[GROOVY]

I need to get 3/8" thick boards, African mahogany. Has anybody done this? I would like to use 4/4 rough but have not ever planed any and wonder if getting 7/8" finished from it to resaw is possible?
These are to be boat planks so 8'+ long..

 

[woodnthings]

That length is tricky

You will need supports on both ends and feather boards or other pressure means to hold it tight against a tall resaw fence using a bandsaw in perfect tune, or a table saw with a thin kerf blade.
You did not specifiy the width, so that's unknown.

Personally I would have them resawn at a mill, very little extra cost and virtually guaranteed good results. There probably will be warping after the resaw... at least in my experience. I would reverse the faces and clamp them back together immediately and let them acclimate to the shop conditions for a week or so. If they are badly sprung, put a block in between them before you clamp them to "reverse" bend them a bit. You may get lucky and have no warp?

You may actually have to start with rough sawn boards, thicker than 4/4 to allow for jointing and milling to thickness after the resaw. The mill will be able to advise you.

 

[mdntrdr]

Depends how well they have been sawed. 4/4 normally provides 3/4 lumber after planing. You would not be able to get 2, 3/8" pieces from that. :no:

 

[MNsawyergp]

We need to know what kind of band saw you plan to use and the size blade that saw can handle. For resawing, you need to use the widest blade the saw can be set up for. The blade needs to be sharp and be set up exactly 90* to the table. Using a fence is tricky because the saw may not track in a parallel line to the table. You need to run a line down the middle of a board and free hand resaw the board as carefully as you can for a few inches, then stop and see how the board lines up to the table. That is where you would set up the fence....but there is still no guarantee that the blade will track on that line all the way through the board if you have an inexpensive band saw.

One way to get around this is to use the end of a squared off board, set up on edge at the distance away from the blade that you want to split the board, instead of a full length fence. This will provide the guide for keeping the board centered, but allow you to move the board left and right on the end to keep the blade tracking down the center. One big thing you have to watch is internal blade wander. The blade can start curving inside the board, which you will not notice until the blade won't track anymore or the blade snaps or you finish the cut only to find that you have destroyed the board.

You will need all the thickness you can get. I doubt that you can get 3/8 boards from a 7/8 planed board. I would get the 4/4 rough boards and do a light pass on both sides just to knock off any high spots, then make the resaw cuts.

 

[GROOVY]

the bandsaw is a Delta/Homecraft 14" have used a 1/2" 3TPI on it. Or 10" Grizzly cabinet saw, These are rough sawn or will be 4/4 I am aware of the needed support, tuning etc. as I have resawn on the bandsaw before , My maximum width would be 6". Trying to take the guesswork out of the planning because I think I am being overly optimistic in getting good surface and having enough thickness left for cleanup to yield 2 boards.. I am trying to convince myself the I can get uncupped straight lumber and do this with minimum waste, but the practical side I think the extra thickness in 5/4 will be needed

 

[mike1950]

Set yourself up with a new blade and try a 4' length. 6" is not that thick- but how straight are boards to start with? how much do you have to take off to get one side flat before resaw?

 

[GROOVY]

The other thing is or thing$, its a long drive to Steve Wall lumber from here so picking up a test piece is going to be difficult. Another is after finding what little info on african mahogany I am cautious as I read things like dimensional stability problems, warping and cupping, spreading these possibilities over 8' makes me wonder if I should consider something with straighter grain. But really don't want to have to use something too expensive or more than $5 BF.. Still in the planning stage so any suggestion are welcome. I have even thought about local wood but here in SC there is not much to choose from. How is it that Asa Thompson and others built such lasting boats without the internet?

 

[woodnthings]

the bandsaw is a Delta/Homecraft 14" have used a 1/2" 3TPI on it. Or 10" Grizzly cabinet saw, These are rough sawn or will be 4/4 I am aware of the needed support, tuning etc. as I have resawn on the bandsaw before , My maximum width would be 6". Trying to take the guesswork out of the planning because I think I am being overly optimistic in getting good surface and having enough thickness left for cleanup to yield 2 boards.. I am trying to convince myself the I can get uncupped straight lumber and do this with minimum waste, but the practical side I think the extra thickness in 5/4 will be needed

If you use the table saw, you can just part them afterward with the bandsaw. If there any question as to the blade bowing in the kerf using ONLY the bandsaw this will eliminate that issue.

The next issue is whether you have enough thickness to flatten, saw and flatten again. If the board is flat on both sides to start with you may be able to get them out of 4/4.

If the application is a bent piece rather than flat this will also help as the thickness is not that critical...possibly? :blink:

 

[Gary Beasley]

One other thing to consider is the squareness of the edges. If at all possible a trip through the jointer to set the edge you will stand the board on for resaw square will help tremendously in keeping the cut straight.