Helldunkel Posted January 9, 2011 Report Share Posted January 9, 2011 I got this idea after purchasing a solid marble table in a pound shop... The cool thing about marble is that its perfectly flat! So the thing to do first is to drill 2 holes in the fingerboard and neck in which you will put two removable nails, this is to prevent the fingerboard from shifting... Apply glue and clamp just like on the pictures, you dont need more clamps, the 2 straight bars will evenly spread the pressure and not only will the glue joint be perfect but the neck will be gluing flat! If your headstock is angled, that's not a problem, simply move the headstock to the edge of the table... Enjoy Link to comment Share on other sites More sharing options...
guitar2005 Posted January 9, 2011 Report Share Posted January 9, 2011 Gluing the fretboard against a straightedge or something like it is something I'm going to start doing from now on. Gluing a fretboard with clamps and wood blocks just doesn't cut it IMO. Link to comment Share on other sites More sharing options...
FireFly Posted January 9, 2011 Report Share Posted January 9, 2011 Gluing a fretboard with clamps and wood blocks just doesn't cut it IMO. Normally you'd use a saw to cut. But i can see where you're coming from! Link to comment Share on other sites More sharing options...
Kammo1 Posted January 9, 2011 Report Share Posted January 9, 2011 Patrick that is a good way and its exactly what I do with mine only my work piece isn't marble but a nice piece of kitchen worktop that is as flat as you are gonna get and its served me well. Isn't it strange that some simple ideas are always the ones that work perfect and with outstanding results. Link to comment Share on other sites More sharing options...
Helldunkel Posted January 10, 2011 Author Report Share Posted January 10, 2011 Patrick that is a good way and its exactly what I do with mine only my work piece isn't marble but a nice piece of kitchen worktop that is as flat as you are gonna get and its served me well. Isn't it strange that some simple ideas are always the ones that work perfect and with outstanding results. Actually thinking about it, its pretty similar to the technique I was using when building my acoustic guitars, using wood blocks and a flat surface to glue the bracing on the top... Its very efficient... Previoussly I was using spoke clamps for the job and placed a flat metal bar on the beck of the neck which I then clamped again so that the neck rests flat on it during the gluing... Now you dont need any metal bar and you dont need any spoke clamps Gluing the fretboard against a straightedge or something like it is something I'm going to start doing from now on. Gluing a fretboard with clamps and wood blocks just doesn't cut it IMO. oh you can inlay some gold in the blocks? Maybe it would cut it better? Link to comment Share on other sites More sharing options...
Mattia Posted January 16, 2011 Report Share Posted January 16, 2011 For epoxy (which doesn't need much clamping power) this would work fine, but from a purely mechanical standpoint you're not getting even pressure across the entire board - the clamp's force is only applied in a roughly 90 degree 'pie slice' shape downwards, so you'd need a clamp every 10 cm or so (4") with the setup you've got there, give or take. You can 'cheat' and get more pressure by putting bits of veneer under the slats and between the clamps, which will tension the cauls and apply additional pressure. Link to comment Share on other sites More sharing options...
avdekan Posted January 16, 2011 Report Share Posted January 16, 2011 For epoxy (which doesn't need much clamping power) this would work fine, but from a purely mechanical standpoint you're not getting even pressure across the entire board - the clamp's force is only applied in a roughly 90 degree 'pie slice' shape downwards, so you'd need a clamp every 10 cm or so (4") with the setup you've got there, give or take. You can 'cheat' and get more pressure by putting bits of veneer under the slats and between the clamps, which will tension the cauls and apply additional pressure. I would just use more clamps. Using too few clamps makes you use a lot of pressure in order to get a good squeeze-out of glue, whilst potentially starving the area under the clamps and is not good for the clamp itself in the long run. I prefer using as many clamps as comfortably possible with moderate pressure. In the end its the power of numbers that does it. Link to comment Share on other sites More sharing options...
Helldunkel Posted January 17, 2011 Author Report Share Posted January 17, 2011 For epoxy (which doesn't need much clamping power) this would work fine, but from a purely mechanical standpoint you're not getting even pressure across the entire board - the clamp's force is only applied in a roughly 90 degree 'pie slice' shape downwards, so you'd need a clamp every 10 cm or so (4") with the setup you've got there, give or take. You can 'cheat' and get more pressure by putting bits of veneer under the slats and between the clamps, which will tension the cauls and apply additional pressure. Sorry but from a purely mechanical standpoint and if everything is dead flat which is the case in this exemple, then you are actually getting perfectly even pressure across the entire board... BTW there is no glue in the center of the board, you must never glue your truss rod and the glue must be spread out of the rod aera... Never put glue in the slot it will hinder the function of the truss rod. ... And I was using titebond on this exemple... Also over clamping produces stresses in the wood that can work against the joint staying together. Too much pressure compresses the joint where glued, and when the glue cures and the wood relaxes, you have a joint that may have different properties of adhesion. In the exemple of a guitar neck this can contribute to add some upbow or backbow to the neck Link to comment Share on other sites More sharing options...
stereordinary Posted January 17, 2011 Report Share Posted January 17, 2011 I do something similar to this when I'm gluing fingerboards. I use a long slab or marble, only when I do it the fingerboard is on the bottom, and I use every clamp I can fit on there Link to comment Share on other sites More sharing options...
