Need Help! cuts not precise


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Thread: cuts not precise

  1. #1

    Default cuts not precise

    very frustrating issue. some of my cuts are not the exact measurements i need them to be. for example - if i cut several pieces that are 8x10, some are 1/32-1/16 longer than what's in the file. i ran several tests and i *believe* i have narrowed down the issues, the cuts going horizontal to the machine are a little longer than when traveling vertical. not sure what's up here! any help would be appreciated, thanks!

    next wave shark hd3 ext
    cut2d pro
    i cut mainly acrylic but this issue happens on different thickness with different size bits, so i don't believe those are factors.

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  2. #2
    Member awerby's Avatar
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    Default Re: cuts not precise

    That could be due to backlash. Backlash is the error you get when a screw changes direction. Since there's a little gap between where the screw threads bear on one side of the nut's threads and the other, the motor will turn a little before the threads engage. Expensive machines have ball screws using double or preloaded nuts that have little or no backlash; cheaper machines have to deal with it. CNC control programs have ways to compensate for it, but you need to measure it accurately first, before telling the program to add a certain number of steps when the screws change direction.

    It could also be that your steps-per-unit settings are a little off - that would be the first thing to check, before dealing with backlash.

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  3. #3

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    Quote Originally Posted by awerby View Post
    That could be due to backlash. Backlash is the error you get when a screw changes direction. Since there's a little gap between where the screw threads bear on one side of the nut's threads and the other, the motor will turn a little before the threads engage. Expensive machines have ball screws using double or preloaded nuts that have little or no backlash; cheaper machines have to deal with it. CNC control programs have ways to compensate for it, but you need to measure it accurately first, before telling the program to add a certain number of steps when the screws change direction.

    It could also be that your steps-per-unit settings are a little off - that would be the first thing to check, before dealing with backlash.

    thanks for the info. i researched backlash and that led to me checking all the bolts. some where loose. although i’m not quite sure where the t-nuts are. i’ll also look into that setting. thanks!



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