Thread: We have a lift-off!

The stuffups will be ok as you get to learn how to fix them as you go. It is costly even if you don't stuff up. Good luck and hope you enjoy. Remember you can ask questions on a forum if you have trouble with Cumpiano although it is a great book.

Jim

Originally Posted by Alastair

Wish me luck!

Good Luck. I will enjoy watching your progress. It is pretty rare to stuff something up that cannot be fixed with patient hands.

Cheers,

Peter

Yay! At last! Go for it!

Go for it Alistair! As Jim said, ask questions, particularly the dumb ones. Cumpiano's book is excellent although he has changed his mind on methods for attaching necks. see http://www.cumpiano.com/Home/Article...headblock.html

Originally Posted by Sebastiaan56

Go for it Alistair! As Jim said, ask questions, particularly the dumb ones. Cumpiano's book is excellent although he has changed his mind on methods for attaching necks. see http://www.cumpiano.com/Home/Article...headblock.html

Thanks Seb,

I am aware of the change. As the classical , (and uke copy) both use Spanish heel, it won't affect me this time

regards

Originally Posted by contrebasse

Yay! At last! Go for it!

Have already done some bending on trial sides cut from scrap IRW, using your pipe, and hot air gun, with varying success. Also have option of installing a ceramic element, or reverting to propane. Will have to address this in earnest in the not too distant future. Fortunately I have a large piece or IRW to play with, once I get a new bandsaw blade for resawing.

regards

Alastair I dont think you'll get enough heat from the heat gun to bend your sides. Go with propane mate.

The neck assembly is looking good...at least you havent done what I did on my first build and glued the heel block on TOP of the neck blank.

Originally Posted by Sebastiaan56

Go for it Alistair! As Jim said, ask questions, particularly the dumb ones. Cumpiano's book is excellent although he has changed his mind on methods for attaching necks. see http://www.cumpiano.com/Home/Article...headblock.html

I used his tapered pin tenon on my first mandolin and found it easy enough to execute but when I made my first guitar I felt that it would be a pain to reverse without damaging the pins and the finish. As the net was not around then I devised my own bolt on neck which is similar the Cumpianos new method except I epoxy and pined threaded rod into the tenon then passed them through the neck block and shoved a couple of nyloc nuts on them. It works fine and was easy to disassemble when I reset the neck ten years later. I don't use that joint anymore though.

Jim

When bending wood, remember that the cells in wood are like lightly interlocked fingertips. When the lignin softens, you can compress the fibres by up to 15% of the original length - this happens on the inside of the bend - but you can't pull them apart more than around 2% without breakage. This is why a bending strap is so useful, it helps keep the wood in compression right through the bending process. And the wood needs to be too hot to touch.

Originally Posted by kiwigeo

Alastair I dont think you'll get enough heat from the heat gun to bend your sides. Go with propane mate.

The neck assembly is looking good...at least you havent done what I did on my first build and glued the heel block on TOP of the neck blank.

Don't we all have tales like tht!

Have done some test bends with HAG, with some success, but agree was not hot enough. I was impatient, and had not waited long enough. Propane is there if needed tho.

Originally Posted by toejam

I used his tapered pin tenon on my first mandolin and found it easy enough to execute but when I made my first guitar I felt that it would be a pain to reverse without damaging the pins and the finish. As the net was not around then I devised my own bolt on neck which is similar the Cumpianos new method except I epoxy and pined threaded rod into the tenon then passed them through the neck block and shoved a couple of nyloc nuts on them. It works fine and was easy to disassemble when I reset the neck ten years later. I don't use that joint anymore though.

Jim

It will be a while before I need to look at this I will need to have a good run with the classical before I will look at an acoustic.

Originally Posted by contrebasse

When bending wood, remember that the cells in wood are like lightly interlocked fingertips. When the lignin softens, you can compress the fibres by up to 15% of the original length - this happens on the inside of the bend - but you can't pull them apart more than around 2% without breakage. This is why a bending strap is so useful, it helps keep the wood in compression right through the bending process. And the wood needs to be too hot to touch.

Well aware of the mechanics involved. There seems to be whole bodies of religion out there regarding what wetting practices to follow however, which is a bit confusing

I hope to pick up a new BS blade Sat, and after resawing and planing practice, will start practicing bending for the Uke sides.

regards

My religion insists that the wetting of the wood is only to generate steam to allow the heat to penetrate efficiently and minimise scorching. Water is not required for softening the lignin. It was an eye-opener at a steam-bending workshop I did a couple of weeks back, we bent 1.5 meter 40mmx60mm sticks of spotted gum around an 8 inch radius. Without end-to-end compression, even with a bending strap, the outside edge just splits and gives way. But if you keep the ends of the wood in longitudinal compression - and this means a really strong compression strap and end-stops, to FORCE the wood to retain its length and not stretch - it worked beautifully with minimal buckling on the inner edge, and NO tearing on the outer edge. Bent like a stick of hard cheese.

The principle is worth keeping in mind, even though longitudinal compression might be hard to arrange for a thin rib stock.



The other thing I learned at the workshop was that AIR DRIED wood is beautifully flexible at temperature, but that kiln-dried wood is much less easy to bend because the lignin has already been "set" at a high temperature in the kilning process. This might explain the propensity of some wood to "spring back" while other wood just relaxes into position as if it grew that way ...

I have bent many different varieties of wood at 2.5mm to 3mm on a pipe with no strap, some woods were easier that others but they all gave up in the end, take your time don't force it. When it gets real hot you will feel it give. The strap may help but you can do without it and if you get the odd split it can be repaired so don't panic. I just wet the area I'm about to bend with a brush and water, I don't soak it, wet it bend it, wet it bend it, etc etc, works fine for me.

Jim

Originally Posted by contrebasse

The other thing I learned at the workshop was that AIR DRIED wood is beautifully flexible at temperature, but that kiln-dried wood is much less easy to bend because the lignin has already been "set" at a high temperature in the kilning process. This might explain the propensity of some wood to "spring back" while other wood just relaxes into position as if it grew that way ...

Another reason I see repeatedly "air dried" timber recommended over kiln dried, regarding instrument making, perhaps?
Certainly it is likely that the IRW I was using for my initial practice bending was kiln dried, as it had been resawn off some 3 x 3 stock I had picked up somewhere. I had put the reluctance down to not enough heat, or moisture, but................

regards

If youre having trouble getting a piece of wood to yield you could try taking it down to your local ATO office....