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Help Please, need a fix idea!
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=24814		 Page 1 of 1
Author:  WendyW [ Sat Nov 28, 2009 8:27 pm ]
Post subject:  Help Please, need a fix idea!
I'm building a small Torres classical and I've got the top braced, attached to the neck, and the sides attached with tantellones. Today I profiled the height of the sides and glued the reversed kerfing to the back edge of the sides. Somehow I profiled the sides wrong and they are flush to the heel and foot, but they must climb too steeply to the widest part of the upper bout. When I lay a 25' radius sanding stick across the upper bout, there is an 8mm gap at the foot and heel. oops_sign The kerfing is 1 1/2mm proud of the sides, so that still leaves a difference of over 6mm. I am not planning on selling this guitar, so I am open to unorthodox solutions and chalking it up to a learning experience. I have thought about trying to remove the kerfing, although that seems like a daunting task, unless anyone knows of an easy way to get it off. The other thought I've had is to go ahead and reprofile, which won't leave enough kerfing in the upper bout area. Then to glue a second row of kerfing below the first, only in the upper bout area, to allow for cutting a binding channel. Any suggestions would be welcome. I can try and post a picture tomorrow if that would help, but for tonight I do not want anything to do with my shop. What a crappy end to a long day! [headinwall] Thanks, Wendy
Author:  unkabob [ Sat Nov 28, 2009 9:03 pm ]
Post subject:  Re: Help Please, need a fix idea!
Wendy:
What glue did you use on the kerfing? If it was titebond original, you can get out your hair-dryer gun or heat gun and pallet knife and remove the kerfing.
I use my wifes hair dryer and my pallet knives came from the dollar store.
bob
Author:  WendyW [ Sat Nov 28, 2009 9:38 pm ]
Post subject:  Re: Help Please, need a fix idea!
It was Titebond regular. I guess I should try the old hair blow dryer tomorrow. I do have some pallet knives. I know removing the kerfing and re-profiling would be the best way to correct the problem. Thanks, Wendy
Author:  Dennis Leahy [ Sat Nov 28, 2009 11:18 pm ]
Post subject:  Re: Help Please, need a fix idea!
If you are in the US, you can get a cheap heat gun from Harbor Freight for $20 - even a bit less if on sale. I don't normally recommend buying the cheapest tools you can find, but this does not sound like a tool you'll use much, and that fits my description for an instance when a cheap tool might be a smart choice. They get a lot hotter than a hairdryer. That can be good or bad, depending on how close you hold it and for how long, so you may want to try on scrap to get an idea how much heat you're delivering. A 6" wide piece of cardboard covered with aluminum foil could be used to protect the rims from the heat blast, and move it along as you go. I would also dampen the linings a couple of times before starting.

If the height of the rims is correct and the height of the linings is incorrect:
Remember, you can make-up 6mm of height between the the top of the rims and the top of the guitar, with bindings. With a 2.5mm thick top, that would mean you could completely hide the fact that the linings are high, with linings sticking up proud of the rims up to about 3.5. But, for 8mm, you'll either be using extra tall bindings or sanding the rims down.

Dennis
Author:  Rod True [ Sat Nov 28, 2009 11:38 pm ]
Post subject:  Re: Help Please, need a fix idea!
Here's what I would do.

Profile the sides now while you have the linings on (it makes the rim much stiffer and less worry of spliting) to the appropriate height. Once this is done, I'd check to see how much lining height I have. If there is 1/2" or more, I'd just leave it and get ready to glue the back on.
If there is less, I would just use a sharp chisel and chisel the linings off. This can go very quickly, much more quickly than heating the glue joint and removing the linings with a pallet knife. Besides, using a pallet knife along the side edge this way can lead to splitting the side if one is not versed in how to patiently let the glue soften and not force the two pieces apart.

