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Constant Velocity doesnt' work anymore?
« on: December 02, 2010, 03:39:43 PM »
Hi all,
  My constant velocity seems to have broken. Let me explain. I'll admit that when I first set up, I didn't understand it. Then after reading alot on this forum and and the pdf Mach put out I thought I understood, but didn't. Then after more reading and fiddling, I got it. It worked fine and great! It really sped up my projects! Now, it seems to not be working properly. I am running a 4x8 router set up in English measurements. When I first started, it was obvious that I was in exact stop the machine was very jerky. Then I got CV figured out (I think) and it smoothed out dramatically and all was right with the world. Now, it doesn't seem to make any difference in performance if CV is on or off, but when I turn on the CV distance (which I have set to .01) the jerkiness returns and it is acting as though CV is off no matter whether it is on or off. If I set CV distance to 1 it is somewhat better, but still pauses at some code lines. Can anyone tell me what I may have wrong or what may have caused this? I bid a project of about 500 circles cut out of wood and it is leaving a slight flat spot on two opposite sides when it runs smoothly (that is whether or not CV is on, but when CV distance is unchecked), but pauses at 4 points around the circle and jerks on the ramp in when I turn CV distance on, leaving an uneven cut finish. The circles are 4" in diameter and my cut speed is 180 and my CV Feedrate is set at 200. Any help would be appreciated.
  Thank You,

        Nostradamus

Offline ger21

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Re: Constant Velocity doesnt' work anymore?
« Reply #1 on: December 02, 2010, 06:14:23 PM »
If you don't know exactly how to use CV distance and CV feedrate, you should turn them both off.

Also, do you have backlash compensation on?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Constant Velocity doesnt' work anymore?
« Reply #2 on: December 02, 2010, 09:37:17 PM »
Gerry,
  Thanks for taking the time to reply.

   No, I don't have backlash enabled.

   I don't want to be a pain, but I would really like to use the CV option to its fullest and it says in the pdf Mach put out that to start you should have CV on and everything else off. I think I do understand CV, but it doesn't seem to be functioning properly. I could be wrong. Is this setting something that would need to be adjusted depending on the type of routing I'm doing? Am I maybe pushing my machine too far? It just seems that it worked differently before.

 Thank You,
       Nos

Offline ger21

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Re: Constant Velocity doesnt' work anymore?
« Reply #3 on: December 02, 2010, 10:08:25 PM »
Quote
but I would really like to use the CV option to its fullest and it says in the pdf Mach put out that to start you should have CV on and everything else off.

which is what I told you to do.

First, try it with everything off and see how it works.

Then, if you want to try other settings, choose one of them, and try it with different settings to see how they affect your machine. CV performance is greatly affected by your acceleration settings, so CV can behave very differently on different machines. Once you're happy with the one option, turn it off, and do the same to the other option. Only once you understand how both are affecting performance, should you try both together. The interaction of the two settings may cause other issues to arise.

Setting the CV angle in general config is another option.

Keep in mind that CV isn't always the perfect option.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline Greolt

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Re: Constant Velocity doesnt' work anymore?
« Reply #4 on: December 02, 2010, 10:42:53 PM »
Nos

The advise is turn all options off,  that means the options on the settings page also.  These are often overlooked.

Greg
Re: Constant Velocity doesnt' work anymore?
« Reply #5 on: December 02, 2010, 11:35:55 PM »
Okay,
   Thanks guys. I thought that turning off the CV distance and CVFeedrate on the settings screen was turning off CV. My mistake. That would be why I thought it was operating the same whether or not CV was on or off. From what you're telling me, CV can only truly be turned off on the General Configuration page. I will check that out tomorrow. Thanks again. I guess I will have to play around with it some more. For future information, are the CV Feedrate and CV Distance settings something that will need to be adjusted according to the type of cutting you want? Or are they more or less constant settings?
  Thanks again,
          Nos
By the way, I've been using Mach for about 6 months now and cannot believe what an awesome system it is, and at an unbelievable price. I have not used any other control programs but I can't believe there would be anything else out there that beats it for value.  Thank you Mach!

Offline Greolt

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Re: Constant Velocity doesnt' work anymore?
« Reply #6 on: December 03, 2010, 01:11:18 AM »

 From what you're telling me, CV can only truly be turned off on the General Configuration page. I will check that out tomorrow.


Yes it can be turned on and off on the Config page.  It also is turned on with G64 and off with G61

Greg

Offline ger21

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Re: Constant Velocity doesnt' work anymore?
« Reply #7 on: December 03, 2010, 11:39:48 AM »
Quote
For future information, are the CV Feedrate and CV Distance settings something that will need to be adjusted according to the type of cutting you want? Or are they more or less constant settings?

I would think that most people leave them as is. I personally have them turned off.

But you may find that they may need to be changed for different jobs. Really hard to say.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html