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cutting accurate 45 degree with Ridgid miter saw

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  • cutting accurate 45 degree with Ridgid miter saw

    Recently purchased Ridgid miter saw ( R4120 ). Was happily cutting 45 degree angles for picture frames, all was well untill glue up, first three were seemingly properly aligned and tight, final joint there was gap. I am assuming that means I did not cut them at aprecise 45 degree angle. I alined the blade, miter fence and bevel the best I could. Is there a tip or suggestion as to how to cut a perfect 45 degree angle that would give me a perfectly alinged picture frame?

  • #2
    Re: cutting accurate 45 degree with Ridgid miter saw

    Hi Don,

    Welcome to the Ridgid forum!

    All saws are different of course, but my 10-inch Ridgid CMS came properly aligned right out of the box. I haven't read any complaints regarding normal miter cuts with any of the Ridgid CMS's... although there have been several "compound" miters complaints.

    First and foremost challenge to any saw is proper alignment and once that is achieved, even the slightest movement of the stock can throw off your cut. For something like a picture frame, alignment error is amplified four times... even off a fraction of a degree will add up to a significant gap by the time you add all four corners together.

    The key to proper alignment is the tool that you use to check your setup. Tri-squares, framing squares, and certainly speed squares are notoriously "off" the mark. I know I must have searched through a couple of dozen framing squares before I found one even close to accurate.

    To go along with that, I have an "Empire" brand tri-square and their aluminum (Best) speed square and neither of them is accurate enough to guarantee that mitering a picture frame would be successful.

    Your best bet is probably to look for a good-quality machinist square or a good brand of drafting square (I'm thinking Dietzen, if they're still on the market). Bottom line is that your "precision" setup can't be, unless you have a significantly precise instrument with which to measure.

    I hope this helps and good luck,

    Last edited by CWSmith; 08-30-2010, 04:35 PM.


    • #3
      Re: cutting accurate 45 degree with Ridgid miter saw

      Perfect Miters are a challenge.

      I agree with CWS that stock movement is a problem. So you can start by clamping your stock.

      Of equal importance is blade deflection. When cutting a 45 through moldings in particular, there are slight side forces developed that can throw your cut off. So lower the blade very s-l-o-w-l-y and deliberately during your cut. And use a light touch on the saw. Yes, even the best saw can and does deflect away from true under a heavy hand.

      On my 12" dewalt radial saw, I prefer a simple fixture rather than moving the arm. But I haven't found it necessary on the CMS - at least on my particular CMS.

      A good square is essential. If you have squares that are not truly square, the way to make them square is to peen the blade close to the fence. There's not a lot of point to a square you can't trust.

      Some people have luck with a jig that perfects the cut edge using a stationary belt or disc sander. I've done this... it is painstaking to set up but once correct, the parts will all be correct.

      If all else fails, there is a special purpose manual miter trimmer that works like a horizontal wood guillotine. It's called the Lion trimmer and is specifically for this problem. You use your saw to get it close and then use the trimmer to shave it to a perfect 45. Grizzly has a clone.... but if you can, Buy American!!

      Count your lucky stars you're not trying to get perfect 45 miters in tile on a tub saw! That makes wood look easy!!

      Good luck.



      • #4
        Re: cutting accurate 45 degree with Ridgid miter saw

        In my opinion the best way to truly "dial in" a miter saw is not by using a square. It is by using test cuts. Here is a document that might be of help:


        • #5
          Re: cutting accurate 45 degree with Ridgid miter saw

          i am planning to buy a miter saw but just didn't expect i have to calibrate the saw myself. May i know how often do you guys calibrate the machine? thx~


          • #6
            Re: cutting accurate 45 degree with Ridgid miter saw


            Welcome to the Ridgid forum.

            While there are the occasional errors in manufacturing, I think most CMS's are properly aligned and setup, right out of the box. I know that was the case with my Ridgid 10" CMS.

