Can you make finger joints w/o a dado blade?

navycop · Post by **navycop** » Sun Jun 07, 2009 4:50 pm

I watched the sawdust video on finger joints. I was going to make a jig, but I don't have a dado blade. Can I just keep making various passes with the standard shopsmith blade?

charlese · Post by **charlese** » Sun Jun 07, 2009 7:28 pm

One if the easiest ways to make finger joints is on a router table. Use a 1/4" bit with a 1/4" spacing and 1/4' bar. Or 3/8"X 3/8" X 3/8".

I suppose you could try to make 1/4" fingers by using a 1/8" saw blade, but that would be very difficult to set up. Everything would have to fit exactly.

I don't believe 1/8" fingers would be very easy to make either.

navycop · Post by **navycop** » Sun Jun 07, 2009 9:00 pm

I just found an old dado 6" adjustable blade. I had it for my stionary saw. I forgotten about it. Will that work (if I get the arbor for it)?

charlese · Post by **charlese** » Sun Jun 07, 2009 9:18 pm

The 6" adjustable dado is what I use making 1/4" fingers. It is used on my 5/8" dado arbor, from Shopsmith. http://www.shopsmith.com/ownersite/cata ... oarbor.htm

JPG · Post by **JPG** » Sun Jun 07, 2009 9:48 pm

navycop wrote:I watched the sawdust video on finger joints. I was going to make a jig, but I don't have a dado blade. Can I just keep making various passes with the standard shopsmith blade?

If you can do so accurately. It is NOT easy.

2manband · Post by **2manband** » Mon Jun 08, 2009 3:15 pm

I've thought about using box joints where each one is as wide as a single saw kerf. I've seen something similar on a cigar box and thought "Wow - now there's a lot of glue area"

Can't comment on the practicality of doing it, as I've never tried.

greitz · Post by **greitz** » Mon Jun 08, 2009 3:55 pm

One of the employees at the local Rockler store made some boxes with lots of small finger joints. He said he cuts the fingers just a little long, dry-fits the joints together, then just runs thin CA glue on the outside of the fingers. The thin CA wicks into each crack, and he just sands the fingers down flush when it's dry.

Gary

charlese · Post by **charlese** » Mon Jun 08, 2009 8:52 pm

A couple more "musts" involving finger joints that have not been mentioned above:

Whatever the diameter of the finger - it is necessary to have the space on your jig that lies between the indexing bar and the closest side of the hole (near side of the blade) to be the exact distance of the size of your finger.

It is not necessary to have the indexing post to be the exact diameter to the fingers. It can be narrower, but not wider. It IS necessary to snug the workpiece up to the post for each cut - using the same amount of pressure each time.

Finger joints work best going into long grain.

navycop · Post by **navycop** » Mon Jun 08, 2009 9:58 pm

charlese wrote:The 6" adjustable dado is what I use making 1/4" fingers. It is used on my 5/8" dado arbor, from Shopsmith. http://www.shopsmith.com/ownersite/cata ... oarbor.htm

I was just nervous about using a 6" blade when the SS originally uses a 10". I guess it is okay to use a smaller blade (i.e. 6" or 8")? Have you ever heard of putting to "standard" blades together to make a stacked dado blade?

If possible, what size would you recommend these blades being?:

reible · Post by **reible** » Mon Jun 08, 2009 11:03 pm

Hi,

A couple of things here and while they may seem nit picky but the joints that seem to be the subject of most of the posts are "box joints". Finger joints are different but similar. One often sees terms used interchangeably but for the sake of those that are new to this stuff if you go in and ask for a router bit to make finger joints when you want to make box joints... well you are going to go home with the wrong stuff.

Blades, where to start here. Blades have different purposes and the teeth of the blade can be made several different ways. To get the cuts you want for box joints the blade needs to cut a flat bottom, and without getting into the dado issues some teeth cut with do not produce what is needed. You can of course use additional operations to correct that but who wants to do that?

Ripping blades often have a flat grind, as do specialized crosscutting blades, some of which come in widths of 5/32" or 1/4" and are designed for doing exposed splines and box joints.

So the best you can say is it is possible to do box joints with any old blade but it depends on the blade as to how much "other work" might be needed to get good joints.

The current shopsmith has a top blade guard that is designed to work with 10" blades and provide kickback protection. I believe that it will work down to an 8" blade but someone should check this as my memory is not clear on that. The system is for through cuts. Once you start cutting grove's/dado's/finger joints the saw can not use the blade guard. Once in to cuts like this the restriction of blade size is gone and indeed shopsmith sells a 6" dado set.

Dado sets have center hubs which are designed to work together so you can say take the two outside 1/8" blades and put them together with off-set teeth and cut a 1/4" wide cut. If you were to take just any two blades the hubs may not match and who knows what sort of nasty things could happen. I personally don't think that is a good idea. Better safe the sorry is not a bad way to go.

Woodworking can be an expensive hobby but getting the right stuff is cheaper then a visit to the emergency room (and sometime the cost is more personal in terms of body parts).

As far as cutting box joints it is very simple to construct a jig to fit on the miter gauge that can get you started with the table saw. It can be done with scrap wood so other then time is will not cost you much. If you have a router table they are also a good option for making a cheap jig for... Lots of options.

Ed