Thread: my sides are splitting!

i'm in the same boat as you, but i'm still researching on my first build.

I heard your ment to soak the wood in water for 5 minutes or such, till the wood opens up.

Originally Posted by fts_sjk

fore bending the sides the wood has to be put in hot water for a few minutes. A bathtub or the saucer of a window planter will do nicely for this purpose. Do not put more than one piece of wood in at a time and put some weight on it to make sure it remains under water. How long the piece has to remain there depends on the type of wood used and on one's own experience: five minutes are quite normal, more than twenty minutes should not be required. Fasten the tube horizontally in a vise and heat it by positioning a blowtorch so that its flame burns into the pipe. The tube is at the right temperature for bending when a drop of water &"dances" on it. If it evaporates immediately, the tube is too hot, and if nothing is heard, the tube is too cold. The gas flame will have to be regulated or even switched off temporarily as the tube must not get too hot to not burn the wood too much. Deep burns on the outside of the wood are almost impossible to remove - so be careful when placing the outside on the bending tube.
Start bending at one end, slowly pushing the wet piece of wood over the tube while pressing lightly all the time. The heat will lead to the formation of vapour. At some point the wood will start to bend and you can shape it - do so carefully and "with feeling&#quot;. Putting on cotton gloves makes the heat more bearable for the hands. By varying the pressure and the speed at which the thin wood is pushed over the tube the radius of the curve can be varied. When the desired curve has been reached continue bending for a little while; after bending is finished the wood will spring back slightly. Be careful throughout the bending process as the thin wood can easily break.
Take the bent piece from the tube and hold it for a short while until it has cooled and the curve is stable. Now is the time to find out whether the wood has really been bent: on the hot tube a curve is easily produced simply by pressure; if the wood loses its curve after it has been released, it has not been bent enough yet. The wood bends properly when its fibers are saturated with water vapour - the moment when this is the case can be felt, but patience is required.
To get the right curve constantly check your progress against a drawn outline and correct the curve if necessary. The latter can be done by hand by bending the piece the other way or by placing it with its outside on the tube and by rocking it until you get the right curve.
When you have finished bending the first side of the body leave the second piece to soak in water and then proceed as with the first piece; try to bend it as symmetrical to the first side as possible. If the body is asymmetric in shape bending the second side will be easier as you as you don't have to make both sides perfectly identical. After both sides have been bent put the two pieces away and leave them to dry overnight or if you use a form clamp them into it.
The morning after you will inevitably find that the curves will have changed slightly. The original shape can, however, easily be restored by bending the two sides over the tube for a short time. This final bending should take place before the lining is glued on as the curve of the sides will keep changing with changes in air humidity.

Where abouts on the side is the split? If its at the edge and will be trimmed before fitting back or top then its not a major disaster. If its in the working area of the side then you could try flooding it with cyano glue (I use Hot Stuff) and after it sets gently carrying on with the bending process.

To minimise risk of splitting:

1. bend gently.
2. use metal slats either side of the wood.
3. If bending near end of the side use blocks to support the end of the side the side rather than bare hands.

mahogany isn't the easiest to bend.....what is the thickness of your sides?

thanks for the replies guys, i ended up going the way that kiwigeo suggested and filled the crack with glue. after this i realised that the curve i put in it was just enough that i could cram it into my drying jig overnight so i think that the side will look ok after some intense sanding and such.

and gratay, i think the sides were too thick when i tried to bend them, i attempted to sand the sides i got from lmii down to 3/32" but i think i got a bit lazy so it was thicker. so before i start on the second side is 3/32 thin enough?

3/32" is just over 2mm...should be ok. Final thickness depends on the wood. I generally work using a caliper guage but final thickness is decided by flexing the wood in my hands and judging "floppiness".

You mentioned sanding your sides to thickness. Did you start with a plane and/or cabinet scraper or sand all the way? I work my sides staerting with a plane or scraper plane (for Rosewood) and then I go to a cabinet scraper. I then sand the outside of the side 180 through to 120 grit.

well, when i said i was doing this low budget i wasnt kidding, i have a hand held belt sander that i used to thin off the wood as carefully as i can. it was a little nerve racking because i was afraid i'd sand straight through the wood, but its actually slow work. i think if i ever have to go through this again that i'd definately invest in some sort of planer just for peace of mind.

3/32 = .093" and nearly 2.4mm

its in the range possibly but I'd probably go a bit thinner myself..
like martin says depends on the piece
I bent my recent ones at 2mm-2.2
around .085"
you would be surprised how much 0.1mm makes

I usually shoot for .080 on sides but I've done them as thin as .075 depending on the wood.

Some Mahogany can be a bear to bend and is susceptible to a fair amount if springback.

Cheers

Yeah 0.080" for mahogany or a tad under. That's what I used on my current build. I'd much rather bend EIR.

Originally Posted by isaysthat

well, when i said i was doing this low budget i wasnt kidding, i have a hand held belt sander that i used to thin off the wood as carefully as i can. it was a little nerve racking because i was afraid i'd sand straight through the wood, but its actually slow work. i think if i ever have to go through this again that i'd definately invest in some sort of planer just for peace of mind.

Yikes man...dump the belt sander and forget about the planer. Both are going to get you into a mess of trouble.

The safest way to thin tonewood:

1. #3 or #4 smooting plane (or thickness sander if youve got one).
Then
2. cabinet scrapers.
Then
3. sand paper (180 through to 120 grit is sufficient).

Notes:

1. if hand plane is tearing out the wood then go to a scraper plane or thickness sander.
2. cabinet scrapers are hard work to use and working a good edge onto same is a bit of an art. That said its time well spent.
3. working tonewood by hand allows you to keep in touch with the wood...you get to know the character of the wood (grain, runout directions etc).
4. I only roughly sand after getting to final thickness.
5. if you can afford it get or make yourself a thickness caliper. My tops and backs vary in thickness so caliper is essential.

yeah, i noticed how the wood varied in thickness when bending it. luckily the variations were slight enough that they didnt affect the bend drastically. whenever i get around to building a second acoustic i'll be sure to thin the wood way thinner than what i have now, and to use some of the methods you guys said.

thanks a ton

if you have a drill press....get yourself a wagner safe-t-planer
you can get them in the states for under $60....
thickness planer attachment for your drill press which has many other uses..
great tool