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Routing ?'s - What the books don't tell you

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  • Routing ?'s - What the books don't tell you

    Still practicing with my $48.00 GMC router which actually seems to be OK. Depth adjustment seems to be right on, etc.

    Anyway, I purchased a sheet of 3/4 Melamine particle board from HD that I plan on using to build an outfeed table for the 3650. Practicing with some scrap particle board (boy does that ever make dust!) cutting slots for the miter gauge.

    First question is, the only way I could tell where the router would make the groove relative its postion against the AIO clamp, was to make a test cut and measure from the clamp to the near edge of the groove; which in my case using the flat side of the base up against the clamp, is 2 1/4". So now I know that if I'm using a 3/4" straight bit, I need to measure 2 1/4" in from the guide clamp.

    Now since I'm new with routing I may not understand this correctly, but is this the procedure used, other than edge cuts, when using various other bits? That is to make a test cut and measure from the fence or guide as the case may be to determine where the cut's going to be?

    Last question is what bit do others use to make the t-slot ( I think its 7/8) after you route the 3/4" miter slot?
    You know, Hobbes, some days even my lucky rocketship underpants don't help.

  • #2
    Re: Routing ?'s - What the books don't tell you

    You can do the math to setup your fence relative to your dado/groove...

    Or... you can make a few jigs to greatly simplify the process:
    Attach a *straight* piece of scrap material (which is long/wide enough to clamp down) to a piece of 1/4" hardboard about 3 inches wide + the width of your scrap. (It needs to be wide enough to at least reach the edge of your bit).

    Hang this jig off the edge of your workbench and run your router with a 3/4" straight bit along that scrap piece (which is the guide fence on this jig) and you will cut off the hardboard at the exact location of the bit's path. I've attached a picture to help illustrate this, since my description is a little muddy.

    Now, you use that jig by placing the edge of the hardboard (indicated by the red line) along the precise line where you want the dado. Clamp it in place and run your router down the fence. No math or measurements involved!

    You can create multiple jigs like this for 1/2", 3/4", 1/4" or whatever sized bits you want and the edge of the hardboard will always show the precise cut line edge.

    Make a couple of these that are about 24" long and they about the right length for 90% of applications but still easy to store.
    Attached Files

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    • #3
      Re: Routing ?'s - What the books don't tell you

      Hooligan you can get t-slot router bits from Rockler or Woodcraft
      Hope that helps
      Last edited by jbergstrom; 05-31-2007, 06:02 PM. Reason: additional url
      Cheers! - Jim
      -------------
      All truth passes through three stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident. - Schopenhauer

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      • #4
        Re: Routing ?'s - What the books don't tell you

        hoolagan I made mine for a half inch bit and use two jigs, one for each side of the dado that way if your making dado's for plywood thats not a full 3/4" thick all you do is use the piece that goes in the dado to size the dado by clamping between the two jigs then make two passes. hope you understand what I'm trying to say, I have a hard time trying to pit it in words lol

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        • #5
          Re: Routing ?'s - What the books don't tell you

          Originally posted by Wood_Junkie View Post
          You can do the math to setup your fence relative to your dado/groove...

          Or...
          Thanks - that makes sense. I was looking for an arrow or slot like they have on circular saw to indicate kerf; in the case of the router - center of the collet.

          Originally posted by jbergstrom
          Hooligan you can get t-slot router bits from Rockler or Woodcraft
          Hope that helps
          I like Rockler's price, wasn't certain it was what I needed 'cause they didn't list the spec's.

          Originally posted by johnyreb
          hope you understand what I'm trying to say, I have a hard time trying to pit it in words lol
          It's not you but me.

          You lost me about the 3/4 ply. Why would thickness matter?
          You know, Hobbes, some days even my lucky rocketship underpants don't help.

          Comment


          • #6
            Re: Routing ?'s - What the books don't tell you

            The thickness of the "3/4 ply" matters because of the dado needed to fit it.
            If you are making shelves that are going to be dadoed into the sides of a cabinet for example.
            With your example of a slot for a miter guage on an outfeed table......it will be a full 3/4".

            Comment


            • #7
              Re: Routing ?'s - What the books don't tell you

              Originally posted by LONGHAIR View Post
              The thickness of the "3/4 ply" matters because of the dado needed to fit it.
              If you are making shelves that are going to be dadoed into the sides of a cabinet for example.
              With your example of a slot for a miter guage on an outfeed table......it will be a full 3/4".
              What he's trying to say is, plywood is undersized. 3/4" plywood isn't truly 3/4" thick. It's more around 22/32" - 23/32", whereas true 3/4" is 24/32". So if you rout a true 3/4" dado, plywood will be loose.

              To elaborate on what johnyreb is describing.... Make two of the jigs in the picture I posted. Face them towards eachother but put your material between them and then clamp them in position. This creates the precise width you want. Run your router on one fence, then back against the other and you'll create a cut the width of your material. This is a great technique, but relies on two things that can go wrong: 1) you have to get two separate fences to line up parallel along the entire path of your dado. This is ok, if 2) your scrap spacer material is perfectly straight and nothing shifts.

              I prefer to use a single jig approach, but it also involves your actual material to get perfect sized dados.
              There's a good short article on FWW that describes this with a picture, but you have to be a subscriber to see it, even if I link it.. so here goes with a description. It allows you to get perfect sized dados for *whatever* you're going to put in that dado. You can setup some a great jig for this, once you understand the basic concept. I'll come back to that jig...

