Conor Russell Posted September 11, 2019 Report Share Posted September 11, 2019 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. Link to comment Share on other sites More sharing options...
David Burgess Posted September 11, 2019 Report Share Posted September 11, 2019 I recently demonstrated bending an un-moistened rib to the tightest curve used on a violin, in less than 30 seconds, for a PBS television program. It remains to be seen if that part airs, or gets edited out. Link to comment Share on other sites More sharing options...
GoPractice Posted September 11, 2019 Report Share Posted September 11, 2019 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. Link to comment Share on other sites More sharing options...
Kae Han Posted September 12, 2019 Report Share Posted September 12, 2019 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. Link to comment Share on other sites More sharing options...
Conor Russell Posted September 12, 2019 Report Share Posted September 12, 2019 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. Link to comment Share on other sites More sharing options...
notsodeepblue Posted September 13, 2019 Report Share Posted September 13, 2019 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. Link to comment Share on other sites More sharing options...
Kae Han Posted September 13, 2019 Report Share Posted September 13, 2019 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! Link to comment Share on other sites More sharing options...
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