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Bandsaw blade direction - does it matter?

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  • Bandsaw blade direction - does it matter?

    I am working on a Marvel 612 horizontal band saw. It is now 3-phase but I'm planning to change it to a 1-phase motor. The replacement motor will probably be a non-reversible motor that turns opposite the original direction. As I received the machine, the blade cuts left to right, pulling the teeth toward the right end, where the motor is. This is just the opposite of my Jet 4x6.
    Is there any reason I can't reverse the motor, and the blade, and let it cut right to left?

  • #2
    My VERY old Tiwanese built 4X6 cuts from left to right, facing the blade. This puts the cutting pressure on the fixed jaw of the vise.
    Steve

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    • #3
      Originally posted by Rex
      Is there any reason I can't reverse the motor, and the blade, and let it cut right to left?
      Technically no, as long as you have the teeth pointing in the correct direction. However, as Steve pointed out you really want the pressure to be toward the fixed jaw.

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      • #4
        That makes ,sense, I had not considered that.

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        • #5
          It was my sense as well that the force should be towards the fixed jaw, but as I think about it and my assumptions I'm not sure it's as important as it might be for a other machines. In a mill, the vise is very carefully aligned to be the reference for straightness and squareness. The band saw vise is certainly squared up but nothing like a mill. The incremental additional pressure from cutting would be practically insignificant I think compared to clamping force, so maybe cutting direction for a band saw just isn't significant - provided the teeth point in the direction of blade travel.
          .
          "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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          • #6
            You should pull through the cut with the drive wheel. Not pull around the idler wheel. Not clear from your description if this would be the case or not.

            Difference will be in the first case cutting forces absorbed in a much shorter length of band and cutting forces subtract from idler load. Second case forces absorbed around most of the band length with the result of less rigidity and forces are added to idler load. To compensate you may find you need to increase initial band tension.

            Whether this argument matters from a practical standpoint you'll have to try it and see.

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            • #7
              OK, looks like the preponderance of evidence indicates the teeth should travel toward the drive pulley/vise fixed jaw

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              • #8
                If you can't get a motor that turns the correct direction & the pulleys are or can be made far enough apart you can flip the belt so it's a figure 8. If this is a chinese saw they're to close. This is not the proper way but if nothing rubs & it's a long enough belt it will work.
                Last edited by flylo; 07-03-2012, 03:20 PM.

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                • #9
                  Originally posted by flylo
                  If you can't get a motor that turns the correct direction & the pulleys are or can be made far enough apart you can flip the belt so it's a figure 8. If this is a chinese saw they're to close. This is not the proper way but if nothing rubs & it's a long enough belt it will work.
                  I sure would not have thought of that. But I've got motor choices, and the pulleys are too close anyway.

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                  • #10
                    Build a bracket/mount and install the motor facing the other direction?

                    Pops

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                    • #11
                      Why change out a perfectly good motor?? RPC, static phase converter or VFD will solve the three phase issue.

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                      • #12
                        X'2 for the VFD suggestion,they keep getting cheaper and you end up with variable speed capability.
                        I just need one more tool,just one!

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                        • #13
                          Most 'non-reversible' motors can be reversed fairly easily, although it requires changing connections inside the motor. If you have access to a motor shop, they may do it very reasonably.
                          Don Young

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                          • #14
                            After having done quite a lot of work a few years ago on bandsaws, bloody big ones that had 1 1/2 Tpi and worked closely with Lennox I learnt quite a few things.

                            Whilst I can see the reasoning behind cutting onto the fixed jaw in practice it doesn't matter as once the vise is tight they are both fixed.

                            If they aren't you have serious problems.

                            What happens in cutting the usual way L to R is the blade is tilted down hill towards the fixed jaw, the larger the diameter the more the tilt.

                            Now if the blade decides to grab by virtue of the angle of cut it digs in resulting in a stall or broken teeth.

                            However if you cut R to L the blade is cutting uphill and any grab tend to lift the blade out of the work.

                            Since changing my large bandsaw over to R to L blade life has increased.

                            This only applies to horizontal saws, if you are using the generic 6 x 4 saw and need to cut in the vertical mode at any time then you need to keep to L to R or the blade will lift the work off the table. If you never use the vertical mode then it's OK to swap.

                            R to L also means a cleaner machine as the chips fall clear into the pan.
                            .

                            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                            • #15
                              Originally posted by strokersix
                              You should pull through the cut with the drive wheel. Not pull around the idler wheel. Not clear from your description if this would be the case or not.

                              Difference will be in the first case cutting forces absorbed in a much shorter length of band and cutting forces subtract from idler load. Second case forces absorbed around most of the band length with the result of less rigidity and forces are added to idler load. To compensate you may find you need to increase initial band tension.

                              Whether this argument matters from a practical standpoint you'll have to try it and see.
                              I would think this would matter the most... Also if you drive it into the cut, only the idler tension spring will try and pull the bandsaw into the cut, meaning if its overpowered you'll get the bandsaw blade hopping around or something else nasty... Not to mention as you said, all the driving force is going to be *removed* from the tension of the blade, instead of added
                              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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