What next?Should i try Smoothstepper?

[sylvester1073]

Hi there from Australia, I need your help please!

I have made a homemade CNC router/mill. All works well except for this persistent problem with the stepper motors locking up on me and missing steps. It is okay at the slow speed settings, but even then you can hear it occasionaly making a "knocking" noise. From mid range to full speed it makes a constant "knock'' or "ticking" noise at about one second intervals, followed by a " lockup" every 20-30 seconds of run time. Apart from this the motors sound nice and smooth.
I have disconnected the stepper motors from the machine and still the same problem, so it is nothing to do with friction etc.
I have tried everything i have read in these forums but to no avail!

My computer is 1.8Ghz Pentium 4, 1 Gig ram, 16meg plugin video card, Windows 2000 pro. running Mach3 and absolutely nothing else. No antivirus, internet, or any other program is installed.
I run 3 x Gecho 251s on heatsinks through a Opto-isolated BOB.(not cheap Chinese stuff), with power supply and motors to suit. All cables are shielded and ground appropriately. I have tried the following:

1) re-installed Win. 2000 and latest drivers.
2) reinstalled Mach3, and tried the latest version.
3) Installed Windows XP. & service pack 4.
4) tried optimization, special driver, 1/2 Sherline mode, various step/direction pulse widths, enhanced pulsing, turned watch dogs off/on, tuned plug-ins off, played with Dir low/active etc. kernal speeds and everything else i have read in these forums.
5) I am an electrician by trade and have checked all connections and ground everything that needs to be.

I have a "hunch" it is the computer or parallel port card putting out a ****ty pulse stream, but i'm open to any suggestions at all! Is it something deep inside the 'Nuts & Bolts' of the operating system that can be interfering? Money is in short supply so i don't want to spend any more( the missus will flip!)
Please put your 2 cents worth in, i'll try anything

Failing this, what do you guys think of trying a Smoothstepper (usb) solution?

Kind regards, Julian.

[ger21]

If you run the Drivertest.exe, how stable is the pulse rate? Are you using 25Khz mode?

Have you disable APCI in the bios?

[sylvester1073]

Originally Posted by ger21 If you run the Drivertest.exe, how stable is the pulse rate? Are you using 25Khz mode? Have you disable APCI in the bios?

Thanks for the reply Gerry,

Yes, i've tried 25, 35 & 45khz mode. Driver test came up excellent and looked smooth. Pulse rating is about 23300. I only tried Driver Test on 25khz mode.
ACPI is disabled and running as "Standard PC.

Julian.

[Dorsal]

Is this a desktop or laptop machine? Laptops regularly turn the parallel port off, and/or reduce the pulse rate to the parallel port in an effort to save power / increase battery life. If it's a laptop, DEFINITELY get a SmoothStepper - - I did, I lost all the troubles I was getting and I have never thought "Gee, maybe I could have tried xxxx . . . "

[eSilviu]

Originally Posted by sylvester1073 Hi there from Australia, I need your help please! Failing this, what do you guys think of trying a Smoothstepper (usb) solution? Kind regards, Julian.

I was in the same situation.
Then I have used a USB controller, and never returned to parallel port.
Now I would recommend CNCusbController from http://www.planet-cnc.com/ . You can try-it for free, if you know how to wire and write a PIC18F4550 (free version has a limit of 20 g-code lines)

[sylvester1073]

Hi Dorsal,

It's a desktop computer. Thanks for your input.

Regards Julian.

[sylvester1073]

Hi eSilviu,

I checked out that USB controller, looks interesting but 69Euros for controller then another 69Euros for license, I think i would go for the Smoothstepper. Plus 12uS minimum pulse width isn't real fine. I read that 2 or 3 uS is recomended for my Gecko drives. Thanks also for your input.

Regards Julian

[eSilviu]

Originally Posted by sylvester1073 Hi eSilviu, I checked out that USB controller, looks interesting but 69Euros for controller then another 69Euros for license, I think i would go for the Smoothstepper. Plus 12uS minimum pulse width isn't real fine. I read that 2 or 3 uS is recomended for my Gecko drives. Thanks also for your input. Regards Julian

I have built my own controller. So it's just 69Eur for me.
It's just a PIC, a quartz, a resistor and some buttons. Can't be easyer

[sylvester1073]

Hi all,

In one last attempt to fault find my computor i hooked up an ossciloscope to my parralel port and discovered it is putting out a very poor wave form. So this narrows it down to the parralel port (i think?), as the driver test worked great so this must mean the motherboard & CPU are capable enough. Is this assumption correct? Anyone.....?

Regards Julian.

[er-mtl]

Is your parallel port a 3.3V model ?
if so, it can create problems with interfaces using 74HCxxx buffers or direct optocoupler interface with anodes to +5V. The reason for the problem is that 3.3V in "high" state still puts (5-3.3=1.7V) across the optocouplers inputs (when it should be below 1V), and that can trigger them randomly (as supply voltages have spikes or slightly fluctuate). same for 74HC buffers that react to a voltage between 40% and 60% of their supply voltage. Interfaces using 74HCT buffers are much less susceptible to these issues.
A simple way to solve most of these problems is to insert a diode (1N400x or equiv) in serie with the interface card's +5V supply. That reduces the voltage to 4.3V, thus reducing the voltage difference between the port and the interface. there should be an electrolytic capacitor on this "new" 4.3V supply line.
I Hope it helps ...

[2ferrous]

Did you end up buying the Smooth Stepper?

I had the same problems with my desktop driving a Gecko G540.
I bought a Smooth Stepper and almost all my problems were gone.
I increased the rapid rate from 48ipm (1200mm/min) to 96ipm (2400mm/min) and it sounded so smooth, no hiccups.

Timothy

[Action-KAT]

Hi all
Just a quick one, I had no parallel port in my desktop so had to add a pci version for my G540 then found out the charge pump wouldn't work because of the 3.3V signal being supplied,
after a lot of reading I went with a LPT Buffer got one for £13.75,
worked great got my 5v from a usb and now the charge pump works fine.
might be a cheaper option to try out first
KAT