Any Tips on Thicknessing a board with one long edge higher than the other?

[Augusto Orosco]

Just looking for some advice on the best way to approach this:
How would you plane a board to thickness when it is consistently higher on one of the longer edges (picture exaggerated for clarity)? My thought was to do this in 3 steps: 1) Go along the grain starting on the high long edge progressively bringing it down to the low long edge level. 2) Go across the grain on the entire board to make it flat on that direction 3) Finish up along the grain to reach final thickness.

Does this sound reasonable? Would you suggest a more efficient approach?

Thanks!

P.S. The board in question is about 7 feet long and 21” wide. The height discrepancy is less than 1/8”.

[Jim Koepke]

A few thoughts on this...

First would be to make sure this can be supported along the full length while working on this. If your bench is long enough that should be fine. If your bench is short, you may want to think of a temporary way to support the board while it is being worked.

21" wide is a pretty big board. That could be challenging if the high side is the far side unless you can work it like a lefty.

Working the high side along the length would most likely be my first choice. Keep it square to the edge and then as you get close work the full side to flat. Be sure to check both sides. Let the board sit awhile to see if it is going to cup or twist.

Going across the could help if you have the high side close to you and keep most of the action to that side it could be quick and easy.

Good luck, post some pics and let us know how it goes.

jtk

[David Weaver]

As long as there is one flat face on it, find the thinnest point of the board, set a marking gauge with that point and then mark it all the way around and plane it to that line. Then mark again for finished thickness and plane it as you normally would any board that size (which for me would end with a coarse jointer setting).

You can do it just with one finish thickness marking gauge line, too removing the high spots visually until the thickness left to the line is fairly uniform.

How you get to relative similar thickness before finishing it off isn't too important, do whatever works best. Just thinking about it, I would probably work from the outside edge of the fat side in part of the way (with through strokes) and then flatten the hill that's left in from the edge so that I didn't accidentally work it hollow and so that I didn't have blowout on the edges. But experience will tell you how you want to work stuff like that after you figure out how you're going to mark it to know where to stop...even if you don't think too hard about it, natural desire to limit the amount of work you have to do physically will point you in the right direction on the details.

[Augusto Orosco]

Thanks, guys!

Maybe I should give a little bit more background. The 'board' I am talking about is actually my laminated top for my work-bench in progress. It's soft maple, 4" thick. I am going to install a Benchcrafted tail vise which will require and end cap secured with a long tenon and reinforced with lag screws. That's the main reason I want to make it a little bit more co-planar (without going crazy), since it will make layout and fitting of the tenon easier (and, have to admit, currently I can notice the imbalance and don't want to obsess about it in the future).

I already have one face perfectly flat (that's the one showing in the picture) and the bottom is planed to reasonably flat, but as I mentioned, not co-planar. I have used a marking gauge and marked along the four edges referring to the flat face; that's how I know how much I have to remove to make it coplanar.

P.S. Jim, I can work the plane either as a right or as a lefty.... flattening this board by hand forced me to teach myself how to do that!

[Jim Matthews]

Do I understand correctly that you're trying to have more material (1/8" thickness) the length of the "far" side to mount the vise?

If it's not for the purpose of fixing a screw, I don't understand why one end can't just be shimmed higher.
This looks as if it would be easy enough to do by hand, but I anticipate it's considerably more difficult than we might imagine.

It sort of cries out for a sled-mounted router (http://www.finewoodworking.com/assets/uploads/posts/38411/Resize_of_IMG_7924.JPG) to achieve the degree of precision you seek over such a broad expanse.

[Andrae Covington]

Considering it's a workbench top, I think I would either use Jim's shimming idea, or just take material off at the leg connection points. There is a section of Roy Underhill's The Woodwright's Guide: Working Wood with Wedge & Edge where he talks about flooring. Because they didn't have power planers in the old days, it would have been crazy to handplane pitsawn floorboards all to the same thickness. There's an illustration of using an adze to chop out a recess on the underside where the board will sit on a joist.

[Augusto Orosco]

Do I understand correctly that you're trying to have more material (1/8" thickness) the length of the "far" side to mount the vise?

If it's not for the purpose of fixing a screw, I don't understand why one end can't just be shimmed higher.
This looks as if it would be easy enough to do by hand, but I anticipate it's considerably more difficult than we might imagine.

It sort of cries out for a sled-mounted router (http://www.finewoodworking.com/assets/uploads/posts/38411/Resize_of_IMG_7924.JPG) to achieve the degree of precision you seek over such a broad expanse.



Considering it's a workbench top, I think I would either use Jim's shimming idea, or just take material off at the leg connection points. There is a section of Roy Underhill's The Woodwright's Guide: Working Wood with Wedge & Edge where he talks about flooring. Because they didn't have power planers in the old days, it would have been crazy to handplane pitsawn floorboards all to the same thickness. There's an illustration of using an adze to chop out a recess on the underside where the board will sit on a joist.

