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Got the rosette done this morning on my OLF SJ and am now off to bending sides. I am using a bending machine with heat blanket I picked up from John Hall. I successfully bent a mahogany side this morning. The side was .075". I sandwiched the mahogany between two pieces of heavy brown paper I had soaked in water and used a paper towel to wipe off the excess water. I took my time and the bend turned out perfect. I've done a lot of researching, and figured maple appears to be a bit more difficult to bend, but I think the same strategy will work based upon what I have read. The key seems to be don't get it too wet and work slowly.

The maple I have is cupped just a bit, but it is still at 1/4+. I need to thickness it and am thinking of running it down to .075" or thereabouts. I am hoping that once it is thinner and run though the bender that the cupping will disappear. No cutaway on this one.

Thanks,

Ken

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Ken my friend it sounds to me like you have a great plan and I am sure it will go great!

Hesh...how do you find time to build? Seems you are always online helping chaps like me or complimenting chaps on their work

If my plan is good, then I am heading back off to the shop!!

Ken

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I have 2 computers in my shop.......

I recently bent 4 sets of flamed maple. Don't use super soft on maple - if it is not completely dry, you will get some nasty brown staining. I sanded the sides to .075, except the cutaway area I sanded to .065. I had no problem on the non cutaway, broke one on the cutaway.

No need to soak the wood. Just wetting it with a spray bottle is sufficient - make sure you have sufficient heat before bending and go slow

Good luck!

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John Ressler

What type of bending machine do you have Ken? If you're using a Fox style, I suggest that you only bend the waist area partially, like 1/3 down or less. Then bend the bouts, then finish the waist. The reason for this is that you won't be supporting the waist area enough on the outside of the curve (inside of the plate) to really reduce your chances of a fracture. By bending the bouts first, you now have some tension on your slats (you didn't mention slats in your "sandwich" but I'm assuming you have some) on the outside of the curve which will support the wood much better and really reduce the chance of snapping the side. Note that this process is best for highly figured wood like curly maple.

I wouldn't take the wood higher than 280*f though. Scorched maple is a real pain to sand out.

Get the wood up to temperature before you start the bend. Be patient and it should go well.

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Well I did something wrong. I cracked the first side I put in. I am using the Fox style bender. I had the steel slats on both sides. I used the same approach I did with the two practice mahogany sides. Following Rod's advice, I kept the heat below 280. Once the temperature was at 275, I snugged up the waist just a touch, slowly worked the lower bout down, then the upper. I then started to work the waist down very slowly and within the first 1/2", still had a good 1" plus to go, the side cracked right at the waist. Looking at the edge through the bender, It cracked from the inside out and got to within 1/32" of the outside edge. I finished buttoning up the waist and let it cook. I haven't pulled it out yet, but I doubt it is salvageable. Looks like I need to order a new set from Jason and start all over. Arghhhh!

I had the thickness just under .08". Maybe that was too thick. I might as well bend the other side for practice, just not sure what to do differently.

Ken

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maple needs a a bit more heat. I like to use 375 I start bending at 250 for the lower then 275 - 300 on the waist. I take the heat to 375 to set the bend.
If you have a high figure of maple use some wet paper to allow the heat to work the wood so it doesn't case harden. You should be finished bending within 4-6 minutes. If you wait too long you can get the wood hardened before you bend.
john hall

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John Hall
blues creek guitars
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I gave it a go with the other side. I made sure the brown paper was a bit wetter. I squeegeed most of the of water off on the counter prior to sandwiching. This time I set the temp to high. Once the temp reached 250, I bent the lower out, by then the temp was around 280 or so, and I bent the upper bout. The temp was running close to 300 when I set the waist. This time I took it even more slowly. I didn't hear any cracks, and all seemed to go okay. I ran the temp up to 350 then worked it back down to 300 where it sat for 15 to 20 minutes prior to shutting everything down. We then went out for dinner. I just took it out, and it looks much better than the first one, but I still ended up with a hairline crack at the waist. I think I shot of superglue and a brace, and it would be okay.

I can't even imagine trying to do a cutaway. I am struggling with the just the waist! My sandwich for bending is steel plate, brown craft paper dipped in distilled water and squeeged against the counter to remove most of the surface water, maple rim, another wet sheet of craft paper, steel slat, and heating blanket. Putting the heating blanket on top is what John Hall's directions show. I have seen videos of others putting the blanket between the top sheet of craft paper and the steel slat.

