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Resawing for beginners

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Forum topic by pashley posted 05-05-2008 05:10 AM 2727 views 1 time favorited 15 replies Add to Favorites Watch
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pashley

1029 posts in 2465 days


05-05-2008 05:10 AM

Topic tags/keywords: question resaw

Ok, so i finally got a decent bandsaw, that can do 7” re-saws!

So I put a board thru, that was flat on both sides, and re-saw it, pretty much right thru the middle. So far so good! I plane the book-matched sides I have just re-sawn. Still, good. 15 minutes later, I have some thin, cupped re-sawn boards!

I’m guessing some stresses were released, or some how the tensions in the board were changed. What to do? I love the pieces I have! Can I “flatten” them some how? I only have a 6” jointer, FYI, and these are 7” wide.

-- Have a blessed day! http://newmissionworkshop.com


15 replies so far

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GaryK

10262 posts in 2736 days


#1 posted 05-05-2008 06:52 AM

Sometimes that just happens. They may equalize after a while.

You could try spraying some water on the cupped side and if a flattens out clamp it while it dries.

Good luck.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

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rikkor

11295 posts in 2622 days


#2 posted 05-05-2008 10:59 AM

I had that happen to me with some cherry. I have it clamped down to see if it will flatten.

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grumpycarp

257 posts in 2493 days


#3 posted 05-05-2008 02:09 PM

Resaw the material and then leave it alone for a day or two. Then surface it (oversized) and leave it alone again overnight. You didn’t mention where your shop was, what the temp was, Hg pressure etc. All of those have something to do with your lumber as does drying rate and how it was dried, air dried or in a kiln. Did you check the moisture content? There is a reason why flitch sawn veneers cost what they do.

I’m sure that with practice you can get spectacular material from your shop but just buying a bandsaw does not guarantee you results from the mere purchase of it.

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Chris

1867 posts in 2739 days


#4 posted 05-05-2008 03:08 PM

I have found that I have better results following the method Grumpycarp proposed. If I go to final thickness quickly mine will nearly always cup or warp. I’ve even had a piece of Purple Heart split up the middle!

-- "Everything that is great and inspiring is created by the individual who labors in freedom" -- Albert Einstein

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ChicoWoodnut

904 posts in 2563 days


#5 posted 05-05-2008 03:45 PM

It’s true, that almost always happens. Follow grumpy’s advice. The cupping will almost centainly get much better after a few days. If the pieces are too wide to surface on the jointer, rip them down the middle with the band saw, surface them on the jointer, plane them, joint the edges, then glue them back together. You can get creative with the panels by bookmatching wide panels inside the frame without a rail in between. Look at this bathroom vanity I made from maple. The left and right doors have bookmatched figure using that technique.

Don’t give up! Wood is not plastic or metal. It moves.

-- Scott - Chico California http://chicowoodnut.home.comcast.net

View dirtclod's profile

dirtclod

169 posts in 2608 days


#6 posted 05-05-2008 09:46 PM

grumpycarp’s suggestions are on the money. It’s notj ust moisture gradients that can cause this. Stress in the tree (leaners, etc.) it came from can also cause wood to move when sawn.

-- Wonderful new things are coming! - God

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John Fry

74 posts in 2448 days


#7 posted 05-07-2008 01:45 AM

I do a lot of resawing and in my opinion here is what happens EVERYTIME you resaw a thicker piece down to multiple thinner pieces. You have just exposed interior wood that has not been exposed to the local environment and now it will try to acclimate.

Wood gains and loses moisture content from the outside in, and it does so rather slowly. So, even if you buy lumber and let it acclimate in your shop for weeks, the internal wood is probably going to have a different moisture content than the outside surface that has been exposed and has already acclimated.

Then when you slice it, the internal wood immediately begins to adjust to the relative humidity of its surroundings, but the external wood isn’t changing because it has already adjusted…....Bingo, this causes cupping!

The three rules I use whenever resawing are to;

1) flat stack the slices under heavy weight immediately as they come off the saw, (I use wrapped bricks) and then when I’m done resawing,

2) I sticker and clamp the slices to keep everything flat and allow good air circulation around all sides of the freshly sawn material until either acclimated, or used in the project.

