Voltage and Line speed settinngs

Discussion in 'CNC Cutting' started by Fastyankee13, Apr 29, 2017.

  1. Fastyankee13

    Fastyankee13 Well-Known Member

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    OK so I use 14 gauge steel a lot so today I decided to take the time to do a few line speed tests a simple cut test and a voltage test. I'm using 30 amp fine cut consumables on my powermax 45 set to 30 A. I'm also using the 30 settings chart from Hypertherm.

    After doing several cuts I determend my best line speed and simple cut speed was 125 ip and 93.2 V.
    Cut my first design piece and the cut had lots of dross and I had a hard time getting the blanks to pop loose.
    So I'm baffled why is this after running several tests.
    So am I to slow to fast the cuts look good but to much dross.
    I'm also using a water table.
    IMG_0445.JPG IMG_0442.JPG
     
  2. nwaPLASMA

    nwaPLASMA Well-Known Member

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    In my experience dross is usually a result of too high or too fast. I cut 14 gauge a lot with my PM45, hand torch, shielded consumables, 30amps at 75ipm. Almost dross free.

    Did you have the THC off while cutting the line test?

    I've also noticed varying results between cutting lines and cutting designs, especially at speeds over 100ipm.
     
    Last edited: Apr 29, 2017
    steelfabrication likes this.
  3. Fastyankee13

    Fastyankee13 Well-Known Member

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    Jason,
    I had THC on auto during the line test and volt test !
    Its definitely not to high.
     
  4. LECS-Chad

    LECS-Chad Moderator Staff Member

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    So the line speed test implies a few things. 1. you cut straight lines. 2. the max speed for the straight lines. It doesnt not take into account that all cuts have inside features.

    When you run the line speed test do it in manual.

    Run the line speed 130-10. determine the best speed by being able to chip off the minimal dross with your fingernail.

    Then once you find that line then generate a small part and run it at that feed rate. Adjust accordingly. Watch the voltage during this part and take the average and add 2. That will be your SET VOLTAGE for that thickness, feed rate, amperage.
     
  5. Fastyankee13

    Fastyankee13 Well-Known Member

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    Can you send me the line speed test. I kind of accidentally over wrote the program.
     
  6. LECS-Chad

    LECS-Chad Moderator Staff Member

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    FYI... g-code is just a TXT document you can alter in notepad/wordpad/notepad++
     

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  7. LECS-Chad

    LECS-Chad Moderator Staff Member

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  8. Fastyankee13

    Fastyankee13 Well-Known Member

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  9. Fastyankee13

    Fastyankee13 Well-Known Member

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    Ok so I ran a job with the voltage set to sample and it kept crashing in to the material. I took it off sample and set it to the voltage of 93v which is were I run it with 14 gauge.
    Why is it crashing on sample voltage?
     
  10. Dnmeistr-LECS

    Dnmeistr-LECS Moderator Staff Member

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    With the Accumove controller when you run it Sample Voltage On you want to check to see if it is adjusting the Set Voltage. Meaning if you change your Set Voltage to 160 then run a job with it set to Auto and Sample Voltage On does the Set Voltage automatically change, meaning does it drop to a lower number. Or does it remain at 160, if it remains then that could indicate it is not reading Arc Voltage, as shown on the right side of the screen under Height Control Status. If not reading voltage then one thing to check would be to swap the polarity of your Raw Arc Voltage wires connected to the VFC box, swap the wires and see if it reads voltage. You can increase the lockout delay so you have more time to read the voltage, under Machine Settings change Distance to Corner to 6.0, height control will remain locked out for 6 inches.
     
  11. Fastyankee13

    Fastyankee13 Well-Known Member

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    When in sample voltage the voltage changed to a lower voltage. Torch kept diving in to the table. I than put it back to my set voltage and set the hight from .02 the recommended to .04 and ran it. It would cut with out diving in to the table. This machine is to finicky. I never trust it. I cut a lot of 14 g and every cut is a new day with machine. I have been dealing with this machine for two years and it will cut fine for a few cuts and than it starts screwing up I spend more time screwing with it when I should be completing jobs.. I know a new machine usually has a few bugs that need to be worked out but this is ridiculous .
     
  12. Fastyankee13

    Fastyankee13 Well-Known Member

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    Talked to tec today and I'm still having issues with the torch diving in to the table. This seems to be a common issue with Torchmate VMC
     
  13. LECS-Chad

    LECS-Chad Moderator Staff Member

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    Can you post a video showing the ARC VOLTAGE during running a job would be helpful as seeing the voltage dip and why/when would be helpful in diaging this issue you are having.

    If you test the resistance between your independent ground rod and your table are you getting less than 3 ohms?

    If you cut a 12" straight line does the voltage stabilize or does it jump around +/-2 volts
     
  14. Dnmeistr-LECS

    Dnmeistr-LECS Moderator Staff Member

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    The height control sample voltage works by capturing the voltage after the lockout led light turns off, this is controlled by the value in distance to corner under machine settings, by default it is set to 1/2 inch. You can modify this by increasing the value to .75 or even 1.0 to allow the voltage to settle down before we capture it. You do want to ensure the material stays flat while the software is sampling the voltage and the lockout led light is on otherwise you defeat the purpose of sample voltage. Meaning if the torch is scraping the material when voltage is captured it doesn't do you any good.

    Also if you find a voltage that works, then why not use it, turn sample voltage off simple as that. Sample is there when you dont know what the voltage should be, you still have to cut at the correct speed and amperage though.
     
  15. Fastyankee13

    Fastyankee13 Well-Known Member

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    I was trying to cut using the voltage that works best for my set up and the torch kept diving in to the table. So I switched to sample to try and get it squared away.
    I also ground the plasma right to the plate I'm cutting. This seems to help hugely on my table. I also cleaned a spot with my grinder were I attached the ground and that seemed to help to. This is a new sheet of steel from the same batch of steel. I will do the checks Chad suggested. This is an on going issue with this table and I mean two years on going I need to get this sorted out. It seems I run a job fine than it starts screwing up. It seems I had no issues till I switched to Accumove . I now have a case #.
     
  16. TeraWales

    TeraWales New Member

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    Hi....is there any accuracy to such a notion that for any given voltage, it can only be a single sine wave (if original phases are sine waves at least)? What would be the best representation of what the load is experiencing? Maybe another way to ask this is to ask if the load experiences one peak voltage per half cycle (i.e. one sine wave) or does it experience 2 distinct peaks in the same time.

    printed circuit board and assembly
     
    Last edited: Jun 5, 2019

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