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Help - bend Reverse Kerfed Bindings or go to laminated?
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Author:  SteveSmith [ Mon Feb 22, 2010 9:18 pm ]
Post subject:  Help - bend Reverse Kerfed Bindings or go to laminated?
I need some help please. I'm at the lining stage on a cutaway 000. I used the reverse kerfed linings before but had trouble bending them. The advice was to use hot water so I did. Results were better but not good enough. I figure I can use these and maybe laminate some maple veneer on top to make them look good. Or maybe I should just make laminated solid bindings. Anyway, here's what I did and I sure could use some advice on getting this done better. It's important to me to get the inside of the box looking good too.

First I put something together so I could soak the linings in hot water. Figured if the method works out I'll build something out of PVC pipe.
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Then I soaked them in boiling water (Hesh - yet another use for the in-shop microwave) and put them on the wax paper-covered mold as carefully as I could. This didn't work out near as well as I expected. It just cannot be the best way to do this. I'm almost embarrassed to show this one. :oops:
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The results are much better than my last attempt.
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But still breaking and faceting around the tight curves of the cutaway.
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How do you guys get these in cleanly?
Author:  LuthierSupplier [ Mon Feb 22, 2010 9:32 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Steve,
I've never done a cutaway, but this last guitar all I did was spritz the Reverse Kerfed linings with a spray bottle until wet, and started fitting right away. But I've see reverse kerf on a cutaway, and it always looks like the builder added more kerfs to the lining. So I say cut more kerfs in the cutaway, and Bob's your uncle!
Author:  Zach Ehley [ Mon Feb 22, 2010 11:12 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I think your going to want to cut some extra kerfs in the tight bends of the cut away. That way each section dosnt have to bend to as hight of an angle and you'll have better contact with the side when you glue it together.
Author:  Pete Brown [ Mon Feb 22, 2010 11:35 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I think a lot of the problem with off-the-shelf kerfed strips is that there's too little wood left between the bottom of the kerf and the opposite face of the lining - they look neat, but they're too easily broken. I make my own strips and leave some meat there. I bend them to shape on a bending iron before gluing them and break very few.
Author:  Dave Fifield [ Tue Feb 23, 2010 3:54 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I'm going to give Kevin Ryan's laser-cut A4 kerfing idea a try. I just got some in. It's VERY flexible indeed. For cutaway sets, he supplies two strips with extra flexible sections (twice as many cuts per inch) to go in the cutaway area. Sometime in the next week or two I'll be gluing some in.....I'll report back later.

Check it out by clicking on the "Advanced Shell Technology" link in the OLF sponsors links above.

Cheers,
Dave F.
Author:  Jeff Highland [ Tue Feb 23, 2010 5:34 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Why not just trace and cut a solid section of timber for the point of the cutaway and butt the flexible lining up to it on each side
Author:  SteveSmith [ Tue Feb 23, 2010 9:11 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Tracy, are you fitting and gluing at the same time?

The idea of extra kerfs sounds good. Wouldn't be too hard to build a quick jig for that.

Pete, I tend to agree that there isn't much solid wood left with the off the shelf reverse kerfed linings. But it seems to me that if I need to break out the bending iron then why not do solid linings?

Dave, I checked out the A4 linings and I bet they'd do the trick. I may try those down the road.

Jeff, if it was a Florentine cutaway I would do that but don't think I'd like the look for the Venetian.

Todd, good suggestions since, obviously, my little technique experiment didn't work as well as I'd hoped. I want the inside of the box to look good since I'm using a sound port and player will see it every time they look down. The suggestion that intrigues me the most right now is your comment The idea of solid linings for very tight curves is a good one, provided they are laminated. Can you, or anyone else, elaborate just a bit on thickness, number of laminations, and the basic technique for making them?
Author:  Dave Stewart [ Tue Feb 23, 2010 9:28 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I make my own reverse kerf linings (old tutorial) and, for part of the batch, I'll reduce the web a hair. So I end up with some "floppy" and the balance "stiffer".
If still not floppy enough for a particular bend, just run an Xacto blade quickly down every slot (increasing flexibility), paint web with water & then glue
Author:  SteveSmith [ Tue Feb 23, 2010 12:16 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Todd, It's the tight concave curve on the cutaway that's giving me trouble, the convex curves do seem to be easier to work.

Thanks everybody for all the suggestions. I'll experiment with these this week and hopefully by the weekend will have the linings in and looking the way I want them.
Author:  John Mayes [ Tue Feb 23, 2010 12:21 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
You can also bend them just like you would a guitar side using a fox style bender. Bring em up to temp, bend and then shut the heat off right away. Leave em be for an hour and you're good to go.
Author:  GregG [ Tue Feb 23, 2010 12:23 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Yeah, I do like John M. mentioned.
Author:  LuthierSupplier [ Tue Feb 23, 2010 1:23 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
[quote="SteveSmith"]Tracy, are you fitting and gluing at the same time?

