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  1. #81
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    I am mostly using Mach3 default settings. Only thing I played with is cv mode which is back to default setting. Is there anything else you suggest I should check?


    Quote Originally Posted by mecosv View Post
    Previously, I had suggested that it could present a backlash or stepp lost (so were servos). I think very wise suggestion to check the Mach3 configuration and test, and test ..., until an optimal point of work. Or even tray linux CNC.




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    Quote Originally Posted by azam1959 View Post
    Nofish and George,
    If there is any backlash I think I will see it in other cuts too, right? Machine is also pretty stiff and spindle is also tight (this time :-)). I think my machining skill is culprit instead of machine itself. Once I get the surface cutter it will help me start with the level surface. I am also using four screws instead of two for small work piece. I am also experimenting with different machining strategies. If there is any specific suggestion for this newbie, I will appreciate it.

    Thanks
    i dont think its a skill thing here unless you are actually drawing those shapes.

    usually when a circle isnt round, theres 2 common issues.

    1 is that the machine has backlash. youll see this as a flat spot on 2 opposing sides of a circle.

    2 is mach 3 is the drive isnt getting "slow" steps. this is common in some gecko drives. the result is that when an axis is going slow, it doesnt move. the result in a circle is again flat spots on the sides, basically making a squared off circle.


    what you are showing is not matching up to the 2 possibilities above.

    so you need to look at other things. if everything is tight, and nothing is moving as you cut, then its really coming down to the servos as the next thing to test. given the history with these motors creating wobbly curves when they were first being set up, this is highly likely to be the issue.

    so, first run the program 3-4 times to see if the result is the same each time. then try a different tuning setting, different speed, etc, see if changes. if theres a change, you know straight away its the motors. it will save alot of grief finding that our first.

    you need to be methodical with issues like this, or youll get nowhere.



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    Quote Originally Posted by azam1959 View Post
    I am mostly using Mach3 default settings. Only thing I played with is cv mode which is back to default setting. Is there anything else you suggest I should check?
    cv mode can cause some strange problems - usually stalling steppers. i dont *think* what im seeing is CV related, but i suppose theres a chance. to check, type at the start of g64 in one program, then g61 at the start of a copy of the program. if both are the same, its not likely cv mode causing the issue. if the g61 program is better, theres a new line of possible things to check (ultimately still pointing to the servos as being the problem).



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    Quote Originally Posted by cabnet636 View Post
    Sorry, it is about helping azam!
    LOL , thats good one. Just like the guy posted about you about being a master manipulator
    Thing is your never there to help someone. Your main goal as it has been years now is to put machines down, plain and simple.
    3500 thats good to hear, glad its working out .
    But don't forget 2 machines that are coming into your market. Then will see.
    With that many members if you have a stinger in GTA toronto i could bring a Raptor and do comparison of cutting, I would love it as talk is cheap

    XZero cnc


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    Quote Originally Posted by ihavenofish View Post
    cv mode can cause some strange problems - usually stalling steppers. i dont *think* what im seeing is CV related, but i suppose theres a chance. to check, type at the start of g64 in one program, then g61 at the start of a copy of the program. if both are the same, its not likely cv mode causing the issue. if the g61 program is better, theres a new line of possible things to check (ultimately still pointing to the servos as being the problem).
    Yes you have to do lots of changing on cv settings

    XZero cnc


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    why? you shouldnt have to do much of anything to the cv setitngs, besides turning it on. the default should be fine.

    if it was to cause an issue, it would be either stalling in a corner (the servo should fault) or it would overly smooth a corner.

    definitely NOT whats happening in the cutting azam has shown.

    all cv mode does is calculate a smoothed over path to allow the machine to not accelerate and decelerate as much, keeping it at higher speeds in contouring. the setting for cv mode just control at what angle and distance to "stop" or "round".

    if cv setting are affecting the roundness of circles, then the servo drive is thoroughly set up wrong (or broken).



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    Havenofish,

    Appreciate the feedback and thank you for taking the time to help and teach me.

    I will follow through your suggestions.

    Just want to add one thing here ... when i was using other cadcam package, my cuts were getting better, so first thing first ... do i really understand different cutting strategies in new cam package. Usually I do not pay attention to my physical limitations but at this point I am feeling very helpless ... instead of writing this post in horizontal position, I want to go down and make few cuts .... well it has to wait ...

    As for your comment on motors ... guess i am the lucky one. yes i pulled my hairs initially and thought i was stuck with 5 ipm and i had serious issues with repeatability and was about to pull the plug on DMM but all of these issues are history. Motors may still be the issues but I will be very surprise. Let me concentrate on low hanging fruits first.

