Is this type of bevel cut safe?

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  • cgallery
    Veteran Member
    • Sep 2004
    • 4503
    • Milwaukee, WI
    • BT3K

    Is this type of bevel cut safe?

    In this book:



    The author demonstrates a method for making a box with mitered corners on all six sides. He cuts six pieces to size with the blade set to 90-degrees. Then, he sets the blade to 45-degrees, installs a sacrificial fence and moves the fence right up to the blade. Now he cuts a 45-degree bevel on all four sizes of each piece.

    I would think this would trap the cut-off between the blade and the fence, which I thought was a no-no. But on the other hand, the top of the blade is touching the fence and preventing the piece from lifting up. All it can do is shoot out the front, I would think at a low velocity. But I don't know for sure.

    You kinda have to be careful w/ these books. He didn't say in his introduction how many fingers he still has or whether he had any professional training. He could be a ya-hoo that was lucky enough to get his book published.
  • BobSch
    • Aug 2004
    • 4385
    • Minneapolis, MN, USA.
    • BT3100

    #2
    I assume he's using a miter gauge of some sort and so shoud NOT use the fence. The only way that's safe is to use an extra block on the fence that's short of the blade — butt the piece up to the block and then when you slide it toward the blade hold the piece in place with your hand. That way the cutoff isn't trapped by the fence.
    Bob

    Bad decisions make good stories.

    Comment

    • LarryG
      The Full Monte
      • May 2004
      • 6693
      • Off The Back
      • Powermatic PM2000, BT3100-1

      #3
      Originally posted by BobSch
      I assume he's using a miter gauge of some sort and so shoud NOT use the fence.
      That's true but something's not adding up here. If he's using a miter gauge, there's not only no reason for the rip fence but there's certainly no need for a sacrificial fence on the rip fence.

      cgallery, when you said cut-off, did you mean workpiece?

      This author has a number of titles under his byline; that doesn't necessarily mean he's not a yahoo, but it makes it less likely. Still, a lot of experienced woodworkers routinely do things that others regard -- and justifiably so -- as unsafe. (When was the last time you saw a table saw with a blade guard on a TV woodworking show?) A lot of folks do things because that's the way they were taught, or because they are comfortable with the amount of risk that's present, and sometimes they pass these things along without really giving what they're doing the thought it deserves. I don't know what the answer is to that one.
      Larry

      Comment

      • Stytooner
        Roll Tide RIP Lee
        • Dec 2002
        • 4301
        • Robertsdale, AL, USA.
        • BT3100

        #4
        My rule on keeping thumbs is like Bob describes.
        Use a miter guage or SMT. If its a large sheet, always move the fence to the opposite side. This means the large sheet should be riding the fence away from the cut. Small peices might be done safer with a SCMS or bandsaw anyway. When bevel cutting, the forces often prove to give poor results on a tablesaw. I think it is an aquired skill in itself. Practice these type cuts before trying it first with good material.
        Lee

        Comment

        • cgallery
          Veteran Member
          • Sep 2004
          • 4503
          • Milwaukee, WI
          • BT3K

          #5
          Originally posted by LarryG
          That's true but something's not adding up here. If he's using a miter gauge, there's not only no reason for the rip fence but there's certainly no need for a sacrificial fence on the rip fence.

          cgallery, when you said cut-off, did you mean workpiece?
          Nope, no miter gauge. He is sliding the material against the fence. With each cut, a small triangle (approx. .75" on two of its sides, minus the blade kerf) is created. I assume he pushes each one through with the next work piece. The cut-off is trapped by the fence on the side and the blade on the top. It can only come out the front or the back.

          These are larger six-sided boxes. So there is enough material to use the rip fence and keep it straight. My main concern is trapping material between a beveled blade and the fence.

          However, maybe it is okay. The beveled blade keeps the material from lifting in the first place. So no real danger of kick-back?

          I'll try to post a picture of what he is doing.

          Comment

          • LarryG
            The Full Monte
            • May 2004
            • 6693
            • Off The Back
            • Powermatic PM2000, BT3100-1

            #6
            Okay, I understand now (I think) how the cut is being made.

            Originally posted by cgallery
            These are larger six-sided boxes. So there is enough material to use the rip fence and keep it straight.
            Until the very end of the cut, maybe? Seems to me you then have a workpiece that's not being guided by anything at all.