3) always complete the resawing of each board without stopping. If you are making multiple slices from some thick stock, and you take a lunch break half way through, you may find upon your return that the “mother board” has also cupped and you can’t continue without re-jointing.

Here is a picture of how I store freshly resawn boards. These are stickered and clamped exotics right after completing the resaw session.

Most people will say to “sticker and weight” and that is fine, but for me, I sticker and “clamp” so I can use the clamps as handles and move the stacks around the shop without them being in my way. The clamps are only tightened enough to maintain flatness, but not so tight that they don’t allow the wood to expand and contract.

Here is a stack of 1/16” shop sawn veneers stored the same way right off the saw.

It is true that there can be other factors, like tension, or crooked growing trees (?), but it is my experience that says 98% of the time it is nothing more than a freshly cut board that has two faces of different MC trying to adjust to the external RH.

-- John, Chisel and Bit Custom Crafted Furniture, www.chiselandbit.com

View ChicoWoodnut's profile

ChicoWoodnut

904 posts in 2563 days


#8 posted 05-07-2008 06:09 AM

That’s a nice bit of information John. I sure like the idea of being able to pick up the stack and move it all at once.

Thanks

-- Scott - Chico California http://chicowoodnut.home.comcast.net

View pashley's profile

pashley

1029 posts in 2465 days


#9 posted 05-07-2008 02:28 PM

Thanks, John – you seem to be the re-saw master!

-- Have a blessed day! http://newmissionworkshop.com

View bobcef's profile

bobcef

7 posts in 2412 days


#10 posted 05-18-2008 11:10 PM

Great explanation and pic’s John. I also re-saw a lot of exotics for acoustic guitar backs, sides and spruce soundboards. I do it just about the same way except that I needed way too many clamps. I use a bottom and top piece of 3/4” plywood or melamine covered MDF. Then I use a couple of wraps of narrow shrink wrap on each end and the middle and remove the clamps. Another problem that causes this is case hardening during the kiln drying process. I cut most of my wood green and air dry with the aid of fans in my humidity controlled shop.

-- Bob C www.rctonewoods.com

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beemerbob

8 posts in 2543 days


#11 posted 06-06-2008 04:51 PM

John, How long do you need to keep the boards stickered?

-- Bob from Northwest Florida

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Al Killian

273 posts in 2500 days


#12 posted 06-06-2008 09:27 PM

I have been told by my lumber guy and a few others, that you should let it set for a week or so. This is the same for brining home lumber.

-- Owner of custom millwork shop

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TopamaxSurvivor

15075 posts in 2423 days


#13 posted 06-08-2008 08:50 AM

Thanks for the hot tips, John. I would have never thought about it untio it was too late!

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View crazycoonass's profile

crazycoonass

7 posts in 721 days


#14 posted 12-31-2012 01:01 AM

hi everyone i saw the advice given by a couple of ya’ll and joined the site. i need some advice on getting some brazillian rosewood (dalbergia nigra) resawn and where to find someone to do it.i do not have the tools i used to have after getting hit by back to back hurricanes and am slowly working my way back into it. any advice will be appreciated and i live south of houma louisiana.

-- mike louisiana, crazycoonass61@yahoo.com

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crazycoonass

7 posts in 721 days


#15 posted 01-07-2013 10:39 PM

hi i resawed one board on the table saw and followed the directions john gave us and every thing has turned out just fine so far. it was a 5 1/2 inch piece and i am looking for a band saw to do the 8 1/2-9 inch pieces i plan to saw as much as i can on the table saw and finish it up with the band saw that rosewood is hard to cut with a hand saw plus the boards are up to 12 feet long. anyone in the louisiana area with a good used band saw for sale? forgive me if i don’t answer right away as i have been as busy as a 1 legged man in a butt kicking contest. and as soon as possible i will post some pictures of this beautiful lumber.

-- mike louisiana, crazycoonass61@yahoo.com

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