Messages

1

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 30, 2015, 01:44:13 PM »

Help needed!!

Hello,

I have built the Chris's pwm to analogue converter circuit. I have tried calibrating it with the built in Trimpot but there seems to be a big problem with it. At full RPM it is supposed to give out 10volts and at the half RPMs it should give out 5.0 volt. Here lies the problem My full rpm are 3000 @ 10 volt dc but when I issue the command for 1500 rpm the voltage drops to 4.89 or 4.90. How can the loss for RPMs in this case be compensated? If anybody can point me in the right direction I will very thankful.

Xtreme

2

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 26, 2015, 01:51:59 PM »

Also I want to tell something ,a so called "expert" friend of mine told me that this is a precise circuit and because of heavy solder joints signal attenuation can be there which may hinder the functioning, can this be the case?

3

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 26, 2015, 01:36:29 PM »

Krypton

You don't need to apologize as you are a contributor, instead I should be apologizing because I'm asking too many questions over a simple circuit. My chip CD4011BE and it can handle 12v, I didn't get time today but I will diagnose the circuit tomorrow and update.

Thanks
Xtreme

4

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 25, 2015, 07:18:16 AM »

right, you have pulses at the input.  Now check the circuit as I have listed.  You don't need the oscilloscope,  just the on/off signal you have been using so far.

There are two signal inversions, one through the optoisolator and the other through the logic chip.

Krypton

Krypton,

I am not an expert so at first I am making the circuit without the opto-isolater(just sticking to the schematics for troubleshooting). Looks like there might be something else which may have gone wrong.  Can this be the problem that I am using capacitors of capacity 10uF 63volt and 100uF 25volt against 10uF 16volt and 100uf 16volt ?? Also I have connected 12volt to pin 14 and GND to pin 7 of 4011 IC, is this to be done or not? These are the gray areas which might be causing trouble as per my brain works.

5

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 25, 2015, 04:18:48 AM »

Fired the circuit but looks like I messed up, there is no analog output coming from it, so gonna assemble a new circuit keeping in mind the schematics, hope for the best

Cheers

==========
It should be very easy to debug.  There should be pulses on the new circuit input (the output from the breakout board).  If you do not have access to an oscilloscope, then an old-style analogue voltmeter would be better that a digital meter because it has inherent mechanical filtering.

So you should be able to control the voltage on the circuit input by controlling the speed through Mach3.  Then look at the optoisolator output (the logic chip input), the logic chip output, the filter output - in turn.

I would expect that your problem is that Mach3 is not yet producing pulses.

Krypton

Kypton,
I dont have a mechanical voltmeter at the moment but I have digital multimeter and I checked the output on pin 14 (defined pin 14 as spindle step pin and dir pin 1, also pwm out enabled in the spindle options) when I gave the command m03 s500 in mdi mode, there was approx 1.5volt coming from it and when I pressed the main reset switch the voltage dropped to zero. So, I guess it's pretty much in order, what do you think? BTW There's an oscilloscope lying unsed in my company's store room from the last 30 years , i will check if its operation.

Gaurav

6

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 24, 2015, 04:43:46 PM »

Some peoples have answered to the gray area by giving mach 3 more than one pulse per rev and compsating the more pulses by increasing the pulley ratio so that the increased RPM display is corrected, but again this remains unanswered as the speed of the LPT port is limited.

7

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 24, 2015, 04:37:49 PM »

I assume also that accurate control of the spindle speed is required where 'Threading operations' are carried out ?

The more stable the rpm the better and set it manualy. ie; don't have a vfd trying to maintain the rpm while Mach is trying compensate for
rpm changes.

RICH

To be honest, I doubt mach 3's capability of threading because it likes one pulse per rev which leaves a lot of gray area between pulses whereas being a cnc lathe machine retro fitter I have seen professional systems like HUST and Siemens go haywire even while having 1024 pulses per rev from a good quality encoder.

8

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 24, 2015, 04:31:14 PM »

Even if it doesn't go well, I am much thankful to the community.

9

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 24, 2015, 04:29:44 PM »

Fired the circuit but looks like I messed up, there is no analog output coming from it, so gonna assemble a new circuit keeping in mind the schematics, hope for the best

Cheers

10

General Mach Discussion / Re: PWM Spindle Control using Mach3 - How I did it

« on: March 24, 2015, 03:53:33 AM »

Hi Krypton,
just a small thing about the optocoupler, in the diagram you have shown pin2 of EL817 is connected to 0 volt, there is no 0volt DC in my circuit or power supply, so can you suggest where and how to connect the pin 2 of the optocoupler?
Many thanks
Gaurav