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Before commencing with this tutorial, you need to ensure that you are confident in the basic setup and adjustment of your jointer. Each step should be read through thoroughly and the reasoning behind them understood before considering powering up your jointer. Jointers excel at producing straight planes on wood. To produce cuts at specific angles requires that a workpiece is presented to the cutters at the correct angle whilst simultaneously maintaining stability on the infeed and outfeed tables. Temporarily adding material to one end of the board as a prop presents a problem - as soon as the workpiece meets the cutter, one of these all-important reference surfaces disappears in a cloud of chips. This drops the cut, leaving both a sniped entry, an incorrectly-cut angle and additional cleaning work. Not to mention it can be unsafe! The key is to produce an angled reference on the workpiece which rides along the jointer and is not removed until the workpiece is stable across the feed tables. This has been adapted from a common technique employed by furniture makers to taper chair legs. It is especially appropriate for guitar makers on the basis that any tolerances in the initial measurements do not express themselves as any significant tolerance in the final cut. WARNING A small amount of trigonometry is involved here! If you have a particular aversion to mathematics of any sort, please seek the help of a trained scientist or other responsible adult! Firstly, ensure that your workpiece is squared on all sides and both ends and that these are all jointed flat. An engineer's square is a better tool than a carpenter's square....essential equipment if you have a jointer! Mark on the face of the blank where you want your cut to start and extend that line over to all sides using your combination square. I didn't do this because the combination square was more than two metres from where I was standing. If there was a cup of coffee next to it, things might have been different. Here is where our trigonometry work comes in useful. We need to calculate the length of the opposite side from the angle within a right angled triangle. In this example, this is a 1° angle starting 260mm from the end of the blank. This leaves us with the known values being the angle (θ), the side adjacent to the angle (A) and our unknown value the side opposite to the angle (O). Remembering the mnemonic "Some Old Hippie Caught Another Hippie Trippin' On Acid" (SOH-CAH-TOA) we can see that our sides (O and A) require us to use the TOA part, or: Tangent (θ) = Opposite / Adjacent Next we re-arrange this formula to put the unknown on its own, giving us: Opposite = Adjacent x Tangent (θ) Plugging in our values we get: Opposite = 260 x Tan (1) Opposite = 4,538 Awesome. We have calculated that a 1° angle drops 4,5mm over a distance of 260mm. We can now note that on the end of the blank. The mark is not important; only the value. Also mark down the halfway point between the end of the blank and the start of the angle. This mark does need to be fairly accurate. Although the photo notes "260mm" next to my mark, this was because I wasn't thinking about the clarity of what I wrote due to a lack of coffee. Still, the mark was in the correct place which is the most important thing. Next, set up your jointer's feed tables to be parallel and joint flat one face of a piece of scrap wood. Then dial in a cutting height exactly half of the height of the mark at the rear of the blank. In this case, 2,25mm. Since tolerances to a hundredth of a mm are impractical, anywhere around 2,2mm and 2,3mm is perfectly acceptable. To illustrate these looseness of this value's tolerance, setting a cutting depth of 2,5mm would leave you with an angle of 1,1°, or 3,0mm an angle of 1,3°. Dust your table free of debris and test feed your scrap in a short distance and pull it back out. Measure that the cutting depth is acceptable. This jointer has a digital readout indicating the cutting depth. I do not trust it. As it turns out, it was over half a mm out. Manually setting the cutting depth is far better! If it's wrong, pass your scrap piece all the way through to flatten it and then try this step again. Now that your jointer is set up, align your neck blank angle and end down as shown: Run the blank through the jointer until the cutter reaches the halfway mark made earlier (130mm). Hold the workpiece still and turn the jointer off before removing it. We do not want accidents here. Now reverse the neck blank so that the small cut you have made is now aligned towards the rear end. Apply pressure at the end so that the blank tips up, pivoting on the end of the cut. There we have it! Two perfectly angled reference surfaces which will continue to guide the workpiece until the cut surface reaches the outfeed table and becomes stable. All that remains is to run the blank through the jointer once more. It is important to bear in mind the points to apply pressure whilst performing this final cut. As soon as the cutter reaches the leading fulcrum point (the halfway point) and cuts it away, the face on the outfeed table is now ready to have pressure applied for feeding the cut out. A long push hook board is vital for this procedure to be carried out safely however I couldn't find where it had disappeared to....sorry.... The finished cut: A very marginal discrepancy existed somewhere in my demonstration piece as the leading edge of the cut erred around 2,0mm or so from the original marked location (cut starts second mark along the edge). Given the acute angle used, this is still an extremely accurate and reliable cut. The end of the blank was perfect, with the cut intersecting the pencil mark exactly. Although the jointer I used in this demonstration is very large, any jointer that has an infeed table long enough for the final cut will work admirably. Any comments or questions on this article? Post them below!

