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Discussion Starter · #1 ·
Awhile back I built a simple box joint jig with interchangeable parts for different width joints from 1/4 - 3/4. I guess it worked OK and I managed to make a few simple boxes. The problem was always too many test cuts and adjusting before getting the perfect cut. Even at its best it still did not have the quality I was looking for.

The Incra toys are nice but cost too much for me right now. I decided to build a screw advance sled version based on Ed Stiles. I'm taking my time on this because there were no actual plans and I want everything to look good and work even better. May take a few days.

Began the jig project today:
BJ04.jpg
Simple design has a carriage which will ride back and forth. 3/8-16 all thread will control the movement. One revolution will move the work piece 1/16". This design will allow me to use a 1/4" dado stack to make any size box joint just by counting how many time I crank it. It measures 2' x 1.5' and is built on 1/2" ply. My goal is to be able to cut great fitting joints the first time every time without making any test cuts. The bonus is I can leave the dado stack at 1/4" and make any size joints. The only adjustment I should ever have to make is for height.

BJ03.jpg
The parts clamp will fit stock up to 8" wide. It is spring loaded so it opens automatically when I loosen the wing nuts. If everything works the way I hope it will, I will replace the wing nuts with some nice knobs.

BJ05.jpg
I made the drive block which will mount to the carriage today but screwed it up so I have to make another one tomorrow.

BJ06.jpg
Carriage removed...the carriage clamp bolt heads are counter bored and filled with epoxy, then sanded smooth. I'll post some more pictures tomorrow when I get more done.
 

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Chester's Gorilla
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Neat project. So will you have to crank it for each cut and then reset for each board?

I made an adjustable box joint jig a few months ago, but just set it up so that the back fence (nearest your belly) slides left or right WITH the registering pin, then locks down by tightening some wing nuts on the back. I can then make any size box or finger joint by using different dado widths and the same sled and registering pin; you just be sure to have your work piece sitting flush on the leading edge of the pin. Used it several times, works great.
 

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Discussion Starter · #3 ·
Thank you. Yes I will need to crank it for each cut. The jaws however will accept about 2" thickness, which means that I will be able to cut a maximum of eight 1/4" thick box sides or two boxes at one time. It will only be limited by how high I can raise the dado blade. For example...if the maximum height above the sled that I can raise the dado stack height to is 1", then the practical maximum thickness of a box joint will be 1". The height of the box and width of the joints will be limited to the width of the jaw/vice which is about 8" between the threaded parts of the jaws.

I am considering rebuilding the carriage in order to make it removable/interchangeable. This would allow for the addition of other future carriages such as dovetail or whatever. I also am hoping that this jig will work well for making hinges.

The gentleman whose design I am basing mine on did not have any plans available so I am kinda looking at pictures and making it up as I go. I am currently learning to use Sketch Up and if this design works well I will not only post pictures of some finished products but also attempt to make actual plans using the program.
 

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Years ago and maybe still, that type jig was called the 'Lynn Jig'. If you put a crank on one end and leave some thread on the other, you can really move along. After you've cut a set, tighten a drill chuck over the threaded end and rewind HI-SPEED!
 

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Discussion Starter · #6 ·
That's a good idea to leave some thread on the end. I'm glad you told me before I cut the all-thread.

Made a little more progress today:
BJ07.jpg
I built another carriage which will come apart if it needs shims or other accessories. Also built another drive block that I only have clamped on right now to test it. I want to dress it up a little more before permanently attaching it.

BJ08.jpg
Started making the crank and decided to give it a little style while I was waiting for glue to dry on other parts.

BJ09.jpg
The carriage slides smooth without any play. This is what I was really hoping for.

BJ10.jpg
BJ11.jpg
This is the left end of the screw. Because one revolution is 1/16" it must have positive and exact location on each turn. The spring loaded flipper can be pulled all the way back and it stays there for easy free spooling. I'm thinking about replacing the wheel with a smaller one that will have less flat area to contact the flipper. Tomorrow I will finish the drive block and crank. I need to make the rear fence and runners also.
 

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Discussion Starter · #7 ·
Finished up on this jig for the most part.
BJ14.jpg
Added a tape measure for reference only. It will help me keep track of where I am.

BJ15.jpg
Still have to put a safety block here to cover the blade as it comes through.

BJ16.jpg
On the inside I added a 3/4" x 3/4" piece that can be relocated for differences in blade height. It prevents chip out.

BJ17.jpg
The first test run went very well. The joints could be a slight bit tighter so I need to remove a shim from the stack. There is no need to "rewind" after cutting one end of the stock. Just flip the pieces end for end and work them in the opposite direction. Left to right, then right to left. It's fast, accurate, and simple to use. Took about 4 hours total to build at a fraction of the cost of some manufactured ones. Like I mentioned in the first post, I based this on Ed Stiles version. If your are interested here is a link to his video:

http://youtu.be/JYxDXHGRRrk
 

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Discussion Starter · #8 ·
I have gotten some use out of the jig now and wanted to post a couple pics of the almost finished results. The joints are exactly the tightness and accuracy I was hoping to achieve. Next, I would like to try a box project that has joint sizes that change throughout the height. For example starting at 3/4" at the bottom and decreasing by increments of 1/16" as it goes up. Maybe a tall narrow box to hold spaghetti noodles.
box01.jpg
box02.jpg
 

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Discussion Starter · #9 ·
Experimenting and learning

My plan is to make a tall box to hold spaghetti noodles. It could also hold wooden spoons or whatever. It should be about 8" tall and I want the box joints to increase in size from the top down, starting at 1/4" and ending with 3/4" joints, increasing in increments of 1/16" so the change is so gradual it's not easily noticeable up close but interesting to look at from arms length. I plan to use contrasting wood.

Before I begin making the spaghetti holder I wanted to experiment on a smaller scale with some left over pieces of 1/4" thick aspen.
boxjointexperiment01.jpg

boxjointexperiment02.jpg

The results turned out ok. I advanced in increments of 1/8" so the change is less gradual. The point behind it was to better familiarize myself with counting turns on the jig as far as gap-tooth-gap-tooth. It's easy to make one size joint but takes a little more thinking ahead to plan out more complicated joints. When I get the spaghetti holder done I'll post some pics.

spagetti holder.jpg

Try not to laugh as I am still learning to use sketch-up:laughing: This is the basic idea although the wood will not be as thick and the plan is drawn upside down.
 
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