Box Joint Help

[mrhart]

Always good info here.

I did cut things maybe 1/32 over as I had read before. I will post a pic of a test cut and maybe you all can tell me if that is a "standard" cut for my dado set. Maybe there is no issue there.
On my jig, I made it of 3/4 ply and have another 3/4 ply attached to the front with carriage bolts and the 1/2 walnut key. So, I should come out one more time (have sone 1/4 ply) with another layer to avoid chip out?

I need Santa to bring me a Bosch Router, table and bits.

Last Q is, just because I cut the joints long, the surface left by the dado tips cutting edge need to be sanded flat to make the inside corners as well as the outside corners, look better. Correct? This is normal?
Best practices here please.

[JPG]

Always good info here.

I did cut things maybe 1/32 over as I had read before. I will post a pic of a test cut and maybe you all can tell me if that is a "standard" cut for my dado set. Maybe there is no issue there.
On my jig, I made it of 3/4 ply and have another 3/4 ply attached to the front with carriage bolts and the 1/2 walnut key. So, I should come out one more time (have sone 1/4 ply) with another layer to avoid chip out?

I need Santa to bring me a Bosch Router, table and bits.

Last Q is, just because I cut the joints long, the surface left by the dado tips cutting edge need to be sanded flat to make the inside corners as well as the outside corners, look better. Correct? This is normal?
Best practices here please.

The dado cut should be the same on both sides. i.e. the dado is cut all the way through. Yes this makes the blades project well into the jig!!!!:eek:

BTW it is about strength, not appearance.

[getnby41]

I watched the Sawdust Session #2 video and downloaded the plans to make the Adjustable finger joint jig. It looks to me like the adjustment will move the wrong piece. Am I looking at this wrong?

http://www.shopsmithacademy.com/SS_Arch ... _Index.htm

[JPG]

I watched the Sawdust Session #2 video and downloaded the plans to make the Adjustable finger joint jig. It looks to me like the adjustment will move the wrong piece. Am I looking at this wrong?

http://www.shopsmithacademy.com/SS_Archives/SS102/SS102_Index.htm

1) The slotted holes in the back board are NOT for attaching to the miter gauge. They allow the screws going through the sliding board to move.

2) The back board is secured to the miter gauge with wood screws not shown in the 'plans'.

3) The wing nuts secure the sliding board(with the pin) to the back board once adjusted.


I am guessing you assumed the slots were for mounting to the miter gauge.
Been there myself at first!;)

[getnby41]

Thanks for the clarification. The plans lead you to believe the screws are for mounting it to the miter gauge.

[charlese]

Thanks for the photos! It looks to me as there is some clamping needed to draw the fingers all the way into the slots near the bottom. pennviews post (No 7) is excellent advice! A piece of hardboard held firmly to the front of the jig should give you a clean, chip free cut every time. You can move the hardboard along with your workpiece so that every cut gets to cut a new slice of the backer board.

The reason you want a backer board is the jig slowly develops a wider slot because of some very slight wobble. Some box cut jigs also use a bottom sacrificial base (bottom) board instead of depending on your jig staying firm on the table/table insert.

[mrhart]

[quote="charlese"]Thanks for the photos! It looks to me as there is some clamping needed to draw the fingers all the way into the slots near the bottom.

So at this point, sand the individual finger depths to get a nice clampable fit, which also looks as good as possible, then maybe the sawdust and glue filler to match as closely as possible.
On the next box, I will put a second runner undernieth that hugs the edge of the table to avoid wobble, and use a 1/2 ply backer board frot he cut out.

On the Shop Smith dado set, the 2 outside blades are in the same position and the inside chipper is staggered a bit. Is this correct?

[charlese]

On the next box, I will put a second runner underneath that hugs the edge of the table to avoid wobble, and use a 1/2 ply backer board for he cut out.

On the Shop Smith dado set, the 2 outside blades are in the same position and the inside chipper is staggered a bit. Is this correct?

Sorry - don't have any experience with the dado set having a chipper. I use a wobble dado blade.
A 1/2" plywood backer seems to be a bit heavy! I use a 1/4" piece of hardboard (that solid dark brown stuff). This gives me an easier time holding it to the jig, while moving it, notch by notch, along with the workpiece. I just think 1/2" plywood would be a little cumbersome.

[JPG]

A couple of comments from one who does not have the dado set you have, but:

The outer blades are not always identical and each may have an inner and an outer face which insures cleaner corners.

Assuming the outer blades cut a 1/4" wide kerf with no chipper, I would use two 1/8" chippers rather than one 1/4" chipper to create a 1/2" 'mortise'.

The chippers should be assembled so that the chippers do not touch either each other nor an outer blade tooth at the outer circumference.

The chippers cutting edges should be roughly equidistant from each other.