This easy to build table saw jointing jig makes it a snap to rip a straight edge on stock that is warped or bowed.
Without that one straight edge, it's almost impossible to dimension your stock accurately on the table saw. The tablesaw jointer jig provides that edge, allowing you to square your workpiece and get on with the job.
I cut a piece of 3/4" mdf 4' long by 8" wide for the jig. Use the factory cut side against the fence.
Even if you have a decent wood jointer, a lot of time and effort can be saved by using this jointer jig on severely bowed boards first, and then finish off with a light pass on the jointer.
This simple table saw jig can also serve as a tapering jig, great for cutting tapers on table legs and other furniture projects. Anything that can be clamped securely, and is not too thick for your blade, can be cut at almost any angle you want.
If multiple copies of a workpiece are needed for a project, the jig can easily be modified with stop blocks to assist in making repetitive cuts.
The table saw jointer that I'm building here is 48" long by 8" wide and made from 3/4" mdf. It can easily be scaled up if you need to joint longer boards, and I'll provide some considerations near the end of this article.
It's best to use a good factory cut edge against the fence because they are usually dead straight.
Once the mdf was cut to size, I drilled and countersunk three holes for 1/4" by 3" long coarse thread tapered head machine screws.
The screw holes were drilled and countersunk. Make sure they're well below the surface.
The holes were drilled 2" in from the fence side -- one in the middle at 24" and the other two 6" in from each end of the jig. The countersink is on the bottom of the jig.
The countersink must be deep enough so that there is no chance the screw head will scratch the saw's table. These holes will be used for wooden (birch) hold - down clamps.
One hold - down clamp will be used on each end of the stock, so the middle hole in the jig is for shorter pieces.
The clamps are 1" x 1 1/2" x 7" long. The big end is 1 1/2" high and the small end is 3/4" high. Both ends were rounded over to allow the clamp to apply downward pressure when cutting different thicknesses of stock. A 1/4" hole is drilled 1 3/4" from the big end.
The fence should be adjusted so that the jig is as close to the blade as possible.
A couple of knobs with washers are used to tighten the clamps securely against the stock to be jointed.
If you don't want the bother of making these hold down clamps, a set of toggle clamps can also be used to clamp your stock to the jointing jig.
To use the table saw jointing jig, set the fence so that the jig is almost touching the saw's blade on the left side. This will give a kind of zero clearance effect and lessen the chances of any splintering.
With the jointer jig pulled back from the blade, set your stock on the jig and adjust it so that it removes only enough material to clean up the edge. Since the left edge of the jig is almost against the blade, you can use it to gauge how much material you are actually cutting off. Tighten down the clamps, making sure they won't interfere with the fence.
Here I am jointing the rough edge on a yellow cedar board. A thin cut was all that was needed. The wood hold-downs were made in the shop.
Adjust the height of the blade high enough to clear the stock and feed the jig in, holding it tight against the fence.
To straighten the opposite edge, remove the board from the jig and set the jointed edge against the fence and rip it to width.
With a good quality sharp blade, this table saw jointing jig is capable of making glue ready edges without any additional milling.
Place the lines you marked earlier (arrows) on the left edge of the jointing jig.
I like to use my tapering jig for cutting tapers on parts like table legs, but if you don't have one, this table saw jointing jig works pretty good as a substitute.
The trick is to mark the start and end points on your stock and line these up precisely with the left edge of the jointing jig. Use a square to extend the lines down the side of the stock to aid alignment.
I had to add spacers under the rear portion of the hold down clamps to keep them level with the 1 1/2" thick board I'm cutting in the photos. Also, if the front clamp won't reach far enough to provide a good hold on the board, a new hole will have to be drilled and countersunk closer to the left edge of the jig.
With the jig set up against the blade, push the jig through the same as when jointing. Only now, it'll cut a taper instead.
If you're only going to taper one or two pieces, this set-up will get you by. But if you have several pieces that need to be tapered the same, I would screw a block of wood at the front of the stock and one on the side to keep your cuts consistent in size and shape.
This jig is made to be modified, so don't be afraid to screw or drill holes in it. When it gets to the point where too many holes and other mods weaken it beyond saving, it's easy enough to make another one.
This tablesaw jointer jig can be scaled to any size needed, but if you make it any longer than six feet, you're going to need a decent infeed and outfeed support system. Also, any longer that six foot and I would consider using 3/4" plywood instead of mdf.
I found an interesting infeed/outfeed setup the other day that would work perfect in my basement shop. It's called the ezee-feed system, and is manufactured and sold by long-time professional woodworker Lee Jesberger.
It's portable, so when you don't need it, it's not taking up room. And it only takes a few seconds to attach to the saw when you do need it. Definitly on my wish list.
A jig of 8 or ten foot will also benefit from an extra strip of plywood screwed to the fence side to add some stiffness. The strip should be at least 2" wide, so the jig might have to be widened if jointing wider boards.
My shop is small, so I tend to cut my stock into usable lengths for each project. Why wrestle with an eight foot board when all you need is three feet.