CNC Rookie - Having Accuracy Issues with increased speed

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    *Registered User* premiersigns's Avatar
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    Default CNC Rookie - Having Accuracy Issues with increased speed

    We are a sign shop and purchased our first cnc machine from china to save money and get our feet wet.

    The machine is a 5' x 10' 4 axis machine with a 12hp HSD ES951 Spindle and a Syntec 21MA Controller. Using V-carve software.

    We are mainly cutting 3/4" melamine currently. I'm using a 1/4" compression bit with a single pass at 20,000 rpm and have no issues with it cutting. The accuracy issues is the small area clears in the job at 1/4" deep that are 3/4"x 2" in size. In order to get an accurate cut I am at 120 ipm which seems to be extremely slow. There was some play in the X and Y gear mesh which is now gone but I still have issues.

    Any help to point me in the right direction would be great.

    Thanks,
    Tim

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    *Registered User* premiersigns's Avatar
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    The one hole with wobble is done at 300 ipm and the smooth one is 120 ipm

    The 3rd photo is at 450 ipm and those should be straight lines with 90 degree angles.

    Attached Thumbnails Attached Thumbnails CNC Rookie - Having Accuracy Issues with increased speed-c32c68d9-2ff5-425a-9e41-226f001545a6-jpg   CNC Rookie - Having Accuracy Issues with increased speed-f8c6279e-c7da-4696-bab3-c64ceac95f04-jpg   CNC Rookie - Having Accuracy Issues with increased speed-3b927bf4-2070-49a4-b2aa-30de2bc46fc1-jpg  


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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Have you tested straight line movements and measured them against programmed versus measured distances?

    Check table and gantry for squareness, perpendicular, spindle tramming etc. Spindle runout can be checked. Looks like some of your mechanical parts are moving that shouldn't be. Eg: motor mounts etc.

    Contrary to popular belief, on CNC machines duct tape and WD-40 do not work for fixing those that move and shouldn't and those that should that don't :-)

    Photos of the machine and sample G-code might be useful to get more ideas of what you are dealing with.



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Quote Originally Posted by premiersigns View Post
    We are a sign shop and purchased our first cnc machine from china to save money and get our feet wet.

    The machine is a 5' x 10' 4 axis machine with a 12hp HSD ES951 Spindle and a Syntec 21MA Controller. Using V-carve software.

    We are mainly cutting 3/4" melamine currently. I'm using a 1/4" compression bit with a single pass at 20,000 rpm and have no issues with it cutting. The accuracy issues is the small area clears in the job at 1/4" deep that are 3/4"x 2" in size. In order to get an accurate cut I am at 120 ipm which seems to be extremely slow. There was some play in the X and Y gear mesh which is now gone but I still have issues.

    Any help to point me in the right direction would be great.

    Thanks,
    Tim
    What brand of servo motors and drives are on your machine, or is it a stepper motor machine, it look like at speed the control is not able to keep up, such a small cutout I would be surprised if you could do it faster than 120 IPM, you need to have quality motors drives and ground helical racks, or Ballscrews for your machine to go at those speeds in such short moves

    Mactec54


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    Quote Originally Posted by mactec54 View Post
    What brand of servo motors and drives are on your machine, or is it a stepper motor machine, it look like at speed the control is not able to keep up, such a small cutout I would be surprised if you could do it faster than 120 IPM, you need to have quality motors drives and ground helical racks, or Ballscrews for your machine to go at those speeds in such short moves
    They are yaskawa drivers and servo motors with a shimpo reducer riding against a helical Herion rail on thk linear guides.

    Attached Thumbnails Attached Thumbnails CNC Rookie - Having Accuracy Issues with increased speed-f6e4b362-4d2d-4c4c-b3c1-4eade6a70cae-jpg   CNC Rookie - Having Accuracy Issues with increased speed-d2e8f94d-b106-4d0c-a6ef-7dbc4c97c130-jpg  


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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    most likely the acceleration too high
    for this small distances, and machine trying to optimize the toolpath

    a 3/4x2 inches part... not necessarly need 120 ipm

    with 40-60 ipm it made same time, without rounded corners



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    I think that as you increase speed, your machine is flexing more.
    Even with our $150,000 Morbidelli, we sometimes see similar issues with small details at high speeds, but not as bad as what you are seeing.

    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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    *Registered User* premiersigns's Avatar
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    This is an arcade cabinet that I am working on and to get accurate cuts it’s taking a little over 25 mins to cut with 2 passes. Am I just being unrealistic with time or does that seem too long?

    Attached Thumbnails Attached Thumbnails CNC Rookie - Having Accuracy Issues with increased speed-2f78d7f1-8f89-4c09-9384-7b3d13d6d4a5-jpg  


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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    I'd try a 3/8" compression, and cut in one pass. I could do that in 10 minutes or less, but my machine probably cost 7x more than yours.

    And use a larger bit to cut those pockets, and it should cut a lot of time.

    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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    *Registered User* premiersigns's Avatar
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    Quote Originally Posted by ger21 View Post
    I'd try a 3/8" compression, and cut in one pass. I could do that in 10 minutes or less, but my machine probably cost 7x more than yours.

