LMI periodically has customers who
tell us how they successfully did this or that ...
We thought we'd pass their techniques along:
HAM'S BRIDGE DRILLING FIXTURE, 2 1/8" spacing
from Rick Weaver
I am a scratch builder mostly working one project at a time. Recently I was building three units at once and the tedious task of drilling bridge pin holes seemed a bit much for three at once. I came up with a simple indexing jig made from MDF with a base about 4" wide and one upright piece about 3/4" high. I then drilled my bridge pin holes,(3/16" with a short piece of 3/16" dowel inserted) into the upright far enough to the right of center to allow the 6th string hole setting at the center of the fixture when the blank is placed tail end to the upright and against the first index pin. Looks plain old simple but works like a dream.
BRIDGE SADDLE SLOTS FIXTURE
from Kevin La Due
La Due Guitars:
Pleasing sound, Aesthetics, Craftsmanship, Stewardship
I built this fixture to mill bridge saddle slots. It’s a platen mounted on linear motion bearings, with a rotating table on top of the platen, all mounted on an aluminum plate. The fixture is quick and easy to set up an a drill press. The rotating table can be adjusted to any saddle slot angle, right or left handed. Stop collars are used to adjust the travel of the platen. Simple toggle clamps hold the bridge blank. I have used this fixture for twenty years with excellent results every time.
I recently saw Robbie's [O’Brien] video using the new LMI back brace sanding jig. Having had problems keeping the gluing surface of the brace at 90 degrees to the vertical sides when I attempted this procedure on a flat sanding board, I knew it was a great idea that I could use. I soon purchased the 15'/25' radius version and have been busy sanding braces. In the video, Robbie describes the "pinch" method of holding the brace perpendicular against the fence. I tried this method but my fingertips seemed to get in the way, especially on the shorter thickness braces. What I thought was needed was some kind of a "handle" that could be temporarily attached to the top of the brace in order to better hold and control the brace as it is moved back and forth over the sand paper while the side is pushed against the fence keeping it "square" to the sanding surface of the jig. My solution was to purchase several wooden oak drawer pulls from a hardware/cabinet shop. They have a threaded insert in each "leg" that accepts a mounting screw from the inside of the drawer. Some of the inserts may be proud of the mounting surface of the handle pull "leg" but that did not seem to cause a problem when I applied four (4) small drops of super glue to the wood area around each of the inserts. I then centered the "handle" over the middle of the top surface of the brace and held it together for 20-30 seconds while the glue began to set. I would usually glue the "handles" to four or six braces (the number of handle pulls I bought) the night before so that the glue would have plenty of time to cure before morning.
The following day I could hold the brace by its "handle" as I easily shaped it on the jig, running through the grits (80 to 180). When satisfied that I had a squarely finished brace, I laid the brace on its side on the work bench and gave each glue joint a tap with a rawhide mallet. Sometimes it would take several taps, but the glue joint would separate leaving the brace free of the handle pull. There were a few wood fibers pulled from the top of the brace where the glue joint joined the "handle," but they would disappear during the shaping of the brace after it was glued to the guitar back.
Thanks for another splendid jig from LMI!
|Before strengthening ............ and AFTER!|
STRENGTHENING AN INEXPENSIVE WORK BENCH
from Rolando Padron (aka Rolo)
I have noticed in many videos and pictures related to luthierie, that many of us have and make use of the smaller, economical, commercially made work benches. Many of these have a built-in vise, a shelf and some drawers. Although functional - they have nice, flat, sturdy tops - one major drawback is that they are fairly light duty. For example, if you try to do any hand planing, they wobble and shake like crazy.
I was wondering if I could find a way to stiffen the whole work bench as well as add some features to it, to make it more efficient and useful. I only wanted to use scrap plywood pieces that I had in the shop and eliminate the need for any fancy joinery.
I feel I succeeded and am really pleased with the result. The workbench is really sturdy, and now I can perform heavier tasks on it with no problem. Hand tools are much more accessible. A tool tray on one side makes it possible to ensure that no tools are on top of the bench that can inadvertently damage a project. Here are the things I was able to add, nonetheless, the main objective was to make the work bench stronger.
- Small shelves on the end side that stiffened the vise end. I added 3/4" ply backing and then narrow shelves that wouldn't interfere with using the vise and if the work piece needed to extend to the ground (ex. working on the end of a neck). I store my hand planes on those shelves.
- I added plywood backing on the opposite end. I was able to find trays at Harbor Freight that fit into a track. This stiffened the side and added some useful storage for bits and other small items.
- I stiffened the back (long side of bench) with plywood. I cut the pieces to approximately 6" wide and screwed into the legs to stiffen the bench and stop it from wobbling. I then installed a shelf approximately 10" deep that is on the inside between the base shelf and beneath the drawers.
- I added a tray/shelf that allows me to put tools in it so I don't take up space on the work bench while working. I have a personal commitment of no tools on the bench unless I am working with it. I want to avoid anything that could possibly ding a top or anything else I'm working on.
