MPG controls.  You'd need to have switches, and a macropump, brain or plug-in to issue the OEM code at the proper time.  If you search the archives, back in about '08 or so I posted macropump code that implemented full pendant functionality - several jog modes on all axes, Run, Stop, Pause, Rewind, and many other things.  Search on my name, and VistaCNC or iMachPro.

Regards,
Ray L.

154

General Mach Discussion / Re: ok enough stepping, how do I add encoders?

« on: March 12, 2013, 08:43:11 AM »

That is a good point, maybe the motors are not at full torque.  (More power )

The motors are 6.4 mH/phase and are rated at 3.5 Amp/phase powered by a 36 Volt 10 A supply.
My drivers are rated up to 50 VDC. 4.2 Amp peak.

I am also running at 1000 Pulse/rev (down from 1600) in an attempt to trade accuracy for power.
Unless I miss understand the concept,  less steps equals more power but less accuracy.
That said 1000 Pulse/rev still should still hold .00025 on my setup.

Maybe a 48 volt supply would help out, just don't want to bake the drivers. 

Randal

And there's your problem - those are high inductance motors.  Proper voltage for driving those motors is 80V, so you're getting will under half the rated torque out of them.  So you can either change the power supply and drivers, or get better motors (and you'll still need a higher voltage power supply), and solve your problem properly.  Nothing else will make that machine perform reliably.  Changing the steps/inch will have essentially no effect.

Regards,
Ray L.

155

General Mach Discussion / Re: ok enough stepping, how do I add encoders?

« on: March 11, 2013, 08:01:01 PM »

What is the inductance of your motors, and what supply voltage are you running?  If the motors are high inductance, and/or your supply voltage is too low, you'll never reach rated current at-speed, and therefore never reach rated torque.  Since you indicate others get good performance with the same size motors, and the same machine, you should be looking at what you did wrong, and fixing that, rather than throwing money at work-arounds.  NO controller can make a bad drive work.  Once a stepper can no longer keep up with the load, there is no "fixing" it, whether you have encoders or not.  If they can't produce enough torque to handle the load, you're screwed, and the only way to stay on-course is to slow down, which NO controller can do on-the-fly, as the trajectory is planned far in advance of being executed, and cannot be changed AS it's being executed.

Regards,
Ray L.

156

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: March 11, 2013, 07:22:42 PM »

Steve,

I've never seen IDC connectors that easily allowed using individual wires - just ribbon cable.  Where did you find those?

Regards,
Ray L.

157

General Mach Discussion / Re: ok enough stepping, how do I add encoders?

« on: March 11, 2013, 10:53:32 AM »

Encoders won't keep you from losing steps, they'll only let you know after it's happened.  You'd be much better off fixing the actual problem, which is one or more of:

1) Your steppers are too small for the job, and don't have enough torque
2) Your stepper drivers are either not driving enough current, or your voltage is too low, preventing the motors from reaching full torque at speed
3) Your motor tuning in Mach3 is too aggressive - you need to reduce velocity and/or acceleration

With steppers, you can't test the maximum no-load performance, then use that in actual machining.  Whatever velocity and acceleration works with no load needs to be reduced 30-50% for actual use.  Rather than wasting time and money fitting encoders, fix the drives.  Stepper drive systems will operate 100% reliably when properly designed and operated.  If you're losing steps, then, by definition, you have either under-designed the system, and/or you are attempting to operate it beyond its capabilities.

Regards,
Ray L.

158

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: March 11, 2013, 10:47:02 AM »

Steve,

Looks good, but needs more wires!  :-)  You know Craig has his Bobs ready?  I got my two a few days ago - they look really nice.

What connectors did you use to connect to the KFlop?  I've never seen any like that.

Regards,
Ray L.

159

General Mach Discussion / Re: BT30 spindle from scratch - with power drawbar and ATC of course

« on: March 10, 2013, 01:45:09 PM »

Thought I'd toss out a "teaser" video of my new teeny, tiny power drawbar.  Works like a charm - capable of >30 ft-lbs torque on the drawbar.  Servo-controlled.

http://www.youtube.com/watch?v=QkkYabNx3Kg

In the video, it's mounted on my knee mill, for testing purposes.  It will very soon go on my new CNC bed mill, which I just received on Thursday.  The bed mill version includes a built-in spindle lock, and spindle sensor, so the PDB can't be engaged if the spindle is powered.

Regards,
Ray L.

160

General Mach Discussion / Re: Load Gcode in Mach3 file from an Image file of the Part

« on: March 10, 2013, 01:40:13 PM »

Terry,

I've been using SheetCAM for almost ten years, and I have no idea what feature you're talking about.  What is it/Where is it?

Regards,
Ray L.