1/2 blind dovetails help needed

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Forum topic by kennyd posted 12-17-2011 11:00 PM 1281 views 0 times favorited 4 replies Add to Favorites Watch
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103 posts in 3142 days

12-17-2011 11:00 PM

Hi Everyone and Happy Holidays.

Let me start out by telling you that I have an Incra LS Positioner for my router table in addition to a Leigh D4 jig.

I’ve been trying to cut 1/2 blind dovetails for some drawers with both of these units but cant figure out what I’m doing wrong. The drawer front is 3/4” Oak and the sides and back are 1/2” Pine. No matter which system I use I can’t get the pins and tails to fit. Is it me or is it that dovetail jigs require that the wood thickness is the same for all of the parts? I have no trouble with either of the jigs when the parts are the same thickness. Can anyone tell me what I’m doing wrong?


-- Kenny... The man who needs a tool he doesn't have is already paying for it.

4 replies so far

View Don W's profile

Don W

18959 posts in 2709 days

#1 posted 12-17-2011 11:56 PM

what size bit are you using? I think for 1/2 inch blind dovetails you’ll need to use a 1/2 long bit. I had a similar problem and found out I was using the wrong size bit. I’ve since gone to cutting them buy hand, so I may not have the bit size incorrect.

-- - Collecting is an investment in the past, and the future.

View pintodeluxe's profile


5756 posts in 2955 days

#2 posted 12-18-2011 12:15 AM

If it looks like the sockets are too big or too small for the tails, then your bit height is set incorrectly. There is only one height for any given bit that will make a good joint. You can have 3/4” fronts, and 1/2” sides – no problem there. In fact that is standard in drawer construction.
I believe on the original D4 jigs, you have to cut the pins and sockets in two passes, whereas the new Leigh superjig and the Portercable 4200 series allow HB dovetails in a single pass.
Good luck

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View blackcherry's profile


3338 posts in 3965 days

#3 posted 12-18-2011 04:42 AM

Did you do the test fit first to set the bit height, check the inst. manuel for this important step. good luck

View tuffruss's profile


38 posts in 2525 days

#4 posted 12-18-2011 08:58 AM

If you have the leigh D4 you will to upgrade it to do Half blind in one pass. GO to the leigh website you can read the manual and they have the upgrade kit for $29.00. Hope this helps I just ordered it and the dust collection kit for my D4. Russ

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