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Offline jwhit

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velocity /accel
« on: July 20, 2013, 11:38:51 AM »
I am having trouble with velocity- acceleration settings! I am cutting some lexan parts and wanted to maximize my feed rate. I sat the velocity to 120" @10 accel.
After cutting the parts i have to place them in a drill fixture to cross drill a pivot hole. The shape was so far off I couldn't fit them into the fixture to cross drill !!!
Have kept slowing everything down and am now @60" @ 3 accel. Now the machine is pausing at every point where two lines meet at a tangent point (i.e. straight line/arc corner)
This an R2E3 B'port capable of 120IPM, shame not to be able to use speed on lexan!!! Anybody have any suggestions.  
 
thanks in advance for any help
jwhit

Offline Hood

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Re: velocity /accel
« Reply #1 on: July 20, 2013, 04:39:16 PM »
The pausing could be it is exact stop mode (G61) rather than CV (G64)
The Vel and Accel could be down to many things most likely hardware related I would think. Without knowing what hardware you have its impossible to suggest anything.

Hood

Offline jwhit

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Re: velocity /accel
« Reply #2 on: July 22, 2013, 03:44:04 PM »
Hood,
  I've been doing some testing and looking over settings in the "cofig" screen. What does the "G's" box in Motor Tuning, denote?  Is this a value resulting from the vel /accel settings.
Also the (Dir-pulse 1-5 us) and the (Step pulse 0-5) were both set at 3, I've lowered them to a 1 setting. Raised the vel /accel back up to 120 @ 8 on all axis'.
After doing so, I ran an "air cut" with the part file. It appeared to cut the proper shape without the pause at tangent /line/ points, or the Z ramp up at the end of the cut I mentioned in my last note to you.
I then put in a piece of scrap material and ran an actual part. It did cut the proper shape (fits the drill fixture), however the machine did revert back to the pause at tangent points.
  I haven't gotten in touch with the previous owner of the machine as yet, but I can give you some information on the "refurb"
       1 converted from 3 phase to Hitachi VFD
       2 operating on dell optiplex mini tower computer "win 2000 pro"
       3 appears to have Original power supply
       4 original style servos with encoders
       5 does have breakout board or control board
       6  3 drivers  mounted on top( no name visabile, similar to geckos although I dont think they are geckos). The wires running into the drivers look to be originals  
          coming from original "ports and pins" connector rail.
  I doubt if I have shed much light on the situation, but I don't want to monopolize your time. I have already been properly chastized by the moderator for inadvertently double posting.
 Thanks jwhit
      
  

Offline Hood

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Re: velocity /accel
« Reply #3 on: July 22, 2013, 04:43:39 PM »
Ha ha dont worry about the ticking off for double posting, its not a good idea to do that but doing it by mistake can happen to anyone :)

The G's is G force, and can not be set directly by the user, it is as you suspect a result of your acceleration.
Dir and Step pulse shouldnt really make too much of a difference, well having it too low for your setup can be bad but having it up to its max of 15 or whatever likely will not  have any ill effects unless your kernel is very high. Talking of kernel, you should not have that set to any higher than you need for motor tuning as that can be detrimental.

As it is servos it could be a problem with the tuning in the servo drives or could even be a weak power supply, ie when using multiple axis the supply doesnt have enough capacity.

Hood

Offline jwhit

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Re: velocity /accel
« Reply #4 on: July 22, 2013, 04:59:43 PM »
I just ran a full plate of good parts at 120" @ 8 acc with a 1 setting on dir / step pulse and everything (profile shape) was fine the only thing is the pause at tangent point.
I dont like it but as long as it cuts the shape correctly at a resonable rate, i can live with it. This is the machine I talked to you about back in March Or April about with the
pulsing in the Z that screws up a surface cut but I'll try to get more info on the machine before I bother you with that again, one thing at a time.

Thanks, jwhit

Offline jwhit

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Re: velocity /accel
« Reply #5 on: November 01, 2013, 11:43:21 AM »
Hood, I have incurred a new anomaly, with my mill. I had just set the 0-0-0 on the fixture, and was standing there thinking,
when the table moved on the Y about 3/4 of an inch. I stood there kind of dumbfounded, and it did it again in about 15
seconds- then again. What on earth could cause this???????????????????????

Offline Hood

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Re: velocity /accel
« Reply #6 on: November 01, 2013, 11:48:53 AM »
Did the DRO in Mach show the movement?
If not then it sounds like you have noise from somewhere getting to the drive.
Hood

Offline jwhit

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Re: velocity /accel
« Reply #7 on: November 01, 2013, 12:09:26 PM »
No, the DRO did not read the move. So , do you think that probably my Z axis problem is related to noise also. By the way, the slight movement of the Z at about 2 second intervals was also noticable in the Y, but never was visable on the parts. This is basicly what I was trying to relay to you in earlier communacations, this machine retains much of the old wiring and is a real "RATS NEST". Being "electrically challenged" as I am, how would you suggest I attack this problem???????????

Offline Hood

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Re: velocity /accel
« Reply #8 on: November 01, 2013, 02:34:17 PM »
Basically 5v signalling has to be shielded and properly grounded, one of the reasons I avoid 5v single ended signals if at all possible.
Hood

Offline jwhit

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Re: velocity /accel
« Reply #9 on: November 01, 2013, 03:38:34 PM »
I'm going to preface this post with?????????????????????????
Number one is, I shut everything down, cleaned up the shop (some), went to lunch, called my son to tell him not tp expect the parts anytime soon.
After taking this extended break I thought I would have one more go at it. I powered everything back up, re Zeroed the fixture and ( here I have to insert the
"I have some good news and some bad news" phrase. The good news is that everything is functioning as it should!!! The bad news is, I have no idea what happened.
 If this thing does this in the middle of a run, its going to be a big time crash. Guess I'll cut till it happens
 On the 5v signalling, I have a vague grasp of the 5v segment of the operation but have no Idea what a "5v single ended signal means".
Back to another one of my problems, the machine stopping at a tangent point. If it happens, I can go to motor tuning and change the Vol setting then restart, and it goes
back CV. I have noticed that when this quirk happens that the CV button on the screeen is "off", and after i reset the Vol it is back on. you made reference to g61/64
The Cam program I use ( Deskcam free ) does not show that on the file. Should I edit the file and insert that (g64) as a precaution?
 If I could figure out how to send pictures of the wiring would help you to decipher my wiring delimma?

Thanks for your effort in helping me Hood. I greatly appreciate it.