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Wood, well most wood, is heavy. Is there any such thing as people ever hollowing out the inside of the wood to make the finished product lighter?

For example, let's say I have a 4in. x 4in. x 8' piece of timber to make 4 desk legs out of. Instead of having four square desk legs of solid wood, could I hollow out the inside of the timber leaving only about a 1/2 inch thickness on each of the four sides? This would save wood for other projects, and accomplish making the desk lighter while hopefully still providing a pretty sturdy, un-wobbly base.

What tools and method could I use to hollow out the inside of this piece of timber?

  • Torsion box construction? – keshlam Apr 8 '15 at 22:26
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If you have a table saw that can rip at least 2" deep, you could do something like this:

"hollowed" 4 by 4

Source: me

Dark gray areas are waste. This assumes you have a .1" thick blade.

Basically, you would take off 1/2" from opposite sides, then take 1/2" off from the remaining uncut sides. To bring the hollowed piece back to square, you remove two blade thicknesses from the edge of each wider piece.

This leaves you with a decent sized "core" that can be used elsewhere.

If you make clean cuts and align everything well when gluing it back together you will have a piece that looks like a 4x4, but is 60% lighter.

To glue the pieces back together, you could just butt join them, but ideally you'd probably use a biscuit joiner to both align the pieces, and give them a little extra strength.

  • 1
    Nice. A band saw might work for the ripping, as well. – FreeMan Apr 8 '15 at 22:33
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    Why wouldn't you just buy 4" x 1/2" boards to start with? – WhatEvil Apr 8 '15 at 23:59
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    @WhatEvil That is definitely an option, and I would advise doing that if you are going to paint the finished piece, or if the grain isn't very complex/interesting. But if you want to retain the appearance of a single piece, this will ensure matching grain. – lars Apr 9 '15 at 0:46
  • I guess so, but if the grain is as featured as all that, the gaps from where you've taken your saw cuts are going to be very noticeable anyway. It's sometimes better to make a feature of a join (e.g. with small chamfers) than to try to pretend it's not there. – WhatEvil Apr 9 '15 at 7:53
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    @WhatEvil Right, I think there are very few cases where it would be better to "hollow out" a piece of wood. But I didn't want my answer to be "Don't". – lars Apr 9 '15 at 16:39
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Rather than hollowing out a piece of 4"x4"x8' piece of lumber, think about how to use thinner stock to come up with something that looks like 4"x4"x8'.

There's a long tradition of this- porch columns are the first thing that come to mind.

Wooden Porch Columns

Those aren't solid wood, they're built up from smaller stock.

As far as the technique, that depends on the overall size of the project, your budget, your tool set, and expertise. For something like table legs, you can use a locking miter bit with thinner stock to make what looks like a solid leg.

Locking Miter Bit

Think of lumber as raw stock to be cut up and put together in various ways.

An 8' 4"x4" would yield about 7 pieces 1/2" thick x 4" x 8' long. (You lose some with the saw kerf.) Four of those 7 pieces could then be split lengthwise and across the grain to make four 2" x 1/2" x 48" pieces.

Use a lock miter on the pieces and you'd end up with four legs, ~2" square, 48" tall.

And you'd have enough lumber leftover to make the skirt of a table frame.

5

The only time I can think of where you would actually need to hollow out a piece of wood, would be when you're making a spindle for a floor lamp. These need to have a hollow core for cabling to run through.

The workshop I currently work in was previously a lamp factory and they left behind a "coring" machine. I don't actually know what the proper name for the machine is, but essentially it was for drilling long holes through timber.

If you do a google search for "long hole boring" there are a few videos and tutorials on how you might go about it. Generally I think you need a lathe, and a long auger bit such as this one but these tools are mostly meant for drilling out narrow holes for cabling and the like.

Honestly I'd say if you have anything wider than a couple of inches that you need/want to be hollow, you'd be better off starting with separate pieces and gluing them together to form a box or tube. You could either start with 4 pieces and glue together at right angles (with or without machined or half-lapped joints) or you could have two half pieces and groove them out in the centre to create U-shaped channels, which you'd then glue together like [ ] to create a box or tube section.

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You would need one heck of a plug cutter to bore a core out of an 8' timber. I don't know of any other tool that would hollow it without turning the center into chips, which would not be particularly useful for future projects. (Except hamster cage lining, maybe.)

An alternative may be to resaw your timber into 9/16" thick slabs (leaving some room to plane one side to a nice finish), then assemble box sections for your legs.

Another option would be to taper the solid 4x4 timber, cutting material off the outside, if your goal is simply to lighten it. You might also consider resawing into 4 2x2 posts and using those as your legs.

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