Official Luthiers Forum!

The steel sheets (6x36) from LMI that are used with the Fox Bender, are they "spring" steel? That is, they do not easily deform and when you are done with them, the spring back to a relatively flat state?

Mike

SPBUSO is the only part number they show on-line and is Stainless steel 24 gauge (.021"). It will retain the waist and cutaway bend shape, but can be mostly flattened back out. Spring Steel does not retain shape as long as it is not crimped (sharp bent). I prefer spring steel but there are advantages to stainless as in low corrosion. if the bluing is scratched on spring steel they will oxidize where exposed. But that can be over come with high temp paint.

Do you know where to get spring steel?

Mikey I use stainless steel under the wood and spring steel on top of the wood. The reason is that even though the stainless slat will have some memory it seems to have selective memory and will keep conforming to any thing that you want including flat.

I like to use the stainless slat under the wood in that it is wimpier and when removing the bent side from the bender the stainless slat does not try to straighten out with a lot of tension thus helping to avoid cracking a side taking it out of the bender. For the same reason I use the spring steel slat on top of the wood - when I take the side out of the bender a slat with a lot of tension to straighten out being on top is not endangering the bent side.

Hesh you have a good thought process on the removal. IE the stainless on the bottom no spring back during removal.

However, and you probably know this; when you are unable to make your sandwich tight and maintain it so during the bend so that in the stressed areas there never opens up a gap between the wood and the lower slat. If you have gaps open upduring the bend at the apex of a deep or tight bend like on some waists and many cutaways you stand a much higher chance of faceting a bend rather than reshaping the fibers intact smoothly around the bend. That is the disadvantage of memory steel. But!!!not a big issue except on real deep tight waists and cutaways and on some high figure woods.

Micheal bro I understand what you are saying but I am able to keep a tight stack with the aid of spring clamps at the ends and the waist caul in the waist area.

Something else that I like about using a stainless slat under the stack is that when I am waiting for the wood to heat up the lack of support under the stack permits me to see the wood relaxing as it heats up. I can see the ends of the stack dropping down with gravity and this helps me know that things are getting hot enough to do the bend.

Lots of ways to bend your cat.......

Re removal, one thing I did was make up 6 U-shaped clips (think 1"x1" staples) from a cloths hanger. One "leg" goes into pre-drilled holes in the form (waist & both ends on both sides) and the other leg goes between the slats. As you release ram pressure, only the top slat (& the wood) is released- the bottom slat remains captured so it can't spring open & damage the side. Don't know if this helps.

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Dave
Milton, ON

excellent tip on the U-clamps for holding the shape while removing the cauls. My form is made the same way. I will try that tonight too!

Joe

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Joe

Brilliant simply brilliant!!!!!!! What a wonderful way to spend $100 bucks

Thanks Hesh. You just gave be an idea


A series of rare earth magnets in the frame of the bending forms to hold the spring steel lower slat in place once bent. A total of 6 per form, three perside recessed a tad below the form surface just enough not to contact the slat but close enough to hold the slat in its magnetic field

Bingo. This is one of the things I like about Stainless slats. With those heavy clamps on the sandwich, when the wood is ready to bend, everything starts drooping. Takes out a lot of the guess work.

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Thanks,
Blain

http://www.ullrichguitar.com

"89.67% of all statistics are made up on the spot."

Some great ideas in this thread, thanks guys!

Anyone tried using aluminum flashing for part of the sandwich? Al flashing is pretty cheap from OSH and other borg outlets. It bends easily, and stays bent (it's cheap enough to throw away IMO). Tom Ribbeke told us that he uses this stuff...

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

I am using the Aluminum flashing for my slats. It sucks for tight radius bending but is ok for standard or dread size guitars. Tonight I doulble the pieces up and used aluminum tape to hold them tight. It helped and supported the cutaway area pretty good. When I get some more cash, I will pick up spring steel ones.

Lots or reasons to the good stuff, just no money to buy it.

J

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Joe

Wow, thanks guys! Way more than I had hoped to learn about such a seemingly simple subject (especially about the part of not putting spring steel under the wood). I would have learned that too late on my own.

Mike

I am also using alum flashing, doubled, on my next bender mold. I screw in dowels almost touching each other so there is lots of support.I will probably use it to bend also, doubled, I will have to see.

I got my stainless from a mvac guy who does ductwork for like $10.00 Always clamp the wood at the ends to the support or it may be ruined, especially blanket on top style.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Exactly what I do, I have six clips made from welding rod, drill six holes two at each end, two at the waist in the bending form and when finished bending pop a clip in each and undo the cauls. I took some maple bindings out of the form last night and the upper bout hadn't taken the bend enough, with the bottom slat held by the clips it was easy to put the bindings back into the bender for another cycle.



Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

This does indeed appear to be a neat solution, but I think I am missing something here. I can see that the clips at the ends can be positioned outside the wood (and upper slat), but how do the centre clips work? Don't they get in the way and prevent the upper slat from clamping down on the waist?

Or are they pushed into place after everything has cooled and the waist clamp released a little?

Rod

"Or are they pushed into place after everything has cooled and the waist clamp released a little?"
Yes

BTW Joe, I think the aluminum is another reason you got faceting, as Todd illudes too. Not enough support

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Dave
Milton, ON

A Dave said, they go in when it's cooled down, just release the clamps off enough to slip them in.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

As you have read some use aluminum. but besides lack of support the big issue with aluminum is it disapates heat rapidly. so you loose about 20% (guess-ta-ment) of the heat you generate.

Colin.... a further thought then.

What would be wrong with permanently fastening the bottom slat to the former?

I just revisited my photos of the Martin factory, and this is exactly what they do there. The waist is clamped down first, and then each end one at a time. You can see in my first photo that the end of the wood is still sticking out horizontally, and a ram pushes it down followed by the upper slat, as in photo 2.

Therefore the sides are bent without the wood being sandwiched between the top and bottom slat as we would do. Only the top slat moves. And of course, when it is released, there is no bottom slat sping-back to worry about.





Rod

Dave, I am quite sure you and Todd are correct. I am looking for a local solution until I can order some spring steel. Economics have hit hard at my house, so I am trying to do things on no budget. But as I am learning you can pay more...once...or less a bunch of times and then need to spend more in the end.

J

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Joe