Re-Sawing Prep

I didn't spend a lot of time in the shop on Sunday.  Lora wanted to get out of the house, and so we went for a movie (the new Sherlock Holmes movie -- fun, but no depth) and Chinese food (a moment of nostalgia for the restaurants in Chicago -- so much better). 

I did, however, put together what I will need to do my re-sawing.  On the left, is a tall fence.  I used it in making the raised panels for apothecary cabinet as well.  I clamp the panel to it, then run it across my table saw with the blade set at a 15 degree angle or so.  For re-sawing, I clamp it to the bandsaw fence, adjust the table so it is perfectly square to the blade, then back it away 3/16ths or so from the blade and slowly, slowly, slowly feed the stock.  In front of it are my thickness calipers (will be buying a better soon) and a push tool.  The push tool I put together from off cuts left from the bench.  Next is the piece of redwood that I hope to re-saw, the template, and scrap perforated hardboard that I will tape over the re-sawed plates to protect them.

The redwood I found at Owl lumber back in Lombard.  It was originally intended as decking, but someone recognized the grain and set it aside (and marked it up).  When you rap the plank with your knuckles, it rings, so I believe it has good acoustic properties.  It book matches beautifully, and finishes well.  I don't know how it will go, re-sawing the wood at my school, but we'll give it a shot.  I want to make some progress on an actual guitar.  I'll also check on the parts for my bandsaw today.  It should be relatively quiet at work -- most people already away for the Christmas holiday.  Peace on earth, good will toward people. 

Go Bar Deck & Molds

Yesterday, I fiddled around with a radius cutter, similar to the Lie-Nielsen tool, but I did not get anything approaching satisfactory results, so I set it aside.  The next big projects, though I won't likely work on it much until after the holidays, will be the Go Bar Deck, the Mold, and a clamping station.   

The Go Bar Deck should be a simple affair.  I visualize a plywood base and a plywood canopy of approximately 24 x 24 inches.  In the corner of each, a  3/8th or 1/2 inch threaded rod with a pair of bolts in each corner to hold everything together and allow for height adjustment.  LMI sells the go bars (CLGO), but they are a bit pricey at about four bucks a pop.  McMaster-Carr also sells 3/16 fiberglass rods at 5 foot lengths (8543K28) for about 2.50.  I will go with the McMaster-Carr, and if they don't quite work out, will order from LMI later.     

The base provides something to think about.  It's easy enough to have a 1/4 dowel in the center to capture the radius dish, and a second (not through the dish) to keep it from spinning like a lazy susan.  I have been wondering, however, should I make the base so it can serve as a sort of supplemental work station?  It's not an original idea, but what I have in mind is a two level base, with one side covered with carpet remnant, the other bare or covered with sandpaper.  The advantage would be a covered work surface that wouldn't mar the surface of the guitar while doing things like trimming bracing.  It would also, so far as the go-bar-deck itself is concerned, make it a bit more convenient to attach the base.  I will likely go for simplicity.

I have been procrastinating on the mold for a while, but have decided to press ahead at the next opportunity.  I intend to do it much the same way that I did the blanks for the radius dishes.  First, with a 1/4 spiral up-cut bit in my router, along with a brass bearing closest to that 1/4 inch diameter, I will trace the outline of the guitar into the MDF at approximately 1/4 inch depth.  That will provide two things, the inside contour of the mold, and the outside contour of a clamping station as well as the pressure pads for the mold itself once complete.   I will clean them up with the pattern bit.  Then do it again until I have enough pieces to stack 4 deep on each side, or a 3 inch thick mold.   I clean up the outside edges on the table saw.  I will talk about the design of the mold as I built it, so I can use photos to illustrate, but it too is a relatively simple affair.

I use the clamping station for a variety of purposes, not least as a test when bending the sides or binding.  It could also be used for a mold when bending sides with a heat blanket.  I have never used that method, so won't attest to it, but I have seen it illustrated a number of times.  I built my first on Sloane's advice, where the sides are essentially boiled soft, then quickly clamped in place.  I never found that workable, but like his model, I use spring loaded clamps when I want to use it for actual clamping -- e.g. letting a side rest after bending freehand.  Here again, it's a relatively simple affair, but I will talk more about the design as I build it.  I figure, if you're building the molds, might as well build the clamping station at the same time and save some scrap.