    Thanks again my friend and I will relying on you and other folks here to learn.

    Cheers

    Quote Originally Posted by ihavenofish View Post
    i dont think its a skill thing here unless you are actually drawing those shapes.

    usually when a circle isnt round, theres 2 common issues.

    1 is that the machine has backlash. youll see this as a flat spot on 2 opposing sides of a circle.

    2 is mach 3 is the drive isnt getting "slow" steps. this is common in some gecko drives. the result is that when an axis is going slow, it doesnt move. the result in a circle is again flat spots on the sides, basically making a squared off circle.


    what you are showing is not matching up to the 2 possibilities above.

    so you need to look at other things. if everything is tight, and nothing is moving as you cut, then its really coming down to the servos as the next thing to test. given the history with these motors creating wobbly curves when they were first being set up, this is highly likely to be the issue.

    so, first run the program 3-4 times to see if the result is the same each time. then try a different tuning setting, different speed, etc, see if changes. if theres a change, you know straight away its the motors. it will save alot of grief finding that our first.

    you need to be methodical with issues like this, or youll get nowhere.




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    Quote Originally Posted by gio666 View Post
    I can see that you having a r/p machine that you would think it was backlash , but they are Ballscrews with zero backlash. Any chance to say something about machines you are there.There is no flex in machine. You should know what your talking about before posting info . It is a problem with Mach3 setting for the Motor kit he has .
    If you know what the problem is, why don't you tell him how to fix it??

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  9. #89
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    In another forum, Xzero had warned a sync problem between the servo and MACH3, and this is sometimes difficult to tune.

    For consideration and review, sometimes the electrical conductors can cause problems. For example, in situations of driving voltage and high frequency pulse signals generated by frequency-speed drives, wiring should be separated and shielded, and this line grounded to earth. This helps the signals of the motors and encoders are very clean and free of noise. Likewise, and as far as possible, servos and structure of the machine should be grounded to earth.



  10. #90
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    Are you cutting the holes in one pass? What size is the hole, what size is the tool?
    How deep are you cutting per pass, and how fast?

    As for CV settings, go to the settings page, and turn off CV feedrate and CV distance.
    Then go to general config and turn off all the CV options there, except "Stop CV on angles" and set that to 90.

    See if you get better results.

    Also, post the g-code you're using if you don't mind.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  11. #91
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    azam1959

    What cutter did you use, & what was the speed & feed you were trying to run it at, Looks like the cutter shank was bigger than the cutter & you were going to deep for the cutter, the shank Large dia was hitting around the top of the hole, or you were getting a lot of cutter flex, with feed rate to high

    Mactec54


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    Mectec54,
    This make perfect sense (and that is the reason I did not use 1/8 to start with). Cutting length is .75 inch and I was going in .95 inch. I will also check the cut if upper part of the cut is rougher then bottom part. Planning on making number of circles of half inch deep with different strategies and see if makes sense. Lets hope I am able to get out of bed in couple of hours.

    Gerry,
    I am using 1/4 inch onsrud end mill. For each round I am cutting .125 in deep for rough and .1 for finish pass. RPM is 18K and feed rate is 225 ipm for rough and 120 for finish cut. I have no problem posting the g code but let me first follow Mectec54 logical solution. If it does not help, next step is cv settings. If that does not work, I will post the g code. Planning on number of half inch dia circles. Will do number of profiles and pockets with different strategies. Will post the results hopefully in few hours.


    Thanks Thanks Thanks Thanks


    Quote Originally Posted by mactec54 View Post
    azam1959

    What cutter did you use, & what was the speed & feed you were trying to run it at, Looks like the cutter shank was bigger than the cutter & you were going to deep for the cutter, the shank Large dia was hitting around the top of the hole, or you were getting a lot of cutter flex, with feed rate to high




  13. #93
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    Drop your rpm to 13,000, and lower your roughing speed and finishing speeds to 75ipm and try it.

    If the machine has any flex, small holes show it the most.
    At 225ipm, each pass of your hole only takes .16 seconds to travel 360° around the hole.
    If your machine can't accelerate to 225ipm and decelerate back to a stop in .16 seconds, then there's a very good chance that CV is causing the issue, or you're never getting anywhere near 225ipm in the first place.

    Also, if you can do the holes with helical cutting, there will be less chance of CV having an effect as the tool won't have to stop and plunge every .16 seconds.

