Building the Woodgears Box Joint jig

[Art Mulder]

Hey Folks,

I have been fascinated by the Woodgears.ca (http://woodgears.ca/) website for years. Matthias Wandel builds fascinating gizmos, jigs, tools as well as interesting wood projects, and posts new items regularly.

In particular I have been thinking about building a version of his Screw Advance Box Joint Jig (http://woodgears.ca/box_joint/index.html) for a few years now. Late last fall I decided that I would try and get started on it over this Christmas holidays as a present to myself. I got started then, and continued off and on in my minimal spare time until completing it in early March.

If you want detailed build instructions, please go to his website and read his web page, and/or watch his instructional videos, and/or buy his plans -- they're quite inexpensive. My intent here is to just post some photos of my own build, with a focus on what I did different, or areas where I had particular challenges, or anywhere that I thought his plans needed a little elaboration. So I will NOT be posting detailed instructions or plans here, and if you are not familiar with his jig you will likely not understand what I'm doing! (I also will post a bit more detail + more photos on my website, linked in my profile)

[Art Mulder]

Getting Started:

257141
The first thing that I advise is to do is go out and buy yourself one of these. Look closely, it is not just an ordinary tape measure! Matthias works in metric; his plans and instructions are almost entirely in metric, so you will want to have a metric tape measure at minimum. I also have a combination square which reads in metric, which is proving to be extremely useful.

257140
I am not used to working off plans other than my own. I've been designing my own projects pretty much since I began woodworking. So working off of plans is already a stretch.

One thing unique about Matthias' plans is the inclusion of these 1:1 plans. I've watched several of his videos where he demonstrates how he uses 1:1 plans in a lot of his projects. It intrigues me, so with this project I went ahead and printed out the 1:1 plans and taped them together. (This took two tries, two sets of plans, to get right. It is not quite as simple as he makes it look in his videos.) And so I am trying out his method of taking some dimensions and cutting instructions directly off of the plans.

257143
You'll need to go shopping for some hardware. Some of the requirements you might already have in your shop. Check through your bolts and jig parts. The threaded rod, 2x10, and other random t-nuts and so on, were easy to find at the local Big Box lumber/hardware store. I also had some jig knobx/bits from Lee Valley which I'd picked up years ago for various projects. The metal bar for the miter slot is also fairly easy to find at the local metal supermarket, though I haven't yet picked it up.

The bearings are another matter. Home Depot did not carry them. Princess Auto has some, but not the right size. I happen to have some broken down rollerblades which also has pretty decent bearings in the wheels -- I plan to try to use one of those for the Idler assembly, since I don't believe that the bearing size is critical there. However, for the bearing that supports the threaded rod, size is critical. You'll need to look up a bearing supplier in your hometown. It was only about $3 each, so I grabbed two to have a spare.

Typically I build with hardwood. Typically, Matthias uses a lot of softwood in his projects. I decided to follow the plans and use the softwood where specified. The plans note that a single 8ft 2x8 piece of construction lumber will provide enough wood for the needed pieces. I would suggest instead buying the nices 2x10 that you can find. Around here, the 2x10 lumber in the local big box store is FAR nicer and clearer than the 2x8 lumber. Check the rings on the end of the wood. With 2x8 lumber they can use smaller trees than with the 2x10s, so by buying a 2x10 and cutting out your pieces from the outside edges, you will get closer to quarter sawn, wich will be more stable, and farther from the pith of the tree. Another thing: Do buy your 2x stock a few weeks ahead of time to let it acclimatize to your shop. Construction lumber is not always the most dry and stable. Even so I would also build the box the same day that you cut and plane the pieces.

257142
Here I am cutting out the slots for the corner splines in the stock holding box. In the instructions/video he just uses a jury rig with a cross cut sled. I can understand that, as it is only a few cuts. However I found that procedure a bit unsteady. As well, building a sled to hold this stable was only the work of about 10 minutes. You can see that it is just 4 pieces of scrap plywood assembled with nails/screw/glue.

