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Wrong size

Discussion in 'General Talk' started by Chuckpie, Mar 30, 2023.

  1. Chuckpie

    Chuckpie New
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    I am attempting to cut a 3" tab and when I run it on my plasma table it try's to cut a tab about 30". Can some one tell me how to get the table to cut the eight size? My table is a 4' x 4' Delusional Designs. I have attached the cam and control screens.
     

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  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Both screenshot sits around 80mm wide and tall.

    So the machine itself may be out of calibration. Check your steps per mm. Dial it in closer, then do final calibration from Wizards and Tools > Calibration
     
  3. Charles Pierce

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    Where would I check the steps per mm?
     
  4. Giarc

    Giarc OpenBuilds Team
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  5. Charles Pierce

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    Where are the GRBL settings located? Sorry to be a pain, but I am a 77yo guy trying to learn new stuff. Thanks
     
  6. Giarc

    Giarc OpenBuilds Team
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    It is one of the tabs at the top of OpenBuilds Control. I circled it in the photo. The Wizards nd Tools tab has a selection for calibrating your machine.
    upload_2023-3-30_19-28-42.png
     
  7. Charles Pierce

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    thanks again. I will give it a go.
     
  8. Charles Pierce

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    My table is still not acting right. From what I get from the manufacture of the table the feed rate is 140 IPM. Where would I put that in? Also how can I change the home to a different part of the table. When I try to run my program not only does it make the part much larger, but the table keeps going to the stop switches when I hit the home tab.
     
  9. Giarc

    Giarc OpenBuilds Team
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    That is put in when you are setting up your cutting operation in your CAM software. For an OpenBuilds CAM plasmaset-up, the location is circled below. For 140 ipm, you would need to use 3556 mm/min.
    upload_2023-4-1_22-14-15.png

    When you hit the "Home" tab, you are telling it to go to the "Home" position and to do so it needs to go to the limit switches to find that position. If you want to go to your work XYZ zero position then you need to tell the machine that is where you want to go. There should be a "goto XY zero" tab. AS for things being cut too large, you still need to calibrate your machine.

    I highly recommend you read the grbl wiki. It is not that long and it will help you to better understand how these machines work, how to set them up, and how to trouble shoot if issues arise in the future. I think I have read through it a dozen times or more by now while helping people with issues. I have yet to have an issue with my machines I have not been able to solve by referring to this wiki. GRB wiki
     
  10. Charles Pierce

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    So if I change the feed rate that will change the X and Y travel distance?
     
  11. Alex Chambers

    Alex Chambers Master
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    Not the feedrate - you need to calibrate your steps/mm (the $100, 101 & 102 settings). Our leadscrews are formed by rolling, not grinding, so they are not precisely (the error is very small) the pitch they are supposed to be. If you are using Openbuilds Control there's a wizard for calibrating your machine - use the longest distance you can accurately measure to do so.
    Alex.
     
    #11 Alex Chambers, Apr 2, 2023
    Last edited: Apr 2, 2023
  12. Charles Pierce

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    So like in the video I need to put a mark at the xyz rails and move them 100mm make a new mark and then measure the distance on the rails and put that number into $100, $101 & $102 in GRBL to calibrate GRBL settings to my table to correct oversizing my part. Is that correct?
     
  13. Alex Chambers

    Alex Chambers Master
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    Not quite - the guide in the attached file explains why you need to calibrate steps/mm and the theory of how to do it. The wizard in Openbuilds Control will do all the sums for you and update your grbl settings but for the best results use the maximum distance you can accurately measure - 100 mm is too short.

    Alex.
     

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    #13 Alex Chambers, Apr 2, 2023
    Last edited: Apr 2, 2023
  14. Charles Pierce

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    My table distance was 26 inches by using the software wizard with the wizard moving the 100mm. That converts 26in to mm = 660.4. So I put that number into GRBL 100, 101 and 103. The result was it made the cut even larger than the earlier too large cut. So, I started lowering the number, no I am to about 30 on those settings and the cut size is close to the actual part size. I will get a sharpie and some poster board tomorrow and test draw the part on the machine to check size. I will let you know how close I am. Thanks
     
  15. Alex Chambers

    Alex Chambers Master
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    You didn't read the pdf I posted - you don't put the distance it actually moved into the grbl settings, and your Y, X and Z settings may each be different.
    Openbuilds Control has a wizard that will do the sums for you - you put the distance it actually moved into the wizard, not into the grbl setting for the steps/mm.
    Alex.
     
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  16. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    include video links :) to avoid confusion

     
  17. Charles Pierce

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    I did use this wizard. When I moved the machine the 100mm the distance between the marks came out to 26 inches between the marks when the software moved the 100mm the wizard moved to the second 100mm mark.
     
  18. Charles Pierce

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    Thanks for all the help. For my Delusional Design Freedom 4ft x 4ft table I was able to get the correct size by setting 100 and 101 GRBL settings to 30. I also set my table size to 46in x 46in in GRBL.
     

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