bending sides

Johni · Apr 4, 2019

Hi all.
I tried my hands at bending a side and have some questions about it.
It went ok. My two main concerns are
1. keeping an edge flat (on a single plane)
2. How close is close enough?

I’m using a low budget homemade rig with an electric bbq briquette igniter... so it’s not the best but hopefully adequate.

I understand I will need to clamp pieces in a form and allow to dry for the final non practice sides but will that true up any out of plane issues and pull the pieces to within tolerance. Right now, I’m outside my line by about .125” in at the head and tail.

Dumb question: why don’t luthiers put a side in a steam box and clamp the whole thing in a form?

As always, thanks for any tips and or advice.

sequoia · Apr 4, 2019

Johni said:
View attachment 116712 Right now, I’m outside my line by about .125” in at the head and tail.

I don't bend by hand but use a form so can't really say what an acceptable tolerance is with hand bending. A tenth of an inch doesn't seem that excessive to me. After you jack the sides into a form and use spreaders that should flatten out.

Johni said:
Dumb question: why don’t luthiers put a side in a steam box and clamp the whole thing in a form?

Actually some do, but that means building a steam box and all that that Boy Scout project entails. I just steam it on the form.

DPO · Apr 4, 2019

sequoia said:
I don't bend by hand but use a form so can't really say what an acceptable tolerance is with hand bending. A tenth of an inch doesn't seem that excessive to me. After you jack the sides into a form and use spreaders that should flatten out.

Actually some do, but that means building a steam box and all that that Boy Scout project entails. I just steam it on the form.

Well a steambox would be a lot simpler to build than a fox bender. A closed box, what could be siimpler?

Johni · Apr 4, 2019

sequoia said:
I don't bend by hand but use a form so can't really say what an acceptable tolerance is with hand bending. A tenth of an inch doesn't seem that excessive to me. After you jack the sides into a form and use spreaders that should flatten out.

Actually some do, but that means building a steam box and all that that Boy Scout project entails. I just steam it on the form.

I gather you use a heat blanket then? Do you get much spring back?

I can get the basic shape without too much trouble but I'm wondering about some building theory. Is the idea to get the desired shape as "relaxed" as possible for best tone and least stress on the overall structure?

Johni · Apr 4, 2019

DPO said:
Well a steambox would be a lot simpler to build than a fox bender. A closed box, what could be siimpler?

Yeah, it's not something I've done before but seems VERY simple to try...
I've got a few more sides to practice with and plan to see if how well it might work.

sequoia · Apr 4, 2019

Johni said:
I gather you use a heat blanket then? Do you get much spring back?

Naw, I don't use a heat blanket. I use a form, aluminum flashing, and a heat gun. Primitive and ugly but it works just fine. As for spring back, yes I get some but am able to tame it. The big advantage to hand bending like you do, is no fancy equipment needed and minimal spring back. In a way a superior way to bend wood. Stick with it. No heat blankets required.

Johni · Apr 5, 2019

Interesting. I've not heard of that method before. Looks like the way you're doing it is a close relative of the blanket technique but with a more variable source of heat.

So many different ways to go about it. I have yet to make a form so that'll be my next step. I like the iron ...it's a good challenge for me.

Sven · Apr 5, 2019

Anything cooked in a steambox will need a shave and a haircut afterwards. Cook something curly and it will buckle. Good for building boats but remember the scale of your work here.

Johni · Apr 5, 2019

Sven said:
Anything cooked in a steambox will need a shave and a haircut afterwards. Cook something curly and it will buckle. Good for building boats but remember the scale of your work here.

That fuzziness requiring “a shave” already happened!
Cedar on my hot iron contraption has me thinking I may want to add a little to the initial thickness.

Thanks for your input

Beau Hannam Ukuleles · Apr 5, 2019

I bend by hand at about 0.060" each layer (i use two layers).

The "top" edge of the sides is flat (ie the edge that will have the top glued to it) - so use that flatline as an index on the top of your heat bender, which is also flat unless you are using a hot pipe like a caveman.

For further help, you can use 90 degree lines all along the side (indexed form the "top" flat edge) to help index off and keep an eye on how you are bending.

Do the waist first.
Then which ever bout- i usually do the lower bout as its less tight hence less difficult to get a feel for the wood (although i already have a sense after the waist being bent).
As you go, lay the side (top side down) on a flat bench top to see if its rocking and if it is, then deal with it.

When both bouts are bent, look along them and their horizons should both match up ( i cant really explain this better)

Johni · Apr 6, 2019

Beau Hannam Ukuleles said:
I bend by hand at about 0.060" each layer (i use two layers).

The "top" edge of the sides is flat (ie the edge that will have the top glued to it) - so use that flatline as an index on the top of your heat bender, which is also flat unless you are using a hot pipe like a caveman.

For further help, you can use 90 degree lines all along the side (indexed form the "top" flat edge) to help index off and keep an eye on how you are bending.

Do the waist first.
Then which ever bout- i usually do the lower bout as its less tight hence less difficult to get a feel for the wood (although i already have a sense after the waist being bent).
As you go, lay the side (top side down) on a flat bench top to see if its rocking and if it is, then deal with it.

When both bouts are bent, look along them and their horizons should both match up ( i cant really explain this better)

Thanks.

You gave me some great specifics to follow that I'm anxious to try. Couple questions, if I may?

Do you laminate the two .06" pieces together to form one side?

Regarding the "horizons"....I think I understand this. Sighting from tail to top, the ends of the bouts are in the same plane?

I'm fully "caveman" for the time being. I can see how the added flat along the top would be helpful to visually square to.

Thanks again for the detailed description.

bending sides

Johni

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sequoia

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DPO

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