Gotta bowed board, no jointer?

[woodnthings]

This tip borrows on a video by Charles Neil on how to straight line rip an edge on a bowed (curved in plan view) board. It's also a tip on how to think out of the box when finding objects in the trash (see the basketball backboard frame as a table saw extension table) or in your closet.
http://www.woodworkingtalk.com/attac...s-100_1237.jpg
This tip uses an aluminum storm door section about 6' 6" long as a straight edge, light weight, straight and stiff. The concave side of the board is placed against the straight edge, it touches at 2 points, front and rear.
Then taped if necessary to keep it secure, then both pieces are run as a unit against the fence to remove the convex side. Then the board is run through the saw with the newly created straight side against the fence, no added straight edge. The result is a board with 2 parallel sides which are straight. An ordinary board with parallel straight edges can be used as well, but the light weight has it's advantages. bill
It's a little hard to tell from the photos, but there is a 1/4" gap between the straight edge and the the bow in the middle of the board.

[Bob Willing]

I use a similar approach but my straight board is about 5’ long and I space 3 flat head screws about 18” apart with one in the center. This way I can adjust the screws to get one side straight (concave or convex side). The reason I use a 5’ piece is because I use a lot of 4’ finished boards. I don’t usually tape mine but after seeing yours I will have to give it a try.

[woodnthings]

I suppose if this were a permanent jig, the storm door section, I would use some sort of clips, rather than the tape, which really doesn't hold very well. I think Grizzly has some clips with hold down screws. The more I deal with bowed boards the less I'm inclined to use the jointer to straighten the edge, only flatten the face. The table saw with a good blade will take out the bow with less effort and by using a straight edge will get it just as straight. That $30.00 Freud Diablo from HD works great.
One pass with the table saw beats 5 or 10 on the jointer! bill
Grizzly Board Straightening Clips:
http://cdn0.grizzly.com/pics/jpeg288/h/h3310.jpg

[Bob Willing]

Originally Posted by woodnthings

I suppose if this were a permanent jig, the storm door section, I would use some sort of clips, rather than the tape, which really doesn't hold very well. I think Grizzly has some clips with hold down screws. The more I deal with bowed boards the less I'm inclined to use the jointer to straighten the edge, only flatten the face. The table saw with a good blade will take out the bow with less effort and by using a straight edge will get it just as straight. That $30.00 Freud Diablo from HD works great.
One pass with the table saw beats 5 or 10 on the jointer! bill
Grizzly Board Straightening Clips:
http://cdn0.grizzly.com/pics/jpeg288/h/h3310.jpg

The screws are on the edge, they are similar to cabinet screws. I have seen the Grizzly jigs (or similar ones) before but I wondered if they hold the board at an angle because I think they raise the board slightly. I would think that they would also catch on the TS table edge as you were pushing the board. I also have a problem with a jointer because I think they sometimes taper the board so now I run them through a planer to get them parallel. I usually hold about 4 boards side by side to keep them parallel and perpendicular.

[dbhost]

What you show here is something I have often thought of (but never had an excuse to try).

FWIW, I have used 8' piece of angle iron as a straight edge for ripping sheet goods as well. Just measure your distance and figure that depth in to where you set the straight edge, and go to town on it!

[maplehillfrm]

pretty neat idea, here is my dumb question of the day, on which table do you put most of your pressure on when using the jointer? infeed before the cut. or outfeed after the board is started thru?

I dont use my jointer enough, I guess I always end up questioning myself 1/2 way thru..

alot of my bowed boards I run thru the saw to get a flat edge too, thanks pat

[woodnthings]

You are right on both. Start by sighting the board for warp:
Wood "warping" definitions
Put the concave side down and start the cut/plane. Remove what is nesessary from both ends by flipping and continuing to joint. You are using the jointer as a hand plane, only you are not doing as near much work. As you sight the board it will become more flat as you repeat the process. THEN when it is "flat" by sight, keep the pressure on the infeed until there is enough stock on the outfeed to apply the same downward pressure. ASSUMING the jointer is correctly set up the entire board will be flat after a few light passes. Then joint the edge and you are ready for ripping to width and thickness planing. bill

[mics_54]

I've never owned a jointer. Never needed one.

[woodnthings]

OK. That settles that. End of this discussion. bill
BTW How do you "flatten" a board with twist , bow, cup or a kink?


Wood warping is a deviation from flatness as a result of stresses and shrinkage from the uneven drying of lumber.

The types of wood warping include:

• bow : a warp along the length of the face
• crook: a warp along the length of the edge
• kink: a localized crook, often due to a knot
• cup: a warp across the width of the face, in which the edges are higher or lower than the center
• twist: a distortion in which the two ends do not lie on the same plane

Wood warping costs the wood industry in the U.S. millions of dollars per year.

[Steve G.]

I cut a 15" wide 3/4" birch ply 8' long... then I get my stock with the bowed part sticking out however much I want to cut it off, and I screw it down to the plywood so the the plywood is the only thing touching the TS table, then I rip it off.
Works for me

[BHOFM]

I look for the bowed boards, some time I get them
at a bargain!



OK>>>, Back on topic people!

[mics_54]

I use a wood stove to fix bad lumber.

[woodnthings]

Do you stack it on top or put it inside? Only short pieces that won't fit on the jointer? Probably "dumb" questions bill

[John in Tennessee]

It's closer to a planer isn't it?

[woodnthings]

Jointer:
"A jointer (also known in the UK and Australia as a planer or surface planer, and sometimes also as a buzzer or flat top) is a woodworking machine used to produce a flat surface along a boards length.
The jointer derives its name from its primary function of producing flat edges on boards prior to joining them edge-to-edge to produce wider boards. The use of this term probably arises from the name of a type of hand plane the jointer plane which is also used primarily for this purpose."

The terms are sometimes used interchangably but obviously they are not the same. Thickness planer is the correct term for that machine since it machines to a constant thickness, planer for short. The most obvious difference is the location of the cutter head, planer above the workpiece, jointer is below the work piece. The planer is self feeding, the jointer is not. You can just lift the work off the tables at any point and restart your cut. I do this all the time, since jointing is not a "one pass cures all" process, especially when flattening a boards surface, to get it ready for planing...heh...heh bill