I don't want this to sound more complex than it really is. I just want to have the top a little more uniform in thickness than it is right now. Right now, I have 1/8" more thickness on one long side compared to the opposite edge (as shown in the sketchup picture in post #1). I don't like a 1/8" difference in thickness, but am not aiming for perfection here... just to reduce the difference a little, say to 1/16" so it's not evident to me by simply eyeing it.

I am not worried about the amount of effort, since I was able to flatten that top with hand planes in a few hours of work, and some of those boards in the lamination were sticking 1/4" higher than others (yeah, I am a newbie and was not very skilled at the glueing part). Remove another 1/8" - 1/16" is not a big deal to me in terms of effort; I just want to be able to do it properly and not mess up what I have already done with the top. Maybe I am just being too picky...

[David Weaver]

Presuming the bottom is flat, just mark it with a marking gauge set at the least thick area and plane it. It shouldn't take too long. enough to induce a sweat, but not enough to put you off your feet for the rest of the day. And once you've got it set to thickness, clean the surface upw ith a jointer. If the grain is running funny (some going one way, the others another) just set the second iron on your jointer close enough to mitigate the tearout. It is a "just do it" job after you've marked it.

[Jim Koepke]

My first thought was that this was a board from which you wanted to make a nice blanket chest or some such.

For a bench top? Fugetaboutit!

Put the fat side to the back, natural perspective will take care of it. We all know all of the imperfections in our work that others look at and say wow.

My thoughts on my bench is to not even bother with smoothing the underside of the top. Shim and trim to make it fit and be done with it.

Want the fat side to the front? Put up a mystery spot sign and tell people your workshop is in a strange natural vortex.

jtk

[Jim Matthews]

Pardon my confusion.

I thought you wanted to make the board thinner at one end.
David describes the method I was taught to get two faces parallel.

[Derek Cohen]

Thanks, guys!

Maybe I should give a little bit more background. The 'board' I am talking about is actually my laminated top for my work-bench in progress. It's soft maple, 4" thick. I am going to install a Benchcrafted tail vise which will require and end cap secured with a long tenon and reinforced with lag screws. That's the main reason I want to make it a little bit more co-planar (without going crazy), since it will make layout and fitting of the tenon easier (and, have to admit, currently I can notice the imbalance and don't want to obsess about it in the future).

I already have one face perfectly flat (that's the one showing in the picture) and the bottom is planed to reasonably flat, but as I mentioned, not co-planar. I have used a marking gauge and marked along the four edges referring to the flat face; that's how I know how much I have to remove to make it coplanar.

P.S. Jim, I can work the plane either as a right or as a lefty.... flattening this board by hand forced me to teach myself how to do that!

Hi Augusto

My initial reaction was the same as Jim's - if it is underneath it does not matter. However, there are other considerations. Firstly, you have to rout out for the BC end vise. I have done this myself and know that it will be easier (essential?) to attach the steel runners if the surface is flat. It is not an issue for the end cap. You can reference a tenon, if you make one as I did, off the flat side. Secondly, how will the out-of-thickness side effect the use of clamps, and will the different thickness affect the use of hold downs?

I have made tables of variable thickness, but a bench is a tool and may not be comparable. In which case the advice given by David should be followed.

Regards from sunny Cape Town

Derek

[Augusto Orosco]

Hi Augusto

My initial reaction was the same as Jim's - if it is underneath it does not matter. However, there are other considerations. Firstly, you have to rout out for the BC end vise. I have done this myself and know that it will be easier (essential?) to attach the steel runners if the surface is flat. It is not an issue for the end cap. You can reference a tenon, if you make one as I did, off the flat side. Secondly, how will the out-of-thickness side effect the use of clamps, and will the different thickness affect the use of hold downs?

I have made tables of variable thickness, but a bench is a tool and may not be comparable. In which case the advice given by David should be followed.

Regards from sunny Cape Town

Derek
Thanks, Derek! Yes, the BC vise cavity is one of the main considerations; but maybe it would suffice that the bottom around that area is flat, although not necessarily co-planar to the top? As long as they are not hugely out of plane (which they are not, as I mentioned I am talking a max of 1/8" along the 24" width), then the dog block for the vise can probably be touched up so it runs smoothly and aligns properly with the dog strip. My biggest consideration was fitting the tenon, but you are right, if I reference from the top which is flat I should be fine. I think I will touch the bottom just a bit more particularly around the vise cavity area and call it a day.

[Bobby O'Neal]

If you were going for a rough effort, could you mark a reference line on the thicker edge based off the thinner edge and then plain along the length till your just shy off that mark? Then go across its width to take out the hump you've created and after cleanup you will hopefully be leveled off.

[Augusto Orosco]

If you were going for a rough effort, could you mark a reference line on the thicker edge based off the thinner edge and then plain along the length till your just shy off that mark? Then go across its width to take out the hump you've created and after cleanup you will hopefully be leveled off.
That sounds good. It's almost the same as the 3 step approach I was considering in post #1, although it seems a little more efficient.

[Jim Koepke]

If you have an apron all around, no one will notice. :D

jtk