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Making a Box Joint Jig - UPDATED

Box Joints are one way of connecting corners in woodworking. They look great and when they are glued together they make a very strong joint which makes them suitable for drawers and boxes, especially ones that get high usage. The problem with most box joint jigs is that they are often finickity to use and very often will only make one, or at the most two sides at the same time. From what we have been able to gather, this jig was originally conceived by Lynn Sabin and later modified by others.
  We have taken the original plans and modified them yet again, by primarily making the base much wider. The advantage to making the base wider is that the jig can now be adapted to cut wood flat side down. This means a type of weave pattern can now be cut into wood and not just on the edges.
Anyone who has tried to cut trivets manually on a table saw will be doing back flips when they see just how easy it is to make multiple cuts, accurately and easily.

We made the original version of this jig first of all to see how it worked and what problems we might encounter along the way. We were so happy with the first version that we decided to re-make the jig with a few modifications and changes to make it even better and more versatile. For more info and links, read on ...

The original plans called for the base to be quarter inch thick plywood. We opted to use a high quality half inch plywood because it was more rigid to work with and held the other jig components more firmly. The remainder of the jig called for three quarter inch plywood, which we did use, and we did select a very good grade for this because we wanted to end up with a quality jig that would last.

Another of the major modifications that we found in our first prototype version was that because the jig is essentially cut in half along the bottom, the whole jig tended to flex somewhat, which wasn't a problem except that we felt some of the joint may not have been as accurate as they could be. To help solve this problem the front sled part was made higher, which significantly improved the rigidity of the jig when it use.

The only other major component, aside from a few nuts and washers, was the threaded "ready rod". Depending on what blades you want to use the size of box joint sizes, you could select a variety of ready rod types. We selected a three eights by twenty, so that means 20 threads to the inch. What this gives us then in the jig, is for every eight turns of the ready rod, it moves the carriage by one quarter of an inch, which is perfect for what we wanted in making quarter inch box joints.

The plans that we used are kindly provided through the website www.sharkguard.com we appreciate that Lee Styron has provided this information ... and you might even find some products that Lee is making that will work with your equipment. The direct link to the slightly modified plans are here on the shark guard site
... www.http://www.thesharkguard.com/lynnjig.php

When cutting and assembling it is very important that all our components are true and that they fit together nicely. If you have the time and the material, we really suggest doing what we did and making up first version to see how it all comes together. Like anything, the second one is always better and in our case we found that during the construction of the first jig the back of the carriage, that is the part where the box joint wood is backed on to, was not absolutely at 90 degrees to the base. This meant that every box joint had a small gap in it and not a nice tight fit like was possible. When we found the problem we were able to partially fix it by gluing a veneer along the top  to offset the angle. We made sure in the final version that we checked this angle as it is probably the most critical angle in the whole jig.

To lean more about box joint jigs see or other video on comparing box joint jigs as there is information on that video that will help you understand why we choose this version. Good luck and good building.

UPDATE: Lee Styron commented on our YouTube site about the t-Nut situation that many of you have asked about, here is his comment:
I do host those original plans on my site. I see a lot of questions asked below about aligning the two T-nuts so that they do not bind. Actually they will find their own position easily enough. Ideally you want them locked into place at the extremes just before binding. This eliminates any backlash and makes for solid travel. If the handle turns any, the carriage moves. No delay at all when turn the opposite direction.
Here is a link at Mcmaster to some nice T-nuts that are better than the standard cleat type.
http://www.mcmaster.com/#standard-threaded-inserts/=reznto
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Thanks Lee for this additional information, always great to hear from you!

 

Copyright Colin Knecht
Woodworkweb.com

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Comments   

 
0 #2 Colin 2013-01-25 23:29
I think mine is about 12" deep as well, maybe a touch more depending on where you measure from. The steel bushing will definitely help the ends last longer ... I should do the same before they wear too much.
Thanks for the info Carl ... great tip !!
Colin
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0 #1 Carl E Jacobs 2013-01-25 21:45
Colin ,Excelent video ,How deep did you end up making yours ,I went to 12 "& installed steel bushings at both ends
I had to revisit my decimals and fractions ,I went to a 1/8"course rip blade ,planing on a replaceable sacrafishial
chip out preventor . you are absolutely right about a proto type and personal changes after use ,and makeing a second to incorporate your experience and uses .This one works fine ,once you get your decimals and turns worked out ,thinking abour 14" to handle 2"bi's easier.
Be checking in more often,now that I found yor site.Thanks ,Carl
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