Announcement

Collapse
No announcement yet.

Concave saw blade.

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Concave saw blade.

    I've recently noticed the blade that came with my TS2424 is slightly concave (dished) on the left side (pulley side when blade is installed). I became aware of the concavity when I started making cuts with it. Although the blade is set perpendicular to the table surface using a square against middle of the blade's protruding disk, the cut ends up off perpendicular by what I estimate to be 0.5 degrees. What is happening is the blade's teeth are not travelling in exactly the plane formed by the blade's protruding disk. The concavity is perceptible when a straight edge is placed across the middle of the blade. The maximum deviation looks to be about a 1/64". Can this problem be corrected with blade stiffeners or should this blade really be replaced? The blade is the 10" Ridgid 40-tooth carbide combination blade with the feed/chip limiting profile. Looks identical to the Sears C200 combination. In addition, the table saw was a demonstrator at Home Depot before I purchased it, could improper cutting by sales staff do this to the blade? Would this void the Ridgid warranty on the blade?

  • #2
    Expecting the plate of a blade to be in plane with the cutting teeth is an error, Dave. A very, very common error, I might add.

    Your blade may or may not have a problem, but you cannot measure from the plate to tell. The blade manufacturer may decide to cup, taper, or otherwise obfuscate the plane of the plate for various reasons (deflection under heat and sound control being two that I'm familiar with).

    Go ahead and readjust your perpendicular stop to reflect what is actually being cut, and then judge if your cut quality is proper. Betcha you are fine. [img]smile.gif[/img]

    Dave

    Comment


    • #3
      Another reason a blade may track cocave is the washer surface at the shaff may not be the same on both sides of the blade this can be caused by wear on the shaft contact washer which is buildin to the shaft bearing surface you made need to check this point for wear sometimes you can corect this problem by using new dampering plates on both sides of blade it the problem gos away you will have a smaller kerf from the blade this problem may not hurt you now but you may lose control of your cut and put unessary stress on the bearings
      Dave the toymaker

      Comment


      • #4
        How many Daves do we have here???

        Anyway Dave L., let me know via email if you are still having trouble and I'll see what I can do for you.

        Jake

        Comment


        • #5
          Dave A.: Isn't this the reason why the books tell one to check for parallelism of the blade to the miter slot by reference to the same tooth at both the front and the back, rather than using two different points on the blade?

          Comment


          • #6
            RGad, actually no, there's a different reason for that. You use the same tooth to eliminate any blade runout from influencing your alignment. Using different teeth, in the worst case, would cause you to misalign by twice the total indicated runout of your blade. That could be a serious problem.

            For measuring perpendicularity, I know of no better test than to crosscut a straight and four-squared piece of wood, and turn the offcut over. When the cut edges are butted back together, a perpendicular cut will fit exactly back together.

            Dave

            Comment


            • #7
              Thanks everyone for replying.

              - The arbor washers on my TS2424 are in good (like new) shape and the same size, so there is no arbor induced concavity. The blade remains concave after removal from the table. I had some one suggest I put a larger washer on the concave side and tighten the arbor nut to reduce the concavity. I don't like the idea of that much tightening on the arbor and that flatness depends on nut pressure.

              - I didn't know that manufactures would intentionally make concave blades. Brings many thoughts to mind. All the devices for directly measuring blade tilt like squares, inclination meters, and protractors would have their accuracy diminshed. Manufactures would need to specify the angular degrees of dishing (hopefully on the blade plate). Blade stiffeners would need to be avoided. Since my blade is a Ridgid blade it should be possible to find out from Ridgid if the blade was manufactured concave. I'll be contacting Mr Schnarre.

              - RGad, alignment of the blade to mitre slot was done using the one marked tooth method as outlined in the manual. My trouble is measuring blade tilt angle relative to the table top. A concave blade adds an unknown angle error to any direct measurement. An error I like to do without. Kerf may suffer but imperceptively with the small deviation I have.

              Comment


              • #8
                Jake or Dave A.,
                I adjusted my TS2424 to 1/1000. How,ever I used the original Ridgid blade. I mainly adjusted it because when the blade slowed down I could visually see it wobble. I thought by aligning it with a gauge would help this. I can still se some wobble. Is is the blade that is bent? The arbor was off by 1/1000 when I checked it but that would not be noticable.

                Also, if it's the blade. Since I aligned the saw with a maybe bent blade, does this mean it is still out of alignment. Do I need to borrow the gauge again if I need anew blade? Or is it good to go?
                Justin

                Comment


                • #9
                  Dave A.:

                  Good points.

                  RGad (a/k/a Bob)

                  Comment


                  • #10
                    Justin,

                    Being able to see blade wobble as the saw slows down does not necessarily mean that there is something wrong with the saw or the blade. The arbor on your saw is within spec (which is 1/1000 runout). Multiply this times 5 to reach the outer rim of the blade and you have .0005 runout. Most blades have a runout of some where between .0006 and .0008 at the edge. Adding those two togather your will get a possible run out of .0011 to .013 which is enough for your eye to catch at certain speeds.

                    I would use my dial indicator ad set it near the outer rim of the blade (just below the cuts) and check the runout. Also the heal adjustment will not have any effect on blade runout.

                    Jake

                    Comment


                    • #11
                      Thanks Jake
                      Justin

                      Comment


                      • #12
                        "I adjusted my TS2424 to 1/1000."

                        Adjusted which part? By using the "one tooth" method previously mentioned, blade runout makes no difference at all to aligning the trunnions to the miter slot. You could literally hacksaw all but one tooth off, because that is all you use.

                        Please note that Jake accidentally added a zero in his decimal numbers, a very easy thing to do. A blade running out at less than 8 ten-thousandths is very flat indeed. Twelve hundredths is the maximum allowable called out by Mark Duginske in "Mastering Woodworking Machines", but for some blades that is really too much.

                        I only measure things like blade runout when someone asks me to. Otherwise, the way I tell if a blade works properly or not is pretty simple. My tablesaw works very well, this I know from good cuts. If I get a new blade, and it doesn't cut as well as the ones I already have, it goes back.

                        Comment


                        • #13
                          Dave: real simple. Don't use a blade to check alighnment. Many companies now sell a machined flat (read square) plate that is within .0005 across. That's 5 tenths. Then there is no question about inaccurate alignment from a slightly skewed saw blade. Just my 2 cents
                          He who dies with the most power tools wins!

                          Comment


                          • #14
                            How often do you have it certified, Dawg?

                            Dave

                            Comment


                            • #15
                              <BLOCKQUOTE>quote:</font><HR>Originally posted by Dave Arbuckle:

                              Please note that Jake accidentally added a zero in his decimal numbers, a very easy thing to do.
                              <HR></BLOCKQUOTE>

                              OOPS!!! I usually need to say to myself tenths, hundredths, thousnadths, to make sure I have the correct decimal spacing. Guess I didn't do that this time...

                              Jake

                              Comment

                              Working...
                              X