I guess I would not mind a bit of backbow, since I've put a bit of too much relief in the neck
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| Fingerboard, how much clamping http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=15188 |
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| Author: | Alexandru Marian [ Mon Dec 31, 2007 3:56 am ] |
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Going to soon glue the FB, classical, fish glue. The fit is perfect, passes the light test. So does it really need a lot of pressure? If not, why not just use a lot of very tight tensioned sticky tape same as for binding? I was just looking at this LMI gadget...quite far from a 2 ton crushing clamp :) |
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| Author: | SimonF [ Mon Dec 31, 2007 4:51 am ] |
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Hey Alex, In my opinion, binding tape is not sufficient. I actually use those fingerboard clamps from LMII and they generate quite a bit of clamping force. There is enough surface area under the fretboard that you really need to make sure you can apply enough pressure to squeeze out the excess glue. There has been a fair amount of discussion lately about fretboard clamping. I use a dual-action trussrod from Allied and any backbow is easily corrected after the fretboard has been clamped and the joint is totally cured. So my clamping method is simply using about 5 of those LMII clamps. |
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| Author: | David Collins [ Mon Dec 31, 2007 5:08 am ] |
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I wouldn't use tape, especially on such a broad surface. You need to be sure you have clamped well enough to get all of the excess glue out from all areas. My general rule is clamp until glue stops squeezing out, and anything beyond that isn't going to too much good. I don't feel fish glue is especially prone to starved glue joints like many epoxies and other synthetic adhesives can be though, so I wouldn't worry too much about a little bit of excessive clamping pressure. Just make sure it's clamped until no more glue will squeeze out. The LMI clamps are no good for gluing on a fingerboard in my opinion. First, the clamping pressure is all at the edges of the board, nothing in the center. More importantly however, is how are you going to ensure you're gluing up the neck in the shape you want, controlling relief, backbow, twist - they're just not designed with clamping against a reference board in mind. I Just can't think of an advantage they have over a bessey or cam clamp holding the neck against a gluing board, but can think of a number of areas they hold potential to underperform. With a water based glue this is especially important, as it's going to swell near the fingerboard joint when the glue is curing, and usually want to spring in to back bow as soon as you unclamp it from a board. This is a main reason many have switched to epoxies for fingerboards. For those that still use water based glues, double action rods have become popular, or I still prefer clamping the the neck against a board to shape it in to slight relief when gluing. |
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| Author: | Alexandru Marian [ Mon Dec 31, 2007 5:22 am ] |
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I guess I would not mind a bit of backbow, since I've put a bit of too much relief in the neck |
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| Author: | SimonF [ Mon Dec 31, 2007 8:02 am ] |
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David, I've used quite a few different methods over the years. For a long while I was using a clamping caul with the appropriate radius and slots for the frets (since I fret before the fingerboard is attached to the neck). If you start with a perfectly flat neck surface and a perfectly flat fingerboard surface, I just don't see the need for a clamping caul. I generally get just a wee bit of backbow but that is easily corrected with a dual-action truss rod. Obviously, if you don't use one of those truss rods then I would highly recommend an epoxy glue-up. I have been using stainless frets for the past couple years and the amount of leveling I have to do after using my current method is minimal to none. Those little tie clamps exert a surprising amount of force. And there is a good distribution of the clamping force. Certainly nothing to cause one to question their sufficiency. Is it any better to have the force dead in the center as oppossed to the edges? - not really. In fact, I remember seeing an aluminum fretboard caul of Frank Ford's that applied pressure right at the edges. Regardless of center or at the edges, the job will get done either way. Obviously, this is just my opinion. But I do believe it is an effective and sensible approach -- and one that has served me very well for the past couple years. Happy New Year's, Simon |
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| Author: | Howard Klepper [ Mon Dec 31, 2007 8:05 am ] |
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Tape would give nowhere near adequate clamping pressure. I use as many spring clamps as I can get on it, one row down each side. |
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| Author: | SimonF [ Mon Dec 31, 2007 8:06 am ] |
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Oh, I forgot to mention why I use these particular clamps over cam clamps or C clamps. I like that they exert no twisting force. These clamp similar to how vacuum does- straight down. Other clamps tend to push or pull the workpieces. I use locating pins to nail down the location but clamping can still move the pieces a little bit. I just find these twist clamps to simplify the process and give me perfect results. If you doubt their effectiveness, try one out on an offcut of the fretboard. I think they are more than adequate. |
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| Author: | David Collins [ Mon Dec 31, 2007 9:01 am ] |
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I used to have about a dozen of those LMI clamps, but never really ended up using them. I've tried them many times, and I still simply don't trust them. I still would not feel comfortable "free clamping" anything like a neck/fretboard joint. Plus, I honestly find it much simpler and quicker to glue up a sort of bar clamp like a cam or Bessey. I'm sure those clamps work fine with the right glues and preparations, but I just don't like free clamping anything like that. Just a matter of personal preference I suppose. I know many folks like to fret the board apart from the neck, but I've never been a fan of this method unless the builder has really done a lot of tests and refined a procedure enough to get consistent results. I see a lot of hand built instruments, and at first glance can almost always tell if the board was fretted before or after assembly. Some folks certainly can pull it off, but very few and far between in my experience. |
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| Author: | joelThompson [ Tue Jan 01, 2008 6:22 am ] |
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i use a combination of spring clamps and releasable cable ties with titebond this seems to work for me so far but i sure are better methods out there. i have the policy of if it aint broke why fix it so i am happy with this method for now and it a great method for beginers as you can experement with out the for lots of expensive clamps. joel. |
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| Author: | Alexandru Marian [ Tue Jan 01, 2008 6:37 am ] |
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Thanks everyone. I ended up doing my own special clamps. 1 inch width 1mm thick steely sheet to go on the back of the neck, and oak thick flat stock on the fretboard, and 2 sturdy screws. When tightening the back sheet conforms to the contour of the neck, while the thick oak presses flat on the FB. Ive made 4 of these. Used a traditional small C for the soundhole, and a lot of strong sticky tape for the heel fret. Why don't I just use some factory made clamps? Only heavy metal types at the local HW stores, and they cost a whopping 35$ each. I should be ordering a few Klemmsias from Germany one of these days.... |
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| Author: | Alexandru Marian [ Tue Jan 01, 2008 11:40 am ] |
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Unclamped..could not wait more than 12h  There is no backbow...yet I have heard spanish cedar is more stable with humidity changes..maybe that is the reason. |
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