    Gerry

    UCCNC 2017 Screenset
    [URL]http://www.thecncwoodworker.com/2017.html[/URL]

    Mach3 2010 Screenset
    [URL]http://www.thecncwoodworker.com/2010.html[/URL]

    JointCAM - CNC Dovetails & Box Joints
    [URL]http://www.g-forcecnc.com/jointcam.html[/URL]

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


  14. #94
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    azam1959

    As Gerry has said your speeds are way to fast to try & do these holes, helical is the way you should be doing them as well

    Mactec54


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    Quote Originally Posted by ger21 View Post
    If you know what the problem is, why don't you tell him how to fix it??
    he has. except every time he does, mactec starts a fight because he reused to believe the dmm servos can have anything to do with it. george has shown another machine behaving similarly (carbon fibre cutting) due to the motor/drive kit not working properly.

    anyhow....

    im not quite sure how cv settings could cause that much wandering? are you thinking the smoothing is blending the circle into an odd shape because the machine cant accelerate fast enough?


    mactec's idea that the tool is going too deep and hitting the top of the work piece is interesting. but id think there would be some visual evidence of that - burning etc. also its pretty clear that its making similar deviations on every level down.



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    Quote Originally Posted by mactec54 View Post
    azam1959

    As Gerry has said your speeds are way to fast to try & do these holes, helical is the way you should be doing them as well
    the speed set shouldnt matter. the machine will only go as fast as it can. if you program it to do the hole at 1000ipm, it wont matter, if the acceleration of the machine can only get it to 5. mach *should* be handling all that.

    the only instance ive seen mach fail to do its job correctly in cv mode is at sharp corners where it doesnt set he acceleration correctly and the motor gets overloaded and stalls. the machine should fault and stop at these points if its set up right.



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    Gerry, Mectec54 and Ihavenofish,

    Thanks a lot. Here is the picture of my experiment. Two left columns of half inch circle are made with 225 ipm and 18K rpm and right two rows are made with 13k rpm and 74ipm. I also made these holes half inch deep to incorporate Mectec input and made six of each to see consistency as per Ihavenofish.

    XZero users group-holes1-jpg

    i was hoping that cutting length will be the culprit but guess it has no play; even half inch deep holes are not accurate. As far as I can see six holes in each category are consistent.

    I am glad Gerry brought up the rpm and ipm and I can clearly see the improvement on right two columns. With this experiment my deduction is if I decrease the cutting mill dia and/or decrease rpm & feed for small holes it will further improve the quality of cut.

    Here is another shot and obviously I miscalculated the positioning but if you pay attention to two one inch dia holes in the bottom, left one is with high rpm/feed and right is with Gerry suggest rpm/feed. I wanted to see the impact of different cutting strategies but oh well I need to learn to measure too. Both these holes are using the same strategy and again low rpm/feed rate is doing better.

    XZero users group-holes2-jpg

    I think before I close this chapter I will make 2 inch, 3 inch and 4 inch circle and my hope is that as circle get bigger I will see better quality. Unfortunately this has to wait.

    One thing more ... I did not use any lead in or lead out in any cutting.

    Is my analysis that distortion in circle quality is purely due to feed and speed is wrong? Do you see any other issue?

    Thanks again and appreciate the input and learning opportunity.

    Regards,

    Quote Originally Posted by ger21 View Post
    Drop your rpm to 13,000, and lower your roughing speed and finishing speeds to 75ipm and try it.

    If the machine has any flex, small holes show it the most.
    At 225ipm, each pass of your hole only takes .16 seconds to travel 360° around the hole.
    If your machine can't accelerate to 225ipm and decelerate back to a stop in .16 seconds, then there's a very good chance that CV is causing the issue, or you're never getting anywhere near 225ipm in the first place.

    Also, if you can do the holes with helical cutting, there will be less chance of CV having an effect as the tool won't have to stop and plunge every .16 seconds.




  18. #98
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    Lightbulb

    azam1959,

    Its time for you to spend the remainder of the summer apprenticing in our bakery making doughnut holes, after several hundred thousand you will be able to cut a perfectly concentric circle.
    Not only that all the dough you cut improperly can still be used for fritters unlike the pile of hardwood you are turning into firewood.

    JoeyB

    A doughnut a day keeps the doctor away.


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    only if your bakery is at the boardwalk ...

    Quote Originally Posted by joeybagadonuts View Post
    azam1959,

    Its time for you to spend the remainder of the summer apprenticing in our bakery making doughnut holes, after several hundred thousand you will be able to cut a perfectly concentric circle.
    Not only that all the dough you cut improperly can still be used for fritters unlike the pile of hardwood you are turning into firewood.

    JoeyB




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    they both seems to still have the error, but the slower spindle speed one seems less obvious.

    still heavily suggests the drives being the issue to me, but also maybe the tool being much too long? a long tool will wander when it plunges into the work piece quickly. usually doest happen with wood as its soft, but hmm.

    got a pic of the tool youre using in the spindle?



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