Messages

311

General Mach Discussion / Gecko G540 Based Stepper Controller Wiring Diagram

« on: December 22, 2009, 06:55:04 AM »

HI,

I have produced a wiring diagram for a 4-axis stepper controller based around the G540 drive.

It should be a help to those wanting to to put their own controller together. The diagram can be found towards the bottom right of the following page.

http://homanndesigns.com/store/index.php?main_page=product_info&cPath=27&products_id=90



Hopefully there aren't too many errors.

Cheers,

Peter.

312

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 18, 2009, 12:29:47 AM »

If you are using a reflective sensor, come black tape will do.  Make it so it covers 50% of the shaft. Mach3 just looks for the edge.


If it is a slotted disk, make sure the splt is not too small.


Cheers,

Peter.

313

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 17, 2009, 09:46:21 PM »

Hi Mike,

Had a quick look at the data sheet. The drives should work fine with the MB-02 breakout board.


Cheers,


Peter.

314

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 17, 2009, 09:36:17 PM »

Thanks Peter,
Any suggestions on what type of breakout board to get and where I can purchess one?

Thanks Mike

Yes, Mine.

http://homanndesigns.com/store/index.php?main_page=product_info&products_id=59

It's a really good solid buffered I/O breakout board.

What stepper drivers to you have?
Cheers,

Peter.

315

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 17, 2009, 09:26:39 PM »

Thanks Peter,
But what is input to a BOB mat be better mean?

Thanks Mike

It might be better to feed the input through a breakout board if you have one.

Cheers,

Peter.

316

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 17, 2009, 09:14:50 PM »

Mike,

Have a look at the Omron EE-SY672 rande of sensors. The nice thing about these is that they take a wide range of voltage inputs (5V-24V) and have a filter and amplifier built in along with a sensitivity adjustment. It's basically a plug-n-play sensor.

They have reflective ones as well as slotted ones. Have a look at this engineering note.
http://www.homanndesigns.com/EN001.pdf

The sensors can be found here;

 http://au.mouser.com/catalog/catalogUSD/640/1873.pdf


Apart from supplying the sensor with 5Vdc you can just feed it straight into your parallel port, although a buffered non-opto-isolated (sensor contains an opto-isolater) input to a BOB mat be better.

Cheers,

Peter.


Cheers,


Peter.

317

General Mach Discussion / Re: HUMS, LOCKS UP, NOISY SERVOs and ERRATIC OPERATION - RF NOISE

« on: December 15, 2009, 01:14:02 AM »

All you need to do now is to ask Santa for a Return key.

Cheers,

Peter.

318

General Mach Discussion / Re: Homann DC04? Threading with pics

« on: December 15, 2009, 01:11:50 AM »

Hi John,

That looks really cool. Even if there is no nut that will fit it.

Cheers,

Peter.

319

General Mach Discussion / Re: Homann DC04?

« on: December 14, 2009, 11:57:01 PM »

Hi John,

Good to see progress is being made. As to the index mark, Mach3 just looks for the transition edge so the width of the mark is not important EXCEPT that it needs to be wide enough. How wide depends on a number of things, including the spindle speed, Mach3 kernel speed, opto sensor sensitivity, etc.

If you are using 1/2" electrical tape, then just leave it at that. No need to make is thinner.

I'll look through my spam later tonight.

Cheers,

Peter.

320

General Mach Discussion / Re: Homann DC04?

« on: December 14, 2009, 06:23:26 PM »

I have just installed a DC-04 and got it working pretty well. I am not getting any response from Peter. Could be that I sent the mail on the weekend or could be computer problems as I have been experiencing all kinds of strange email problems. Almost no email for a week or more including no junk mails then a flood. Anyway, I can use the tach and in manual mode I can attain a 1450 rpm, however under automatic I can only get 1096-1100? I have tried changing the PID values and it did help me to understand what those settings were for, they didnt help. I had read about a trimpot adjustment but the way it was worded made me think it was for the manual setting. Anyone have an idea? I did get to do some threading and it is very close to correct and cool to watch without having to worry if you are going to engage into the correct location manually. Speed control matches the S command perfect until 1100 rpms.

Hi John,

Not sure what is going on with the emails. I'll go through the spam box and see if they are there.

Under automatic control, the max speed you can achieve is about 5% less than under manual control. This is because the DC-04 needs to steal a bit of the voltage for its own use. The trimpot allows you to decrease the max manual speed to match the max automatic speed if you desire that.

The closed loop control in Mach3 does not work unless things have changed . So I wouldn't bother using that. As to the linearity you need to keep in mind that the DC-04 is an open loop control system.  There are a number of things that influence the linearity of the spindle speed. I have done a lot of testing and can confidently say that the DC control voltage generated by the DC-04 (And the other Digispeeds) is linear with respect to the PWM signal it receives from Mach3.

With the DC motors, there is the initial friction of the spindle drivetrain to overcome. This will cause the spindle to turn slower than you would expect at low RPMs.

Then there is the DC motor characteristics at the top end. Once the motor gets to approx 95% of its max speed the response is no longer linear. For a machinist this is usually not as issue as at this stage you basically wantthe spindle to run as fast as possible rather than an exact speed.

Between 10% and 90% the DC motor should be very linear.

You also need to keep in mind that the spindle speed usually creeps up a bit once all the bearings are warmed up, so I suggest that any sspindle speed tuning should be done after the spindle has been run for 20 minutes.

For tuning, I do the following.

• In Mach set the max pulley speed to 1000 rpm.
• Turn on the spindle and set the speed to 1000 (maximum).
• Record what mach is reporting as the actual spindle speed and enter this into the pulley setting.
• Set the spindle speed in Mach to about 50% of the maximum speed.
• Tweek the max value in the pulley setting to get actual speed to mach the set speed.
• If 50% of max is not where you normally operate, then do the tweek at that speed.

Cheers,

Peter.