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  1. #1
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    Default Tool path changed

    Hi all.. this one has me completely stumped and I could use some help from those with far more knowledge of all things CNC.

    Background.... I build displays for Honey Stinger and recently switched over to UCCNC/2017Screenset with a UC100 to replace mach3/PP setup. I have also changed over from sheetcam to fusion 360 for all my programs. Nothing else changed on the hardware side of the router which is a highly modified ShopDroid (nema23s, R&P) that is working well enough to get me by until I build a new one. I've made over 500 of these displays and I'm working on an order of another 90. So after all the changeover and outputting new gcode with Fusion 360 I set up and cut 30 sets of sides, changed programs and cut 60 sets of shelves, then back to 30 sets of sides. I'm loving the new UNCNC control and it has shaved a few minutes off of each run besides just feeling like everything is running smoother. 30 sheets of plywood cut, sanded and ready to ship in a little over 3 days so Life is good until.......

    Problem.... I was finishing up the edge sanding on the second batch of sides and noticed that one of the angled slots looked a bit off. My router has some flex and I'm pushing it pretty hard so corners aren't exactly "square" and have a little overshoot but nothing too bad. This one though looked a lot worse and sure enough the shelf was more of a press fit than the normal loose fit. Measured and the slot was around .04" narrow but the corners were in the same place so it is the i-j movement that is off. So I start looking into what is going on and the first set of 30 were all perfect mirror images of each other which is what you would expect since it is the same part in fusion only flipped 180 degrees. Looking at the second set of sides I realized that every other one was off and one was exactly like the first set. Turns out the top side is the one that is off and I'm running the exact same g code that I did for the first set.

    Trouble shooting so far..... Given nothing changed between the first set of sides and the second I verified the g code was indeed the same I had used for the first ones I assume it is a hardware issue with the Y axis since the bottom side is good and the top one is bad. Assume the X and Z are good because if the error was coming from them it would be the same for each side.

    So I cut the feed rate down 50%, single stepped through the code, rebooted everything, turned off CV mode, checked all of the set screws, and gave the cnc a general look over for any issues but it still cuts the same way each time. I also added in a y axis offset so it is cutting in the same general area as the good slot and one is good and one bad so I'm thinking less of a hardware issue than when I first started looking at it.

    At this point I'm at a loss as to what is going on since it worked great on Monday and Wednesday it cuts different with no changes to setup. The slots are the same size and one is a / and the other a \ which shouldn't matter? It would be one thing if everything was off but it is just 2 slots that are different. Anyone have a suggestion as to what to try next since I have another 30 sets to cut. One other data point, the error is at the start of the cut as the router is traveling in a counter clockwise pattern. Only "good" thing is I could sand out the problem and not waste all of the material but I really need to figure out what is going on...

    Thanks!

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Tool path changed-20170621_180312-1-jpg   Tool path changed-20170622_091214-1-jpg   Tool path changed-20170622_093829-1-jpg  


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    Default Re: Tool path changed

    Are you absolutely sure you are running the same code? Generally i like to copy and file a working program. There may be some advantage to using a source vode management system to corral your G-Code files. Such a system is for the future though

    Pictures might help too, im having problems vizualizing what is being discussed here. It is a bit strange that you are only seeing errors on the mirror image part.

    The other thing to consider is a controller reboot to go back to defaults. The thought here is that your other part run might have set a parameter that isnt being cleared by the problem program.



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    Default Re: Tool path changed

    Thanks for the reply.

    I'm as sure on the code being the same as I can be. I generate the code on my laptop and then copy the file to the cnc pc and there are only 2 files in the Honey Stinger folder to run. One for sides and one for shelves. If I regen code I write over the file on the cnc pc to prevent having multiple files to run and the date on the file is from the 14th. I did load a previous version on the cnc pc but that was after I started having the issue and it didn't help. I will do a search on the cnc pc though to make sure there are no other files on it just to be sure but I try my best to keep things straight from a configuration management standpoint (retired systems engineer that learned to understand the importance of good CM the hard way).

