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Messages - MachinistSF

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1
Show"N"Tell ( Your Machines) / Re: EMCO VMC-100 upgrade ready
« on: March 13, 2014, 07:42:14 PM »
Here are some schematics.

2
Show"N"Tell ( Your Machines) / Re: EMCO VMC-100 upgrade ready
« on: March 13, 2014, 07:40:53 PM »
Here is the M06 macro I programmed for the ATC.

3
Show"N"Tell ( Your Machines) / EMCO VMC-100 upgrade ready
« on: March 13, 2014, 07:40:23 PM »
I have replaced a 80s EMCO TM-02 controller with MACH3 PC based control system including new electronics for a VMC-100 CNC mill.

There is a servo controller, stepper controllers, programmable logic controller (PLC) and some power supplies and minor things. Interface to PC is via parallel port, using a VSDEPI break-out-board (BOB) from Granite devices, and another Chinese BOB. The original EMCO mill connectors are cut away and cables are connected to new electronics located in a metal cabinet bolted to the left side of the mill. There is also a large transformer for changing 230Vac voltage to 110Vac for the Vexta stepper controllers - this voltage is also handy for the servo powersupply, and offers isolation from mains.

Servo controller is Granite Devices VSD-E 160. It has a simple 150Vdc high-voltage powersupply based on a rectifier bridge and storage capasitor. PLC controls a relay that short-circuits a current inrush limiting resistor at the DC powersupply circuit. There is a bleeder resistor to bleed the charge from capasitor when power is switched off - the energy stored in the capasitor is easily enough to kill a person. Spindle control is with step-direction -control from PC. The tool changer rotation is based on spindle servo, so spindle had to be a true servo spindle instead of a more simple RPM control. In the servo controller there is scaling of the input pulses so that the full speed of spindle can be reached with the limited pulse rate of PC parallel port. This limits angular accuracy of spindle, but is a necessary compromise.

Stepper controllers are Vexta (Oriental motor) UDK5128. They can drive the 5-phase penta-connected original Berger-Lahr steppers of the mill. The control is with step-direction -control. I have also added X and Y axis limit switches, as EMCO design relied on software limits only. The overheat output signal goes to PLC from stepper controllers, and PLC controls enable input of stepper controllers. The stepper input/output signals are optically isolated so interfacing is simple.

4
I have not read the manual but the way I have always treated things in motor tuning is.
Steps/Unit
Units/minute
Units/s/s

So what I would say is set is
steps per unit to 20 as you are wanting one unit to be 1 revolution
set velocity to 3000 as you are wanting 3000 rpm
set accel to whatever you want but probably around about 20 for a start, that would be 20 revs/sec/sec so 3000rpm in 2.5 sec.

Set your spindle pulleys Max to 3000.

Hood

Thanks for your support. That pulley max speed setting solved the issue.

5
I have a servo spindle (using step+dir for Granite devices VSD-E) which I have configured both as spindle and as A-axis, so they have both the same LPT port pins in Mach config. .

It works.
It has been a while since I have used a parallel port, but it seems you are saying that both the Spindle and the A axis are sharing the same physical pins. If that's correct, I can't imagine the thing is working at all unless by sheer coincidence.

Why not?

As long as I don't use the A-axis (servo-spindle with angular control) and spindle (as constant RPM spindle) at the same time, there is no problem. When I use the A-axis at ATC macro code, I make certain the spindle is not rotating. Outside the ATC macro, the A-axis is not used. Much more clear to me than using swapaxis to do the same.

The pins go the the servo amplifier running the brushed DC spindle servo motor with encoder. The servo amp doesn't know whether the steps come from A-axis or spindle rotating in MACH3. When using A-axis, I have to home the axis anyway to get initial angle correct - using spindle encoder index pulse as home switch.

6
Quote
(so A axis tuning is working ok and spindle tuning steps per unit acts funny). When running at higher steps/s, the servo amp will smooth the rotation. With that slow movement, it really jumps, stays, jumps, stays..
It acts not funny, it acts how you set it up. 1RPM = 20 pulses per minute thats 1 puls every 3 seconds. The A axis acts the same, try
G0A0
G1A1F1
This behav is due to your poor resolution. You should increase it.
Alex

I was referring to "acting funny" as requiring a steps/unit value that is not corresponding to a real value in servo controller, unlike the A-axis which uses the real value. The 20steps/rev is plenty in my application and does not act funny at all in normal speeds as the servo controller motion planner smooths it just fine. Why use a higher steps/rev when that is ok and already gives plenty of steps/s at higher spinds RPMS.. I rather keeps the steps/s with parallel port as low as possible.

It was indeed the pulley maximum RPM value that caused it. Changing it to same value as maximum speed at motor tuning for spindle solved the issue.

7

So spindle max. velocity and pulleys max. velocity need to be same, to get reasonable steps/rev for spindle even if ratio=1. Ok.

I read carefully the manual at pulleys, and section 5.5.5.3 refers to motor tuning velocity of spindle: "The Vel box should be set to the number of revs per second at full speed. For example, a 3600 rpm
motor would need to be set to 60.". So, in that case the ".. per min" text at motor tuning dialog is really confusing, if it is mm/min for axis motors, and rev/s for spindle motor..

Does this mean I really should put 3000rpm = 50 rev/s to motor tuning velocity, and 3000rpm to pulley dialog max speed?

This is a really good discussion! That might have caused havoc. I'm surprised it worked as well as it worked, by chance.

8
Ok I reckon it may be your max speed in Spindle Pulleys setup that is the issue. Set that to the same as your Spindles Motor Tuning and see.
Hood

Why would the maximum speed or acceleration have any relation to the steps/rev value?
I can try it tomorrow but even if it affects the steps/rev, why?

Spindle pulley ratio is 1:1 so no effect there.  Max speed at pulleys is just default value.

9
Here is the XML. I appreciate your effort, this really bugs me.

10
Can you double check the spindle by commanding S1 and seeing if it takes 1 minute to revolve.
Hood

Yes, it does.

It has only 20 steps per revolution, so the spindle jumps 20 times in a minute, 360/20 degrees per jump. I forgot to mention that the 20 steps/rev is the real value from servo (so A axis tuning is working ok and spindle tuning steps per unit acts funny). When running at higher steps/s, the servo amp will smooth the rotation. With that slow movement, it really jumps, stays, jumps, stays..

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