NOTE: If you build a little jig like this, think in advance of where you are going to cut. For the sides, I kept the nails in the upper half of the boards. For the cradle portion, I only put in two screws, and kept both of them at the extreme edges. This leaves lots of room in middle for the saw blade. Note that for this cut you are raising up the saw blade quite high, so you need a lot of clearance around it.
Keep those nails away!

[Art Mulder]

257145
Early in the process, I realized that I needed the plans close at hand. Fortunately I happened to have an old clunker laptop that I could bring into the shop, which I did not care too much if it died due to the dust or other shop hazards.

This way I now had the plan package close at hand, and I could flip through the files, photos, instructions, as needed. Even more importantly, I could play snippets of the instructional videos. I found I would play another 1-3 minutes of video at a time, which would give me pointers as to what would be the next step in the process.

257144
This is what happens when you cut a dado on the WRONG SIDE OF THE LINE. ARGH. The tolerances on this project are very precise, so I did not think I could just adjust the result, so I glued in a carefully ripped pieced of maple and then proceeded. Thank goodness for modern glues and long-grain joints! And thankfully I caught this before I'd make the next cut, as that would have really set me back!

257146
Here is the next cut, which was fairly complicated to set up. This is the half-dovetail which is cut along the front of the stock-holding box, for where the box rides along the front rail.

[Art Mulder]

Here is my first quibble with the plans -- and it's a minor one. (These plans are awesome.) The 1:1 plans show the screw locations for fastening the frame-front-rail to the base of the jig. The instructions suggest that you just lay the plans over the base and tap a scribe on each mark to transfer the location to the wood and then drill the holes.

My quibble is that the screws for the front rail are all centered on the front rail, which makes perfect sense. However at the left side of the front rail, we have earlier cut the rail skinnier, so it is only 3cm thick there. So those two screw locations are NOT positioned over the center of the rail. On my build, my front rail split when I screwed into it from the base. It was a small split and I was able to force in glue and clamp it closed, and then reposition the screw. I'm sure part of that is just the way the grain moved through my piece of wood, but I do think that positioning the screws so they were properly centered there on the left would have helped. And yes, it is also partly my fault in that I did not pre-drill the holes -- I figured it was just spruce softwood, and Matthias didn't predrill either in his video... (He has since started predrilling almost all of his holes in more recent videos.)

257147

So, I suggest you move these two screw holes 3-4mm closer to the front, which positions them properly in the center of that part of the front rail.
(And yes I emailed that suggestion to Matthias at Woodgears, and he will be modifying the plans at some point to reflect that.)

[Art Mulder]

Here is some work on making the idler pulley assembly. This keeps the stock box pulled tight to the front of the jig. Here I used a scrap bearing from a scrap rollerblade wheel. Since the inside/outside diameters really are not crucial, this is a good place to substitute for something free.
257148

Unfortunately, on my first try, it is positioned too low. Note from the photo how the bearing is riding against the softwood section of the front rail. Not good. The bearing is already digging in.

Fortunately, it was a simple matter to reposition the hinge a few mm higher on the side of the box.
257149

Later I decided that it might be helpful if I put TWO bearings on the idler pulley. Since they're from a scrap rollerblade wheel, they're essentially free. And it would spread out the pressure on the jig.

A view of the jig partially assembled.
257150

[Art Mulder]

257151
Drilling out the axle hole from one of the two gears that fit on the threaded rod.

257152
The plans call for 39cm (15") of 3/8 threaded rod, and of course I could not find that exact length in the store. It's easy enough to cut with a hacksaw. After cutting, roll it along a grinding wheel at a 45 degree angle, and you'll take off the burr and rough edges caused by hacksawing, and you should have no trouble getting nut on or off. (this is illustrated byRon Waters's in one of his video shop tips (http://woodgears.ca/reader/walters/shop_solutions2.html). If that link goes dead, simply google "Ron Waters cut threaded rod".)

