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OT: time for a new table saw?

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  • #31
    So, the arbor belt pulley was, in fact, loose. I fixed that, but the saw still isn't working well. It starts out cutting fine, but bogs down as the board goes deeper into the blade. This is with trying to cut 3/4" particle board. I've checked the alignment of the blade and the fence and adjusted them. The blade looks well used, but not too bad. I should probably get it sharpened or buy a new one (or both). I'm wondering if I have a problem with the motor. Do they need any maintenance? Are there brushes that need to be checked / replaced? It's only a 1 HP motor. Maybe I should replace that too. Or, continue to keep my eyes open for a good deal on a good used cabinet saw.

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    • #32
      Originally posted by Paul Ebert View Post
      So, the arbor belt pulley was, in fact, loose. I fixed that, but the saw still isn't working well. It starts out cutting fine, but bogs down as the board goes deeper into the blade. This is with trying to cut 3/4" particle board. I've checked the alignment of the blade and the fence and adjusted them. The blade looks well used, but not too bad. I should probably get it sharpened or buy a new one (or both). I'm wondering if I have a problem with the motor. Do they need any maintenance? Are there brushes that need to be checked / replaced? It's only a 1 HP motor. Maybe I should replace that too. Or, continue to keep my eyes open for a good deal on a good used cabinet saw.
      A few thoughts on that.

      1.) Use a sharp blade, always.

      2.) Consider using a thin kerf saw blade with an added blade stiffener on your low powered saw. A thin kerf saw blade chops less wood in the kerf, does less work in making the cut, so at similar feed rate it uses less power. It has less structure, so vibrates more easily, but that can be ameliorated by using a blade stiffener which is a specialized thrust washer that is thicker at the rim than in the body. The added thickness preloads the saw blade axially deflecting it slightly in the direction away ftom the washer. That preload increases the force needed to increase that deflection, and it shortens the unsupported radius, both reducing the maximum amplitude of blade vibrations.

      3.) Do not adjust the rip fence exactly parallel with the blade. It should be very close to parallel, but the outfeed side should have slightly more clearance, no more than 1/32 inch difference. Stated another way, with the blade at maximum height, the teeth at the front of the blade should be roughly 1/32 closer to the rip fence than the teeth at the back of the blade. It should be close to parallel, but there will be some error, and that error should be on the side of slightly opening the gap toward the rear of the cut. That avoids the workpiece getting squeezed between the blade and the fence during a rip cut. Don't overdo that. Keep it slight.

      4.) Blade height requirements are different for various materials and cuts and blades, but...
      With carbide tipped saw blades, for most cuts, adjust the blade height so that the gullets between the teeth are aligned with the top of the workpiece. Rotate the blade to place a gullet at top dead center, adjust the blade height to place the bottom of that gullet even with the top surface of the material. Carbide tipped blades are designed to work best at cutting angles created by that height. The teeth near the front of the cut are doing all of the cutting, while the others drag through the kerf and generate heat. That blade height gets a lot of the teeth out of the kerf during the cut instead of dragging them through the kerf when not cutting chips. It also avoids setting the blade too high where teeth are working at inefficient angles. Excessive height can lift the rear of the workpiece which is part of the recipe for kickback, which can be very dangerous. And yes, that blade height is very different from what was used with old school blades without carbide teeth.

      Doing these will combine to create less drag in the cut, generating less heat, requiring less power, eliminating or greatly reducing any scorch in the kerf, and helping to make cleaner cuts.

      Woodworkers' Guild of America on topic of blade height:
      "Our Nation’s interests are best served by fostering a peaceful global system comprised
      of interdependent networks of trade, finance, information, law, people and governance."
      - from the October 2007 U.S. Naval capstone doctrine
      A Cooperative Strategy for 21st Century Seapower
      (a lofty notion since removed in the March 2015 revision)

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      • #33
        Sounds like you just need a sharp blade in there. The less powerful the motor, the more a dull blade will slow things down. If the blade you are using has carbide teeth, it will be hard to tell how sharp it is by feel, unless you have a lot of experience. Sounds counterintuitive, but it's true. There are lots of good blades out there for sale, but also some pretty bad ones. I've had the best luck in the past ten years with Diablo blades. Fortunately, they are reasonably priced. Many cheaper ones won't cut well right out of the package, and will dull really fast. I just replaced the blades in two saws at work today, with Irwin's newer blue blades as that's what the local lumber yard had. I've used them before and they seem to be pretty good. The prices are about the same as Diablo. I don't get to Home Depot or anywhere like that much these days, since it's well over an hour to the closest one and it's really small.

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        • #34
          I ended up with a somewhat thin Diablo blade on my little ancient 8" Craftsman saw. That size is not very popular, and selection was sparse. It cuts fine. Plywood, MDF, particle board, lumber.

          JRT seems to know a lot about the subject, just wanted to pimp the Diablo. I also have a Diablo on my old cheap Skil saw. Cuts great.

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          • #35
            Here are a couple more thoughts about your existing table saw. I have a 1990s Craftsman contractor's saw that I'm happy with, but I'm not sure if that's the model you have. If it is, I encountered some strange noises when the motor mounts loosened a bit. On my saw, the mounts are clamps around the ends of the motor. See below...

            Click image for larger version

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            Once I tightened them, my worrying noise problems vanished.

            If your belt has stretched, you may reach the limits for tensioning it, and that would bog cutting. On my saw, the motor's weight provides the belt's tension as it hangs from its pivoting mount. The slot in the mount must have some "daylight" left at the end, with the pivoting frame not bottomed out, or you won't be able to achieve enough belt tension. Also make sure that the motor can move freely as you swing it through its arc. It's possible that the bolt that goes into the slot arc is binding, not permitting motor weight to properly tension the belt.

            Those are just a couple of additional thoughts about the ongoing issue with your current saw.
            Bill Schneider
            -+-+-+-+-
            www.afterness.com/audio

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            • JRT
              JRT commented
              Editing a comment
              Another issue with old table saws is sometimes the belt is also old. An old belt, especially if unused for a long while, can take a set shape, and that can cause vibration in the types of saws that use only the weight of the motor to tension the belt, causing vibration when the saw is running. As compared to a conventional vee belt, a link style belt does not take as much of a set, and the link style belt can help to reduce vibration in the saw, but those also tend to increase noise level of the saw (runs smoother, but louder). 
              Last edited by JRT; 03-31-2021, 08:27 PM.
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