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Silk purse from a sow's ear

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  • Silk purse from a sow's ear

    I made this plate so I can accurately dial in my radial arm saw. Normally, this is done with a saw blade on the spindle, but even expensive blades aren't truly flat and the saw teeth make squaring up tricky. Since every adjustment relies on the previous one, stack-up error will occur.

    The plate is made from a new ductile iron stub axle our shop was discarding. DI wasn't my first choice of materials, but I couldn't beat the price.
    I turned the plate on my 7X12 lathe with a faceplate and finish ground it with an ersatz spindle grinder cobbed together from a Dremel tool, a piece of oak, a some creative clamping. Not pretty, but effective.

    The next project is to completely disassemble the lathe, clean it, and reassemble. I usually do this around Thanksgiving anyhow and iron chips get into everything!








  • #2
    Just how accurate does a radial arm saw have to be? Seems that a square against any blade would be good for woodworking tolerances. Bob.

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    • #3
      For some people it is a sense of pride in their work.

      And, as with metal working, the more accurate your cut, the easier it is to assemble, and the tighter the finished product is.

      Edit: I typically align cuts from a bar spanning the blade, so it 'covers' the kerf, issue is that some blades seem wobble on start up. Even with nice tight bearings, watching the edge of the blade on start up, shows what looks like an 'S' curve, goes away almost instantly but lasts long enough to see, and on some the cut is not where it should be.
      Last edited by kendall; 11-18-2013, 10:00 PM.

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      • #4
        They make excellent overhead grinders, too. Plunk an xy table on the saw table with a vise and with your work in it and grind away. Keep the motor stationary, of course.

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        • #5
          What woodworking tolerances do you have in mind? The tolerances applicable to building a shed, perhaps?

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          • #6
            Originally posted by Bob Fisher View Post
            Just how accurate does a radial arm saw have to be? Seems that a square against any blade would be good for woodworking tolerances. Bob.
            As said by OP....

            "Normally, this is done with a saw blade on the spindle, but even expensive blades aren't truly flat and the saw teeth make squaring up tricky. Since every adjustment relies on the previous one, stack-up error will occur."

            Having done this setup myself, I can vouch for what the OP said. Of course, yes, I was fussy... For instance, I prefer that the blade should cut a kerf no wider than the tooth width has to. I don't like to have the blade sidling through the wood like a Chevy sedan.
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              Sorry, I stand by my statement. A good square against a 10 in blade should be more than adequate for any woodworking joint. I have posted before about carrying over metal working tolerance to woodworking, and I can appreciate the desire for accuracy, but how square is square enough? Some of the finest woodworking was done without power tools of any type. Most likely by eye alone. Bob.

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              • #8
                Eh, whatever....

                "Hit's good enuf fer me an' it otter be good enuf fer you too, er yer jus' not rite in teh haid...."

                Takes all kinds and that's a fact.
                1601

                Keep eye on ball.
                Hashim Khan

                Comment


                • #9
                  Last year I bought the oddest radial arm I've ever seen. 16 or 20" metal cutting with powerfeed & the motor says 5 to 30 HP with an amp gauge built in.
                  "Let me recommend the best medicine in the
                  world: a long journey, at a mild season, through a pleasant
                  country, in easy stages."
                  ~ James Madison

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                  • #10
                    Originally posted by Bob Fisher View Post
                    Just how accurate does a radial arm saw have to be? Seems that a square against any blade would be good for woodworking tolerances. Bob.
                    How accurate does any machine tool have to be?
                    I set up my wood working machines to be as accurate as possible- it makes quite a difference in quality of cut and final fit and finish.

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                    • #11
                      Wow, I have to wonder will there be enough spindle sticking out to mount the blade, washer and nut????
                      I have an older Craftsman radial arm saw. With a good Freud blade mounted on it I've indicated the blade wobble at less than .005.
                      I did however grind both the hardened washers and the one side of the nut.
                      There is really no point in getting that fussy with the blade as the arm of the saw has more flex in it than the blade.
                      I like to be accurate with everything to and do tend to carry over my metal working tolerances to my woodworking.
                      At least you should get a nice fly wheel effect out of your disc. Maybe you could rig a disc brake caliper on it for fast stopping.

                      Will the guard fit over it?????

                      JL....................

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                      • #12
                        Originally posted by JoeLee View Post
                        Wow, I have to wonder will there be enough spindle sticking out to mount the blade, washer and nut????
                        ..................
                        At least you should get a nice fly wheel effect out of your disc. Maybe you could rig a disc brake caliper on it for fast stopping.

                        Will the guard fit over it?????

                        JL....................
                        Um................ I believe the disc is a fixture for alignment..... more accurate than a saw blade, if you have carbide teeth that stick out, they are hard to register on.

                        I nowhere got the idea he was intending to keep it in place when sawing....
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #13
                          Originally posted by JoeLee View Post
                          Wow, I have to wonder will there be enough spindle sticking out to mount the blade, washer and nut????
                          I have an older Craftsman radial arm saw. With a good Freud blade mounted on it I've indicated the blade wobble at less than .005.
                          I did however grind both the hardened washers and the one side of the nut.
                          There is really no point in getting that fussy with the blade as the arm of the saw has more flex in it than the blade.
                          I like to be accurate with everything to and do tend to carry over my metal working tolerances to my woodworking.
                          At least you should get a nice fly wheel effect out of your disc. Maybe you could rig a disc brake caliper on it for fast stopping.

                          Will the guard fit over it?????

                          JL....................
                          It's a measuring fixture, not meant to be used under power. Just a nice flat surface perpendicular to the spindle.

                          Comment


                          • #14
                            So if you take off the crooked blade and put on this "Micro" alignment device to set up your saw, what happens when you put your crooked blade back on? Way too much micro stuff going on here.
                            _____________________________________________

                            I would rather have tools that I never use, than not have a tool I need.
                            Oregon Coast

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                            • #15
                              LOL Not to mention that tightening the blade will probably throw it off as well. Now you claim there is a bending or movement of the blade at startup? Perfectly understandable but I'll bet dollars to donuts it's the torque of the motor spinning up the blade and the whole arm is moving.

                              I can appreciate being exact but for woodwork I have more variance with temperature and humidity than worry about a half thou of run-out on the blade.

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