Replies

1. 
   bones | Jan 02, 2010 08:49pm | #1

   If i understand you right you have some 6/4 that will be ripped down to 1"x4"'s. If the final length is 90", I would want it flat laterally across the 4" width and I would run the face across the jointer, but 90" is a long piece and it would flatten out if that is the final lenght and I would not worry about it. If that piece is to be cut down to smaller pieces only check it after the cut down.

2. 
   WillGeorge | Jan 02, 2010 09:08pm | #2

   I have laminated some Panga-Panga (inside) to Sapele (outside). 96 inches long tapers... 8 OF THEM...

   They stand long and true! The Sapele was quarter sawn. Panga-Panga was just flat sawn I think...

3. 
   joinerswork | Jan 02, 2010 09:11pm | #3

   Jointerman,

   It depends on the straightness of the stock you begin with. If you are looking to end up with straight finished stock, you ought to select for the straightest rough stuff you can pick out. A board that has a knot right in the middle of its length (or even if it was sawn off the log next to a knot) will often have a crook at that point as well- you could easily get two 4' long straight pieces by cutting either sde of the crook- but a full 8' straight piece will be very thin, if you can get it flattened at all (jointing the face of such a board frequently releases drying stresses that cause the thing to keep crooking more and more as you attempt to flatten it). So, choosing straight, mild grained stock to begin with will go a long ways toward ending up with flat stuff at the end. Carefully chosen, carefully dried stock can be faced flat with just a pass or two across the jointer.

   Ray

4. 
   FrankDrackman | Jan 02, 2010 09:17pm | #4

   I might not fully comprehend the questions but I think that you might have it backward.

   Depending on what you are making you might want to ensure that the stock at your final dimensions is as true as possible. I find it really hard to make quality projects if I start the joinery process with materials that have not been prepped properly.

5. 
   jointerman | Jan 02, 2010 10:27pm | #5

   So I should only run it through the jointer/planer to make sure that any cupping across the faces is out, but at the 90-inch lengths I don't have to worry too much about flatness?

   BTW: the long pieces are for two table aprons and and there will be two short lengths for the short aprons. The 90+ inch length is to account for snipe, final length will be about 8-inches shorter.

   I will also likely have bracing to support the long aprons and support the table top.

1. 
   DonStephan | Jan 02, 2010 11:07pm | #6

   Is your question asking if there should be some twist over 90"? If you are starting with stock 6/4 thick, it will be pretty stiff so you should be able to get one face pretty flat and true with no twist if your jointer infeed bed is at least 24" long. It's always okay to remove most of the twist with a hand plane, which will make the power jointer work easier.

   You might consider leaving the apron rails thicker given the length of the sides. There's nothing wrong with a rail 7/8" or even 1" thick, and it will provide more support to the table top than one 3/4" thick.

6. 
   Lataxe | Jan 03, 2010 04:34am | #7

   DOn,

   I found that it helps to consider how much force it needs to take out the bend you are concerned about.

   If it takes just a bit of man-push, the bend will easily be pulled out when you assemble the piece, assuming all the other parts are not wonky. If it takes more than man-push, it will likely be a problem and bend the rest of the piece rather than itself becoming straightened by the piece.

   It takes enormous force to untwist the wind from a plank that is anything other than very thin and/or narrow. You have to plane-out wind.

   It takes enormous force to press the cup out of a u-profiled board unless it is very, very thin. Cup has to be planed out.

   Bowed boards, even quite thick ones, can often be unbent easily. As others have noted, long ones bend under their own weight. You can see bow disappear, often, if you turn the plank so the concavity faces down. If you can bend the bow out with a bit of hand pushing, the board will be compliant enough to stay straight by being placed within the joinery of the rest of the piece, assuming that joinery is configured to force it to unbow to "straight. Bracing your aprons with a central cross-brace the same length as the end aprons should do it.

   View Image

   View Image

   Lataxe

7. 
   SteveSchoene | Jan 03, 2010 08:46am | #8

   A 1x4 "joist" or apron with a nearly 8' span, seems a bit skimpy, both structurally, and visually. A bit deeper (like 5" instead of 4") would add a lot to stiffness and apparent sturdiness.

   And, as Lataxe's pictures show, a cross brace, or even several, joining the sides together, would also do a lot to increase the strength of the table support.

   And, keeping the aprons as thick as your stock allows will also add to the substantiveness of the table.

   I've been assuming from the long length of the apron that there are only 4 legs at the corners. Is this correct? Or is there another structural system that supports the top, with the aprons being more decorative in character?

1. 
   jointerman | Jan 03, 2010 04:14pm | #9

   Yes, your assumption is correct, 4 legs. Similar to Lataxe's table, but with through mortises on the short aprons.

   I do plan on having at least one, likely two cross braces. I was looking at the stock this morning, and thinking that I may push for 1-1/8" thickness. When I say 1x4, I truly mean 1" thick. As for going more than 4 inches, it will seriously start have the possibility of hitting the knees. I'll see if maybe I can go 4-1/4" or 4-1/2".