Inbcra i box

[johnnyb]

Thought I'd give this an unbiased review. I brought it brand new secondhand with no box. It's a jig with a single purpose... finger joints or box joints. It's modus operandi is derived from a myriad of home made jigs using a sliding carriage and a guide finger, so the next tooth is indexed from the previous. This usually results in really annoying cumulative errors on home made stuff. And interminable setting up. The I box is really nicely made and if you follow the instructions and watch the 1/2 dozen or so vids on YouTube a couple of goes and your making perfect box joints. Now the negative is it requires an accurate us style table saw with a dado set or a suitable router table with us style mitre slot. The jig requires sandpaper to be glued to the backboard as router put sideways pressure on the workpiece(and side spelnching can cause issues)
Now I can make perfect super strong boxes in minutes. They are remarkably strong even without glue.
If you've got suitable equipment then it's a very effective jig.
Other box joint jigs use the dovetail jig method.
Incra have very cleverly semi automated the setup arrangement. It's helped by using a set of digital calipers when doing a new set up. And perfect (space and finger the same size) results in far to tight a fit. 4 or 5 thou "space" allows room for assembly.

 

[fleyh]

Thank you for the review @johnnyb

Can this Incra jig be used to cut box joints on a table saw without dado support?
i.e. can it be used if the blade kerf is narrower than the required box joint gap?

I use a mitre guide fence from the Far East - it’s fiddly to set up to begin with, but once configured - can be used with any blade kerf width.

 

[johnnyb]

No it's a dado/router jig and doesn't allow any method beyond a simple single width pass through.(I think!)
But with the correct equipment it's super accurate and easy. It can be used with the hinge crafter to make hinges(at least the notch part)
It does have a depth restriction as well of about 30mm(otherwise you cut the jig)

 

[recipio]

I have one and it's a super bit of kit. It can be used on a router table but is really designed for an American style saw which has two slots to guide the jig and of course the ability to use a dado stack. It is adjustable so your finger joints are really tight with no infuriating hairline gaps.
For small boxes 6 mm is about right and Infinity tools make three flat ground blades at 4 , 5 mm and 1/4" which are worth the investment.
Ideally you should clamp the work to the fence when cutting and the pocket hole clamps sold by Axminster are great for making multiple cuts.

 

[johnnyb]

The strength of precise box joints is amazing. Almost no glue required on birch ply. It also gets the grey ticking as to potential uses(beyond boxes)
I keep thinking about frames with jointed corners for some reason.(only 30mm to play)

 

[recipio]

The strength of precise box joints is amazing. Almost no glue required on birch ply. It also gets the grey ticking as to potential uses(beyond boxes)
I keep thinking about frames with jointed corners for some reason.(only 30mm to play)

Yes, always check the cutting height or you will end up cutting a slot in the aluminium fence ( don't ask me how I know )
I would always use a little glue and make the fingers a tad oversize. Avoid sanding them down especially with Baltic ply as you will quickly sand a mm too much. Better to use a sharp hand plane or a router to make them flush.

 

[Peter Sefton]

Thank you for the review @johnnyb

Can this Incra jig be used to cut box joints on a table saw without dado support?
i.e. can it be used if the blade kerf is narrower than the required box joint gap?

I use a mitre guide fence from the Far East - it’s fiddly to set up to begin with, but once configured - can be used with any blade kerf width.



View attachment 190883

I Googled your narrow blade question and came back wit. Yes, the Incra iBox can be used with a cutter that is narrower than the joint width you want.

The Ibox can be used with standard 3.2mm (1/8") saw blade for narrow fingers, so sounds like 3.2mm and upwards.



Cheers

Peter

 

[johnnyb]

The 2 index pins will close down enough for a sawblade as long as its flat topped.so narrow fingers are fine But I can't see how the jig would cut gaps wider than that using a narrow blade. If its possible then It would be a faff which is kinda against the best aspect of the jig(it's almost self setting) i get its a mostly u.s. jig as it's intention is use with dado set. But it can be used with a router table if you address the issues of tearout/movement.
I'm lucky enough to have and occasionally use an American saw and dado set sio it's very well suited.
I can't help but think if it was possible to make fingers deeper say 40mm it would have much greater utility for frames albeit the narrow reference may cause accuracy issues. The problem would then be safety as it already feels slightly dodgy pushing work over a blade(safety is quite well addressed as long as the blade is low)
Incra mention some slightly odd things such as on a right tilt saw put the red knob on the right...whose going to tilt a dado?
As I mentioned it is a one trick pony but it will easily make dentil mould.
People stateside have struggled with set up as youtube comments are littered with complaints and gripes. But if you've got a vernier caliper it's quite straightforward.

 

[recipio]

For stock over 30 mm in width you are really into using a spindle moulder with a sliding table. The Incra excels with thin stock like 12 mm for boxes. It will machine super strong joints which are otherwise difficult to do with thin stock. Using thin ply is a bit pointless as the laminations tend to fall apart when you get below about 4 mm.

 

[johnnyb]

One thing that did cross my mind was by tilting the work forward or back multi sided boxes could be possible...

 

[johnnyb]

Also by cutting a guide board using the same set up its easy to ensure a full finger at the board ends.(just measure your board. It would involve reverse working if your making drawers I guess ie make the drawer then make thole

 

[johnnyb]

Another thing I pondered was how making 2 props that snug into 2 opposite corners an immensely strong item could be made. As the only weakness is it collapsing like a paralellogram.

 

[johnnyb]

Another observation is thickness of the sides can be variable as long as the fingers protrude past the thickest side.