    I'm not sure what you mean by a "controller reboot". I've rebooted the pc and cycled power to everything else but at this point I'm willing to try about anything. I guess I could go back to the stock UNCNC screenset which I think should run it although I never cut any parts with it. All I used it for was to make sure everything moved ok before getting Gerry's 2017 screenset and cutting parts. I guess I could also load mach3 back on the pc to take UCCNC out of the equation. I had some family things to deal with yesterday afternoon so heading back to the shop now to see if I can figure something out.

    Oh... and the slots are also all cut from the same 2-d pocket setup in fusion so there are 8 geometries selected for that operation and only 2 of them are not cutting right.



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    Default Re: Tool path changed

    Here are some more pictures so you can see what it looks like put together. These will be going to SafeWay stores in Colorado.

    Attached Thumbnails Attached Thumbnails Tool path changed-20170608_211039-1-jpg   Tool path changed-20170608_211057-1-jpg   Tool path changed-20170621_180224-1-jpg  


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    Default Re: Tool path changed

    Are you plunging, or ramping in?
    Are you using the same tool? Maybe the tool is getting dull? Are all cuts in the came direction? (conventional or climb)

    That last pic is showing a lot of flex somewhere. Is that the issue, on the left side in the pic?

    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)


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    Default Re: Tool path changed

    Quote Originally Posted by ger21 View Post
    Are you plunging, or ramping in?
    Are you using the same tool? Maybe the tool is getting dull? Are all cuts in the came direction? (conventional or climb)


    That last pic is showing a lot of flex somewhere. Is that the issue, on the left side in the pic?
    Thanks Gerry... hoping you would drop in.

    Ramping in. The machine does have a lot more flex that I want but if I rerun the cut it doesn't take off any more material (at least not .04" worth) so I don't think it is flex causing this problem. I do the cut in 3 passes with the first two being fairly deep at approximately .375" deep and then a finish pass at .030" deep to clean up the sides from the flex so it does take off a small amount on the final pass from the sides.

    I'm using a 1/4" downcut spiral and it was changed out in the middle of the second set of sides so about 1/2 were done with the "worn" bit (I change them out when I the bottom of the cut isn't as clean and this one wasn't as dull as I've ran them in the past) and half were done with a brand new bit with no change that I could see by eye.

    All cuts are in the same direction and from the same 2-d pocket setup cam file in fusion.

    It is almost like I'm getting backlash in one direction but the bit goes to the corner in x/y coordinates ok and actually has to move out of the way to start the i/j cut in the wrong spot. I'm generating a new similar pattern and will cut it to see if anything changes. First though I have to load all the completed displays as they are on their way over to pick them up.



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    Default Re: Tool path changed

    If you can send me the g-code, I'll take a look at 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)


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    Default Re: Tool path changed

    Try a run with your curves linearized, just in case G2/G3 are acting weird, which can happen with decimal places (and probably other reasons)....just to see what happens. I am assuming they are curved moves right now as its tough to check the code with lots and lots of linear moves.

    Good luck.

    Sent from my Gemini using Tapatalk



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    Default Re: Tool path changed

    I did a test cut with just 2 slots, one the forward slash and the other the back slash at the size of .780"x8.25" and the backslash looks "good" and the forward slash has the blip in it.

    So my wife came down to the shop (software engineer) and we stepped through the setups and code again and as always when you are showing someone things and explaining it looks different. The code that is giving the problem is just 4 points in x/y. I mistook the i/j commands as the ones that went from the four points of the rectangle when they were just the ramps.

    The cpu is maxing out when it is cutting so I'm going to load my engraver pc (i5 with 16 gig of ram and a hybrid SSD) with UCCNC and see if it makes a difference. At this point I'm guessing it will. UCCNC is the only thing running on that machine. Seems like when I was looking at cpu usage earlier in the week it wasn't maxing things out. I was wanting a better pc for it anyway but was going to wait until I built the new router.



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    Default Re: Tool path changed

    Well crap.... cpu is coasting along now at 4% and still cutting the same way Seems like it has to be something mechanical but why just when it goes from lower left to upper right?



