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DIY bandsaw blade welding?

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  • DIY bandsaw blade welding?

    I might have a chance to buy some bulk (100-foot) bandsaw blade, in the size just about perfect for my Wells horizontal.

    I don't, however, have a blade welder. I do, however, have a TIG, among other things. If I made a quick and dirty little jig for holding the blade section straight as I welded them, how well do you think a carefully-done TIG weld would work- either fusion only or with a tiny bit of filler rod.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  • #2
    Bevel opposing thicknesses to make a lap joint and Silver Solder.

    Regards Ian.
    You might not like what I say,but that doesn't mean I'm wrong.

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    • #3
      I've TIG welded a few bandsaw blades, and it will work; but it takes a little experimenting. I didn't have as much luck with fusion as with stainless rods. I was getting too much undercut with fusion.

      Make sure to anneal after welding, and the blades should hold up fine.

      Kevin

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      • #4
        Originally posted by joeby
        Make sure to anneal after welding, and the blades should hold up fine.

        Kevin
        I wonder if that's where I screwed up? I tried MIG with mine and no luck.
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        • #5
          There have been a couple of posts by people who TIG welding, the anealing is probably what gets missed. The butt welders with the machines have an annealing cycle.

          For most, it is just as easy to bevel and silver solder.
          Jim H.

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          • #6
            Ya HAVE to anneal, no exceptions

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            • #7
              Originally posted by ahidley
              Ya HAVE to anneal, no exceptions
              I understand why to anneal so the joint stands up - but don't you then end up with soft teeth. Would tempering be better?

              As i understand it, blades rapidly deteriorate once a tooth is broken - puts a shock load on the next tooth, it breaks etc. I wondering if it makes sense to grind in a slight ramp into and out of this area of now softened teeth so the blade just rides in the is area and there are no soft teeth to go missing and start the deterioration?
              .

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              • #8
                Bandsaw blades will shed teeth if there's a gap large enough to get material into. A blade should have at least two teeth in the cut at all times. That in itself will prevent one missing tooth from causing too much grief, then there's the fact that the blade speed is probably high enough to keep you from stuffing in that much material at a time (unless you already have several teeth missing from the blade).

                I have had more trouble with broken saw teeth from the maintenance guys cutting sheetmetal on a 6p blade than from annealing.

                Kevin

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                • #9
                  I just use my torch and silver solder, I have also had good luck using regular Bronze brazing rods although that gets a bit tricky. Soldering with the torch works so well I hardly see the need to spring for the cost of a dedicated blade welder, nothing to it really.

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                  • #10
                    I thought the rule of thumb was 3 theeth in the material at a minimum.

                    When the blade is welded it is red hot. This means that it is now as hard as possible, (assuming its air hardening). Annealing takes some hardness away and adds some durability. this allows it flex vs snap off when its bent.
                    This is why hardening is a two step process. The teeth are still hard just not brittle hard.

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                    • #11
                      so how would one go about anneling the blade after its silver soldered?

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                      • #12
                        Anealing Bandsaw Blades

                        I was taught, and found to be true, that after induction welding a bandsaw blade, you heat the blade (at the weld area) to dark cherry red. If you heat it to bright red it will be too hard and break. I don't know but I would think that it would be the same for any other welding process, wouldn't you?
                        Jim (KB4IVH)

                        Only fools abuse their tools.

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                        • #13
                          To harden steel it has to reach the curie point, about or somewhat above 1300 deg F, transform to austenite, then quench relatively rapidly, thereby forming martensite.

                          Martensite formation leaves internal stresses and is itself brittle, so after martensite formation tempering is usually done, and soon.

                          Old time 45% silver braze filler (what I use) melts just above 1125 deg F
                          In silver brazing a blade with this filler, If you keep the blade to 1150 to 1200 degrees F, tempering (anneal) is not necessary. Just let it cool slowly.

                          -------------------------------

                          Several "modern" silver braze fillers do require 1300+ deg F (know your alloy)
                          and tempering will be required, because of the jig quickly sapping the heat when you take the torch away.

                          If you clean this joint and reflux and reheat in a way to JUST get to where the flux starts to melt, about 1000 deg F and manage a cool down time of half a minute, or a little more this should be somewhere close to the temper you need.

                          Reflux is not really required if you have a way to tell the temp.

                          Flux that has been over heated or hot too long takes longer to clean off.

                          Hth Ag
                          Last edited by agrip; 02-02-2009, 06:00 PM.

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                          • #14
                            I always just let it cool slowly and I have never had a problem doing it that way.

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                            • #15
                              I've been welding blades from 1/4 to 1" at school with a regular
                              Do-All blade welder. After the weld I aneal imediately, pretty bright
                              orange and then bump the switch at a slower and slower rate to
                              let it cool slowely. Then take the blade to wooden jaw vise and grind
                              the flash off with a Dremel (smothe the back edge too). The go back
                              and aneal again the same way, just in case the grinding caused it to
                              harden any. Been doing the blades for the wood shop 1/4 to 1/2
                              and the metal shop 1/2 to 1" now for a couple years.
                              Every now and then I get one (from the wood shop) that just won't
                              stay. I don't know if it's some crummy metal or what but they just
                              break again at the weld if I flex it. :-( The good bulk blade material
                              from Starret works fine. I always make up new ones to be at the
                              max limit of length so they can be trimmed and re-welded when
                              (not if with the kids using them) they break. :-)
                              ...lew...

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