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Only getting 85% of kernel speed in mach 3
« on: November 04, 2011, 11:26:31 AM »
Hi everyone. 

Having this problem - have posted on CNCzone, but don't know if it's kosher to link to a different forum, so I won't unless someone asks for it.  Has a similar title as this one.

Anyway, running a Dell E510 Windows XP Pro, 2.92Ghz, 4Gb ram.  Clean install windows.  Nothing but OS and Mach.

I can get everything running, and everything runs great in driver test - all the way up past 60kHz. 

I leave it set on 25kHz for now (for some reason if I up the kernel, I have to LOWER my speed in motor tuning or my motors lock up...that's a different topic)

So...for example, if I tune to max rapid at 100IPM when I jog I get 85 IPM.  If I MDI a feed of 10 IPM, I get 8.5 IPM.

Very werid.  When I look at the diagnostics, is shows I'm getting mid 21,000's kernel, not 25kHz. (21250 is 85% of 25000).  It is pretty stable there.

I have tried converting PC to 'Standard PC' from a UniProcessor ACPI via a suggestion from Gerry at CNCZone.  End result after some difficulty was still 21kHz, but it wasn't stable (if i just bumped my mouse it would drop to 100-300 Hz, then back up).

He said I must have a driver conflict somewhere.  Any thoughts on how to fix this?

Thanks,

Doug
Re: Only getting 85% of kernel speed in mach 3
« Reply #1 on: November 04, 2011, 11:55:18 AM »
is your slow jog rate set lower than 100%
Re: Only getting 85% of kernel speed in mach 3
« Reply #2 on: November 04, 2011, 01:40:09 PM »
is your slow jog rate set lower than 100%

Yeah - everything at 100%.  Something else is going on with the drivers...if the diagnostics were reading 25kHz like they should be I would be looking for something tuned down.

Thanks

-Doug

Offline Hood

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Re: Only getting 85% of kernel speed in mach 3
« Reply #3 on: November 04, 2011, 03:12:51 PM »
Sounds like your computer is just not too great for Mach, Dells can be problematic especially ones with onboard graphics.
What does the driver test actually look like?
If you want to attach your xml I can have a look to see if there are any issues there but to be honest sounds more computer related.
Hood

Offline RICH

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Re: Only getting 85% of kernel speed in mach 3
« Reply #4 on: November 04, 2011, 05:54:38 PM »
I tend to agree it's computer related. I would also bet that depending on the file your running it may drop even lower. 
My Dell's did the same and would drop down to as bad as say 14000 or so.
Great computer for everything except CNC, for the ten or so we tested they just plain outright ....sucked!
RICH

Offline BR549

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Re: Only getting 85% of kernel speed in mach 3
« Reply #5 on: November 04, 2011, 06:07:02 PM »
SOunds like the PC is adjusting it's cpu speed on the fly.

(;-) TP
Re: Only getting 85% of kernel speed in mach 3
« Reply #6 on: November 04, 2011, 10:57:22 PM »
I tend to agree it's computer related. I would also bet that depending on the file your running it may drop even lower. 
My Dell's did the same and would drop down to as bad as say 14000 or so.
Great computer for everything except CNC, for the ten or so we tested they just plain outright ....sucked!
RICH

Thanks for that input on the Dell cpu's. 

In that case, it might be worth the cost in less frustration to just get on Craigslist and get a new box.

Any brand you recommend in particular (seems like a lot of Dells out there) - and what minimum specs should I get if I want to run "nicely". 

That's a bummer - bought a new PC for the house a while back, and saved this one specifically for this task....oh well.

Thanks,

Doug
Re: Only getting 85% of kernel speed in mach 3
« Reply #7 on: November 04, 2011, 11:06:56 PM »
Sounds like your computer is just not too great for Mach, Dells can be problematic especially ones with onboard graphics.
What does the driver test actually look like?
If you want to attach your xml I can have a look to see if there are any issues there but to be honest sounds more computer related.
Hood

I'll try to attach XML tomorrow.  No internet on the Mach box.  "What does the driver test actually look like?"  - Not really sure what you mean.  It stays pretty flatlined.  If I shake the mouse around i get a few tiny jumps like lines perpendicular to the flatline.  If I switch kernel speeds it will take a couple seconds then be at "system excellent" - All the way up to 100Khz.  Once at speed, it is pretty stable - especially at 25, 35, 45 Khz - maybe moves a couple hundred Hz at most.  Looks ideal on the surface.  :(

As another note.  If I have the Mach diagnostics up, showing 21 khz, and I open driver test at the same time and run 25khz, the diagnostic window also changes.  BUT...then I can't go and have mach actually move the axis around, so I have to restart it and its back to 21 again.

Probably is cpu related.

Thanks for the help

-Doug

Offline ger21

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Re: Only getting 85% of kernel speed in mach 3
« Reply #8 on: November 04, 2011, 11:47:24 PM »
I use an old Dell GX150, 1Ghz PIII. $25 for motherboard and processor on Ebay, and it runs great at 25Khz. Only problem is the screens are a bit sluggish.

Just like this one. http://www.ebay.com/itm/190447069240?ru=http%3A%2F%2Fwww.ebay.com%3A80%2Fsch%2Fi.html%3F_from%3DR40%26_trksid%3Dm570.l2736%26_nkw%3D190447069240%26_fvi%3D1&_rdc=1

Just be aware that the power supply pinouts are non standard, so you need the correct power supply.

A lot of people have good luck with Atom motherboards, which you can get for $50-$75 new.
Gerry

2010 Screenset
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http://www.g-forcecnc.com/jointcam.html

Offline RICH

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Re: Only getting 85% of kernel speed in mach 3
« Reply #9 on: November 05, 2011, 08:07:23 AM »
Doug,
If you want to know more about the driver test have a read of section 3-3 in Using Mach3 Mill Manual.
I don't have a listing of the PC's we tried here and say 5 of them were laptops. So would be rather unfair on my part to label all Dells as bad.
A friend uses a Dell laptop and has no problems and an external device such as the SS worked fine with mine.
On mine,  there was ringing on the pulse signal coming out of the PP and by that i am meaning additional signals were
mixed in with the pulse causing erratic pulses from the drive to the motors. IE;  steppers got a pulse and then another very close to the original.
There is NOTHING that you can do to correct that.

So maybe irrelevant of what shows on the driver test, one should try and see how the motors work.
In my case a pc was put together that works, end of story.

RICH