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BoxJoint question.

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Forum topic by Psydoc posted 04-14-2019 06:55 PM 357 views 0 times favorited 6 replies Add to Favorites Watch
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Psydoc

2 posts in 8 days


04-14-2019 06:55 PM

Topic tags/keywords: boxjoint korschgen

I have been unsuccessful at creating reasonably good box joints consistently. I am trying to use a technique I saw being used called the Korschgen box(?) His jig uses wood pieces cut in the width of his dado blade. These pieces are lined up blocking a carriage. He lifts a wood piece and then moved his carriage – cuts and then moves another piece and so on. I’m using a 1/4 ” dado blade so I imagine I would need each board to be 1/2 ” – correct? Also, in a setup like that, how would you adjust for the size of the gap next to the finger?


6 replies so far

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dbw

270 posts in 1967 days


#1 posted 04-14-2019 08:38 PM

check this out:

https://www.thesprucecrafts.com/how-to-make-perfect-box-joints-3537042

-- measure 3 times, cut once

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waho6o9

8626 posts in 2908 days


#2 posted 04-14-2019 08:53 PM

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JohnDon

87 posts in 1500 days


#3 posted 04-14-2019 10:05 PM

Okay, I’ll try to answer your question the best I can, rather than giving you an alternative jig design. From the video that Korschgen has posted, it appears that each of the “flippers” has to be exactly twice the width of your dado setup. Also, each flipper has to butt up tightly against its neighbor. You didn’t say how your joints aren’t fitting. If some fingers are tight, and some loose suggests that the flippers aren’t all the same width, or warped, or debris is getting trapped between them. If the fit is consistently too loose, the flippers are less than twice your dado width. If the fit is too tight, they’re wider than twice your dado. I don’t know how the jig adjusts for the matching fingers. My guess is that when you clamp that piece in the jig, you offset the alignment with a spacer exactly the width of your dado.The design of the jig is interesting- once you have it tuned up, it should go faster than the “mainstream” setup previous posters refer to. The width of your joint is limited by the number of flippers, while the typical jig has no theoretical limit to th number of fingers. Good luck!

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Psydoc

2 posts in 8 days


#4 posted 04-15-2019 09:41 PM

Thanks for the reply! I was thinking that the flippers could have a small spacer after each flipper that could make the fingers tighter or loose. I’m also wondering if it would be much simpler to just make a notch every 1/2 inch (for a 1/4” dado) and move the carriage over to the successive notches.

BTW, I have recently taken up woodworking and prior to starting this hobby, my only tool was a hammer which I rarely had use for.

Again, the replies were appreciated.

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Redoak49

3883 posts in 2319 days


#5 posted 04-15-2019 11:53 PM

I will give you a couple of thoughts…

1. I have never been very successful making them on the table saw.

2. I made a jig to use on my router table which uses a key and I can easily adjust the distance between cuts by small amounts.. I have made 1/4”, 5/16” and 3/8” finger joints with this method.

3. With the router table method, I found that different species of wood need slightly different settings to get best fit.

4. I now make finger joints using a Leigh D4R jig.

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Woodbum

866 posts in 3396 days


#6 posted 04-16-2019 10:22 AM

IBox

-- "Now I'm just another old guy wearing funny clothes"

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