Squaring a board with a tablesaw

[Nate Miller]

If a board has one flat face, can I use a tablesaw to square it?

I was thinking that if I put the board against the fence and rip 1/4" off one edge, then flip it and take 1/4" off the opposite edge, the sides should be parallel. Is that correct? And I could then use the mitre gauge to square the ends, making the board square?

Or am I missing something?

[Frederick Skelly]

Hi Nate. Welcome to SMC! Glad you're here!

You really need one face flat and one edge straight to square the board. If one edge isn't straight (eg, rough lumber), I screw a long straight piece of wood to one edge of the rough board, place it against the fence and rip the opposite side straight. Then unscrew the board and rip the other edge straight. Then, square the ends.

Fred

[Andrew Hughes]

I can be done that way Nate, but it might not be a good practice since it's always safer to have a straight edge to run on the fence.
Ive done it when the piece is short or not too thick.
When you start using this technique on thicker hardwoods with a crooked edge you start running the risk of a kickback or a face full of sawdust.;)
This might be consider cutting corners,and I'm against that.
Always best to practice good safe habits woodworking then safety becomes your normal.

[Mike Cutler]

If a board has one flat face, can I use a tablesaw to square it?

I was thinking that if I put the board against the fence and rip 1/4" off one edge, then flip it and take 1/4" off the opposite edge, the sides should be parallel. Is that correct? And I could then use the mitre gauge to square the ends, making the board square?

Or am I missing something?

Yes, but you need to make a jig to do it safely. Not that I haven't done it without a carrier board, but the carrier board makes it easier. There are no guarantees that you'll get it parallel in two cuts. It would have to have a pretty straight non jointed edge already. You would also be limited by the length of you fence. Once the non jointed edge gets to the end of the fence it's going to be able to move.

Google "jointing a board with a table saw" and you'll find many, many references and you tube videos on how to make the carrier board.

[Nate Miller]

Very helpful-thank you everyone.

[lowell holmes]

You might want to consider a push stick with a tab sticking down on one end.
It sure makes the package stable. That's what I have. I made mine out of 1/2" plywood.
Mine is about 2" thick.
I rip one side and then turn it over and rip the other.

[scott vroom]

If a board has one flat face, can I use a tablesaw to square it?

I was thinking that if I put the board against the fence and rip 1/4" off one edge, then flip it and take 1/4" off the opposite edge, the sides should be parallel. Is that correct?

Or am I missing something?

Yes you are missing something. If on the initial cut the edge against the fence is not straight, the curvature will follow the fence resulting in a curved cut. As Frederick points out, you first need to straight-line one edge and then put that edge against the TS fence for your initial cut.

[Pat Barry]

Your method works better for shorter boards. 8 footers, for example, are more of an issue due to the concerns noted above. You can creep up on it with your method taking thinner rip cuts

[Prashun Patel]

I have clamped a straight edge to the table saw fence (well, a 'straight' 2x4) to serve as a long, auxiliary fence. Then you can run your board against that - placing the concave side against the auxilary fence.

The key is that the target piece does not need to be straight; it needs to run through the blade straight. If the concave side can ride through the blade on 2 points, it will be fine.

Again, this works only with shorter boards.

Nowadays, it's just easier to knock down high spots with a hand plane to make the reference face fairly flat. THEN, you can do exactly as you mention and it will work pretty well.

[Ted Reischl]

You should rough cut the lengths you need from the board first. There is no point in straightening the edge of an 8' piece and then cutting it up into shorter lengths. Unless the parts have to be 8' long. I try not to build anything that big, it gets to be cumbersome, heavy and most people cannot move it around.

As mentioned above it is a pretty trivial matter to straighten the edge of short boards. I have a piece of straight maple about 1 inch thick, 4 inches wide that is straight. I drilled two holes in the edge of it so that I can easily clamp it to my fence with those fence clamp thingies. Works great!

The other simple method is to use a piece of plywood, usually about 12 inches wide, mount some toggle clamps and away you go!

BTW, I sold my jointer years ago because I rarely used it for face flattening and never used it for creating a straight edge. Jointers are very old technology, fussy and generally a PITA when it comes to resetting blades, getting the tables parallel, etc. The sawblades manufactured these days are a way different animal than what was used in the "good old days".

[Mark W Pugh]

I use my track saw for the first cut on my rough lumber. Then to the table saw.