understanding resawing

[Assaf Oppenheimer]

Hi all, I have this fantasy of buying 4/4 stock and resawing it for my needs: 2 x 1/4"-3/8" boards out of one 4/4, etc... I understand that doing so will require significant planing to fix cupping bowing etc.. but is it really possible?
what are the guiding principles of resawing stock (not for laminations)?

appreciate any help understanding this

[Michael Bulatowicz]

Hi Assaf,

I have done this a number of times, with varying degrees of success depending on the wood and its internal stresses; in one example with long-dry (10 years or more) oak, the material cupped so badly during resawing that the kerf had to be wedged open to keep going. Stubbornly, I kept going anyway. The next morning, the ~3/8 inch thick pieces were cupped almost an inch from center to edges, both bending toward the freshly sawn face. Other examples with oak, maple, and pine have gone well and remained flat.

Make sure the stock you are resawing is at equilibrium moisture content. Straight grained is also preferable.

When I resaw a board, I use my coarsest rip saw (for me, 5 tpi). First, I sharpen the saw if it’s not already quite sharp. This is a labor intensive process, and a sharp saw helps it go faster and easier.

To make two boards of equal thickness, I make a mark down the center of each edge and across the center of one end; the goal while cutting at all times is to keep the saw centered on the line.

Placing the board vertical in the vise, I make a shallow cut across the end of the board, centered on the line. Drop your hand slowly, trying to let the end grain kerf guide the far end of the saw while you cut down the line on the near end—try to avoid cutting the side you can’t see. When you have angled your saw as far as is comfortable for accurate sawing, tilt the board away from you in the vise and continue as you are comfortable and accurate, still trying not to cut the far side of the board.

Flip the board around in the vise, again vertical. Follow the same procedure, cutting until you need to tilt the board and then until you’re nearly cutting the far side. Flip the board again, tilted away from you rather than vertical (the kerf is now deep enough to guide the saw when the board is tilted away from you, so you no longer need it vertical to start) and repeat the process of cutting and flipping the board around, cutting only the line you can see, until the board is just about cut through.

For the last cut, I like to wedge the kerf open somewhere in the middle of the board with a shim about the same thickness as the saw kerf and clamp the wedged area in the vise; the idea is to be able to saw through the last little bit of the board with the work still held securely.

After that, it’s all about the planing.

Things to watch out for while resawing in this way seem to mostly include warping of the cut sections of the board: twisting, cupping, and bowing can all drive your saw off the line, cause a cupped cut, pinch the plate, and so on (DAMHIKT); when these happen, wedging the kerf open helps tremendously but be careful to avoid prying it open too far and preventing the existing kerf from helping to guide the saw.

There may be others here with more experience resawing by hand who can offer more advice, but I hope this helps.

[Ben Ellenberger]

Resawing 4/4 is do-able, but if it is a very wide board you will have to be pretty precise to get 1/4” boards out of it. 5/4 would give you more margin for error.

4-5” wide stuff is pretty simple. As it gets wider it gets harder to keep your cuts straight. I’ve used a 26” rip saw with 5 tpi to re-saw panels in hard maple and walnut. I defintely screwed up one or two before I got the hang of it. It is a lot of work, but really satisfying when you get it right.

I’ve decided I will re-saw by hand if I want a book matched piece, but it is more work than I want to do just to save money on lumber.

1/4” panels will probably cup after being re-sawn. But, if you are using them for drawer bottoms or frame-and-panel assemblies, they should be usable. I wouldn’t try to,plane them completely flat, I would just get them good enough to go in the groove and rely on the panel or drawer to keep them flat.

also: I second the recommendation to sharpen your saw before beginning. It makes a huge difference.

one more thought to help you gauge the time and effort: if I wanted to take a 1/2” of thickness off a board, I would use a scrub plane before I would re-saw, even for pretty expensive wood.

[Stephen Rosenthal]

Oh to be young again and ennobled with the romanticism of resawing by hand. Well I’m neither young or ennobled, and while Michael and Ben offer good advice, I’ll use a bandsaw.

[Tom Trees]

+1 Stephen, to be able to clamp the timber down to something flat immediately is a plus, if it's not going to be glued to anything.
I'd be looking for quartersawn or flatsawn stock which doesn't have any twist at the very least.
Often one piece stays straight, and the other bends, so it may take two rounds of sawing to make a pair of flat pieces.

Tom

[Phil Mueller]

I’ve watched with amazement Tom Fidgen resaw dozens of board feet into perfectly flat pieces. I’ve done it myself, but fairly often the result with anything around 1/4” or less quickly turns into a potato chip. That’s actually fine when using as a veneer which is glued down to a stable, thick substrate…like a table top or apron. It’s satisfying. Frankly, I enjoy the experience of a well sharpened hand saw. I made a 1/4” kerf saw to create an initial “groove” around the board and that does help to guide the saw. Rotate the board often to cut from all sides to keep the cut as even as possible. It’s only time and exercise. When it’s not about production work, it’s only about doing what you find makes the hobby enjoyable.

