As the luthiers building experience grows, they will want to add additional luthier tools to their shop, which will give more versatility and focused attention to certain tasks, and at the same time giving better accuracy and repeatability to the build. The adjustable inside form is one of those tools. The adjustable inside form is a variation of our standard fixed inside forms that we offer with every ukulele drawing we have listed on our site GenOne Luthier Supply. This tool does many tasks and does them well, with minimal time and maintains a high degree of accuracy in the instrument building process.
The adjustable inside form gives you the freedom to use this tool with any size ukulele that we offer and therefore you don't need a different form for each ukulele size. The process that makes this form adjustable is the use of a series of (6) adjustable retainers at the upper bout, the lower bout, and at the waist of each instrument.
The Form Base: The base is the 19mm piece of cabinet grade plywood where all the other adjustable elements are anchored. It consists of several curved channels which allow for complex adjustment angles of the side retainers. Also you can optionally install an option to this base so the form can easily be clamped into a woodworkers vice. This give the form incredible rigidity so major operations such as crown sanding can be completed without the concern of the form sliding around on the workbench.
The Inside Form Shape Insert: This is an additional insert made from 19mm plywood fits onto the top surface of the base. By installing smooth-shanked pocket screws around the perimeter of each of these inserts, you can glue down top and back plates with surprising speed. We include ample pocket screws to easily go around the edges of the insert for either rubber band attachment or elastic banding.
Side Retainer Clamps: The 6 retainers are key to the working of this form. Each retainers is attached to the base with a carriage bolt/free-spinning knob assembly, giving the luthier easy adjustability for any size instrument. The retainers can easily retracted to release the the instrument body, and again easily tightened to secure the instrument back in the form. The form is shipped with the front surface of the retainers that contact the instrument body curved to easily fit the subtle curves of the body. The retainer bases are slotted giving a lot a adjustability for different instrument body types.
If it is your intent you use this tool for attaching strapping or rubber bands to clamp
the plates of the instrument, you will need to install the included pocket screws into the Form Insert. Here is the procedure to accurately accomplish this task:
These forms basically operate and are setup identically. Of course the Guitar Form has a much larger footprint and the Retainer Clamps are large for more stability. The biggest difference is the Guitar Form has optional head and tail block retainers available as an additional option. Again this is for more stability for certain tasks. These instructions apply equally to both the guitar and ukulele versions of this tool.
With minimal sanding to take out some light planer marks the plates should finish out about .10" or 1/10" (2.6mm to 2.8mm), which is just about right for a steel string acoustic guitar. For classical guitars take the plates down by a few more tenths of a millimeter or thickened to about 2.4mm. Ukulele tops are usually about 2mm thick. For an easy method of doing this, visit articles on plate planing on this blog. There are a lot of opinions on thickness of tonewood, so do your research. Here are some general guidelines for finished plates and sides:
Take each half of the top or back plate and lay them out book-matched. Trace the Instrument shape on the wood with a white pencil on dark wood or a lead pencil on light wood. Choose the most flattering grain pattern and if there are any defects in the wood, try to work it out so they are in the waste portion of the plate.
If the grain is not perfectly parallel to the joint, now is the time to straighten it . Lay a straight edge parallel to the grain and mark the difference on the top plate (at the joint side of the plate). Mark with a pencil and carefully plane to joint(s) to your mark.
Now flip the plates over and use a hand plane, power hand plane, sand or some other method to smooth up the backside of the plates. Your goal is to eliminate all saw marks, planer scorch marks and other inconsistencies.
Once you are satisfied with the result, load a dual action electric sander with 80 grit paper and go over the entire surface until it is very smooth, level and consistent. Use long light strokes with the power sander and keep it vertical. Try not to work in any small areas to get out defects as these will cause thickness variations. This work can also be done with a sanding surface just as effectively, but you will really get a workout!
Now that the backside of the plates are smooth and level we can address the center joint of the plates, which is an extremely important joint and its critical that this be a perfect glue joint here.
First take a plate in each hand and hold them up against a strong light source so you can analyze the joint tightness. If you can see any light leakage, you will need to work on the quality of the plate joints.
Here is the best way to get this joint razor-tight and you will need a couple of tools to do this.
First to be the most efficient you should make your first pass at this joint with a very, very sharp jack plane. These planes are 10 to 12" in length and when sharpened properly you can easily take small amounts of wood off the joints.Start by laying the plane on its side. Alternatively if you have a stationary belt sander, that will work very good as well. You should have a fence setup on the belt sander though to keep the joints square.
When the joints are roughly straight you are ready for the next step. Stack the plates on top of one another and overlap the lower plate by approximately 1/2" or thereabouts. While tightly applying pressure on the top plate to hold it in place, make long consistent strokes with the jack plane for the entire length of the joint. If the blade is set correctly, this should only take 2 or 3 passes. Reverse the plates and do the other joint. If the stationary belt sander is used, sand both plates at one time - in about 10 seconds!
Hold the joint up to the light again to check for light leaks. Repeat if necessary.
