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Thread: Router jig question

  1. #1
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    Router jig question

    I have a porter Cable router jig and have made successful dovetail joints with it before. However, the last few days I am scratching my head bald trying to figure out why the pins come out too fat when cutting half blind dovetails.

    I am leaning toward the idea that the angle of the dovetail bit is not right. The book calls for a 7 degree bit and I think the one I have is more like 12 degrees.

    I have gone over and over the book and have all the right parts in place.

    Anyone experience this?
    I'm a certifiable tree hugger. (it's a poor mans way of determining DBH before cutting the tree down)

  2. #2
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    I think you will find that you must use the recommended bit angle to have them come out right , at least I Have to do that with my Omni Jig
    Chuck

  3. #3
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    Quote Originally Posted by Paul Downes View Post
    I have a porter Cable router jig ...trying to figure out why the pins come out too fat when cutting half blind dovetails.

    I am leaning toward the idea that the angle of the dovetail bit is not right. The book calls for a 7 degree bit and I think the one I have is more like 12 degrees...
    If it's the older 'fixed template' jig, then the bit you need is actually a 14 bit, which is what it sound like you already have.

    "Fat" pins usually means you've got the bit's cutting depth set incorrectly. Try moving the bit out about another sixty-fourth of an inch, and see if that makes a difference. A very small change in bit depth makes a big difference in the dovetail fit, so go in or out in very small increments.
    Jim D.
    Adapt, Improvise, Overcome!

  4. #4
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    I tried moving the bit up and down and there is no change. The issue seems to be that the bit angle is too steep. The manual calls for a 7 degree bit and I suspect I have a 14. I have the right bushing in and am using the right templet. I guess I need to go shopping.
    I'm a certifiable tree hugger. (it's a poor mans way of determining DBH before cutting the tree down)

  5. #5
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    Quote Originally Posted by Paul Downes View Post
    I tried moving the bit up and down and there is no change. The issue seems to be that the bit angle is too steep. The manual calls for a 7 degree bit and I suspect I have a 14. I have the right bushing in and am using the right templet. I guess I need to go shopping.
    Okay, I looked up the 4200 series jig on the PC site, and they do specify two bits, both of which are 7. You need those bits - or another manufacturer's equivalent - to make your jig work. The older jigs used the 14, which made a pretty steep tail.

    Apparently, the newer 4200 Series uses a shallower pitch - not unlike the Leigh, which uses 8 bits for some types of DT.
    Jim D.
    Adapt, Improvise, Overcome!

  6. #6
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    I looked up the jig also and got to wondering what happened to the bit which came with the jig. Found it after a little look around and the joints now fit. Feel like a lame brain. The old memory just ain't what it used to be.
    I'm a certifiable tree hugger. (it's a poor mans way of determining DBH before cutting the tree down)

  7. #7
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    That is why I have one router setup just for HB DT and the router is clearly marked in several spots so no one adjust it or change the bit on me.

  8. #8
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    along Al's thought process is to write the bit degree down on the jig paul so yu wont be a lame duck next time i also write down the height of the bit in the router so i can get close the first time threw if i am making them by machine.
    If in Doubt, Build it Stout!
    One hand washes the other!
    Don't put off today till tomorrow!

  9. #9
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    I may be slowly migrating to the Neanderthal dovetail method. One of my next projects is to build a workbench so I can easily clamp boards. I've been thinking about weather to go with square or round holes in the bench for dogs. Meanwhile the jig works O.K. but the joints in some materials seem to lack the tightness I want for that look where you get accused of being a craftsman.
    I'm a certifiable tree hugger. (it's a poor mans way of determining DBH before cutting the tree down)

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