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Author Topic: mach 3 feed rate speed running faster than it should,  (Read 4662 times)

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mach 3 feed rate speed running faster than it should,
« on: October 11, 2014, 02:53:33 PM »
i have a problem with the feed rates in mach3 in that they run faster than they should, if i have a feed rate of 600mm per min, g1 f600, the programe screen will show a feed rate setting of 600 but the actual speed it will show that its  runing at is about   11% faster 660, also under a g0 code between cutting moves it will run aprox one third faster than the volocity set in the motor tunning, eg, with a setting of 1000 mm per min  it will run in excess of 1300, i compensate for this by slower settings in the motor tuning and slower feedrates in my programes so as to end up with the speed i want, does any one no the problem, shaun wainford  had a look at it running and looked at my setting and described it as bizare,
« Last Edit: October 11, 2014, 03:06:45 PM by magee »

Offline Hood

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Re: mach 3 feed rate speed running faster than it should,
« Reply #1 on: October 12, 2014, 06:33:12 AM »
Is this single axis moves or multi axis moves?

Attach your xml and I will take a look.
Hood
Re: mach 3 feed rate speed running faster than it should,
« Reply #2 on: October 12, 2014, 05:02:54 PM »
thanks, over speeds on all moves,

Offline Hood

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Re: mach 3 feed rate speed running faster than it should,
« Reply #3 on: October 12, 2014, 05:56:19 PM »
Ok xml looks ok from first glance.
Can you go to diagnostics page and tell me what the Frequency says and also Time in Int.
Hood
Re: mach 3 feed rate speed running faster than it should,
« Reply #4 on: October 13, 2014, 03:20:52 AM »
frequency is 27896 when not running and when running machine code between 27800 and 28000, time in int is 2.7 to 3.5 when not running, when runing code between 2.1 and 7.8, thanks,

Offline Hood

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Re: mach 3 feed rate speed running faster than it should,
« Reply #5 on: October 13, 2014, 03:43:23 AM »
Ok that could well explain it then. Your frequency is about 12% faster than the kernel you have set.
Try setting the kernel to 35KHz and restsrt Mach and see if the frequency is close to 35KHz.
Hood
Re: mach 3 feed rate speed running faster than it should,
« Reply #6 on: October 13, 2014, 02:56:47 PM »
on 35khz its about right, with in 1%, thanks,

Offline Shaun

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Re: mach 3 feed rate speed running faster than it should,
« Reply #7 on: October 16, 2014, 03:14:57 PM »
Paul, I currently run on my machine an older version than you, so I installed the version you are using on my old computer just for a test, and I have the same problem, requested and dro speed are about 10% out, after searching the forums it seems the way Mach3 displays feed rates was changed in version 3.039 see here.

http://www.machsupport.com/forum/index.php?topic=6640.0

S
Re: mach 3 feed rate speed running faster than it should,
« Reply #8 on: October 16, 2014, 05:48:37 PM »
well that explains the speed on moves under the g0 code, my feed rate is about right now on 35khz as well,
Re: mach 3 feed rate speed running faster than it should,
« Reply #9 on: October 17, 2014, 05:10:37 PM »
thanks shaun the early version you have installed for me is far more consistent on the feed rates than the newer version and it does not run amock on the g0 codes and upset me steppers,  runs fine on 25000khz, the newer version certainly does not suit my computer,