Re sawing Wood ?

[lildesertwoodshop]

 I tooled over to the local wood supplier in town this after noon to collect some materials for a project. I purchased 4’ Of Mahogany 3/4 thick and 16” wide. I wanted the mill fellers to re saw the board in half, they could only re saw boards 11” and under , so I said chop it in half and re saw the two giving me 4 boards out of the 4’ board. When don I grabbed my bundle and headed home, upon arrival looked at the four boards, two of them were perfectly strait and the other two had a hockey stick vibe. ( The board that I picked out was Perfectly strait to start with I went through half the stack to find it). Also It seems as though he planned or sanded them all down to 1/4” thickness , that I did not ask for at all. And charged me $23 bucks for the ten mins of work. ( not mad about mill fee makes a good argument for the Mrs to let me buy the band saw I have been needing as well the planning / sanding thing Ill be more clear next time)  However The question is in regard to the 2 Non strait boards, Is this normal in re sawing , does this have something to do with the planning / sanding he did ?   Is there a way to straiten out the two boards?

[Levi Rathje]

That is the result of internal stress in the board. Or it can be from moisture differential if the board from center of the board to the outside. This is why it is generally best to mill off each side evenly. This isn't uncommon when resawing, at least not for me on wide boards.

[krtwood]

When you resaw you may release some tension in the wood, and the thinner the wood is the less it can resist any of those forces that want to warp it.  So it is really common to get some movement.  The best thing is to resaw it and then leave it stickered for a while to give it a chance to reach a new equilibrium.  Then you joint and plane to get your flat stock.  If you need it to be long and straight and thicker than 1/4" you probably want to start with something thicker than 3/4", or at least start with rough stock that is still 1" thick to give you a little more meat to work with.

 

It really depends on what you want to do with it whether a little bow is a problem or not.

[Rapid Roger]

I have (and I'm sure you have too) ripped boards on the table saw and have one side (usually the fence side) come out nice and straight and the off cut curve and /or warp. Sometimes it will pinch together just past the splitter and could cause a kickback or spread and the kerf gets wider but, the offcut board is definitely not usable.

Resawing does the same thing only in the other direction.

 

As they say, "Poo Poo Occurs!"        

 

Rog 

[Boatworks Today]

As they were sawing through the board the grain may have been running differently as they worked through the thickness / width.  A board that wide probably was vertical grain towards the outside edges but possibly more flat grained through the center sections giving the different appearance..  

 

Just a guess

 

EDIT:  Just re-read the OP; the grain may have played into it somewhat but sounds more like stress..  If you re-wet both surfaces and clamp them stickered they may straighten out after re-drying... 

[wdwerker]

I have seen people book match those thin pieces and then back them up with 1/2" or more of the same species to stabilize the thin stock and provide a panel thick enough to cut joinery etc.

Either a lot of clamps or a vacuum press would be a good idea. It is not a cure all, I have seen a thin warped piece warp a thicker backing when it was pulled out of the clamps, but it is better than not trying.

[lildesertwoodshop]

Ok Thanx Gang , so yea it happens. I was not really unraveled by the whole situation but as a new guy just wanted to know the what and why. The chap that did the re sawing is a great guy that has helped me out with plenty of knowledge and insight and I know he is well versed in wood working and knows his P&Qs, so again good to know it was no fault on his part. So I dont think this hockey stick issue is going to be a huge deal breaker for this project, and my inquest was more relative to future situations. So I do have a vacuum press , would I if inclined to experiment now for future reference use a similar situation to pressing Veneer flat for pressing the bend out of these boards  IE: wet boards with water (or the veneer soft i have for softening veneer) place absorbent paper replacing now and again until wood pressed dry ?

[wdwerker]

Pressing might help but I was referring to laminating the thin resawed pieces to thicker stock of the same species with all the grain going in the same direction.

Try dry pressing first, then just a bit of water if dry doesn't work. I wouldn't bother with veneer softener.

If the warp is gradual putting the panel in a frame might hold it flat, just be sure there is room for it to expand and contract across the grain.

[dwacker]

Mahogany is one of the tougher woods to get good cuts so you have to be careful with selection if your going to resaw. Most of this is caused by the way its being dried. To give you and idea of how bound up it can be here are some wide scraps face cut from a slab I used for a table.

 

 

 

Those are 1/2" faces off a 3" slab. Then you have the release at the end of the cut. You can see in the photos the jaged end because the piece blows apart from the pressure. This sounds like a gun shot.

 

 

Now you can see a piece that was relieved by bring the MC up and then back down with the sole purpose of cutting into wide veneer slabs. This is just a scrap but remained flat because it was relieved.

 

 

 

 

[lildesertwoodshop]

Yup ok I see guys Thanxs for that!  So If I was to be doing some small projects using 1/4 -1/2" " ish re saw lumber wood that would be a higher end material (Say between $12- $18 Bf pre re saw) what would be some good candidates ? Heres the thing with this particular project, Im building this wall hanging Jewelry box for a client, its sorta like a medicine cabenet with jewelry and a fold out mirror in it.  I think is an Item that I might want to do a short production run of as I have been approached to produce some items like this for a few of the shops I do Higher end Items for. It fits in the criteria and formula to be profitable.  So as Im building this for a client , Im also investigating the possibilities of multiple units for short runs or future short runs having the build logistics already specked and be able to knock out a short run fast if needed.

 So basic Ideas :  Have an A/B Scenario product ,light or Dark wood on the higher end, A guideline of wood thickness Pre re saw and final product thickness for each that would facilitate an easy build, A material that would not involve a long finishing time,