In the meantime, I have a piece of redwood that I have been using for guitar tops.  Since the parts have still not come in for my band saw, I have set up a time Tuesday to use the one at the school where I administer to re-saw some plates.  The responsible dean found it all very amusing, the Provost in the wood shop, and wanted to be there with camera should I happen to cut off a finger.  I can get a start on some sound-boards while slowly putting everything else together.   I've made the jointing jig, and I will likely use the zip flex pearl from LMI for the rosette itself, along with some perfling material.  I'll likely order all that after the holidays.

 
      

Radius Dishes Continued

I have pretty much followed through on my plan for the radius dishes.  I had enough scrap ply left from the shop cabinets to build the jig that I used to cut the plates.  There are a couple of things that I should mention up front.  It makes an unholy mess of MDF dust.  Wear a respirator.  If I were making these dishes for a living, I would have figured out some method of dust collection, but for the two-off that that I'm making, I assumed clean up would be easier than rigging some elaborate method of dust collection.

Pictured, you can see the Xmas Tree Stand that serves as the base, the two end pieces to the right, the two rails for the router on the left, and the two sides on the foreground.  The 1/4 inch MDF attached to the one side is a template for the radius that will be cut into the side piece.  I have a nice one inch pattern bit that cuts such things like a champ and the template was an excuse to use it.  Since we're not talking a ton of material that has to be removed, you could join the two side pieces together, scribe the arch, then remove the material with a belt or bench sander.  Either way, it would work, but I recommend the investment in the bit.

Pictured, you can see the dish blank mounted on the Xmas Tree Stand.  It's a rather simple affair.  Use a wooden dowel.  I used a 1/4 inch dowel.  Your router bit is going to hit it, and you don't want to waste a router bit on this project.   To make the blank, I did as described.  I cut the MDF to size into two 22 inches squares.  I then used a very simple circle jig.  In a scrap of 1/4 MDF, I cut a hole large enough to accept a brass bearing on my router.  The measurement is to the outside edge of the bit -- in this case a 1/4 inch spiral upcut -- and I marked the location on the MDF for a 21 inch circle (10 and 1/2 inches from the edge of the bit).  I drove a finish nail through the MDF at the radius mark into the center of the dish, and viola!  A circle cutting jig.  It's pictured in my previous post.  I cut the circle in the MDF to a depth of about 1/4 inch, then used my jig saw to cut the majority of the scrap away.  On the router table, I finished the edges of the blank using my pattern bit running the bearing against the circle cut with the  router.  Since MDF chips easily, I rounded over the bottom of the dish with a 1/4 round over bit.

Pictured, you can see the router channel assembled.  It didn't work exactly as I had imagined.  With classic engineering oversight, on the length of the box, I had taken into account the width of the of the router base in determining the long end of the box, and so cut it only 3 and 3/4  inches longer than the 11 inch radius.  I didn't take into account the handles on my router base.  Also, I profiled the radius only on the long end of the box to the center marker.  In another well-duh! moment, I messed up the measurements on the first go round and didn't take into account the off-set of the long end.  I cut the radius from the center line of the side, not the center-line of the Xmas Tree Stand.  I disassembled, trimmed it off and started over, but you can easily see that you would want the center line over the center of the dish not the side and the 1/4 deflection (or 1/8th) should be at the edge of the dish not the end of the side.

Here you can see the whole set up put together and ready to rout.  Again, it makes an unholy mess of MDF dust, so use a respirator or something to protect your lungs.  On the router, I used a 3/4 inch straight bit.  The router wants to throw and spin the dish for you, but I could easily hold the router, hold and control the dish, and slowly advance the router from the outside to the center while turning the dish.  The rubber pads on the clamps helped with that.  I lightly pushed them against the dish and that too helped against the tendency to spin.  I had thought of taking the handles off the router to make it fit the channel better, but thought better of it, and was glad I didn't.