The idea of extra kerfs sounds good. Wouldn't be too hard to build a quick jig for that./quote]

Steve,
I spritz both sides and then clamp them loosely in position so I can cut them to length. By the time I cut them to fit, they are almost dry. I add glue and put them on. Hadn't had one break yet.

I used to use a wet paper towel with a clothes iron and heat/bend/clamp around the outside of the guitar until fitted. I would leave it clamped to the outside of the rim for about 1 hour until they dried. Then I would take them off and cut them to length, and glue them in. This worked too, but too much time!
Author:  Mike Collins [ Tue Feb 23, 2010 3:36 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
For a cutaway or any other tight bend with store bought reverse I thin the backing(the solid part)down to It's almost gone.
Then a Super Soft sprit -let sit -and dampen a bit and it will follow any curve.
Also as mentioned -extra saw kerfs do help allot.

Mike
Author:  SteveSmith [ Tue Feb 23, 2010 6:27 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
My Fox type bender won't help as I don't have it set up for a cutaway, I bent these sides on a pipe.

Didn't think of trying SuperSoft on it or thinning the backing; makes sense.

The only bad part of this is I won't be able to get back into the shop until Thursday evening so I have to wait to try out some of these great suggestions.
Author:  SteveSmith [ Tue Mar 02, 2010 7:55 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Just to follow up.

Like many things it turned out to be easier than I was trying to make it. The biggest lesson I've learned is to use the bending iron to bend the linings to the desired shape; makes them easy to install. On the cutaway I just built a jig so I could use the band saw to add a kerf in between each of the factory kerfs. I had also sprayed them with SuperSoft but I don't think that was necessary.
Author:  muthrs [ Tue Mar 02, 2010 9:02 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I just bend on a pipe with no water. Seems like using a side bender is overkill for doing linings. They bend really easily since the web is so thin. Of course they are fragile and you have to handle them carefully, but the bending itself goes easily. Having said that, I do notice that mahogany linings seem less brittle than cedar linings. I won't lie, I have broken a few. I now make my own reverse kerf linings out of willow as suggested by Al Carruth. Willow is really springy, light and glues very well. Perfect for this application.
Author:  SteveSmith [ Tue Mar 02, 2010 9:59 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I was surprised how well the pipe worked; actually a pleasure. I can see where willow would be good for this but don't know where I would get it around here. Academic, I guess, unless I start kerfing my own.
Author:  Todd Rose [ Wed Mar 03, 2010 9:57 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
This may be of little help to you, but I have two comments. I just used basswood linings for the first time, and I was very happy with how easily they bent. For really tight bends, I just pre-bent individual webs/kerfs right in my hands (cold and dry). I could bend them quite sharply and the basswood didn't break - other woods I've used certainly would have. Surely, some of the fibers in the wood were breaking, but it held together beautifully and didn't appear broken at all, just faceted, like any lining is going to look when bent sharply.

The second comment is that I've gone back to regular kerfed linings rather than reverse kerf. There are several reasons for this, but one of them is that it doesn't affect the look if the linings break, because the visible surface is all kerfed anyway. In fact, what I'm doing now is installing the linings in short sections rather than doing a whole side in one length. It makes life a lot easier and works well with some of the other things I'm doing with the design of the inside of the box. It ends up looking very neat. For one thing, you don't see any faceting, because that side is glued to the sides.

Those who may be questioning the reverse kerf bandwagon may want to reconsider the advantages of regular kerfed linings.
Author:  SteveSmith [ Wed Mar 03, 2010 10:22 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
Todd, Good info on the basswood and good point about the regular kerfed linings. I really like the look of the reverse kerfed linings but they do have the disadvantages you pointed out. I think I may try to laminate some solid linings next time to see how hard that might be.
Author:  Laurent Brondel [ Wed Mar 03, 2010 10:37 am ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
SteveSmith wrote:
I think I may try to laminate some solid linings next time to see how hard that might be.

It's easy and will work if your rim is flat and not radiused. I make solid linings with five .040" strips. No need to bend them, I laminate them directly on top of the side clamped in a 1/2 mold. The fit can't be better than that, and one can get fancy with wood colour combos.
If the rim is radiused it's a lot more involved, as a solid (or laminated) lining will not conform to the compound curves like kerfed linings do. Then there are cutaways…
If I recall Burton had a very good tutorial on how he does laminate linings.

I'm with Todd, regular kerfed linings are great.
Author:  RaymundH [ Wed Mar 03, 2010 2:46 pm ]
Post subject:  Re: Help - bend Reverse Kerfed Bindings or go to laminated?
I second Dave Fifield in recommending A4. We have it at the shop and this stuff is crazy flexible and easy to deal with. Yes, the price is double, but you are done in minutes no matter how severe the radius of the B&S or how complicated the cutaway.
We also installed the Zipflex product on an all Koa OM and it was very simple to navigate all the angles. Looked great too.

Ray
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