This is a little trick that I devised. Purchase a good 2' level with aluminum edges with milled faces. Place 180 to 220 grit adhesive backed sand paper on each face of the level and trim to fit the face. This type sandpaper is best purchased in rolls.
Next stack the plates as before and make smooth, consistent strokes on the plate edge. As you progress make the passes with lighter pressure. Repeat with the second half of the plate. The joint should now be perfect.
Now that the plates have been rough sanded on the bottom side, they are ready to insert into the plate joining jig for glue-up. If you would like to build one of these great devices, be sure to visit our Plate Joining Sales Page. We also sell Plate Joiner Plans where you can build your own form our easy to follow plans.
Completely open the three cams on the Guitar Joining Jig and run the fence to the completely open position. For easiest access to the plate joint, remove the center hold-down retainer. For the Ukulele Plate Joiner, open all 4 of the adjustable cams.
Note that in order to use the Plate Joining Jig you will need to square-up the plates to fit in the jig. Also, it works best when the plates are cut about 1/4" oversize. This will help to obtain the best clamping pressure without the plates bowing out of shape.
Place a light bead of glue on the joint on both wood surfaces. If you are gluing a guitar top, you can use Titebond Glue. You can also use Titebond to glue any of the non-resinous hardwoods, which can be and of the Mahogany Family, Maple, Walnut or Sapale.
Exotic Species such as Bubinga, Ebony, Paduck, Zebrawood, Rosewoods etc., should be glued with slow-setting epoxy glue. Epoxy is best applied with a small stick of veneer or scrap stick and spread evenly over the entire surface of the joint until all surfaces of the joints are shiny with glue.
Place the plates centered over the non-stick HDPE sheet on the base of the jig. Gently rub the two halts of the plate back and forth to distribute the glue smoothly over the surface of the joint to begin adhesion.
Set the center retainer bar into place and spin the knobs down so the retainer comes in contact with the plates, but no pressure is placed on the plates by the retainer. This is just meant to hold the wood plates in alignment without restriction in sideways clamping pressure.
Move the fence into position to the edge of the plate and tighten the fence down tightly. Begin to engage the cams one at a time with gentle pressure. If the plate starts to slide out of position, carefully slide them back. Apply a little pressure on the center retainer bar.
Crank in more pressure on the cams and tighten the knobs one at a time. Again check the center joint and adjust as necessary. Crank in more retainer pressure.
Repeat as necessary until the plate begins to buckle very slightly (You will note that some of the stiffer woods will hardly buckle at all). Back off just enough pressure on the cams to relieve the buckling and completely tighten the center retainer. Let the plate dry thoroughly.
Once you remove the plate from the joiner, it is time to thickness plane the plate (if necessary). See our chapter on Thickness Planing Guitar Plates.
The simplest and most efficient way to glue-up an acoustic guitar or classical guitar neck is to use the Georgia Luthier Supply Neck Assembly Jig. Using this jig you can cut your neck blanks to size, cut the scarf joint very accurately, and glue the headpiece and the heel blocks at the same time.
A bit of background needs to be addressed. To give a guitar neck the ultimate in strength and bending resistance please review our articles on static neck reinforcement, properties of wood in neck construction, and adjustable truss rods.
Since wood for guitar necks tends to be quite costly, and if you are new to guitar construction, it may be a good idea for to follow this procedure with a scrap piece of wood rather than ruining a $25 piece of neck stock. Upon mastering the process feel free to start using the jig for production.
In order to get the most out of the neck stock, square up the piece of neck stock before the start the construction process. Usually a piece of neck stock will measure about 3” x 36” x 7/8” thick (75mm x 900mm x 22mm). Place the entire length of neck stock into the jig if possible with the head block end of the neck tightly against the end closure of the jig. Clamp the neck stock in place with a couple of quick-release clamps, or Bessey Clamps check that the bottom of the stock is flat against the jig floor.
Install the miter slot guide bar to the bottom of the Neck Jig with the 3 Free Spinning Knobs and run the Neck Jig slowly through the band saw. Keep the feed rate slow and consistent with only forward force and no sideways pressure. The quality of the scarf joint will only be as good as the band saw setup, Also double check the blade tension. (Note: if you wish to construct a laminated wood neck - see the instructions that follow this section).
Upon making the scarf joint cut, the head piece needs to be cut to length. First mark out the thickness of the headpiece on the cutoff you just removed from the jig. When you determine the proper headpiece length, cut the headpiece from the cutoff wood. Next cut the headpiece to the proper thickness using a band saw. Finish sand the headpiece surfaces as needed.
Even though the saw-cut from the band saw may be very smooth, it does need to be sanded smooth for a proper glue joint as this joint receives a lot of prying force from the strings. I choose to do this on a stationary belt sander, but it can easily be completed on a large sanding surface as well, such as a piece of marble or corian countertop with adhesive sandpaper attached to the surface.
With the neck stock still loaded in the jig, insert the headpiece into the jig with the angled face of the cut facing up toward the fence. Mount the heel block retainer in place and cut the heel blocks to length from the cutoff portion of the headpiece. Note that there is one of the heel blocks that is longer and that piece is mounted directly to underside of the neck.
