G64 causes the processing acceleration to slow down

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10 Jul 2024 13:22 #304809 by SummerLotus
I hope my processing path and programming path are accurately controlled within a certain range, so I use G64 P0.01 to control.
But after using G64 in the G code, my acceleration became slower.
It is not just that the acceleration at the inflection point becomes slower (for example, I draw L).
it will take a longer time at the line acceleration of the X/Y line (from 0 to MAX_VEL or from MAX_VEL to 0).
Only one axis participation movement will be longer.
why is that? Can I let it run according to the maximum acceleration I designed?

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10 Jul 2024 13:39 #304810 by jimmyrig
Huh weird.

Someone more knowledgeable will probably step in. The only thing I can think of is the acceleration set the same for all the axis in motion?
E g. If x is 1000 and y is 500 g64 might limit things to 500 even if moving x only to make the math easier.

With no g64 linuxcnc rounds corners substantially to maintain speed. So it makes sense it would take longer with g64.

Try with a bigger g64 and see what happens. Often you can use a big g64 for roughing and a small one for the finish pass if machining. However if you are running a plasma/laser/3d printer etc obviously you can't do that

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10 Jul 2024 14:19 #304812 by tommylight
What is the required part tolerance?
If it can be 0.1mm then
G64 P0.1
Should be much faster
Or if doing decorative stuff, even G64 P0.3 or more should be OK, and much faster to run/finish.
0.01mm is very high tolerance, even metal fitting parts can deal with a bit more tolerance.

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10 Jul 2024 21:33 #304848 by rodw
Its probably expected due to the laws of physics. Without G64, motion will set a large enough arc so it does not have to change the cut velocity.
With G64 you are telling the maximum deviation that is permissible so the tool has to slow down due to the laws of physics to meet your settings.
 

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16 Jul 2024 07:20 #305320 by SummerLotus
The acceleration of X/Y I use, such as 500

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16 Jul 2024 07:40 #305323 by SummerLotus
Yes, I can understand that the overall speed will be slower, and he needs to reduce the speed to reduce excessive angle.
However, what I noticed was that his acceleration became slower.
Pay attention to it, weird things…, when use G61 or G61.1, I observe the servo waveform, accelerate the time meets the expectations, such as I can get the acceleration time curve of 100MS according to the acceleration I set over G61
But when I use G64, my acceleration time has slowed down, which is nearly twice the relationship, that is, I continue to observe the waveform and get a 200MS acceleration curve.

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16 Jul 2024 07:41 #305324 by SummerLotus
I found that the G64 will be slower than G61, twice or even more slower, in the stage of acceleration and deceleration.

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17 Jul 2024 07:42 #305457 by rodw
Yes acceleration will reduce if you enforce a reduced radius. This is because of centripetal acceleration where the acceleration determines the arc radius. The velocity is meaningless.
The following user(s) said Thank You: SummerLotus

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17 Jul 2024 13:31 #305487 by SummerLotus
ok,thanks,may i should read code of the planner carefully~

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