Below are some pictures of my completed bench that can now handle much heavier tasks with ease, keeps tools handy and the area tidy. It was a win-win-win for me.
|Add small shelves
|Stiffen & add trays
|Stiffen back & long tray (#3&4)||Completed bench
REMOVING A PVA GLUED TOP
From Tyrone Rivera - Windsor, CA
This is a method I took from Stuart Day, a former apprentice of Bryan Galloup (Galloup Guitars). After searching the internet for methods or instruction on safely removing a guitar top glued with PVA glue for months and finding nothing, I decided to give it a go. I experienced no scorching and it went perfectly. It’s a scary operation, but I had good success with it.
Here is how Stuart told me to do it and how I successfully removed the top:
- My tools were a putty knife with two sharp edges, a bevel (Hock knife or very low angle chisel) for prying, a torch, and an X-Acto blade.
- I warmed the X-Acto blade momentarily then inserted it between the top and the head block to start the glue separation. I started here in case there was any scorching. If there was scorching I could hide it under the heel of the neck.
- After I had the separation started I switched to the putty knife. It was a bit thicker than the X-Acto, so I let the heat do the work. The knife was warm at best, if I heated it too much it would start to scorch the wood. If the glue is bubbling, the knife is too hot. You just want to soften the glue. Around the kerfed areas it went pretty smoothly.
- I never applied pressure to the point where I felt I was muscling the top apart from the sides, but just enough to make the glue gummy so I could slowly release the top.
- Around the transverse braces I used the X-Acto first between the brace and the kerfing notch then the sides of the brace as deep as I could with the blade pointing into the sides, not the top. Those areas took some finessing as I didn't want to break the grain on the top. Once I had carefully pried the brace up I used the X-Acto to start the separation on the other side to continue.
- The tail block, because of the glued surface area took a little more time but no more heat.
- I then repeated the transverse brace approach all the way back to the head block and *POP*.
|TRANSITIONAL ARM BEVEL CONSTRUCTION NOTES
from Rolando Padron (aka Rolo)
(This is not a stand-alone instructional guideline. Use these notes along with Kent Everett’s video).
These notes are just my personal observations that made making my second arm bevel easier than the first. It also incorporates some of the comments Kent made in the video as alternatives and also some that were so quick and subtle, that it is possible to not catch them while watching the video and appreciate the benefit of applying his comments in your bevel design. Please note, I want to respect Kent’s hard work on his video, and I am therefore not including design parameters or dimensions, as these are included on his DVD, and I highly recommend it to any who want to learn how to execute it into their builds.
Principle: The transitional arm bevel gradually goes from zero (near binding at waist), widens out to maximum width and depth (near widest point of lower bout) and transitions back to zero (near tail end, before tail block).
It seemed easier for me to cut and shape my arm bevel smoothly onto the bass side after thicknessing it, but before bending it. It’s easy to pin down where your waist is on the side. Layout an arc. Cut it with band saw. Smooth out the arm bevel transition on a spindle sander.
The bevel block can be made of a soft, light wood that is easy to shape. I used a block of western red cedar I had - basswood is fine too. You end up with a banana type shape by the time you are through that transitions smoothly back to your kerfing.
Note the ledge between the bevel block and the side in the center picture. This will hold the binding you will place on it later.
Once the purfling and binding channels are cut and smoothed out, purflings are installed on guitar as normal and along ledge formed by top that sets on bevel block. Kent Everett recommends an extra strip of the same color on the outer purfling to act as a buffer for the veneer in case you sand through it. In addition to that, I highly recommend another piece of binding material after the outer purfling. When you smooth out the veneer later, if you do slightly sand through it, you will hit the binding instead of a different wood that will tell on you. Also note the binding on the lower section of the bevel. Notice how the depth of it has been cut and smooth to allow it to bend easier into the the side. Thin the binding in this area AFTER the bindings are already bent. I recommend getting this transition on your bindings as smooth and the depth thickness to be as consistent as possible and with as much material on the bindings as possible. This will make the transition with the veneer smoother later on.
Notice how the piece of top cutoff material that is shaped to fit in after the purfling and binding piece on the top.
I told you it would be used later.
I smoothed the bevel flat along the curve using a block plane and finished off with a scraper and finally with a sanding block. This doesn’t take very long. Try to leave as much material on the binding pieces along the top and bottom as possible. It gives you more of a safety net for your veneer later.
Kent recommends gluing the veneer differently than I did by spreading glue on the bevel and also the veneer, letting it dry and then activating it again with a veneer iron. I found it easier to just glue it on and taped it as shown. It held fine for me, seemed to be more flexible, and I had no air pockets. You have options, I just wanted to show you what I felt more comfortable with and what gave me the best and easiest results. Note: the veneer cut is oversized. Pay attention to grain direction and color so it blends well later with your binding. I cut the veneer with a razor blade parallel to the top and then parallel with the side. I did final smoothing with a sanding block. Please be careful when cutting and sanding. The veneer is thin.
Pictures above show gluing and taping of veneer and finished bevel. Notice how the veneer blends into the bindings on both the top edge and side edge.