# Lynn's Box Joint Jig Revisited



## rjconti1 (Sep 29, 2013)

I made a box joint jig per the plans on the Internet, and found that the jig was very accurate, in spite of the poor quality of my attempt…… I then went to my model “2”. I found modifications that really worked well. I have attached photos of the model “2” with a sample “box” made with all sides prepared simultaneously. For me, this seems to put the Lynn jig at the top of “preferred” box joint jigs, especially considering 4 sides of a box are processed simultaneously and quickly. It is also easy to make the fingers tighter or loose. Amazing this jig is not commercially available, even as a “kit”. 
Some “tips”….
1.	I recommend a wood like poplar rather than plywood. Although I used high-grade plywood for the carriage rail. Special reason for that selection.
2.	Holes for the four parts utilizing the threaded rod should all be made on a drill press simultaneously, using double backed tape to keep parts together. 
3.	I did not glue joints…. Used no. 6 screws to minimize tendency to split wood.
4.	Used a thrust bearing at crank, and metal sleeves in wood holes for the rod.
5.	Used dado saw blades for ¼ inch spacing plus required shims.
6.	Used crank obtained from hardware store (crank is for window louvers). 
7.	Pay special attention to clamping pieces during use of jig. 
8.	To “tighten” fingers, use slightly more than 8 cranks per cut
9.	To “loosen” fingers, use slightly less than 8 cranks per cut (Wooden hinges are easily fabricated).
10. Test dado cut to be sure you get a ¼ inch wide cut, or slightly greater. 
11. The carriage is very critical…. I can detail some tips regarding fab and assembly if forum readers have further interest.


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## harrysin (Jan 15, 2007)

Your jig looks very nice and I'm sure that it works well for you but there really are much simpler jigs for making box joints like the no longer available Oak Park spacer jig which can be easily made.


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## rjconti1 (Sep 29, 2013)

*Some Additional Notes*



harrysin said:


> Your jig looks very nice and I'm sure that it works well for you but there really are much simpler jigs for making box joints like the no longer available Oak Park spacer jig which can be easily made.


Thanks for commenting.

Additional notes:

•	3/8 or ½ or other spacing using a dado blade is fine. 3/8 would involve 12 “cranks” per cut with 3/8 inch dado blade. ½ inch fingers would require 16 “cranks” per cut. 
•	The ¾ X 4 ½ inches “legs” on the carriage ends is not a critical dimension (allow excess of ¾ width to permit “guidance” solely by the carriage rail. When assembling carriage, the gap to rail is set by using ¾ inch spacers (actual ¾ inch) during assembly, then using good quality ¾ inch plywood as rail…. The normal plywood “undersize” makes an ideal “slip” fit for the carriage..
•	The jig is not very “pretty”. If I made another, I would probably round off, or taper certain areas to give the jig a more streamlined appearance.


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