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Author Topic: Unsolicited Pauses Between G00 and G01 Commands?  (Read 10783 times)

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Unsolicited Pauses Between G00 and G01 Commands?
« on: April 10, 2007, 06:41:00 PM »
This code creates one fluid movement:
G01 x1
G01 x2
G01 x3
G01 x4
Great.

This code creates 4 acceled/decelled movements with no pauses:
G00 x1
G00 x2
G00 x3
G00 x4
Well, one could manifest a reason for why you wouldn't want constant velocity with G00 commands, I would disagree, but I can live with it.

But THIS code creates 4 accelled decelled movements with a PAUSE between each segment:
G00 x1
G01 x2
G00 x3
G01 x4
Don't understand it, and it's majorly slowing down my file, because my cam package sometimes draws an object as many lines, tangent end to end, so it goes to safe Z between each one.

Hopefully I'm just doing something wrong, but I've looked everywhere twice. I would prefer it if each of the above 3 samples created one fluid movement.

Thanks for any help you can offer.

-Ryan.

Offline Chaoticone

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Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #1 on: April 10, 2007, 06:55:47 PM »
The last bit does that because you have a rapid G0 then a feed G1 then rapid G0 then feed G1. It is going to move you z each time it sees a rapid. Things can be done to eliminat this but it is not advised. Also your code should be G0 or G1, not G00 or G01. If you want smmoth motion at full speed just give it some code with a feed in it that is equal to your max speed.
Something like this.
G0 X0Y0Z0
G1 X2Y2 F 100 (insted of 100, out your max speed)
G1 Z2 F 100
G1 X0Y0 F 100

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #2 on: April 10, 2007, 07:12:00 PM »
Hey!... Thanks for the quick reply.
Quote
The last bit does that because you have a rapid G0 then a feed G1 then rapid G0 then feed G1. It is going to move you z each time it sees a rapid.
Yes I know, but why is there a PAUSE between them... Like for a third of a second. I didn't ask for that?  ???
Quote
Also your code should be G0 or G1, not G00 or G01.
Huh? I think popular opinion on the interweb disagrees with you. :-\ Not that it matters I guess.
Quote
If you want smmoth motion at full speed just give it some code with a feed in it that is equal to your max speed.
But it's not me that's generating the thousands of lines of Gcode, it's the CAM program. :o I'm not about to start coding by hand. But the point here is that it's not my mistake. There should be no stops unless I ask for them.
But again, I sincerely appreciate your suggestions.

Anyone else?

Offline Chaoticone

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Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #3 on: April 10, 2007, 08:20:08 PM »
How long have you been running CNC equipment? Your post processor could be tweaked I'm sure.

Brett
« Last Edit: April 10, 2007, 08:21:48 PM by Chaoticone »
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #4 on: April 11, 2007, 11:27:32 AM »
    Sounds like you're questioning my compotence? But why would someone of a thousand posts do that? I built my first CNC machine around 1990, and wrote the software to control it on a first generation commodore amiga. Since then, I've had many different machines and operating scenarios which we have used every day in our business which is designing and manufacturing custom electronic based equipment.

Back to the subject...

I find Mach3 to be a brilliant piece of work, well worth the money. I've noticed that it adds delays where it seems to me that there shouldn't be any. I thought it would be helpful to point it out in case anyone on the development team wants to look into it.

Thanks!

Offline Chaoticone

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Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #5 on: April 11, 2007, 12:37:33 PM »
Quote
Sounds like you're questioning my compotence? But why would someone of a thousand posts do that?

Sounds like you're getting rude. But why would someone of 3 posts do that?

Back to the subject.......

The reason I ask is because I have never heard of that being preferred. I use two cam packages and neither one generates code like that. Maybe they should, I don't know. Are you running the code on a machine or just simulating? If you are simulating, did you install the drivers for Mach? Have you tried the code I posted? Did it help? Are the dros pausing as well or does it seem like it is pausing because the accel rates are set very low in your motor tuning?

Just trying to help
Brett

 


;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Hood

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Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #6 on: April 11, 2007, 01:24:28 PM »
Are you using exact stop mode? Also why does it go to safe Z between a G0 and G1?

Hood
Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #7 on: April 11, 2007, 04:12:33 PM »
There is a noticeable delay going from g0 to g1 or g1 to g0. It isn't there going from g0 to g0 or g1 to g1. If you like, try it & you'll see what I'm talking about.

Hood

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Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #8 on: April 11, 2007, 04:24:57 PM »
I am not at my mill, I am at the home computer but I definitely dont get a delay if for example I do the following
G0 x2
G1 Y2F10
G0X4
G1Y0F10


I cant say whether I get a delay if I am going from a G0 to  a G1 on the same axis but I will test out tomorrow.
I still dont understand why going from a G0 to a G1 move your machine goes to safe Z, mine doesnt and I have safe Z enabled.

The only reason I could see that you would have a delay in between a G0 and G1 would be that maybe in exact stop mode it would pause slightly.
 Not sure how the read ahead would affect things, ie if you had the read ahead set to 0 then possibly that would cause a delay?

What feeds are your G1 moves at and what is the rapid of your machine?

Hood
Re: Unsolicited Pauses Between G00 and G01 Commands?
« Reply #9 on: April 11, 2007, 06:29:34 PM »
Try my example. cv or exact stop doesn't matter. Maybe it will be different on yours, but I've tried 2 PCs here, both about 1.7Ghz. This example is all the same axis so that the delay is more noticeable.

F100
(accel decelled moves:)
g0 x1
x2
x3
x4
x5
(one fluid movement:)
g1 x4
x3
x2
x1
x0
(now with pauses:)
g0 x1
g1 x2
g0 x3
g1 x4
g0 x5

When I use the term safe z, I may be using it in an inappropriate way. To be honest, I haven't looked into the safez options in mach3... I am using it to mean any movements on my mill that are made at a high level to clear the work area Here's an example to explain what I mean (typed in off the top of my head so I hope I get it right heh heh):

(engrave a square on lamacoid.)
f100
g0x0y0z0 ;initialize to known state
x1y1 ; go to first corner at rapid, 'safe z height'
z-1 ; drop engraving bit
g01 x2 ; draw bottom of square. There was a delay before this command.
g00 z0 ; this is the 'safe z' command that the cam program puts in. There was a slight delay before this command.
g00 z-1 ; it would take me a long time to remove these, plus sometimes they're needed, sometimes they're not. Mach should process these without delay anyway.
g01 y2 ; draw right side of square. There was a slight delay before this command.
g00 z0 ; go to safe z to move to beginning of next line. There was a slight delay before this command.
g00 z-1; (coincidentally, we are already here - no 'safe z' xy moves needed at this time)
g01 x1 ; draw top of square. There was a slight delay before this command.
g00 z0 ; go to safe z before moving to beginning of next line. There was a slight delay before this command.
g00 z-1
g01 y1 ; left side of square. There was a slight delay before this command.
g00 z0 ; There was a slight delay before this command.
x0y0 ; back home for something to do.

I suppose I should be clear about this too... I'll mention again I am talking about around 1/4 to 1/2 of a second of delay (haven't measured it). Doesn't sound like much, but in a gcode program with thousands of little segments, this can add up to a lot of extra time. Imagine a cnc machine emulating an artist with a sketch pencil & you'll get the idea.

*sigh* I was really hoping this would be a small, easy deal.