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Author Topic: feed rate display error.  (Read 4061 times)

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feed rate display error.
« on: March 16, 2009, 01:22:08 AM »
I have a problem with the units/min dro not reeding what it should!
I am re-tuning my drives and have set the max velocity to 1000mm/min.
when I jog at 100% it reads 992-995 mm/min, but if I type G00 X100 it runs at 1750 ish mm/min. (shouldn't that be impossible?, faster that set max?)
I upgraded to the latest lockdown version but no change? I then rolled back to 2.56 (oldest thing I have) and all is fine ????
All on original screens.

Any one else having this issue?

Cheers,
James.

Offline Hood

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Re: feed rate display error.
« Reply #1 on: March 16, 2009, 03:23:37 AM »
The DRO now reads the true speed you are moving, it has something to do with the clock rate of your CPU if I remember correctly, so shows slightly different from computer to computer. With older versions it is still travelling at the same rate just the DRO doesnt show the true rate.
 With your G0X100 move it should not read so high though, are you definitely only commanding a single axis move when you see that?
Hood
Re: feed rate display error.
« Reply #2 on: March 16, 2009, 03:33:01 AM »
Yes, only one axis at a time.

I have tried this on 3 different computers all with same result???
One of the computers is a high end gaming machine!

There is also an issue with the value being out by a factor of 5x. I had to set the max vel to 5000mm/min to get 1000 on the dro and real life on the machine?

Cheers,
James.

Offline Hood

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Re: feed rate display error.
« Reply #3 on: March 16, 2009, 03:38:43 AM »
So you are saying that to get a G0 of 1000 you need to set the velocity in motor tuning to 5000? If that is the case then it sounds like you have the FRO set lower than 100%. The FRO now can be linked to the Rapids so if you have the FRO set low the Rapids will also be low. If you prefer not to have that then uncheck the box on the General Config page, its something like Lock rapids to FRO.
Hood
Re: feed rate display error.
« Reply #4 on: March 16, 2009, 04:00:12 AM »
I have just reinstalled the .042 version. I see now what you are saying about the feed rate being actual not theoretical.
I checked the FRO with the rapid g00 and when set to 50% is feeds at 50% as expected.
I never lowered the FRO when testing on the mill that I can remember!, so I will have to re-test on actual machine and get back to you.

I am also using smooth stepper, this wouldn't have any thing to do with it would it?

Thanks forthe help.
James.

Offline Hood

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Re: feed rate display error.
« Reply #5 on: March 16, 2009, 04:13:12 AM »
Ah ok SmoothStepper, make sure you have the kernel set to 25KHz on the main ports and pins page. This was an issue during the Beta testing and may well be still present. Its not really an issue other than if you had the Kernel set to anything other than 25KHz when using the SmoothStepper the DRO would display wrongly however the axis would move at the correct rate.
Hood
Re: feed rate display error.
« Reply #6 on: March 16, 2009, 04:59:19 AM »
You hit the nail on the head I set that to 45 khz as I normally did.
I will try 25 and a few other values and get back to you.


Cheers,
James.

Offline Hood

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Re: feed rate display error.
« Reply #7 on: March 16, 2009, 05:28:00 AM »
Only 25KHz will work if its the same as it was back in the Beta testing. It is as I said just a display issue, the axis will feed at the correct rate just the DRO reads wrong,  so if your axis feedrate is actually wrong then it must be something else.
Hood