            Be that as it may ... I don't think there's a huge potential for anything resembling true kickback with this setup. The offcut is not only very small in cross-section, but it's also (as you say) pretty well contained by the blade and the fence. Since it can't lift, it can only shoot straight back out toward the front of the saw and that sort of thing is typically low-velocity and harmless. Standing off to the side will take you out of the line of fire in any case. I would personally make the cut with a different setup (because of the guiding issue, above) but I don't see this one as being unusually dangerous.
            Larry

            Comment

            • scorrpio
              Veteran Member
              • Dec 2005
              • 1566
              • Wayne, NJ, USA.

              #7
              If the blade top is buried in the sac. fence, and its height is set so that top edge of workpiece rides against the fence just above the blade, there should not be a guiding issue.

              Comment

              • LarryG
                The Full Monte
                • May 2004
                • 6693
                • Off The Back
                • Powermatic PM2000, BT3100-1

                #8
                Originally posted by scorrpio
                If the blade top is buried in the sac. fence, and its height is set so that top edge of workpiece rides against the fence just above the blade, there should not be a guiding issue.
                That would be true if he was just beveling a portion of the thickness. But he said that the corners of the box are mitered, which I took to mean a thru cut, meaning the blade WOULD be raised higher than the top of the workpiece.

                The picture he said he'd try to post should help ...
                Larry

                Comment

                • scorrpio
                  Veteran Member
                  • Dec 2005
                  • 1566
                  • Wayne, NJ, USA.

                  #9
                  Originally posted by LarryG
                  That would be true if he was just beveling a portion of the thickness. But he said that the corners of the box are mitered, which I took to mean a thru cut, meaning the blade WOULD be raised higher than the top of the workpiece.
                  Said portion might be entire thickness minus 1/64" or so. Tilt the blade, then set its height just a hair less than workpiece thickness. Then move up the fence so blade's highest point is in fence plane. You'll still have about 1/64" of workpiece thickness riding the fence, but the result would be near identical to full bevel.

                  Comment

                  • LarryG
                    The Full Monte
                    • May 2004
                    • 6693
                    • Off The Back
                    • Powermatic PM2000, BT3100-1

                    #10
                    Originally posted by scorrpio
                    You'll still have about 1/64" of workpiece thickness riding the fence, but the result would be near identical to full bevel.
                    Until you fitted the two pieces together, at which point it would become immediately obvious you have a very poorly cut miter. A 1/64" "ledge" on each of the two pieces would form a noticable notch in the finished corner.

                    I'm still hopeful of seeing a picture.
                    Larry

                    Comment

                    • BobSch
                      • Aug 2004
                      • 4385
                      • Minneapolis, MN, USA.
                      • BT3100

                      #11
                      Originally posted by cgallery
                      ...The cut-off is trapped by the fence on the side and the blade on the top. It can only come out the front or the back...

                      However, maybe it is okay. The beveled blade keeps the material from lifting in the first place. So no real danger of kick-back?

                      I'll try to post a picture of what he is doing.
                      Any time I hear "trapped" my alarm bells go off. Unless I'm not following this correctly there's no way what you're describing could be considered safe. Yeah, a pic would help.

                      JMHO, YMMV
                      Bob

                      Bad decisions make good stories.

                      Comment

                      • Stytooner
                        Roll Tide RIP Lee
                        • Dec 2002
                        • 4301
                        • Robertsdale, AL, USA.
                        • BT3100

                        #12
                        Thats what I was thinking. good miter using the rip fence as a guide is very hard to do well. Especially if crisp corners are what you are after.
                        Lee

                        Comment

                        • cgallery
                          Veteran Member
                          • Sep 2004
                          • 4503
                          • Milwaukee, WI
                          • BT3K

                          #13
                          I've included a photo of the bevel cut which is shown in the book. Anyone care to comment? I realize getting the fence/blade set "just right" is the key. But safety is paramount.
                          Attached Files

                          Comment

                          • Anna
                            Senior Member
                            • Feb 2006
                            • 728
                            • CA, USA.
                            • BT3100

                            #14
                            Originally posted by cgallery
                            I've included a photo of the bevel cut which is shown in the book. Anyone care to comment? I realize getting the fence/blade set "just right" is the key. But safety is paramount.
                            From what I understand of the mechanism for kickback, it's the motion of the saw blade in the back (going up) that drives the piece towards the user when it is pinched, trapped, or caught by the blade. In this case, the saw is angled 45 degrees. If the piece is caught by the blade at all, it will be driven towards the fence. I might be worried about the front end being pivoted towards the saw.

                            Comment

                            • BobSch
                              • Aug 2004
                              • 4385
                              • Minneapolis, MN, USA.
                              • BT3100

                              #15
                              Still looks like an easy way to redecorate your navel. I'd rather use the SMT or miter guage and a block on the rip fence.
                              Bob

                              Bad decisions make good stories.

                              Comment

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