Ibox finger joints that begin mid board? TIPS or suggestions?

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I am essentially making a box with legs.
I can use a 13/16" dado ( freud ). The end piece is 9 5/8" . If I could figure out what size finger joints would work perfectly I could start the finger joints at the end of the pieces. I just don't want to have a gap mid board with what ever is left over..

I guess considering the IBOX, I wouldn't be able to start my first cut mid board anyway because the pins would be in the way.

The issue is I need the box joints to fit exactly within 9 5/8"

I am not good at explaining things....hopefully someone will see what I mean.

I love this type of problem and know EXACTLY what you mean. I've an iBox too and I love it.

The answer is simple. But involves an extra step.

I preface my entire answer on the fact you have dado spacers etc to create an accurate modulo to fit 9 5/8".... I'll be honest, I really don't know how anybody can do the maths in imperial. Divide 13/16ths into 9 5/8ths.... I studied a masters in maths at Stanford and think this is ridiculous... So I'm using metric... Anyway, you need to firstly get very close to ensure a full N-number of fingers fit your desired height, or very very close to it.

Step 1: get the joints tight with scap boards first. Use the little winder to make them goldilocks. They won't be exactly 13/16ths but just a few atoms wider :)

Step 2: Start with the centre boards first. It must be slightly wider than N*FingerWidth. Let's pretend this is metric.... again, let's pretend each finger is magically exactly 10mm and there are 10 fingers....the two centre boards must start life at > 100mm....make them 105mm

Mark the "tops" with pencil lines (to avoid confusion later). One starts with doing the fingers on both sides of the middle section first. Do both back to back at the same time...as you do to save time. Nothing new here.

Now, on the last finger there will be an overhang of that last ~5mm. It may be 4.9 or 5.2mm but it doesnt matter. With the table saw off (!!!) and centre bits still in the iBox, scribe an line on the board by pushing the iBox to kiss the blade. The outside blade tooth will mark the very edge of the 100mm...or in your case 9 5/8ths....mark it with a micropencil, take the boards out, make the marks bigger and then rip them to exact width using your TS or a few good strokes on your hand plane.

Count the fingers (which you'll know is 10 from my example)

Step 3: Then flipping a centre board over, matching your top marks and putting the finger into the gap-o-matic, use this as your starting key (there is nothing new in this)... But, don't finger down all the way on the taller outside boards, only do as many as the centre has... 10.

Refit the centre board and do the other end. Again, no magic.

You will be left with an exact centre board and two outside boards that are longer per diagram.

Hope this makes sense. If not, I can make a quick video easily enough tomorrow.

13/16th" is just the MAX width I can use a dado on my table saw, and it doesn't have to be 13/16th of an inch but this is the max.

So what you are saying is not to wrap my head around imperial measurements ( egads man ), and go decimal or metric....I can use any size dado . I had a calculus teacher like you, everything was clear to him hahahaha!

[ So initially I thought I could start the box joints in the middle and work to the end but the remembered how the ibox works ..]

Quote:

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Originally Posted by Evanism

I love this type of problem and know EXACTLY what you mean. I've an iBox too and I love it.

The answer is simple. But involves an extra step.

I preface my entire answer on the fact you have dado spacers etc to create an accurate modulo to fit 9 5/8".... I'll be honest, I really don't know how anybody can do the maths in imperial. Divide 13/16ths into 9 5/8ths.... I studied a masters in maths at Stanford and think this is ridiculous... So I'm using metric... Anyway, you need to firstly get very close to ensure a full N-number of fingers fit your desired height, or very very close to it.

Step 1: get the joints tight with scap boards first. Use the little winder to make them goldilocks. They won't be exactly 13/16ths but just a few atoms wider :)

Step 2: Start with the centre boards first. It must be slightly wider than N*FingerWidth. Let's pretend this is metric.... again, let's pretend each finger is magically exactly 10mm and there are 10 fingers....the two centre boards must start life at > 100mm....make them 105mm

Mark the "tops" with pencil lines (to avoid confusion later). One starts with doing the fingers on both sides of the middle section first. Do both back to back at the same time...as you do to save time. Nothing new here.

Now, on the last finger there will be an overhang of that last ~5mm. It may be 4.9 or 5.2mm but it doesnt matter. With the table saw off (!!!) and centre bits still in the iBox, scribe an line on the board by pushing the iBox to kiss the blade. The outside blade tooth will mark the very edge of the 100mm...or in your case 9 5/8ths....mark it with a micropencil, take the boards out, make the marks bigger and then rip them to exact width using your TS or a few good strokes on your hand plane.

Count the fingers (which you'll know is 10 from my example)

Step 3: Then flipping a centre board over, matching your top marks and putting the finger into the gap-o-matic, use this as your starting key (there is nothing new in this)... But, don't finger down all the way on the taller outside boards, only do as many as the centre has... 10.

Refit the centre board and do the other end. Again, no magic.

You will be left with an exact centre board and two outside boards that are longer per diagram.

Hope this makes sense. If not, I can make a quick video easily enough tomorrow.

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11/16ths goes into 9.625 exactly 14 times.....

YEAH...


thanks

It agonises me that dados are only in imperial. I'd love a metric one.

Anyway, as a thought exercise (keep in mind it's 4am).... 9 5/8" mod 13/16 .... 9 37/16 ... 11 5/16. Damn, doesn't fit.

Since 9 5/8 is our constraint, let's find a modulo! 77/8 or 154/16 ... Looking up the chart:http://www.freudtools.com/admin/manu...pper_Chart.pdf nothing neatly fits.

I tend use my Freud SD208 dado, namely as the two outer cutter blades stacked are 1/4". They look very nice on smaller boxes. 1/2" on bigger ones.

Now, obviously we can get close to 9 5/8, but we are 1/8" out. Half a finger..... ~3.2mm.... Bummer.

Perhaps revise the height of that middle section a smidgen?

Sorry I can't help with the maths, but at least my procedure will pull you out of the pickle! :)

Thank you have led me to the path of enlightenment!!!! Thank you!!!

Quote:

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Originally Posted by Evanism

It agonises me that dados are only in imperial. I'd love a metric one.

Anyway, as a thought exercise (keep in mind it's 4am).... 9 5/8" mod 13/16 .... 9 37/16 ... 11 5/16. Damn, doesn't fit.

Since 9 5/8 is our constraint, let's find a modulo! 77/8 or 154/16 ... Looking up the chart:http://www.freudtools.com/admin/manu...pper_Chart.pdf nothing neatly fits.

I tend use my Freud SD208 dado, namely as the two outer cutter blades stacked are 1/4". They look very nice on smaller boxes. 1/2" on bigger ones.

Now, obviously we can get close to 9 5/8, but we are 1/8" out. Half a finger..... ~3.2mm.... Bummer.

Perhaps revise the height of that middle section a smidgen?

Sorry I can't help with the maths, but at least my procedure will pull you out of the pickle! :)

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