Dovetails by jig - Woodworking Talk - Woodworkers Forum
 
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post #1 of 7 Old 04-03-2020, 04:09 PM Thread Starter
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Dovetails by jig

I have a P-C 4216 dovetail jig that has been set up according to the manual and multiple youtube videos. When I cut half-blind dovetails, the half pin on one side is wider than the half pin on the other side--by about .030 to .050". If I cut the joint on the right side of the jig, the difference is almost nil. Anybody have any ideas why this would occur? I'm ready to pull out my remaining hair.
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post #2 of 7 Old 04-03-2020, 06:44 PM
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I have the same jig set up.



it is absolutely required to first make a cut in each finger/tail/pin, then come back thru and "chase" the previous cuts.

what I suspect is a slight deflection due to left/right "handedness" of bit rotation (ala 'climbing cut') - no, it does not matter how careful you think you are being - my experience says: cut, then cut again.
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post #3 of 7 Old 04-05-2020, 07:20 PM Thread Starter
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Thanks for the tip. I'll try cutting through again on the next one. I did find out my router base plate was not centered. I re-centered it and it got better but still not perfect. I always keep the router oriented the same way and don't feed it too fast.
I got out an ancient craftsman jig that only cuts half-blinds that a friend gave me. The price tag on the box was $29.95. It is all plastic and cuts 1/2" dovetails on 7/8" centers. The first two I cut were absolutely perfect. Go figure.

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post #4 of 7 Old 04-07-2020, 03:56 AM
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I don't know the specific jig,but I have had the same experience with a router base guide bush not being concentric with the spindle.My dovetail jig is similar and very sensitive to the depth at which the tool is set.It also took a fair amount of fine tuning to get the stops at the sides set absolutely accurately.
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post #5 of 7 Old 04-07-2020, 10:41 AM
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the plates I use have precisely drilled holes that fit my router model exactly - they have essentially no play/slop.
there is a cone device that is very handy for centering (many manufactures - sample here):
https://www.homedepot.com/p/Bosch-Ro...1151/205412357


as to depth adjustments, I gave up on the cute little plastic tipped buttons.
stand router bit up, stack the waste piece + template on the plate, adjust depth so it _just_ catches on a straight edge.
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post #6 of 7 Old 04-08-2020, 02:07 PM Thread Starter
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I'll definitely give this technique a try. I'll let you know if that eliminates the operator error.
Thanks,
Dave
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post #7 of 7 Old 04-08-2020, 02:11 PM Thread Starter
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TomCT2, thanks. I had a devil of a time setting the depth so I started using a centering tool to mark the center of the workpiece and use a process like you describe to set router depth. The depth stops on the jig are useless, imho.
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