Thread: Finger joint jig problem

Hi,

Do you have any pics of the jig and the different thicknessers of board you are wanting to joint?

Is your jig like this?

How to Make Box Joints/Finger Joints - Easy Joinery - YouTube

Sounds like your dado stack might not be sitting at 90 degrees to the table; check the tilt angle with either a square (or a digital clinometer if you have one).

Thanks guys. As far as I can tell the blades are square with the table, I`ll try putting a 250mm blade on and make a cut in some plywood, that might give me more of an idea than putting a square against the dado.
Yes Camelot, the jig I made is the same principle as in the video you sent the link to, I`ll take a pic and send it tomorrow but main difference is I can adjust the width of the finger via a set of feeler gauges.

As said the blade is probably not spot on 90*. I would be tempted to try cutting both sets of fingers the same length then trim off the high ones when the joint is assembled. Blade is in same position for both cuts then.
Regards
John

I think I`m going to have to do what Orraloon suggested and cut both sets of fingers to the same size and trim the ones I need to be shorter. The suggestion by you guys that the blades are not 100% square to the work does make sense though the amount that they`re out is smaller than I can measure or rectify.
I`ve attached a picture of some small cuts next to deeper ones. only change was raising the blades and you can see in the deeper cut a ridge from the first smaller cut.

Two things to consider:

-- the trunnion of the saw is loose. Look inside, blade off, and see if there are grub screws along the lengths of the dovetail-mitres for the trunnion. These get rid of any slop.
-- the height winder, or angle winder are loose. Try seeing how they might lock in place, or with friction, and rectify that.

Getting a saw to cut at 90° regardless of height is the first step in getting a good setup (the other is at 45° without getting it to burn on the blade! THAT is HARD!)

Thanks Woodpixel, I`ll have a look at the trunnion (after I discover what a trunnion is)

Its this part of the saw:

massivetrunion.jpg


There are a few ways to raise and lower the blade. On the pictured example, the blade pivots around the big joint where I've put the arrows. You'll also see some small adjusters in a few places.

I think, however, that your saw might be something like the one I used to have. It was a left-tilt. The whole trunnion raises up and down in a huge sliding dovetail. I know this as it used to build a bit of sawdust RIGHT IN the bottom of that slide and needed the odd blatt of air to clean it