Messages

5481

Mach4 General Discussion / Re: Mach4 Button OFFLINE

« on: January 26, 2018, 01:08:05 PM »

Hi,
open the script editor and select m210. Press F5. Now press F11 until the little green arrow is one step past the last statment.
With the cursor hover over hsig. Does the number look reasonable?

Rather than carry on single stepping until you run out of code and crash the debugger at the last 'end' press <shift>F5.

Craig

5482

Mach4 General Discussion / Re: Mach4 Button OFFLINE

« on: January 26, 2018, 01:03:01 PM »

Hi,
yes they work, I'm using my mill profile. Is use an ESS controller but the controller has no bearing on whether the macro runs or not.

The pin is depends on what you assign to Machs output.

Have you run through the macro single step with the debugger?

Craig

5483

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 26, 2018, 01:58:08 AM »

Hi,
you will no doubt have seen proper pro CNC mills with spindles of 10-15-20-30 and more horse power. One reason that they appear so grunty is that they require
very large and generous torque at slow speeds for rigid tapping but the same spindle needs to be able to do 15000 rpm. The combination of lots of torque and high speed
is high power and with high power comes high cost.

One technique to try to overcome that combination is called 'field weakening'. An ordinary AC servo has a permanently magnetized rotor, usually with powerful neyodium magnets.
The strong magnetic field means that the motor can generate high torque but it also means that it generates a high back EMF at high speed. The high back EMF defeats
high speed operation. With some clever control techniques its possible to apply current in the three phase windings which have a component that opposes the magnets of
the rotor thereby weakening them temporarily. So you can have high strength magnetic field at low speed for good torque but can reduce the magnetic field at high speed to
reduce the back EMF for even higher speeds.

While its possible to do that with any field controlled motor its not that common. My Allen Bradley servo does not use it. I notice that some of the high end manufacturers use
it on their axis servos to get amazing high speed traverse speeds, but they all use something similar in their spindles. You want one....join the queue....and bring your cheque book.
I'm building one, I have a big kick-arse  3kW servo and I'm building my own Field Oriented Controller and it will have field weakening to extend it from 3000 rpm to 4000rpm
and still maintain 12Nm continuous, 48Nm peak.

5484

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 26, 2018, 01:31:31 AM »

Hi,
another distinguishing feature of rigid tapping is that a thread tap goes direct into the spindle and the spindle has to supply the torque necessary to cut the thread.
Not to much torque required with small, say less than 1/4'' but try driving a 1/2" tap in stainless steel and you could be up around 20-40 ftlb. Can your spindle do that,
mine sure as hell cant.

I bought an Allen Bradley 1.8kW servo to make a spindle. It is direct coupled so has a max rpm of 3500 rpm and a continuos stall torque of 6.2Nm and a temp overload
torque of 24Nm. I haven't tried rigid tapping with it yet but I expect it to go to 1/4 -5/16 with 70% engagement and maybe up to 3/8 with 60% in mild steels. Nothing is surer
that it won't do much more than that...no matter how grunty I think it is!

Craig

5485

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 26, 2018, 01:11:50 AM »

Hi,
have you done any turning on an ordinary lathe? If you have then you'll know that speed needs to be right but its not supercritical.

For threading on a lathe accurate speed is not that critical but a CONSTANT speed is important. Any and every time you take a cut on a lathe the spindle slows a little
bit. Trying to minimize the speed variation is the key to threading with Mach3/4.

Rigid tapping is a term more commonly applied to mills than lathes but the idea is that a spindle turns a tap, usually fairly low speed, say a few hundred rpm, and the feed
axis advances the pitch of the thread with each revolution of the tap. When the bottom of the thread is reached the spindle decelerates, the reverses and the feed axis
follows suit and backs out. Whats critical is not the speed but the angular accuracy of the synchronization of the spindle/tap and the feed axis. Ordinary DC and 3 phase
induction motors with a VFD are not really suitable, for rigid tapping you really need a servo spindle, that is to say a spindle which can maintain angular position.

Rigid tapping is pretty ambitious for a hobby machine. Single point lathe threading is achievable.

5486

Mach4 General Discussion / Re: Suggested OS

« on: January 26, 2018, 12:36:51 AM »

Hi,
no trouble with Win7 32bit except when loading the lathe profile. I thought it was a memory issue but maybe its a firewall or virus problem...haven't
sorted it out yet.

Craig

5487

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 25, 2018, 10:38:58 PM »

Hi,
a three phase induction motor and a VFD will usually get within a few percent open loop. Beyond that level of accuracy
you have to go closed loop.

Most VFDs will accommodate an encoder and will get you to very close, an AC servo on the other hand will be accurate to
within a few thousands of a percent and will maintain ANGULAR accuracy of better than a quarter of a degree.

Still I have to ask 'Do you really need that level of accuracy', I like lots of others spent a lot of time and money trying to get
the speed spot on only to find that except in a few unusual situations it doesn't matter that much.

Craig

5488

Mach4 General Discussion / Re: Suggested OS

« on: January 25, 2018, 10:30:00 PM »

Hi,
my machine has Windows7 Embedded Standard 32 bit, has been fine.

Until recently my laptop was Windows8 but it had a meltdown. As I had a licence for Windows7 Embedded I loaded
that onto my laptop, 32 bit. May have been a mistake, only effectively have 2.5G RAM despite 8 G being fitted.
Have had trouble trying to fire up Machs Lathe profile.

Will over the weekend try my machine just to see whether the 32bit Windows7 Emmbedded is adequate to allow
Machs Lathe profile to load.

It seems that the GUI load but my laptop trips up when loading the canned cycle module and the lathe panel.
Have yet to work out how to overcome that limitation, it does load OK from time to time, and once it loads it runs
fine. I have to hold my tongue to the left!

Craig

5489

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 25, 2018, 07:58:44 PM »

Hi,
an open loop controller like Mach3 is not likely to result in a really accurate speed with either a DC motor or a VFD driven
induction motor.

You could achieve very tight speed control with a servo but a 2.5hp servo and drive will set you back a pretty penny!
Do you actually need such tight speed control? Forget bragging/swaggering rights, this is about what you need not want
you want.

Craig

5490

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 25, 2018, 06:38:25 PM »

Hi,
the DC voltage to frequency converter is unlikey to be that linear. As it stands you have 100 rpm error at 4000 rpm
ie 2.5% error, is that not close enough?

Craig