257153
What is going on?!? This is NOT going to fit in that space. There is no way to tip in the threaded rod with the bearing and nuts into place. I was perplexed. On the video, Matthias said it was tight, but this is way more than tight! I double checked against the 1:1 plans and the dimensions of the gap are correct.

The problem is thickness of the plywood. In the written instructions, it is explained that he was using 9mm baltic birch plywood, which requires a 2mm wooden washer between the two gears. I had been watching the video, and NOT reading the written instructions, and I simply stuck in the washer. I was using 11mm baltic birch, and that extra thickness is enough. The parts list notes that either thickness of plywood is fine.

The video instructions are so good, that I had mostly been building this by watching the four step-by-step videos a little bit at a time throughout the build. But these two situations drove home that I also needed to check the written instructions for more details that are omitted or glossed over in the video.


Fortunately this was easily remedied by removing that wooden spacer.
257154

And that is much better. Time to make another big gear!

[Art Mulder]

I printed out the 48-tooth gear plan, stuck it to some Baltic Birch, and started work. The 48 tooth is a good choice for 1/4" fingers.

I found a section of the video where he explained a bit of the gear ratios... The threaded rod is 16 tpi (threads per inch), so each turn of the rod is a 16th of an inch in travel for the stock holding box. Using a 48-tooth gear with the larger 16 tooth gear on the shaft gives a 3-to-1 ratio, and with the 12 tooth gear a 4-to-1 ratio. (48 divided by 12 gives 4.)

So if you use a 48 tooth gear on the lower setting, so it engages the 12 tooth gear on the shaft, then with each turn of the 48 tooth gear, the 12 tooth gear spins 4 times, which yields four times 1/16th of an inch, or one quarter inch of movement of the stock box. 1/4" fingers in my box joints is what I'm aiming at to start, so that works well.

But back to the cutting of the gear. I first tried drilling a few holes for the back of the gears, as you can see in the photo, but I didn't like how it was working -- I mostly have twist drillbits. This would work a lot better with a brad point bit! So I cut it all out on the bandsaw. I tilted the table to the right for cutting one side of the teeth, and then I wanted to tilt to the left for the other side. My table does tilt a bit to the left, but I don't like to do that, since it involves resetting the 90-degree stop that is on the saw. So I built this little ramp for simulating the left-tilt. Works quite well.

In hindsight, I wish I had first taken the time to review his videos on making gears. (Link Here (http://woodgears.ca/gear/howto.html)) I was worried that drilling the holes was affecting the teeth. In that tutorial + video, he uses a drill for drilling out the insides of all his gears. I now realize that the depth of the notch between each tooth does not really matter much. What matters is the spacing between each tooth. I had to do a fair bit of filing and fiddling to get my gears to mesh nicely. I'm still not 100% satisfies. If you build it, go check out that tutorial first!
257155 257156

[Art Mulder]

I had the gears meshing well, I thought. But the mechanism was still not working well. The gears did not seem to fit properly, and they would jump out of the shaft gear's teeth all the time. I was very puzzled for a time... Eventually I realized that this was yet another problem with plywood thickness. Again, I used 11mm plywood for my parts, and I think Matthias was using 9mm. The plans say that either will work, but I don't think that is quite true.

Fortunately, while I did not have any 9mm plywood, I did have some 19 or 21mm (3/4" equivalent) Baltic Birch. So I had a go at resawing that down to 9mm in thickness, which actually worked perfectly.


