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Bending iron


Anthony Panke

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I bend ribs  a little  at a time, inching my way around, and just bending  exactly where the  rib parts company  with the line I'm following,  or the form. I usually bend them  dry, except  sometimes  in very  tight  corners.

It's  very  quick and accurate, and the ribs fit pretty  exactly, so there's  no worry  about tensions or distortions, and I'm left with a nice ripple with the figure. 

 

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5 hours ago, HoGo said:

There is quite simple physics/ chemistry behind bending wood. Perhaps a bit simplified, water and heat act as plasticizers (both work alone, but most effective when combined) - they loosen the bonds beween the wood fibers and after drying and cooling the bonds will reconstitute. So if you use cld bending with just some water the bonds don't get as plastic as possible and bending stresses will remain in the wood (they will stabilize after time) If you use heat the wood becomes more plastic and after cooling less stress is left in the wood (you don't need to add too much water to thin ribs as wood contains some water already and the extra water acts more as heat conductor than plasticizing agent and can cause wood become weaker along the cross frain on curly maple - water and thus heat penetrates faster along the open endgrain).

 ( ... )

BTW: here is some sophisticated bending jig by Tom Ellis:

https://www.ruttlist.com/features/lets-build-a-mandolin-tom-ellis-464-2

This is a nice reminder of what i have been taught. I assume that i take too much time bending with an iron and that results in what i consider to be stiffer ribs. This may not be a valid conclusion but when comparing the identical rib material, unbent, the frequency "pitch" of the bent rib sounds higher than that of the unbent rib. These were casual observations and i might have missed something. In handling other maker's garland assemblies, their assemblies, i felt, were more flexible from block to block and also the ribs felt softer, edge to edge. The feel is certainly subjective and touch might not be able to feel the difference in thicknesses of the ribs. And perhaps flexible might be the wrong description, maybe lively? or alive? would be the a better description for a goal. The assemblies i make often feel nice, light, but i do not sense any excitement at the fingertips.

The bending skills just need to be improved. Being able to visualize the curve should also reduce the ironing time. Still, alternative methods are interesting. When i was a kid, i saw a maker bind guitar ribs on to a form using what looked like twine on to a form. It looked pretty natural as a guitar's curves are larger. After that, i just assumed that luthiers assembled violins that way, except for the c- bouts. I imagined that there was a roller based c- bout bender like a pasta maker. That was the only explanation in my mind until i saw an iron. Then it was assumed that there were dozens of ways to bend wood.

The Tom Ellis jig is very cool. It makes me want to think through an outside vacuum mold. Then on what form? And that it would not be practical. But beautiful to see production techniques. 

 

 

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On 9/12/2019 at 12:43 AM, Conor Russell said:

I bend ribs  a little  at a time, inching my way around, and just bending  exactly where the  rib parts company  with the line I'm following,  or the form. I usually bend them  dry, except  sometimes  in very  tight  corners.

It's  very  quick and accurate, and the ribs fit pretty  exactly, so there's  no worry  about tensions or distortions, and I'm left with a nice ripple with the figure. 

 

"A little at a time", and "inching around" sounds straight forward and reasonable. What is the shape of your iron?  Because I found it difficult to bend inch by inch with the bend iron I have.  Do you have a special shaped iron, or there are some tricks involved?   ( The one I have has a flat oval shape.)

Enlighten me if you will.  :)

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2 hours ago, Kae said:

"A little at a time", and "inching around" sounds straight forward and reasonable. What is the shape of your iron?  Because I found it difficult to bend inch by inch with the bend iron I have.  Do you have a special shaped iron, or there are some tricks involved?   ( The one I have has a flat oval shape.)

Enlighten me if you will.  :)

My bending  irons are pretty  normal  oval ones.

I start  at one  end  of each rib and bend it to the line bit by bit. I hold it to the form, and put my finger exactly  where it needs to be bent - where a gap appears.  Then I bend it there, and only there, then on to the next bit. Most of the work  is  done  towards the end  of  the  iron, or at the end.

Most of the time  I make the upper  and lower ribs in one, and as I approach  the corner I cant fit the rib in to try the fit, so I bend to a line drawn on a sheet, and make any little  correction afterwards.  The same for the c bouts. Hope  this  makes  sense. 

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9 hours ago, Conor Russell said:

My bending  irons are pretty  normal  oval ones.

I start  at one  end  of each rib and bend it to the line bit by bit. I hold it to the form, and put my finger exactly  where it needs to be bent - where a gap appears.  Then I bend it there, and only there, then on to the next bit. Most of the work  is  done  towards the end  of  the  iron, or at the end.

Most of the time  I make the upper  and lower ribs in one, and as I approach  the corner I cant fit the rib in to try the fit, so I bend to a line drawn on a sheet, and make any little  correction afterwards.  The same for the c bouts. Hope  this  makes  sense. 

This is such a helpful description - thanks for taking the time to post this.

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19 hours ago, Conor Russell said:

My bending  irons are pretty  normal  oval ones.

I start  at one  end  of each rib and bend it to the line bit by bit. I hold it to the form, and put my finger exactly  where it needs to be bent - where a gap appears.  Then I bend it there, and only there, then on to the next bit. Most of the work  is  done  towards the end  of  the  iron, or at the end.

Most of the time  I make the upper  and lower ribs in one, and as I approach  the corner I cant fit the rib in to try the fit, so I bend to a line drawn on a sheet, and make any little  correction afterwards.  The same for the c bouts. Hope  this  makes  sense. 

Thanks a lot, Conor! :)

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