The lining is sacrificial here IMO. Get the profile right, then worry about the linings.
Author:  Ken Franklin [ Sun Nov 29, 2009 2:03 am ]
Post subject:  Re: Help Please, need a fix idea!
I'm assuming that you have a spanish foot that extends into the upper bout and that is where the problem is. Just add a piece to the foot and profile it to match the arch. If you do a nice job it will be hardly noticeable and should provide no structural weakness.
Author:  Michael.N. [ Sun Nov 29, 2009 6:40 am ]
Post subject:  Re: Help Please, need a fix idea!
I think Ken's fix is by far the best solution - providing I'm understanding the problem correctly. If you have an off cut of the same neck wood I doubt that it will be visible at all. Even a wood that doesn't match but is of the same species will give a perfectly acceptable fix.
I've knifed/chiselled linings off before and it's not an easy task, although it's certainly possible. The heat method should also work but you have to be mindful that it may introduce a little distortion in the side - I don't know if that will happen though because I've never tried it.
Author:  WilliamS [ Sun Nov 29, 2009 12:41 pm ]
Post subject:  Re: Help Please, need a fix idea!
I agree with the guys above that you should glue a piece to the foot. That is actually the way Courtnall tells you to build in his book and the way I did my first: glue the sides flush with the heel then build up and profile the bottom of the foot to match the arch of the back.
-William
Author:  WendyW [ Sun Nov 29, 2009 3:19 pm ]
Post subject:  Re: Help Please, need a fix idea!
Hey, thanks for all the ideas. I had thought about adding a piece to the foot and heel last night, and I may consider that, depending on how off my profiling is. I made a side template this morning out of thick paper and I will put that on the side and see what is up. I also thought about profiling the sides while the lining is on, simply because it means there will be less of the lining left to remove. I'm not crazy about the idea of having to heat and remove the lining, a long job and risking damage to the sides, although I remembered that I have a tacking iron from when I used to have a frame shop years ago. It is like a very small iron maybe 3" long x 1"wide with a curved bottom and a long handle. It seems like it would be the perfect tool to use, putting the heat only where needed. I'm thinking that I may do a combination solution; add a thin piece to the foot and heel to make up 1/2 the difference, and profile down some, but still leaving a usable amount of lining. I do still have some of the wood left that the neck was made from. I will let you know what I decide. Thanks, Wendy
Author:  WendyW [ Sun Nov 29, 2009 3:50 pm ]
Post subject:  Re: Help Please, need a fix idea!
I guess I had things backwards. The sides are actually the correct height at the heel, and it is the lower bout and waist that are too high. Since the sides are already low enough at the heel, I can't add to the heel and foot because the sides and the lining will then be too low in that area. My best bet is to profile the rest of the perimeter properly and then see how much lining is left. It looks like there will be about 10mm left, but then I will probably lose some more when I radius it to accept the top. I think that the reason this happened is that I made my heel the correct height by subtracting the thickness of the top and back from the total height on the plans. Then for some reason I made the tailblock the total height and got confused when I profiled the sides. idunno Does anyone know why, when building a classical, the profiling is done after the top, neck and sides are assembled? Wouldn't it make more sense to profile the sides before bending?
Author:  Ken Franklin [ Sun Nov 29, 2009 5:29 pm ]
Post subject:  Re: Help Please, need a fix idea!
Some people profile their sides before bending. As long as the waist ends up in the right place it works fine.

You should probably make the sides the right height at the heel and then see if your spanish foot is still too low. If it is then you won't have to add much to the foot to make it right, but you need to taper it back away from the middle of the bout so it's flush with the sides.
Author:  WendyW [ Sun Nov 29, 2009 6:19 pm ]
Post subject:  Re: Help Please, need a fix idea!
I took the sides down and I don't need to add very much to the foot now. When I was planing the sides down I tried to take the radius of the back into account and planed at a slight decline toward the outside of the rims so I won't have to sand very much more off. What I usually do is line my radius dish with sandpaper and lay it on top of the rims and gently rotate it back and forth. I make sure the rims are well supported. I think the linings can stay, they may be just under 1/2" in the worst places. I won't know for sure until I radius sand it. The bindings are not going to be very tall on this guitar, and they are the same wood as the sides and back, so I just need enough depth for a short binding and simple purfling on the sides. I can always change it to a contrasting binding with no purfling on the sides if need be. I won't be able to work anymore on it now until next weekend. I had originally hoped to have the back on by the end of the day today, and a weekend off next week, but oh well.
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