Shopsmith Forums

I bought a Shopsmith edition INCRA iBox (box joint jig) a over a year ago when they were on sale. When I first got it, I played with it but couldn't seem to make it work. So I left it on a shelf.

Today, I had a project that just screams out for box joints: a 1/4" thick plywood "wannigan" (canoe camping box) that is 22" long by 16" tall by 16" wide. So I decided to break out the iBox jig and try again.

After reading completely through the manual (again) and doing all the recommended alignments and several frustrating test cuts on scrap, I FINALLY got an acceptable joint. There was nothing easy about it. I really had to play with both the red and silver knobs to get an acceptable joint.

But with everything locked in, I figured I was good to go and confidently began working on my project pieces.

I did the first two pieces and got a good box joint along a 16" corner. Did the next corner and got another good box 16" joint. Moved on to the third corner and, you guessed it, it doesn't go together.

The worst part isn't that I just ruined the work piece. Bad as that is, I've got more plywood and can cut another piece and try again.

The worst part is I am totally frustrated and out of confidence to continue the project with box joints because I have no idea whatsoever what I did wrong. I did not change any settings on the iBox or the Shopsmith. Moreover, so far as I could tell, I did everything exactly the same way on the third corner as I did on the first two corners and "by the book." Obviously that's not the case, because something went wrong. But who the heck knows what.

I am about ready to toss that iBox in the garbage.

What doesn't fit?

The top 3-4 inches of the joint go together. After that, nope.

algale wrote:The top 3-4 inches of the joint go together. After that, nope.

So is the spacing off or are the pins too wide to fit in the slots? The blade used to cut the slots determines their width so that can't change. The adjustments on the Ibox determine the width of the pins. So if the pins changed width something on the Ibox moved. If the spacing is off then something on the SS moved to change the blade position. Either the table moved slightly or the quill moved slightly.

I use my Ibox on my Powermatic table saw so the relationship of the blade to the miter slot that the Ibox runs in is fixed and can not change. As we all know the SS is a bit of a different animal. The blade to miter slot relationship can change if the quill or table carriage moves. Even a very small movement will cause a spacing problem with box joints. Even if you do another test cut after the error the joints will fit as long as there is no further movement.

After all you did 35"+ of perfect joints. Something had to have moved slightly. I have taken my Ibox (currently set for 1/4" joints) off and on the saw many times and every time it cuts perfect joints without adjusting.

algale wrote:The top 3-4 inches of the joint go together. After that, nope.

OK, I have had that happen. I don't know how you did it, but your setting changed. Period. Since you had 3 successful joints, you proved the jig works (and believe me it does work). Using your ruined piece, make some short test pieces and make a small box with it the same height just shorter legs. You will get it.

Post some pictures. When the fingers fit at one place but are spaced (check it out for yourself) so they don't mesh down the joint, your setting simply moved. Blade, table, silver/red knobs, headstock. (You know the drill LOL).

It truly is an amazing jig. I have made a 100 box joint corners. Took me a while to really get it dialed in, but it does work.

JMHO

The spacing is very slightly off; but it is enough to prevent the joint from coming together. Since I didn't adjust anything, I'm at a loss for how anything could have moved. I guess I will cut up the ruined piece and run some more test cuts when my mood improves.

algale wrote:The spacing is very slightly off; but it is enough to prevent the joint from coming together. Since I didn't adjust anything, I'm at a loss for how anything could have moved. I guess I will cut up the ruined piece and run some more test cuts when my mood improves.

Again, if the spacing is off but the pins still fit the slots one at a time it is not the Ibox. Something on the SS moved slightly. The Ibox runs in the miter gauge, it can't move. The only thing on the SS that cane move to change the spacing is as rjent said. The blade/quill, the table or the head stock. Even a 1/2 a thou with a joint that long will do it since it is cumulative. Particularly if your pins are a tight fit to start with.

When I cool down, I will make a closer inspection to determine if the pins fit and the spacing is off or the spacing is ok but the pins are too wide.

One thing I have found when trying to more precise work is that if you add an extension table and then tubes to the main table it is much more stable a set up. Some where way back when I did a post about this and later Nick did a video. I can't say this will fix the situation but it sure would hurt to try it.

Anyway you can salvage the box by trimming off the "bad" joint and making the box just slightly smaller?

Just out of interest what kind of plywood are you using?

Ed

take the thing apart and put a good end back into the jig then see what changed ? you could have flipped the front side with the back side , I all ways mark front and back top and bottom?