Brazilian Cherry - Jatoba problems or a resaw issue?

[Jared Cuneo]

I tried resawing an 8/4 slab (6inx2ft) this weekend into 3/8 sheets. The plan was to mill them down to 1/4 for some boxes.

Well, every damn piece came off the slab warped. I thought one might come off touching end for end it was so bad

Did I just get a chunk with a lot of tension (very little figure in the wood), or is Jatoba just like this naturally?

A piece of ash I resawed came out good, though one of the pieces started warping after cutting....

I'm using a 1/2 in 3TPI blade, the panels are coming off in consistient thickness, so I think the saw is doing its job, I must be doing something wrong....

JC

[Mike Spanbauer]

Jatoba is one DANG hard wood. Like 1/2 again as hard as red oak (2300 or so Janka iirc).

In order to resaw it you'll have to have your saw tensioned and setup dead on I'd think or you might get some curious results. Also, due to the density you have to resaw it slower than you would domestics or you will get blade drift from the force.

I would try it again w/ a small sample by slowing it down a bit.

The other possibility is that your blade is simply too dull for the task (remember my hardness comment above? Jatoba will trash your blades almost as fast as Teak from my experience). If it's dull, the blade will be more prone to wander.

Gorgeous wood, just a bit particular to work with.

g'luck

mike

[Bert Johansen]

I've resawed lots of jatoba without incident or warping. However, most of the resawing was from 8/4 to 4/4 or so. I've done a few resaws to 3/8, also with success. I used a really good, sharp blade, if that makes a difference. I am particular about the grain structure, having spent hours pouring over rough-sawn planks at the source. I look for straight grain. Please let us know what you ultimately learn about your problem.

[Mark Duginske]

If it is warping after it it cut it is either tension in the wood
of moisture differential withing the piece.

To save wear and tear on the band saw blade I would try
to do as much removeal with the table saw blade as I could.

Make multiple passes with the blade raised in 1" intrivals.

[Jared Cuneo]

Thanks for the comments so far, but I think the resaw itself actually went ok. I used a caliper and measured the thickness and it was VERY close (1/32) from top to bottom of the resaw, so it seems as if the wood was warping as I was cutting it, if that makes any sense.

Also, the ash I cut after this came out great.

BTW, its a new timberwolf blade, tensioned as directed on the package....

Am I still missing something, or can I chalk this up to tensioned wood?

I'd like to learn from this, but I'd like to diagnose it to eliminate as many variables as possible before I discount bad technique OR the possible tensioned wood.

If the board is a consistent thickness from top to bottom, but warped, could that still be a user error?

Thanks!

JC

[Joe Jensen]

Do you have access to a moisture meter? I suspect the wood isn't dry enough. 8/4 takes longer to dry than 4/4, and if a remember correctly it's like 2.5 times longer than 4/4. If the wood is wet in the middle and dry on the outside. You cut it wet and straight, but as side of the cutoff dries it will shrink on that side of the board and warp. You need to make sure the board is as dry as the ones that have been sitting in your shop.

Also, I always resaw thicker so I can surface to flatten. I've rarely had resawn boards be flat enough for me straight off the saw.

[Howard Acheson]

I'm with Joe. I suspect you have wood that is not fully dry and/or acclimated. When you say "slab" what do you mean?

[Alan Turner]

Jared,
Any 8/4 wood may contain moisture which is unequal at the surface and in the center. If this condition prevails, then you are likely to get pretty prompt cupping and/or bowing as you resaw. This condition is especially common with harder woods which are harder to dry evenly throughout the thickness. White oak is among the woods that have been troublesome in this regard.

Jatoba is a hard, dense wood, and this type of reaction to resawing thicker tropicals is not at all uncommon. It is not your bandsaw, it is the wood. You may need to cut it thicker, let it move, and then flatten, resulting in fewer slices per inch.

[Jared Cuneo]

Thanks for the replies, I'm going to try to get some confidence back and maybe try some walnut or cherry before cutting up the other 8/4 BC board I have....

JC

[J.R. Rutter]

Agree with Alan - The wood is difficult to begin with, being dried overseas and shipped in a container in who knows what conditions. Some of those containers can see very big temp swings and the botton can get condensation soaking pools while the top is re-kilned.

I used to resaw 5/4 jatoba for 7/16" flat panel (reverse raised) cabinet doors. There was always some amount lost due to tension release. Now I just burn down warped 4/4 planks after crosscutting to salvage wood that would otherwise be too unflat to use. We use flat sawn for panels and QS / rift sawn for rail and stile.

BTW, I found a carbide TriMaster blade to be best for jatoba. I went through many steel blades and almost put a larger motor on my 20" bandsaw. But a 1/2" carbide blade cut straight and felt like the motor grew by 100%

[Brad Olson]

Thanks for the comments so far, but I think the resaw itself actually went ok. I used a caliper and measured the thickness and it was VERY close (1/32) from top to bottom of the resaw, so it seems as if the wood was warping as I was cutting it, if that makes any sense.

Also, the ash I cut after this came out great.

BTW, its a new timberwolf blade, tensioned as directed on the package....

Am I still missing something, or can I chalk this up to tensioned wood?

I'd like to learn from this, but I'd like to diagnose it to eliminate as many variables as possible before I discount bad technique OR the possible tensioned wood.

If the board is a consistent thickness from top to bottom, but warped, could that still be a user error?

Thanks!

JC

I've done quite a bit of jatoba resawing and this happens from time to time with 8/4. If the grain pattern looks funky then the boards are more prone to doing this. I had one piece of 8/4 that the THICK part of the wood turned into a hockey stick as I took off a 1/2" slice. The 1/2" slice twisted up into a nice spiral. I tried one more cut and gave up. Took the board back to my supplier and they replaced it no questions.