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My bench is pretty flat when using my straight edge widthwise in some areas it is perfect. My worst spot may be 1/16" cup in the middle (is this a problem). Now my big question is how important is the bench to be flat lengthwise? I seem to have a hump in the middle. I have a 48" straight edge and when I hole it down on one side and let it take the lengthwise measurement it is coming up @ the other end by a little less than 1/4 of an inch. Lastly, I took a 45 degree and ran my straight edge across the length of the bench and it was all pretty flat except for one corner where I have 1/8 cup.

Do I have to worry about these gaps? If so how do I correct them? My bench is 30" x 60" and i do have a #7 jointer but it is hard to plane width wise and almost impossible to plane @ 45 degrees to go diagonally on the bench…
 

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Depends on what you do there. If you just work on small things I wouldn't worry too much. If you use it as an assembly table for larger furniture you may run into problems with a sub assembly ending up racked. I'm sure someone will chime in and tell you that you have to take it to shop with a massive belt sander or something, but that's nuts to me. Hand planing or belt sanding will not be very precise, but you could do that.
 

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Discussion Starter · #3 ·
I probably won't be putting large furniture together for awhile the biggest thing would be a coffee table. I do plan to use it as an assembly table.

If I do need it flat for assembly how flat? And how do I get rid of the hump in the middle of my bench… It is weird I have cupping and a hump.
 

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IMO a bench should be as flat (period). Before I flattened my bench (recycled bowling lane) I thought it should be flat, but soon found while working on it, that I was having alot of difficulty with various tasks.

So I decided to check it and was quite surprised to find one whole corner of the bench was almost 1/4" low and the bench was warped (skewed) after I put winding sticks on it.

If your face planing a board and your bench is not flat, there will be issues keeping your stock flat because it will flex under the pressure of the plane (similar to sending a warped board through the planer).

If you're doing joinery or any precision work, you don't want your wood rocking on the bench.

I recommend the video by Wood Whisperer on flattening a workbench with router.

I used a 1 1/2" planer bit.

Table Furniture Wood Wood stain Flooring


I don't know what kind of bench you have, but before you do anything, I would make sure the bench support system is planar. Usually there are stretchers running the width of the bench and they need to be even with each other. They also need to be flat and square. You'll have to take the top off. The last step is use winding sticks to make sure the two stretchers are planar. Anything off in the support will transfer to the bench when you bolt it on.

Even if you think its ok and have a good flat floor I would check this first.

The video give a good demonstration on using strings to establish parallel routing guides.

Once you get it set up, the process is pretty quick.
 

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It is strange that you have a cup and a hump. But it should be possible to plane those out.

What are you using for your straightedge ? How does that check out for straight ?

The flatness you can live with is up to you and the projects you'll be doing. If you have a 1/4" hump in the table than you'll have 1/4" of error in assembling anything that is almost the size of your bench.

I suggest you spend some time with a thick pencil making a topo map on your bench top. Keep moving the straightedge to find high spots. When you find the spots the straightedge is pivoting on, circle them and spin the straightedge slowly around them to find if it's longer in one direction. Try and draw lines that show areas of differing height.

Take your jack plane and use short strokes just inside your penciled high spots. Check again with the straightedge often. If you're dealing with 1/4" hump over 60" then it's only 0.05" over each foot. With a coarse set jack you can peel that off quick and if you don't check every few strokes you could make a new hollow.
 

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Discussion Starter · #6 ·
My straight edge is square. I have two 48" long pieces of steel that are 1/4" thick. And I don't have a hump I guess one end i planed more than the other. So one end is 1/4 of an inch lower than the rest. Probably the last 18" or so is lower than the rest of th bench. Thank you all for suggestions and I will watch the video but I don't have a router nor will I be buying one. I am trying to go more hand tools then maybe a few years from now when I have shown my wife I can do this well lol she will allow me the larger budget for some power tools to speed up my processes.
 

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I have posted a link below to my blog showing how I flattened my bench top using only hand planes.
I recommend you work in the following sequence:
1. mark out the hump and use your jack plane to bring it down to the level of the rest of the top. Make sure you use your winding sticks to check your progress so you don't create a hollow. I would start with cross grain planing, then shift to diagonal planing, then with the grain. Remember you are just trying to remove the hump, don't bother trying to get the top flat yet as you have more planing ahead of you.
2. Next, using your jack plane, I would cross plane the top to try and lower the top to meet the part of the bench that is now 1/4" lowest. Stay away from the lowest area right now, you are just trying to get the top into one plane. Continually use your winding sticks to make sure you don't over do it. I would take a pass from one side of the top, then move over to the over side of the top and repeat. You are looking to plane across so that you will at least overlap the middle of the top each time. Once you winding sticks show you are close to one plane, I would switch over to the jointer plane. This time taking diagonal passes from each side of the top. Start at one end in one direction, then start at the other end planing in the other direction. Once the diagonal passes have leveled the top, then change to taking passes with the grain using the jointer.

Good luck and be patient, sharp blades will make this job so much easier.

https://woodworkingweb.com/entries/180-flattening-seems-like-for-ever
 

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If you don't have a straight edge long enough, use string. Pull it as tight as you can, us blocks under each end that are the same height. Then just measure.
 
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