Mattia Posted January 17, 2011 Report Share Posted January 17, 2011 Sorry but from a purely mechanical standpoint and if everything is dead flat which is the case in this exemple, then you are actually getting perfectly even pressure across the entire board... Sorry, but based on what I've been taught about clamping force distribution, you're wrong. Any mechanical engineers can feel free to correct me if I'm confused here. This is easy enough to demonstrate using a fairly extreme example: clamp a flat fingerboard to your marble table with just two clamps, one at each end. You'll note you can, in all likelihood, lift up the bit in the middle, between the two clamps, because the downward force is acting the most strongly right over the clamp head, disappating as you move outwards. Same applies if you use cauls, although the additional distance (vertically) means the force is spread more evenly horizontally. You can quantify this by, for example, using the 2-clamp setup with a thin board (say a guitar side in thickness) and placing a thin lever of some sort underneath it in the middle. Hang weights from the lever arm and measure the deflection, and you'll note the deflection decreases as the clamps get closer to the lever arm. Using more clamps, spaced closer, is also better because it doesn't run the risk of over-clamping - you evenly distribute sufficient pressure across the whole board. The setup you've got there has three points with maximum pressure applied, although (eyeballing it) based on the height of the caul, you're probably only missing overlap of clamping force by a few cm on the top. The stiff caul on the back means you are getting pretty damn good pressure distribution from that side, but the distribution is far less even on top because the caul is less stiff and will flex more. Same principle of a veneer press: heavy, steel plates with zero give can distribute pressure evenly over a larger distance (horizontally) and the lack of flex will prevent excessive pressure in the middle. Here's my bad force diagram doodling, with guesstimated force vectors taking into account the various cauls: Link to comment Share on other sites More sharing options...
DC Ross Posted January 17, 2011 Report Share Posted January 17, 2011 That's why it's better to use a curved clamping caul. It distributes the pressure more evenly. Link to comment Share on other sites More sharing options...
Buter Posted January 17, 2011 Report Share Posted January 17, 2011 My technique is very similar except I use a vac bag instead of clamps. 15 psi is magic. B Link to comment Share on other sites More sharing options...
westhemann Posted January 18, 2011 Report Share Posted January 18, 2011 I think you may all be overthinking this just a bit...if it isn't sufficient,it will show up in the glue line..if it doesn't show in the glue line,it was sufficient... Theoretical discussions based on "vectors" and "dissipation" bum me out Link to comment Share on other sites More sharing options...
Helldunkel Posted January 18, 2011 Author Report Share Posted January 18, 2011 I think you may all be overthinking this just a bit...if it isn't sufficient,it will show up in the glue line..if it doesn't show in the glue line,it was sufficient... Theoretical discussions based on "vectors" and "dissipation" bum me out Same here, its just pointless arguying really... (not saying its bad or anything, the reasons of the above comment are perfectly valid but I dont adhere to them at all - scientifics can also contradict themselfes ) But having built over 50 guitars using this technique (funny, I never post something without full hands of experience on it), I can definitively say that this is a very good technique which is giving me better and cleaner results then with the previous 230 guitars I have built using various other techniques... And I just wanted to share it... PS: My work is also famous for poor jointery which shows glue lines... Link to comment Share on other sites More sharing options...
Kammo1 Posted January 18, 2011 Report Share Posted January 18, 2011 I guess there are some negative and positive things about this gluing technique but I have to say that I've used it for many,many years without a single ever glue failure or fingerboard separation and everything all the guitars I've built to this day have never had a problem not saying that it will never happen (Pray) the only problem I can see of this failing is with the glue and nothing else. I will still use this method as its tried and trusted and until the day I have a malfunction I'll report back and post pics, guys be prepared you could have a long,long,long,long wait. Link to comment Share on other sites More sharing options...
guitar2005 Posted January 18, 2011 Report Share Posted January 18, 2011 One thing that comes to mind with this technique. When you place the flat reference surface UNDER the neck, you're assuming that both sides of the neck are jointed and perfectly flat. I always joint the fretboard gluing surface only and that is my reference. There's no point in jointing both surfaces since the other side will be carved out anyways. Ideally, you'd want to glue the fretboard with the fretboard facing your reference surface, not the other way around, unless you joint both surfaces. Link to comment Share on other sites More sharing options...