After resawing, and then some sanding and drilling the proper mounting holes, I now had a thinner mount under the gear, and the gears would now full engage each other.
257159

I was now nearly complete. The next step in the plans is to use some 3/4" x 3/8" bar stock to fit into the miter slot of the tablesaw and fasten to the base of the jig. I don't have a tap-and-die set, and could not find one at a price I was willing to pay. So I waffled on this for a while, and eventually decided I would first give it a try using just hardwood for the runners. I've had hardwood runners on my Table saw cross-cut sleds for 10+ years with no worries so I thought this was at least worth the attempt. I also discovered some well seasoned tight grained white oak in my leftover pile. This is very hard, and very dense, and I was able to cut out some strips that were practically quarter-sawn with their grain arrangement. I'm hoping that these will be stable enough to serve. I did go ahead and put two of them on, one for each slot. The plans call for just one steel guide bar.

257160

[Art Mulder]

Time to test it. I did not take pictures during my first cut, but I did during my second test cut. I took several shots, which I hope does a good job of explaning how to use the jig. As well, there are several videos on the woodgears website that show the jig in use.

To start with, I want 1/4" finger joints, so I put in a Freud Box Joint blade set. (That was the most expensive part of deciding to build this jig!) Blades like this are not mandatory, you can make box joints with a regular dado set, or with other blades. What you really want is a blade that leaves a flat-topped cut, and my dado does not. I layed a piece of stock down, and set the blade height to be just a touch higher than the thickness of the stock. My goal is to have fingers that are just a bit proud of the joint, which can then be trimmed flush.

Next, stand up the two pieces for the test cut. If I was building a box, I would have all four piece in at once. Snug up the pieces in the corner of the stock box, and turn the crank until the pieces are just touching the side of the blade. Then back the jig away from the blade.
257161

I am making 1/4" finger joints. So I need to turn the 48-tooth gear one full turn to move the stock box 1/4". Then carefully slide over the front piece of your stock, while leaving the back piece untouched. And then clamp them securely in place.
Honestly, this was one of the most difficult bits to get right, as the two pieces wanted to slide together. I would think it would become easier with practise, and also if I was using heaving hardwood stock.
257162
Turn on your saw and begin the cutting process. Push the jig with the stock through the blade and back. Then turn the gear the required number of turns and repeat until done. Again, I am making 1/4" finger joints, so I need to move the stock double that -- 1/2" -- each time. So I turn the large 48-tooth gear, which is meshed with the small 12-tooth drive gear, two full revolutions.
257163

And here is the result.
257164

As an aside, I do not like the thin finger on the right edge of these pieces. However, for utility shop projects, I probably would not care. As well, these were just random test pieces that I grabbed from the scrap pile. For ideal finger spacing, I would want to use stock that is sized to be a multiple of my dado width, which is 1/4".

The joint slipped together perfectly. It was like magic. No sanding, no chiseling, no fiddling. I just slipped it in, and tapped it together. Note that this photo is actually of the very first test joint that I cut with my jig.
257165 257166

And that is pretty much the end. I think I'm going to really enjoy using this jig, and I can forsee a lot of use of it in future projects!

[Phil Thien]

And that is pretty much the end. I think I'm going to really enjoy using this jig, and I can forsee a lot of use of it in future projects!

That is an awesome write-up, Art.

I've often thought of building one of those. I like the fact that he can make very narrow, very deep finger joints as he did for his shop-made C-clamps.

[Art Mulder]

very deep finger joints as he did for his shop-made C-clamps.

Those C-Clamps (http://woodgears.ca/clamps/index.html) are on my "that's a neat idea, build it someday" list. :D

[John TenEyck]

No offense Art, but all that work to make a jig that works no better than a purpose built one you can make in 15 minutes for the job at hand just doesn't make much sense to me. It would be easy to turn the wheel the wrong amount and ruin a joint, too, whereas the old, pin style finger joint jig is pretty much fool proof once set up. Maybe it's just me.

John

[Art Mulder]

No offense Art, but all that work to make a jig that works no better than a purpose built one you can make in 15 minutes for the job at hand just doesn't make much sense to me. It would be easy to turn the wheel the wrong amount and ruin a joint, too, whereas the old, pin style finger joint jig is pretty much fool proof once set up. Maybe it's just me.

