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How do I cut a long groove in square tubing?

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  • How do I cut a long groove in square tubing?

    Hi all, this is my first post.

    I have just bought myself a Miller Multimatic 215 and am putting my skills to the test as a DIY wannabe.

    For my first project, I am building a welding table (probably not Robinson Crusoe there). I just wish I had a welding table to build it on.

    So I can adjust the height, I am sliding some thicker square tube over some thinner square tube and fixing the height by putting bolts through.

    The inner tube is 90mm x 90mm with 6mm wall thickness (overkill I know) and the outer tube is 100mm x 100mm with 4.8mm wall thickness. This gives me 0.4mm of space on the inside.

    I thought this would be enough, except that there is a welding seam on the inside of the outer tube. I can't get in there to grind it flat (if you know a way, please let me know).

    What I thought I would do is cut a groove in the outside of the inner leg so that the welding seam on the inside of the outer leg can slide up and down (confused yet?)

    I have attached a couple of photos and a quick sketch to help explain.

    I don't have a milling machine and would be grateful for any recommendations as to how I can cut the groove. I don't really want to grind it as I was hoping for a nice finish. If I was making it out of wood, I would use a router or circular saw set very shallow.

    Any thoughts appreciated. (Not sure if you can see the photos)

    Cheers, Al Click image for larger version  Name:	image_35360.jpg Views:	1 Size:	2.1 KB ID:	583689
    Click image for larger version  Name:	image_35358.jpg Views:	3 Size:	2.4 KB ID:	583690
    Click image for larger version  Name:	image_35359.jpg Views:	3 Size:	1.8 KB ID:	583691
    Last edited by Nautilus; 08-08-2017, 02:07 PM.

  • #2
    Grinding wheel on edge. Draw a line to follow and if you take your time you can get it pretty clean looking. Not sure the bolts will work to hold the height once you start loading the table and banging on things. A through pin would be better.
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    • #3
      You could buy tube that is made to telescope.
      You could build a rolling guide to keep your angle grinder at the proper height, clamp the tube to a flat surface and use a cut off wheel.
      You could (with the proper bushings), put a cut off wheel on a table saw and use the fence to maintain the correct spacing or build the equivalent equipment using your angle grinder to power it.
      IIRC you can buy tube with the weld seam already removed.
      You could fabricate the larger tube from flat bar to have the clearance you need.
      You could build a device to pull/push though the tube to cut the weld out.



      • #4
        Grinder with a slitting disc.

        Plasma cutter and a straight edge.

        Change to DOM tubing.

        Scrap the adjustable leg idea.


        • #5
          Metal-cutting circular saw, but I'd also try to use DOM tubing instead.


          • #6
            Keep in mind, once you slit that square tube, it won't be square anymore. It'll probably pop open and only be sort of square-ish.


            • #7
              Originally posted by ryanjones2150 View Post
              Keep in mind, once you slit that square tube, it won't be square anymore. It'll probably pop open and only be sort of square-ish.
              He could always clamp it back to spec and weld a piece of 1/8" x 1" band iron over the cut. That would have the additional benefit of covering whatever sins exist in the cut from view.


              • #8
                This seems like a lot of work for something that will not likely be used much. I can't think of ever wishing my welding bench had adjustable legs. But then again, maybe if I had adjustable legs on my welding table I'd use it all of the time.


                • #9
                  Thanks for all the tips. There are some really good ideas. I am inclined to agree that it is unlikely that my I will adjust the height much, but I was working on the theory that sometimes I would want to sit for delicate TIG work and then stand for pretty much everything else. The table is massively overengineered and I will need a car jack to lift it anyway, but is more just an experiment rather than anything else. Thanks again, I expect there may be a few more questions along the way! Cheers, Al


                  • #10
                    Have fun with it. It might have been easier to have an adjustable stool to move you rather than the table.


                    • #11
                      Unless you have an easy way of adjusting the legs, I would think a heavy table with adjustable legs would be a pain in the keester. But I'm not a spring chicken anymore, either. A friend of mine got tired of putting his welding table away, every time he had to park the cars in the garage, so we cut out the concrete in the floor, poured a recess to hold a cylinder and the table top, and when he wanted to weld, he'd plug in his compressor and raise the top up, then fold down the legs and weld away. When he was done, bleed off the cylinder and the top was flush with the surrounding floor.


                      • #12
                        Ha ha Meltedmetal, as I was writing my reply, I thought to myself, maybe a taller chair is a better option here! Still, I am too far down the track to turn around now. Metjunkie, that sounds like the ideal option which I am definitely going to keep in mind if I ever own my own home. I am renting at the moment, so those sorts of awesome (but extreme measures) will have to wait.


                        • #13
                          If I have a long cut in steel and I am using a wiz wheel is tack a strip of flat stock to it and rub the wheel right against it. Nice straight edge...Bob
                          Bob Wright


                          • #14
                            It's a welding bench, don't over think it. Sturdy and flat, that's what you need. If you need it taller, put a couple of cinder blocks under the legs.


                            • #15
                              Have you considered using uni-strut, to save you from having to cut the slot?