Bending deep curly maple.

[murray kuun]

I have not been here for years and I don't often make violins, but I'm re visiting making. I've thicknessed the sides to about 1,4mm, is that ideal for deep curly maple? Then what is the correct temperature to bend at?  I'm really struggling with breakage, in the old days I don't remember having such trouble.

Thanks,

Murray Kuun

[jacobsaunders]

1 hour ago, murray kuun said:

I have not been here for years and I don't often make violins, but I'm re visiting making. I've thicknessed the sides to about 1,4mm, is that ideal for deep curly maple? Then what is the correct temperature to bend at?  I'm really struggling with breakage, in the old days I don't remember having such trouble.

Thanks,

Murray Kuun

1,4mm sounds to thick,. In violin making school one learns 1,2mm.

[JacksonMaberry]

Agreed, take it as thin as 1mm if necessary. 1.4 is heavy. 

[nathan slobodkin]

Stronger flame may need to be thinner not thicker. I would go to 1 mm. For the Cs maybe 1.1-1.2 for the bouts

[JacksonMaberry]

Yep!

[FiddleDoug]

Are you using a bending strap? That can make a huge improvement on curly wood.

[Michael_Molnar]

Get your rib thickness down to about a mm. Do not soak the ribs before bending. Wipe some water only on the maple surface that goes against the iron. Push the rib against the iron using the bending strap slowly sliding the rib back and forth as you carefully curve the rib with the strap. I like to wrap the strap with a cloth (old t-shirt). The hot iron should turn the water quickly into steam, which softens the maple momentarily for bending. Too much water makes the flames separate. When the steam dissipates in 10 to 15 seconds, repeat damping and bending until you get the shape you need.

I use the bending strap for the c-bout ribs and long curves of the upper and lower bouts. For the small reverse bends at the corners of the upper and lower ribs, I do not use the strap, but use instead a small wood block to press the rib against the iron. Again, just dampen. Do not soak.

The iron should not burn (scorch) the maple.

[nathan slobodkin]

2 hours ago, FiddleDoug said:

Are you using a bending strap? That can make a huge improvement on curly wood.

Huge improvement? I can't imagine bending any rib without one.

[Dennis J]

I've had problems bending deeply figured wood. But something I've noticed is that cracks seem to occur where the flames are narrowest, which makes sense. So avoiding tight bending there if possible might help.

Recently I've bent rib material with a less pronounced, more even figure fairly easily. This was planed accurately to 1.3-1.4 mm. And, after cutting to length I reduced the thickness at the block locations to about 1.2. I think thicker ribs hold their shape better but it does require accurate planing and measuring to control the process.

I set the bending iron to 200 C, warm up the thin stainless bending strap, and dip the ends in hot water for a few seconds just before bending to deal with the tightest radius parts. The rest I just slightly dampen before bending.