Before adjusting anything make sure your guitar is strung up correctly and that your neck has the correct amount of relief and is not excessively bowed or warped. If your neck is bowed you first need to adjust the truss rod and check that the nut is good. If your neck is warped it will require a more extensive repair. Also check that the angle of the tremolo unit is correctly set and not floating at an angle. This would require setting up prior to any work on the rest of the instrument. In general it is recommended that all other avenues of instrument setup are checked before resorting to the use of shims otherwise one can easily end up going backwards and forwards finding that adjustment of one things changes those of another! Shimming a neck should be the last resort if all other setup adjustments run out of usable range. Try to imagine the strings of your guitar as a flat plane and the fretboard as a parallel plane running underneath them. The angle of the top plane which contains the strings is controlled by the position of the tremolo unit and the nut. The angle of the lower plane which is the the fret board is controlled by the neck pocket of the body. If your setup is perfect these two planes will have a more or less equal distance between them at any point. If your guitar doesn't look this way try adjusting the height of the tremolo bridge unit first. This will usually take care of the problem unless you find your action becoming too high or too low equally across the length of the fret board. If adjusting the height of the bridge corrects the problem but leaves you with too high or low of an action (distance between the strings and fretboard) or the bridge unit is left excessively high or low then you will need to to use shims to adjust specific areas of the instrument's geometry. Shims are commonly used in two different areas of the neck. One is under the nut and the other is directly under the heel in the neck pocket of the body. Nut shims are usually made out of one or more thin sheets of metal such as brass or steel. Shims located in the neck pocket are usually made out of wood rather than metal as the pressure between the two mating faces can deform the wood of the neck or body. In either case you can produce your own shim by using a sheet of paper, a business card or preferably a slice of hardwood veneer such as Maple. For shims in the neck pocket you might need to fold or layer paper stock 3-4 times to get the required thickness needed then trim to fit properly. Softer cardboard stock may compress in use creating a thinner shim than expected. A nut shim acts as a spacer between the nut and neck raising and lowering the distance of all of the strings at the headstock end. A neck pocket shim acts as a spacer between the neck and body, changing the angle from which the neck protrudes out away from the body. First determine if the distance between the strings and fretboard is too close either at the headstock end of the neck and remedy this if so. This can be determined by fretting the strings at the 3rd fret (or fitting a capo) and measuring the clearance between the first fret's crown and the strings. In the case of the string clearance being too low under the first fret, progressively add shims under the nut until a clearance of at least 0.005"/0,13mm is achieved with the strings fretted as described. You can now fret strings at the first fret (or move the capo here) and adjust the bridge height until the strings are a more equal distance from the fret board down the entire length of the neck. If adjusting the distance between the strings and the fretboard at the body end requires an excessive correction in bridge height you can place shims in the neck pocket to create a more appropriate neck angle and correct this problem. If the strings are higher on one side or the bridge sits at an uneven angle side-to-side, placing a shim in the neck pocket parallel with the length of the neck on the respective side raises the entire neck down that side when the neck is reattached. It is important to check that the neck does not possess any kind of twist or warp as this cannot generally be corrected through simple adjustment/shimming and will require professional repair. If the bridge is set too low in the body a shim can be fitted at the back end of the neck pocket (the end nearest to the bridge) to increase the neck angle. The opposite approach can be taken if the bridge is set too high on the body. A slice of veneer cut to cover the entire surface of the neck pocket can be progressively sanded thinner at one end to achieve a more permanent angled shim however creating layered paper shims is often more than adequate. In some instances you might find that you need the shim to raise only one corner of the two planes as described above. In these cases make a smaller shim and place it in the appropriate area of the neck pocket. Of course upon removing the nut from the neck or the neck from the body, if you find a shim already there determine what action it was doing in the first place then make the necessary corrections using as few shims as possible.