John

John,

No offense taken John. I think it is an issue of education. It seems from your note that you don't know much about the woodgears jig. Have you watched some of his videos or browsed his website? I have been a fan of his website for years, and had watched ALL of his videos that showcase the box joint jig at least once or twice, before deciding to build it.

I do agree with you; It would be silly to go through all that work to build a jig that is not better than a purpose-built jig.
However, I believe it is better. So does Matthias, who designed it.

First, every other jig I've seen, including the ibox (which looks like an amazing well built jig! I considered buying it instead.) cuts ONE piece of wood at a time. So to make a box, all four sides have fingers on both ends, which is EIGHT cutting operations. In this jig, you load up ALL the sides at once and cut one end, and then flip them and cut the other end. That is TWO cutting operations. I built my first test box in less than 10 minutes, and most of that was in double-checking plans and layout. the actual cutting added up to less than 2 minutes.

Also, from all my reading, the old pin style is not quite fool proof. If you get one dimension a bit off, the errors add up with every pin you cut. So after 10 pins what started out as an error of "x" is now 10 times "x". (Full disclosure -- this is all from reading forums and mags over the years. The woodgears is the first box joint jig that I built.)

Finally, that bit about turning the wheel wrong is a valid question that I've heard on other forums also. So I went ahead and worked out the math, which I covered in detail on my web page (http://wordsnwood.com/2013/boxjig/) of the build. (I put more detail on my web page, and just a summary here.) Basically, when cutting 1/4" finger joints with this jig, if I was off by 2 notches when turning the wheel, the error in the cut itself would amount to about 10 thousandths of an inch, which is .0104" or about 3/256ths of an inch. Also, the errors don't add up, so the next time you turn the wheel you are likely back on track.

Note that if you line up the handle of the wheel before starting, it is HARD to actually be off my even one notch in turning it, let alone two.

[Art Mulder]

PS: I think youtube links are allowed? http://www.youtube.com/watch?v=yuFHurrWswQ
(if youtube links are not allowed, then you can go to this woodgears web page: http://woodgears.ca/box_joint/jig.html and scroll to the bottom to find the link to the video)

John, here is what I think is the best video on the woodgears website about actually using the jig for a basic box joint.
It's less than 4 minutes long. And in it he cuts a finger joint that is around twelve inches long.

Unfortunately, most of his videos are actually about building the jig, rather than using it. As well he made a few videos about esoteric use of the jig (finger joints in a dowel, double-stepped finger joints, through finger joints, etc) so that this video was kind of getting lost in the pile. As well, he's using the old version-1 jig in this video, so he also was not high-lighting it.

This video shows, I think, just how quick and easy it is to cut a finger joint with this jig.

[John TenEyck]

Hi Art, That is an impressive video of how easily the jig works. You can gang cut parts with the pin method, too, or with the original Incra jig, which I often use. For the pin jig, however, you have to pick up the stack each time to reposition it over the pin, and for a stack like shown in the video that would be quite difficult. With the Incra jig you just slide the stack sideways, so it's not as hard to do, but you can just as easily make a mistake repositioning the jig itself as you could counting teeth with the Woodgears one. I would agree for sides as wide as those shown in the video the pin method would be a challenge to set up properly. Normally, the parts I'm making are more like drawers less than 8 inches wide or so, and the pin method works quite easily. Thanks for your feedback; I may just have to reconsider the Woodgears approach if I ever need to make some finger joints in really wide parts, like a big chest of drawers or something similar. I imagine it could be adapted for use with a router table and a dovetail bit, too.

John

[Art Mulder]

Hi Art, That is an impressive video of how easily the jig works. You can gang cut parts with the pin method, too, or with the original Incra jig, which I often use.
...
I imagine it could be adapted for use with a router table and a dovetail bit, too.

I did not know that about gang cutting. I stand corrected!

I would guess that you could make one like this work on a router table, but I've never seen it done.