Why does my bandsaw warp the wood?

[woodworker1]

I have just bought a Record Power BS350 bandsaw. It has a brand new blade and the table is square to the blade. i have tried to cut some 150mm X 50mm oak in to 2 150mm X 25mm planks.

The saw cuts fine without straining the motor or making any strange noises, however when the work piece comes out of the other end it is bowed in the middle on both pieces.

It is the same thickness throughout.

As far as i can see, the blade is tensioned correctly.

Am i doing something wrong or is this just the usual effect from cutting timber in half along the grain?

 

[DaveL]

Hi Woodworker1,

Welcome to the forum.

When you say bowed, do you mean that the face you have cut is curved or that the two pieces you now have are no longer straight?

If the faces are curved then the blade does not have enough tension on it, is the blade the one supplied by Record? Most supplied blades are not that good, do a search for Dragon and Dure Edge on the forum, they are thought of as the best you can get.

If the timber is no longer straight, then you have released the tension in the timber and that has caused the movement, this not uncommon, kiln dried timber is more prone to this than air dried.

 

[johnjin]

Hi woodworker1

First of all welcome to the forum

It sounds to me as if your bandsaw is cutting perfectly.
As long as the two pieces are the same thickness along their length then the saw is cutting straight and it means that the wood has moved due as Dave said above to the stress that is in the wood. This is more common in kiln dried wood as it is dried more quickly instead of leaving it to dry out naturally.

Hope this helps

John

 

[woodworker1]

Thanks for quick replies.

The blade is not the one supplied with the saw, however it is from the Record Power plant. I have heard good reports about the Dragon blades so will try one of those.

It is warping on the side of the wood that faces the blade on both pieces.

I cannot say if it is kiln dried or not. It was given to me by a local joinery business as it was off-cuts (1 metre long 2" thick offcuts!!).

It isn't a major problem, i just need to take it in to account when making cuts. I have a shiney new planer-thicknesser to sort out the problems anyway.

 

[BradNaylor]

As the other guys have said, this is a perfectly normal occurance when you try to saw a piece of wood in half accross it's thickness.

I learnt this the hard way when I first had a load of drawers to make in oak. Instead of planing 1" boards down to the 16mm I required, I bought in a load of 1 1/2" boards and sliced them down the middle on the bandsaw. The resultant boards were banana-shaped! I had to start again planing down 1" boards.

As nearly all wood is kiln dried the suggestion of using air dried timber isn't that helpful. You just have to buy the appropriate thickness for the job you want to do.

 

[Big John]

I had the same problem resawing some Ash. Providing the pieces you need are not too long you can machine them again without losing too much thickness.

 

[devonwoody]

I had the same problem resawing some Ash. Providing the pieces you need are not too long you can machine them again without losing too much thickness.

But after thicknessing it can still have timber stress and move again