              Put on a clamping straightedge. Put a (true) 1/2" spacer along the length of the straightedge (1/2" MDF suffices). Insert a 1/2" straight bit in your router. Route your dado, using the 1/2" spacer as your guide fence. This will give you a 1/2" wide dado, ok?

              Now, remove the 1/2" spacer and replace it a spacer of the material you are creating the dado for (for example 3/4" plywood... actually 23/32"). You do NOT change your router bit.

              The exchange of the 1/2" spacer for the 23/32" spacer moves the *FAR* edge of the router bit by the difference between the two materials. In this case, it widens your dado by 23/32" minus 16/32", so 7/32". When you run your router back, against the new 23/32" thick fence you are creating a dado that is the precise width of... ta da! 23/32".

              You can do this same thing with a 1/4" bit and a 1/4" fence to start... or with a 3/4" bit and a (true) 3/4" spacer. The important thing is the bit and spacer must match to start.

              Two things to keep in mind:
              1) When you do the second pass you most likely need to take the router in the opposite direction!! Make sure you aren't climb cutting. The second cut isn't a "true" dado cut anymore, since there's only one edge. Make sure you're feeding against the bit rotation.
              2) Try to keep the same point of your router base against the fence.. No guarantees your router base is 100% equally round, and rotating the base as you go possiblly introduces waves into your dado.

              Now, if the above made sense and you can imagine it.. go back to my original reply with a picture and make that jig. BUT, instead of cutting the hardboard off at the normal bit location, put in that 1/2" spacer and make the cut with a 1/2" bit. Now you'll have a jig that allows you to precisely align and see one edge of your dado. And then you're in business!
              Last edited by Wood_Junkie; 06-03-2007, 11:57 PM.

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              • #8
                Re: Routing ?'s - What the books don't tell you

                Wood Junkie: Your approach sounds very good. I measured the "3/4" ply at HD and Lowes this past week (Sandply, Classic Birch, Furniture grade Birch and Oak, Pine BCx). The pine BCX was 23/32. The stuff listed as 23/32 was only 21/32 (1/32" over 5/8"). IMHO, calling it 3/4 is fraudulent.
                Your approach will ensure the correct dado, tho, regardless.

                Good tip

                Go
                Practicing at practical wood working

                Comment


                • #9
                  Re: Routing ?'s - What the books don't tell you

                  Originally posted by Gofor View Post
                  Wood Junkie: Your approach sounds very good. I measured the "3/4" ply at HD and Lowes this past week (Sandply, Classic Birch, Furniture grade Birch and Oak, Pine BCx). The pine BCX was 23/32. The stuff listed as 23/32 was only 21/32 (1/32" over 5/8"). IMHO, calling it 3/4 is fraudulent.
                  Isn't it though! The stuff has gotten thinner, too. But, I think companies get away with it because lumber is "dimensional"... a term I equate to "bite-sized"... Sounds like a feature, but really they're just giving you less for the price. Same mess with 2x4s. Lately, they're not even 3 1/2" x 1 1/2".

                  This is one of the main reasons I've come to like MDO (and MDF) for certain projects. When it says 3/4" it is precisely 3/4". Same with the other sizes. Makes it a LOT easier to sketch up a plan with accurracy, and not be left scratching your head when the darn thing is 1/8" out of whack.
                  Last edited by Wood_Junkie; 06-05-2007, 02:09 PM.

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                  • #10
                    Re: Routing ?'s - What the books don't tell you

                    Originally posted by jbergstrom View Post
                    Hooligan you can get t-slot router bits from Rockler or Woodcraft
                    Thanks for the links. I see that they sell extruded t-track, too. Does anyone know if their t-track is the same dimensions as the 3650 t-slots? I could not find complete specs. I am finishing up my router table insert and would like to add an aluminum t-track that the Ridgid miter gauge will slide into.

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                    • #11
                      Re: Routing ?'s - What the books don't tell you

                      Originally posted by VegasGuy View Post
                      Thanks for the links. I see that they sell extruded t-track, too. Does anyone know if their t-track is the same dimensions as the 3650 t-slots? I could not find complete specs. I am finishing up my router table insert and would like to add an aluminum t-track that the Ridgid miter gauge will slide into.
                      Here's Rockler's version: http://www.rockler.com/product.cfm?O...Select=Details
                      It does NOT have the "T" slot shape, so the Ridgid stock miter guage will not work in there.

                      Here is Woodcraft's version: http://www.woodcraft.com/family.aspx?familyid=3782
                      It DOES have the "T" slot shape and specifically says it works with most table saw miter guages. So, there ya go.

                      Comment


                      • #12
                        Re: Routing ?'s - What the books don't tell you

                        Originally posted by Wood_Junkie View Post
                        What he's trying to say is, plywood is undersized. 3/4" plywood isn't truly 3/4" thick. It's more around 22/32" - 23/32", whereas true 3/4" is 24/32". So if you rout a true 3/4" dado, plywood will be loose.
                        ... And then you're in business!
                        Sorry for the delay in responding. Excellent tip. And very complete. Thanks for taking the time.
                        You know, Hobbes, some days even my lucky rocketship underpants don't help.

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