    And use a larger bit to cut those pockets, and it should cut a lot of time.
    I’ll try that. I mean don’t get me wrong it’s not a $100k+ machine but we did spend $40k on it with all the upgrades.



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Ideally in the future we were looking to get a Biesse Rover J because of the sign shop applications with an eot-3 knife and camera system.



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    Quote Originally Posted by ger21 View Post
    I'd try a 3/8" compression, and cut in one pass. I could do that in 10 minutes or less, but my machine probably cost 7x more than yours.

    And use a larger bit to cut those pockets, and it should cut a lot of time.
    What would you recommend for a bit? Brand wise and 2 flute or 3 flute?



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Quote Originally Posted by premiersigns View Post
    This is an arcade cabinet that I am working on and to get accurate cuts it’s taking a little over 25 mins to cut with 2 passes. Am I just being unrealistic with time or does that seem too long?
    Your machine has all the good mechanical parts to do it, it would depend on what encoder resolution they are using, and what the control can handle, with those Yaskawa drives the encoder resolution is adjustable, and if the control can't handle / control the Yaskawa full Encoder resolution, so there will be a combination of inertia from the speed and resolution at play,

    It may seem to be a long time but they are quite big parts with a lot of small pockets, a lot would not be running over a 120IPM on the small detailed parts, the fact you can get 120IPM when doing the detail is quite good

    I would say that it is more about the control not being able to control at those speeds, the out of position settings must have a high tolerance set or the servo drives would of faulted out with cuts like that, you have tool flex as well because of the high feed rate

    You can see in the cut that the cutter is flexing also,( from to much speed ) so there are a lot going on when doing detailed work at high speeds, the machine may be able to do it, the cutter will not, I know of another machine similar to your machine, and they don't go over 80 IPM for detailed work

    If you could use a larger cutter then you would get some more speed before you get cutter flex, there will always be a trade off between Control speed Inertia and flex

    There may be a lot of people say they can cut faster than that, but in reality they are not, they may program those speeds but there machine will never reach the programed speed when cutting small detail work

    There are expensive machines that can work at those speeds, but they too would have to use a larger cutter as well or they to would have tool flex just the same

    Mactec54


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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    I'd try a Vortex 3130XP, or 3135XP.

    Or a 3150XP, which may allow you to cut the pockets as well with the same tool?

    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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    *Registered User* premiersigns's Avatar
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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Thanks. I have a 1/2" compression bit here that I'll try to see if I get less flex. I just have to adjust for the difference of the radius of the bit in the detailed areas.



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Quote Originally Posted by ger21 View Post
    I'd try a Vortex 3130XP, or 3135XP.

    Or a 3150XP, which may allow you to cut the pockets as well with the same tool?
    Yes those cutters work very well, but if he can't use more than a 1/4" diameter he is not going to gain a whole lot for the extra cost, if cost is a factor

    The 3150XP is 1/2"

    Mactec54


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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Quote Originally Posted by premiersigns View Post
    Thanks. I have a 1/2" compression bit here that I'll try to see if I get less flex. I just have to adjust for the difference of the radius of the bit in the detailed areas.
    If you can use 1/2" that would be a good starting point, but if the control can't keep up with small fast movements you will still see some problems but should be an improvement with a 1/2" cutter

    From the Vortex website you can get speeds and feed from there catalog page 14 they also have a phone app for speeds and feeds for there cutters

    https://www.vortextool.com/wood-tool...n-spirals.html

    Mactec54


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    Quote Originally Posted by mactec54 View Post
    If you can use 1/2" that would be a good starting point, but if the control can't keep up with small fast movements you will still see some problems but should be an improvement with a 1/2" cutter

    From the Vortex website you can get speeds and feed from there catalog page 14 they also have a phone app for speeds and feeds for there cutters

    https://www.vortextool.com/wood-tool...n-spirals.html
    I went with the 1/2” bit and shaved about 5 mins but the dust collector doesn’t pick up nearly the same amount of dust with the longer bit on it so after cleanup I think it pretty much negotiates the time savings. Haha.

    I guess I can look at it this way. We are only a couple guys doing this so if it takes even 30 minutes to get it perfect it till saves me hours of doing this by hand and I can’t assemble and wire an arcade cabinet as fast as the machine can cut them.



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    There is a bit of play in the 4th axis which I’m regretting even having gotten now as we don’t really have a need for it. I feel that’s part of the issue. The factory is working with me on resolving that so I’ll keep you updated. I took a video but it’s too large to upload here.



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    Default Re: CNC Rookie - Having Accuracy Issues with increased speed

    Quote Originally Posted by premiersigns View Post
    There is a bit of play in the 4th axis which I’m regretting even having gotten now as we don’t really have a need for it. I feel that’s part of the issue. The factory is working with me on resolving that so I’ll keep you updated. I took a video but it’s too large to upload here.
    That is what happens there is always a trade off somewhere that in the long run does not make any difference, quality cutters can make an improvement though

    Just post the link to the video

    Mactec54


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