One thought I have is that after I bent my first side, the steel slat had a slight bend at the waist. I never tried to remove this, and located the waist of the next side under the bend in the steel slat. I wonder if this bend is not allowing the wood to be supported as well as it could be at the waist and thus cracking. I am going to order one or two more sets of sides from Jason at CVT, but any additional thoughts you can share, I am open to.


Ken

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Ken, Have you tried useing supersoft,then let the maple dry before bending so not to get a stain? It should work.

It appears that you have some runout , Expect figured woods to do that. In 4 years I lost 3 sets and all were figured maple. I never used super soft but if you want to , go ahead. You said you went slow , maybe you went too slow. If your wood dries out totally you can case harden the wood , at which point you make the wood too brittle to bend.
I am finished bending within about 4 minutes from the time I turn on the machine till the wood is on the pattern. I have sent you an email and maybe we can hook up later today and see what you may need to change in your technique. Matching the woods to the correct temp can be usefull. Place your thermometer between the blanket and the top layer of steel. You want the blanket on the top . Here is my temp list
Rosewood 250 to 325
Mahogany 275 to 375
Maple 275 to 375
Figured woods
I use the double paper technique. I will soak kraft paper and layer the wood with this. I take the bender to avout 325 and want to see it steaming. Keep the paper wet until you have the bend compete . After the heat cycle remove the paper and run a drying cycle . Total bend time should be 4 minutes and not longer than 6. Never let the paper dry.
john hall

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

There are some real gems of info in John's comments including the case hardening issue and the speed that he does the bend. I find that 5 minutesish is all it takes me to complete a bend too and this is yet another advantage of using a heating blanket in that you don't have to be heating the side for as long as it takes to make lasagna.....

Also two of the three slats that I use are stainless and they do have some memory and are not flat any more. When I set up the stack in the bender prior to bending it seems to greatly help to uniformly heat the side to use spring clamps on the two ends of the stacks and I even use them near the waist caul to keep the slats in contact with the wood at all times during the pre-heating of the stack.

Of course one has to remember to remove the spring clamps from the waist area prior to lowering the waist caul and at that point the waist caul will keep the elements of the stack in contact with each other.

I can see where my method and John's differ. Honestly, John is a master at bending sides so I'd take what he says as the gospel.

I use a different style of bender, and I also always put my heat blanket on the inside of the wood, next to the craft paper.

The advise about making sure you don't dry out the side prior to bending is important. Cracks can happen when there is no moisture.

I also find that maple does not hold water like mahogany or rosewood does. Also it doesn't have the oils that rosewood does which I think really helps bending the wood easier.

Curly maple is one of the hardest woods to bend without cracking, so don't feel like you're doing something wrong. Sometimes it can just be ornery.

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techniques may differ a bit between us , that doesn't me one is better than the other . only we found a methodology that works for us. Wood is not intellegent and it only knows it is hot. Patience is key and never give up. If it were easy , anyone can do it. Maple is one of the hardest of the figured woods to bend. Mahogany is one of the most common woods I have bent for brackish cracking and springback.
john hall

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Everyone, thanks for the comments and support. I think John's email footer about learning more from mistakes than successes is quite appropriate for what I am dealing with here. Lot's of encouraging words, a personal chat with John, and even an offer by Rod to provide some orphaned sides have me determined to figure this out. I think my mistake was not using enough water and not moving quickly enough. I'll have a small delay until I get some more sides. In the meantime, I'll move on to the top bracing.

Thanks again everyone.

Ken

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Not to get off track but I have bent a couple maple sides one set quilted and one curly maple. The quilted set I wet slightly and had no problem. The curly set I did not wet at all and they came out great. Did I just get lucky? Does anyone else bend curly dry? And thanks John Hall for the brace pattern layout.
Dean

Don't start bracing your top yet, especially if you don't have humidity control. You really want to wait till the rims are assembled and ready to receive the top and back before you brace the plates. This way the braced plates have less chance of changing before you glue them to the rims.

Instead, work on the neck or make a new jig or something.

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson

I do my assembly in my somewhat humidity controlled basement. It varies from 40-50% humidity. For the first two guitars, I assembled the rims first. I did it that way for no other reason than that is what builders seemed to do. So do you try to get the top on the rims as soon as possible after bracing? Interesting. Learned something new.

Ken

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Yup, same with the back

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"There's really no wrong way, as long as the results are what's desired." Charles Fox

"We have to constantly remind ourselves what we're doing....No Luthier is putting a man on the moon!" Harry Fleishman

"Generosity is always different in the eye of the person who didn't receive anything, but who wanted some." Waddy Thomson