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    Default Re: Tool path changed

    Are you sure the toolpaths for both pockets are both conventional or both climb, or are you "flipping" the toolpath as well?

    It could also be the USB cable you're using. You should get a high-quality cable. As added insurance I put ferrite chokes on all my cables.



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    Default Re: Tool path changed

    My guess is that you have a bit more backlash in one of your axis, and because you're climb cutting, the tool is grabbing and getting pulled into the corners. Maybe something got loose recently?

    I'd try conventional cutting, and leaving maybe .02" for a finish pass?

    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)


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    Default Re: Tool path changed

    Quote Originally Posted by ger21 View Post
    My guess is that you have a bit more backlash in one of your axis, and because you're climb cutting, the tool is grabbing and getting pulled into the corners. Maybe something got loose recently?

    I'd try conventional cutting, and leaving maybe .02" for a finish pass?
    It even looks as if one pocket is cut conventional, and the other climb....



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    Default Re: Tool path changed

    He sent me the code, and everything is climb cut.
    It also may have something to do with where the leadin moves are.

    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)


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    Default Re: Tool path changed

    Quote Originally Posted by ger21 View Post
    My guess is that you have a bit more backlash in one of your axis, and because you're climb cutting, the tool is grabbing and getting pulled into the corners. Maybe something got loose recently?

    I'd try conventional cutting, and leaving maybe .02" for a finish pass?
    It "seems" as tight as it was before but I I cranked on all the nuts and bolts and I'm going back over everything again to make sure. I cut a 8" circle and it isn't quite a circle (1/32" off on diameters at the 45s) so there must be some backlash there somewhere that wasn't before. I'll keep digging and thanks for all the suggestions.

    I also tried to generate a conventional cut and for some reason just changing from climb to conventional causes uccnc to go into sloooooow motion. It runs the simulation fine in fusion. Just one of those days

    Thanks again everyone.



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    Default Re: Tool path changed

    Quote Originally Posted by lambodesigns View Post
    I did a test cut with just 2 slots, one the forward slash and the other the back slash at the size of .780"x8.25" and the backslash looks "good" and the forward slash has the blip in it.

    So my wife came down to the shop (software engineer) and we stepped through the setups and code again and as always when you are showing someone things and explaining it looks different. The code that is giving the problem is just 4 points in x/y. I mistook the i/j commands as the ones that went from the four points of the rectangle when they were just the ramps.

    The cpu is maxing out when it is cutting so I'm going to load my engraver pc (i5 with 16 gig of ram and a hybrid SSD) with UCCNC and see if it makes a difference. At this point I'm guessing it will. UCCNC is the only thing running on that machine. Seems like when I was looking at cpu usage earlier in the week it wasn't maxing things out. I was wanting a better pc for it anyway but was going to wait until I built the new router.
    Have you tried reverting back the Mach and the parallel port as you mentioned before, and recreated the problem? Maybe you have the motor settings a bit on the aggressive side with UCCNC? Also, have you tried swapping out USB cables or even USB port? Finally, have you tried running Mach3 with the UCCNC plugin?



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    Default Re: Tool path changed

    Turns out is was a problem with a belt drive/motor mount on the y axis although I'm not sure exactly what it was that changed and had nothing to do with the software. It didn't feel that much different when I pushed/pulled/twisted but it did have a bit more flex than the others so I took it apart and put it back together and now it is cutting as well or better than before. . It is my homemade design/build for the belt drives and not one I would recommend or ever duplicate. I'm really looking forward to building the next cnc and hopefully using all my mistakes from this one and knowledge I've gained from all of you to have a much better machine. I really don't know how I would have gotten this running and keep it running without you guys. Now it is time for a beer and listen to the free concert that just started down the hill from us. Life is good again



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    Default Re: Tool path changed

    Glad you figured it out.

    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)


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    Default Re: Tool path changed

    It is good to be "good".

    It is fairly common in motion systems to have problems with mechanical connections between motor and leadscrew (or rack, belt or whatever). The constant back and forth, with stiff acceleration, is very hard on components that try to remain locked on a shaft. This might have been your problem, something rocking on a shaft



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