            But like any precision tool, they can get knocked around in shipping and of course, if you are hauling the thing in and out of your pick-up and it works hard and travels from one worksite to another... it can get knocked around.

            Such treatment will of course cause any machine to loose it's alignment and therefore it probably needs to be checked everytime you setup.

            For us homeowner guys, the same thing applies... but of course our movements are only a fraction of the day-to-day activity that the tradesman have. The more you subject your tools to abuse, the higher the chance of an alignment problem and the more you need to pay attention to maintenance and re-alignment.

            There are of course, those particular models or brands that simply have a design problem and/or a consistant error in its manufacture. With Ridgid, it appears to be in the tool's ability to do absolutely accurate bevel cross-cuts. At least that seems to be a common complaint. On my particular unit, I've found that such cuts aren't perfect, but I've also noted that there is enough variation, that much of the problem is simply ME!

            (If any cut is consistantly off... then it's probably the tool and hopefully re-alignment or part replacement may be in order... but, if the "off" varies and sometimes it's perfect and at others it just a little, then more, then less.... then that is a very good indication that it is the operator.)



            • #7
              Re: cutting accurate 45 degree with Ridgid miter saw

              I like Ridgid as a good value but I must say their miter saws have never worked out for me . I tried 3 times with different models and never had one that consistently cut accurate angles. I think it was due to the machining of the base and or fence. Run out of the arbor bearing was also an issue. the worst saw was the 12" SCMS. I now have a DW706, DW717[most used by me] ans a Milwaukee 12" digital SCMS which is very accurate for miters w. the digital readout. Sold my ls1013l Makita but that was an excellent saw too. Some companies just make certain tools better. My JP610 Ridgid is excellent for example.

              I find if the saw does not hold its settings barring abuse say in transport, or can not be set easily, often it is the manufacture and or design. Look at the base and fence carefully to be sure they are dead flat, parallel, or perpendicular depending on the case. Sliding fences can also be inaccurate .

              The DW718 is not a good saw but the newer 10" DW717 is for example.


              • #8
                Re: cutting accurate 45 degree with Ridgid miter saw

                I agree a good quality square is critical chek Woodpecker , Incra square, or Starrett squares.. but what I have found that works is to cut the 45 about a 1/4" too long then trim it slowly to your line this lets the blade run more free so to speak and this helps .. I hope it helps Ya out


                • #9
                  Re: cutting accurate 45 degree with Ridgid miter saw

                  Originally posted by tomapple View Post
                  In my opinion the best way to truly "dial in" a miter saw is not by using a square. It is by using test cuts. Here is a document that might be of help:

                  A helpful guide for MS setup but I wonder if the order of adjustments is correct. I think squaring the blade to the table at 90° would be the first step, then square to the fence at 90. Third would be 45° to the fence and lastly 45° to the table.

                  I think if you follow their order of operations the blade could be out of sq with the table when you are trying to set the 45 stop. Also during the test cut where you are making 4 mitered pieces to form a frame, you need to work with either 45 left or 45 right. If you were to swing the blade to the other side to make some of the cuts, you will introduce error into the operation and you'll never get it tuned. Same would apply for an actual workpiece, not just the test cuts.

                  As others have said lay a known good straight edge across the table and check for flatness. Also check the fence halves as one, lay the straight edge across both fences and see if they are in the same plane.
                  "It's a table saw, do you know where your fingers are?" Bob D. 2006



                  1/20/2017 - The Beginning of a new Error


                  • #10
                    Re: cutting accurate 45 degree with Ridgid miter saw

                    If your really looking for accuracy in cutting picture frames I would use a sled on the table saw. A simple google search of " 45 degree table saw sled" should turn up what you need.

                    But, if you need to use the miter saw, your biggest issue is going to be slipping stock. Either place sand paper or tape on the fence to prevent it from slipping. You could also either wet the back of the piece of wood, or clamp it to the fence.

                    Hope it helps,