Size and glue your headpiece veneer sandwich, if you are going to add that detail to your guitar. There are many options that you can use to add this very attractive detail to your handmade guitar.
If all looks well, glue all blocks in place using the clamping cauls to prevent denting of the stock. Note that is is a good idea to place waxed paper beneath the neck prior to gluing to minimize cleanup and damage to the jig.
In order to obtain the best and most warp resistant neck construction, arrange the neck wood so each half of the neck grain of each half of the neck stock runs in opposite directions (refer to illustration). By doing this we are using the properties of woods' ability to shrink and contract and have these forces create an even stronger, more warp-resistant neck than is attainable with a single-piece vertical piece of wood. I have always constructed my necks this way and have experienced very few problems with warping.
(Note: to have the laminations run continuously from the neck into the headpiece, complete this task prior to cutting the scarf joint in order to best align the laminations.) Also, to keep things aligned, cut each half of the neck wood exactly the same width. This will make it easy to line up the laminated wood pieces in the Neck Assembly Jig.
I prefer to use a table saw for this operation. To obtain this grain pattern you will have to flip one of the pieces of neck stock 180 degree. This is most easily done by looking at the freshly cut end grain. Finally cut the center strip or or
Glue all the wood lamentation together as shown in the diagram. After the neck laminations are dry, square-up all sides and sand smooth. Lastly, the neck width has to match the width of the original wood blank (about 3”). Measure the difference in width from the laminated neck and the remainder of the headstock and split the difference. Cut this amount from each side of the neck to match them up correctly.
Use plywood clamping cauls to protect the neck wood from denting during clamping. Place the laminated neck into the Neck Assembly Jig and cut the scarf joint. Remove the neck and sand the scarf joint on a stationary belt sander or smooth with a hand plane or sanding surfaces. Continue to assemble the neck as per the one-piece neck construction above.
Now that the neck has been squared up, it is time to channel the neck to prepare it for reinforcing. There are many options available to the luthier and we cover many of them in this blog. By keep the neck consistently square you can easily use a shaper or a router or even a tablesaw to cut the required channeling.
Now that the reinforcing has been installed and the surface of the neck has been leveled, it is time to install the headpiece veneer. My reinforcement of choice is Aircraft Aluminum, or T6 tempered aluminum. This is tough stuff and when it is epoxied into the center of your neck combined with the wood lamination that we talked about earlier in this article, you will have a neck that is hard to beat. For this reinforcement, be sure to visit our Aluminum Neck Reinforcement Product Page so you can use the same superior reinforcement that is used in all of my necks.
The uppermost headpiece veneer should be approx. 1/16" thick (1.5mm). This veneer more often than not matches the hardwood of the guitar back and sides, but occasionally it can be a feature veneer such as curly or bird’s eye Maple, Ebony, or other exotic wood species.
Additionally you can choose to build up several layers of alternating light and dark veneers giving a very nice layered look, and this can match the purfling of the fretboard or the guitar top/side binding.
Another alternative is to trim the headpiece with either wood or plastic purfling by cutting a small channel with a dermal router after the veneers have been laminated and trimmed to the headpiece.
You have received your PDF downloads - Congratulations. You are half-way there. Now what? Since these PDF's are of the highest quality and very accurate full-sized drawings, you should seek out the best printing solution.
While many customers use such services such as Office Max or Kinkos (and many of these stores can do a very respectable job for you), your first try should be with a commercial digital printing company, such as the type used by architects and engineers. They often have the highest quality and most up-to-date equipment. You will find that in a matter of seconds, these large digital printers can turn out several sets of drawings for you, and these printing companies know about the taboos of resizing prints and the problems that are caused by this.
The PDF drawings are all formatted to print at full-size automatically without any assistance from the printer. The typical guitar plan sheets are sized for metric sized paper called A0 (note that this is slightly smaller than the US size of 36" x 48"). Many of the tools are also on this same size paper, but here you will find more variation. If you are printing the plans in the USA, be sure that the digital printing company does not resize the PDF's to fit the paper. They are all pre-formated and should print without any additional input from the operator.
Our Ukulele Plans are are sized for 24" x 36" paper, which is also called Architectural Size "D".
How to Deliver The PDF Plans To The Printing Company
1. Copy your PDF files that you download here onto a read/write CD or DVD.
2. Copy your PDF files onto a memory stick
3. Most digital printers will accept emailed files, which can be sent and printed when you arrive to pick them up.Why PDF's?
With digital plans you can conveniently print half-sized sets for reference, often called 50% sized sets. Also, if you have access to a printer that prints 11" x 17" paper, you can print your own reduced sized sets. Also portions or details of the plans can be printed on any printer.
Many builders will want to print limited areas of the print, like a bridge layout for instance. This can easily executed with our plans and a letter-sized ink jet or laser printer. In the page setup of the printer, select the 100% option to keep everything to scale and you can then print a small area or if you need to print a larger area, it can be printed on multiple sheets and then carefully taped together.
With the advent of tablets and their wide usage, many customer have found it very convenient to sidestep the "hard copy" step and build most of their instruments using only a tablet, such as the Mac iPad.