[Jim Braun]

Assaf,
An article in fine woodworking, if you subscribe, by Bill Pavlak, helped me with my resawing. In general the more you do it the better you get at it.
https://www.finewoodworking.com/membership/pdf/269613/011275022.pdf

I didn’t have any issues with severe cupping, etc. some tips:
1. Sharp saw, I used a 5 tip rip saw.
2. Some set but not too much.
3. Let the saw do the work, don’t try to force it down into the work. Just a nice steady push and pull.
4. Only saw on the line or lines you can see. Flip the board to see the other side. Flip often.
5. If you have trouble starting, use a scratch stock or back saw to give yourself a “groove” to start.

jim

[steven c newman]

Afraid I cheat a bit...I use the tablesaw to cut a kerf all the way around the board. Usually 1-2" deep...less wood to cut through with the 5-1/2 D8 I have....and I use as much of it's 28" length as the handle will allow, I bought a 28" saw, so I'll use the entire saw.....
469961
469963
A simple wedge to keep the kerf in this 1 x 6 Ash board open..
469964
Worth the effort?
469965

Ehhh, could be...

[chris carter]

My fantasy in resawing was forced upon me by lack of a large bandsaw to do the work for me. I used a 4-1/2 tooth hand saw and for anything wider than a few inches it was painfully slow and came with a lot of sweat and a water bottle nearby.

Then I got this 48” giant toothed bad boy!
470014

Now resawing is laughably fast and effortless.

[Mark Rainey]

Now resawing is laughably fast and effortless.

Chris, I have tried to master resawing in the past, only to be defeated from exhaustion. I now resaw on a 14 inch bandsaw, which is not exactly fast and does take a bit of effort. I am somewhat incredulous about your claims, but if you have discovered the magic, please reveal - I will be an eager student

[Ben Ellenberger]

Chris, I have tried to master resawing in the past, only to be defeated from exhaustion. I now resaw on a 14 inch bandsaw, which is not exactly fast and does take a bit of effort. I am somewhat incredulous about your claims, but if you have discovered the magic, please reveal - I will be an eager student

That is my reaction too.

Chris, I don’t think that word means what you think it means.

[Richard Coers]

Glad I'm not the only one. If you are using your arms, it's not effortless! LOL

[Warren Mickley]

I have been resawing by hand for over 45 years. Here are some notes.

A board that is well seasoned does not have cupping problems. The most common reason for this problem is boards that were dried too rapidly. In this case, the outside dries while the inside is still too wet. So the outside shrinks and compresses the inside to he point where is is somewhat damaged. When the inside later dries it want to shrink smaller than the outside (because it has been compressed). When the board is opened, the inside can shrink and form the cupping. This drying defect is called case hardening.You are somewhat safer with air dried stock.

I recommend resawing before any flattening. Some people like to flatten one side with the idea that they are going to saw parallel to the flat side. It is better to preserve all the thickness you can until after the resawing and then do flattening.

One big problem in resawing is that the blade curves to the left or the right inside the cut. This can be caused by teeth on one side that are longer or sharper than those on the other side of the saw , causing it to pull right or left. The biggest cause, however, is that the operator in trying to slightly alter the direction of cut, leans or twists too much to one side, causing the blade to buckle inside. For this reason, corrections to the cut should be very gentle. If you get off the line a little bit, think about making a correction over the next five inches, not the next inch.

I think it is best to cut straight across the grain or at a slight angle upwards, but best results come from sawing all from one side. Check the backside frequently or saw with a partner.

You ought to be able to get two 3/8 boards from 4/4.

[chris carter]

Chris, I have tried to master resawing in the past, only to be defeated from exhaustion. I now resaw on a 14 inch bandsaw, which is not exactly fast and does take a bit of effort. I am somewhat incredulous about your claims, but if you have discovered the magic, please reveal - I will be an eager student

Here's some of my observations with the saw: https://sawmillcreek.org/showthread.php?290097-What-I-learned-about-Roubo-frame-saws
And a few other comments about it are in another person's frame saw thread: https://sawmillcreek.org/showthread.php?289824-36-inch-Hickory-Frame-saw-Eats-wood-like-a-Great-White-eats-Seals&highlight=

The saw kit was an Xmas present from my father-in-law who has been woodworking for 40 years and has a really awesome retirement dream woodshop (power tools - all the nicest stuff). Anyway, he came to visit a couple months ago and I gave a little demonstration with the saw. I had to pick his jaw up off the floor. He was not expecting it to cut as fast as it did.

[Mark Rainey]

Chris, Warren, my interest in hand resawing may be rekindled. Thanks for the information.

[James Pallas]

It pays to listen to the experienced like Warren. I was lucky to be able to listen and watch some excellent craftsman. I learned early to watch carefully no mater the task. I’m no expert at resawing. I have learned a little though. Assess the material, choose the right tool, get the work properly fixed, make sure you have a comfortable working area. The biggest mistakes I made at first was the wrong saw. Sharp goes without saying. The wrong tooth size will make for a saw that will not clear. If that is the case your done before you start. Just relax it takes as long as it takes. Of course you have to have white shoes with plaid socks too.
Jim

[Scott T Smith]

We have resawn literally tens of thousands of square feet of material with a horizontal resaw in my shop. Rarely have I experienced any wood movement after resawing. We are able to maintain tolerances within a few thousands of an inch across a 16” cut too.

As others have indicated, if the wood was properly dried and at EMC throughout the board it should not cup. The only other advice that I would give you is to ensure that you use a very high quality blade, that it is both sharp and that the teeth are consistent.