Unusually long pauses

[NeoMoses]

My mill has been "pausing" for 3-7 seconds before some, but not all G02 and G03 curves while cutting. I'm wondering why this is happening. At first I thought that it was a problem with the programming of the NC file, but after carefully studying them by hand, I have found no apparent reason that it should.

A quick run-down of my computer:
PIII 850 with 512 MB RAM
Running DOS 6.2 and TurboCNC

I'm running Camtronics 600 oz.-in. servo motors and Gecko G320s.
Using a 36V, 20A Iota Power Supply

Does this sound like a hardware or a software problem? The NC files appear to have no reason to pause, and the mill runs great with G00 and G01 codes, but sometimes in code that has G02 and/or G03 curves, it has unusually long pauses, much longer than is needed to take up the backlash in the leadscrews. Is my computer not fast enough to run this? Do I need more "processing horsepower" to calculate the movement for curves quickly?

[ger21]

There has been some discussion of this on the TurboCNC group at ***** in the last few days. Check there. I'd give you the answer here but I don't recall it off hand.

Gerry

[NeoMoses]

are those asterisks intentional, or is that VB censoring your post? I'm guessing that's at ***** groups, so i'll go check there.

[NeoMoses]

yup, I answered my own question. Y.A.H.O.O. seems to be censored by VB. That seems pretty stupid.

[castguy2003]

Are you 'drip feeding" your program from the computer (DNC) or does your CNC hold the program in memory?

[CNCadmin]

Originally posted by NeoMoses
yup, I answered my own question. Y.A.H.O.O. seems to be censored by VB. That seems pretty stupid.

I don't think that is stupid at all, thank you very much.

[NeoMoses]

Originally posted by CNCadmin
I don't think that is stupid at all, thank you very much.

Ok, let me re-state that: We all know that the real power of the internet lies in the links. No single site can hold all the information. Also, there happens to be some very good resources for CNC conversion at an "unmentionable" site. Unfortunately, no "Ultimate CNC Forum" will be complete without many references to it.

Realize this: The "forum" layout is much better than that of any other "group" or usenet channel that I've seen. It will ultimately be the preferred site, due to its speed and ease of use. It's just going to take a lot of time, and some "cross-breeding" of members. I joined this forum to share information openly and fully, in the hopes of helping others. I hope that is the purpose of this forum, and not my misunderstanding.

[NeoMoses]

Originally posted by castguy2003
Are you 'drip feeding" your program from the computer (DNC) or does your CNC hold the program in memory?

I'm not sure what you mean. My computer contains the only memory in the system. I'm using TurboCNC, Gecko G320s, and Camtronics 600 oz.in. Servo motors.

If the problem persists, I'll boot into EMC Linux and try the same code there.

[CNCadmin]

Originally posted by NeoMoses
Ok, let me re-state that: We all know that the real power of the internet lies in the links. No single site can hold all the information. Also, there happens to be some very good resources for CNC conversion at an "unmentionable" site. Unfortunately, no "Ultimate CNC Forum" will be complete without many references to it.

Realize this: The "forum" layout is much better than that of any other "group" or usenet channel that I've seen. It will ultimately be the preferred site, due to its speed and ease of use. It's just going to take a lot of time, and some "cross-breeding" of members. I joined this forum to share information openly and fully, in the hopes of helping others. I hope that is the purpose of this forum, and not my misunderstanding.

I agree, but if you mension a website like this there, you will most certainly be BANED from them. I have NO problem with links to anyother site but, I don't want to support that site and all it's groups. I hope you understand, my postion at this time.

[castguy2003]

It sounds like you are "drip feeding" which means as the computer sends the G-Code, the machine reads and executes it, then dumps it. If you need to cut a second part, you must resend the code.
The problem arises because arcs are actually read by the machine as a lot of tiny straight line moves. If your Baud rate between the computer and control is low it can cause the studdering problem. Also the sheer volume of data the control is trying to process can overwhelm and slow down low grade controls.

[wms]

Castguy,
On these small systems the pc is the control,(a program on the pc acts as the control) so drip feed really dosn't apply per say.The steppers / servos and drivers are "hooked" up to the pc. And it's highly unlikely that the computer can't keep up.

Neo,
Is there a parameter in the program to control the "feed rate of arcs as a percentage of the feed rate"? This common in most cnc controls. If so, is it set real low say 10 - 20 percent. Normal would be at about 60 - 70 percent.
Also your post says that the pause occures before the arc, is that true or is it just as the arc code starts?
Also as Castguy suggests in his post, is the code for the "arcs" true G2-G3 or is it tiny little lines (IE: G1). If it is all lines, then is there a way to set your tolerance in your cad/cam system to some thing larger than it is, to reduce the amount of code that is generated each time an arc is broken into segments? You may have to "mess" with this because if you set your tolerance to large then the arcs start to lose their shape as arcs.
Sorry I don't know more about the system you are using.