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Bandsaw boxes - Dealing with parts warping

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Forum topic by tpastore posted 01-23-2008 12:04 AM 1212 views 0 times favorited 4 replies Add to Favorites Watch
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tpastore

105 posts in 3815 days


01-23-2008 12:04 AM

Topic tags/keywords: bandsaw box warpage

Hello all, On my last project I made a bandsaw box where I needed to slice off the top and bottom to allow me to hollow out the center layer. The issue is that when I sliced off the two 6”diameter x .5” thick sections (top and bottom) they turned into pringles potato chips. I put oil on the parts as soon as they were cut to minimize the moisture impact but that did not solve the issue. In the end I had to reflatten the interface to the middle piece. Well I am making another box similar to this one and would like your suggestions on how to avoid this.

You can see the box in my projects.

Thanks

Tim


4 replies so far

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LONGHAIR

94 posts in 3813 days


#1 posted 01-23-2008 03:01 AM

It sounds to me like you are using wood that is too wet. Your top/bottom slices are drying fast because you cut them from the block. This is causing the warping. I would think that you would have gluing problems with wood that is this wet anyway? What happens to the rest of the center section when you hollow it?
I would suggest that you start with dry wood. If you have to use a specific piece that is green, you nedd to dry it deliberately….not just let the pieces sit after cutting. Depending upon the size of the pieces and the timetable required, there are a few ways to go about that. Alcohol soaking, microwaving, wrapping and bagging, etc.

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tpastore

105 posts in 3815 days


#2 posted 01-23-2008 03:14 AM

The block is one of the turning blanks from Rockler:

Turning Blanks

I will borrow my father’s meter, but my intuition is that they are fairly dry. If nothing else they have been sitting in the store for months. The edges are sealed and they are stamped with a grade AAA.

Tim

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Blake

3443 posts in 3873 days


#3 posted 01-25-2008 09:00 AM

It might not have anything to do with moisture in the wood at all. If the movement is instantaneous, it is probably from tension in the wood due to growth. Wood which twists as it grows, trees which grow on a slope, and wood from branches grow under massive amounts of strain against gravity. This creates tension in the wood which will “spring” back when it is cut and the tension is released.

-- Happy woodworking!

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LONGHAIR

94 posts in 3813 days


#4 posted 01-27-2008 11:37 PM

tpastore, I clicked on your link and didn’t see one word about how/if those turning blanks are dried. I have bought similar blanks from a local WoodCraft store and found some to be surprizingly high in moisture.
If they were truly dry, you shouldn’t have to do anything to the cut off parts to keep them from curling.

Blake has a point, but I wouldn’t think stress would make as much of a curl as you indicated, especially on a piece that small. Large,long planks yes…I have seen them open (or close) right on the table saw, but I wouldn’t think you would have that much tension in a small block.

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