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Plasma cutting a straight line all the time??

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  • Plasma cutting a straight line all the time??

    so the more and more i cut lately the more i realize i have better cuts when i freehand it then trying to use a straight edge.. in my current projects im needing to cut out around a 5/16" slot about 2 or 3 inches long.. and the material is only 1.5" wide flat bar.. so i have to make sure i stay in the middle and cut as precise as possible and when i use a straight edge, my tip gets stuck to the metal or builds up and then throws the cut out of alignment.. is there a better way to use a straight edge to get cleaner cuts?

  • #2
    Make a jig to match your slot. I had lots of different ones
    Bob Wright

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    • #3
      jig materials to consider? I had a small one made of 1/8" flat bar that i was trying to use, but the slag that was being created was being thrown against the jig and straight edge which was then causing the cutter to bump out of line.. would it be best to use another type of material to make the jig out of?

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      • #4
        Jig can be something non-conductive. I usually just use wood and make another one when it wears out.

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        • #5
          i have plenty of that laying around, ill make one tonight and test it out

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          • #6
            How are determining output power and travel speed? You shouldn't be slinging a lot of slag if you get it adjusted properly.

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            • #7
              Well keep in mind i have a cheap "yeswelder" plasma cutter, im running it on 220v, I have it set on 55amps and there are times i can get clean straight cuts and other times i dont.. so its def how im doing it, but i do need to setup a jig to at least be more consistent on my attempts so i can dial it in. Eventually in the future if i do more and more fab work, then ill invest in a better cutter, but for now, this has helped and saved me so much time. already.

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              • #8
                Put that cutting tip right down on the material, get rid of that wheel guide thing if you’re using it and make sure you’re consumables are in good condition. Worn consumables will make for a bad cut. If you’re making a critical cut, use fresh consumables for nice, crisp lines and then change back if you want to.

                I’m confused as to how using a straight edge leads to not straight cuts. It would be my guess there’s a technique issue over a straight edge issue. I actually use an aluminum framing square as my cutting guide and it’s never been contaminated by slag. Put the cutting tip right down on the material and drag it along. It’ll be fine.

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                • #9
                  Originally posted by ryanjones2150 View Post
                  Put that cutting tip right down on the material, get rid of that wheel guide thing if you’re using it and make sure you’re consumables are in good condition. Worn consumables will make for a bad cut. If you’re making a critical cut, use fresh consumables for nice, crisp lines and then change back if you want to.

                  I’m confused as to how using a straight edge leads to not straight cuts. It would be my guess there’s a technique issue over a straight edge issue. I actually use an aluminum framing square as my cutting guide and it’s never been contaminated by slag. Put the cutting tip right down on the material and drag it along. It’ll be fine.
                  I def agree its a "me" issue lol... didnt think to use aluminum as my straight edge, i was using a scrap of 1/8" steel flat bar.. and the slag or blow out from the cut is what was being splattered onto the scrap, which would then block my traveling along it..

                  But ill dig around for some of my aluminum scrap i have somewhere and try both your suggestions..

                  Before this time around, its been probably a good 7yrs since i last used a cutter and that was a friend of mine that had it and we were cutting some expanded metal.

                  But im learning and will eventually get it
                  thank you for the suggestions..

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                  • #10
                    You may not be letting the arc completely cut through. You can’t use it like a razor knife, the arc must completely cut through as you drag the torch along. If slag and dross are flying out ahead of your cut, then it sounds like you might just be trying to make multiple passes on a single cut. Doing that will yield a poor result for sure.

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                    • #11
                      Originally posted by ryanjones2150 View Post
                      You may not be letting the arc completely cut through. You can’t use it like a razor knife, the arc must completely cut through as you drag the torch along. If slag and dross are flying out ahead of your cut, then it sounds like you might just be trying to make multiple passes on a single cut. Doing that will yield a poor result for sure.
                      So im def letting it cut thru before i even move, i will say though that for the most part, i was def not keeping the tip on the metal, i was trying to hold it just a hair above the metal, but this weekend will def be trying and testing all the suggested technics mentioned here since ill be needing to cut the slots again on my next order.

                      I really appreciate all the suggestions and advice, i wasnt able to find my aluminum scrap, so ill go get me a new straight edge ruler or anything that is aluminum that i can use for other purposes as well ..

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                      • #12
                        I don’t think it matters what the straight edge is made out of, to be honest.

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                        • #13
                          I have made lots of cutting fixtures from steel, alum, wood some over 8’ long. Some for straight cuts some for curved. Some cutters need the tip up 1/8” off the metal, some right on the metal. You just need to figure out what you have, what you want the cut to look like and try to make it happen. Some of my patterns used 2 rails and some only one to guide it. I cut square and round holes almost daily for years at work. That pattern was cut the shape plus a little bigger so the hole was the right size. The easy way is use a straight edge and make a test cut. Then measure from the inside of that cut to the straight edge edge. If it’s say 3/8” put the straight edge 3/8” from your cut line.
                          Bob Wright

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                          • #14
                            I use yard sticks and paint sticks most of the time.

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