Helldunkel Posted January 18, 2011 Author Report Share Posted January 18, 2011 One thing that comes to mind with this technique. When you place the flat reference surface UNDER the neck, you're assuming that both sides of the neck are jointed and perfectly flat. I always joint the fretboard gluing surface only and that is my reference. There's no point in jointing both surfaces since the other side will be carved out anyways. Ideally, you'd want to glue the fretboard with the fretboard facing your reference surface, not the other way around, unless you joint both surfaces. Where did I mention that the fingerboard is flat? The radius has been pre cut before I glue the board you can clearly see on the pictures that the fingerboard surface has a radius... The neck however must be flat on both surfaces since its down to final dimention... I've never heard of anybody who leaves one side not flat and who carves the excess wood away when building a bolt-on neck, this is new information which is in no books about guitar construction... Unless I misunderstood your comment? You probably have good reasons for the techniques you are using and I have also found ''the ideal'' solution for my building ways... I wonder if there is so much going on when somebody posts pictures using a go bar deck to glue bracing on an acoustic guitar top because I am actually using the same principle, myself being a formely trained acoustic guitar builder first... Link to comment Share on other sites More sharing options...
guitar2005 Posted January 18, 2011 Report Share Posted January 18, 2011 One thing that comes to mind with this technique. When you place the flat reference surface UNDER the neck, you're assuming that both sides of the neck are jointed and perfectly flat. I always joint the fretboard gluing surface only and that is my reference. There's no point in jointing both surfaces since the other side will be carved out anyways. Ideally, you'd want to glue the fretboard with the fretboard facing your reference surface, not the other way around, unless you joint both surfaces. Where did I mention that the fingerboard is flat? The radius has been pre cut before I glue the board you can clearly see on the pictures that the fingerboard surface has a radius... The neck however must be flat on both surfaces since its down to final dimention... The neck is jointed and PERFECTLY flat on the fretboard side (in my builds). The carve side is usually flat, but not necessarily within 0.001", you know what I mean? Do you true up both sides? If so, this technique would work, otherwise, you should clamp fretboard facing the flat surface. Link to comment Share on other sites More sharing options...
Helldunkel Posted January 18, 2011 Author Report Share Posted January 18, 2011 Do you true up both sides? If so, this technique would work, otherwise, you should clamp fretboard facing the flat surface. Both sides are of course totally trued up and perfectly flat. And I dont understand why somebody would not perfectly true up his work before starting working on it, makes no sens to me. But since the very first OP I been repeating countless times that I work on perfectly flat surfaces Everyone his own techniques and his reasons... Link to comment Share on other sites More sharing options...
guitar2005 Posted January 22, 2011 Report Share Posted January 22, 2011 So I tried gluing the last two fretboards using a straightedge (completely flat and solid surface) and when everything has set and the clamps are removed, the surface is still not 100% flat even though the neck and fretboard were 100% flat (within 0.001"). I guess that trueing up the fretboard surface after glueup is inevitable. Regardless, after carving the neck profile, there's been enough movement to warrant flattening the fretboard. Link to comment Share on other sites More sharing options...
Woodenspoke Posted January 23, 2011 Report Share Posted January 23, 2011 Sorry I didn't read anything past the first post. If some of the posts said what i am about to say. First you idea sounds sound but the two strips of wood used plus 3 minimal cross pieces are way to small and the distance between clamps too far apart to make this anything but a non starter. I dont suggest anyone follow this procedure. If the table was perfectly flat why didn't you just flip the neck and clamp the thing up 180 deg with the FB facing the stone? That would have given you a much larger clamping block using the neck itself. If you cant afford more clamps buy a bigger wood block that cannot flex under clamping pressure..this is one of the most important glue ups on a guitar dont wing it. sorry to be a downer Link to comment Share on other sites More sharing options...
guitar2005 Posted January 23, 2011 Report Share Posted January 23, 2011 This is what I do: Link to comment Share on other sites More sharing options...
Helldunkel Posted January 23, 2011 Author Report Share Posted January 23, 2011 Sorry I didn't read anything past the first post. If the table was perfectly flat why didn't you just flip the neck and clamp the thing up 180 deg with the FB facing the stone? Indeed, read the posts and you will find the reply to your question.... easy, 4 posts above yours.... If you cant afford more clamps buy a bigger wood block that cannot flex under clamping pressure.. this is one of the most important glue ups on a guitar dont wing it. sorry to be a downer You guys are really starting to get funny This is what I do: sweet, I do exactly the same when gluying a flat fingerboard but unlike you, I spread the clamps more evenly, in your case your are really missing pressure on the sides... Link to comment Share on other sites More sharing options...
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