When the dish comes out of the jig, you'll want to sand down the ridge on the edge and take away the router marks.  But it worked, and I now have two radius dishes, one for the back and the other for the soundboard.  The stuff in the jar is a mixture of titebond glue and water at about 50/50 mix.  It's mostly just glue from nearly empty glue bottles.  I rinse out the bottles and save the remnants.  For lack of a better term, I call it sizing and I use it to harden MDF for sanding and just generally.  I'll also put a coat of poly on them.        

 

 

Shop Cabinets & Radius Dish

I did dig through my available plates, and unfortunately I didn't have one that would allow me to get a start on an actual guitar -- mostly scraps saved for various purposes, but mostly because I couldn't bear to throw out exotics, no matter how badly stained by the flood water.  So, I am still awaiting parts for my band saw.  I'll be able to re-saw some redwood for a soundboard, and I will probably buy the back and sides from LMI.

In the meantime, I have decided to go ahead and build a couple more shop cabinets.  I had gone to the Depot to get what I needed to make my radius dishes, but they had cabinet grade ply on sale for a little over twenty bucks, so I took the opportunity.  I will have scraps sufficient to make the router jig, and I did buy the 3/4 MDF that will be the dishes.   The shop cabinets are relatively simple affairs.  They are basically plywood boxes, joined with a tongue and groove -- that is, I cut a 1/4 groove on the sides of the cabinet, and a tongue on the top and bottom ends to fit the groove.  One will be used for my routers, and the other will be used for miscellaneous power tools.

As I was building the lattice jig, I did get a start on the jig to cut the radius dishes.  The plan is this:  I built what I am calling a Xmas Tree Stand, which is basically just a plywood X with each arm 22 inches long.  The MDF dishes will spin on this base.  The router jig will be similar to the one used to shape the drum for the thickness sander with a couple of exceptions.  My router base happens to be 6 inches wide, so two end pieces will be cut at 6 inches wide by about 8 inches tall.  The sides will about 6 inches wide as well (conservation of scrap) and about 25 inches long.  One end of the jig will be attached to the Xmas Tree Stand and the other will overhang about three inches or the radius of my router plate.


I plan to profile the sides with the arch on one side for the back using my router and a flush cut bit.  The first step is the creation of a template for the arch.  I use my metal shop ruler to create the arch.  I c-clamp a small block of scrap to the back-side of the rule, then clamp that down at the center of the arch.  I then deflect the ends up to create the arch, scribe it, then sand to the line on 1/4 inch MDF.    Remember, the low point of the arch should be over the center of the Xmas Tree Stand, and should allow enough clearance to attach the sides of the jig to the ends.  To accommodate that, I measure in 3/4 inches from one end of the side (where it will attach to the fixed side) then 11 and 22 inches from that mark.  The 11 inch mark is the center, and I deflect the rule up 1/4 inch on each of the other marks.  I then double stick the template to the side, and cut with the pattern bit.

The amount of deflection at either end can be easily calculated (though I had to be reminded of high school geometry and algebra to do it).  Take the radius of the dish (in my case, 11 inches) and square it (121 inches).  Take the radius of the back and square it (in my case, 20' or 240 inches, squared is 57,600).  Imagine a line tangent to circle 20' in diameter.  Now, imagine a point 11 inches out on that line from the point where it intersects the circle.  Using the Pythagorean theorem (a squared + b squared = c squared), you can calculate the distance between the point 11 inches out and the center of the circle (in my case the square root of (121 + 57,600) or the square root of 57,721, or 240.25195, which I rounded to 240.25).  The difference between the radius of the back (or the distance to the point where the circle intersects the tangent) and the distance to the point 11 inches out on the tangent line is .25 or 1/4 inch.  So each end needs to be deflected up 1/4 inch.  For the soundboard, I'm going with 1/8th inch.

When I have the arches correct, I will attach a 7 and 1/2 inch wide strip of thin ply to the arch with screws.  I'll clamp the ends to the sides so I can get the width exactly right, and then I will attach it to the Xmas Tree Stand so there is sufficient clearance for the MDF dish.  Before I cut the dish, I will cut the slot in the 1/4 ply for the router bit, put the dish in place, and cut up and back to the center mark while spinning the dish slowly. 

I finished the shop cabinets, but didn't get as far beyond that as I had imagined -- focus on one thing at a time.  So the dishes are a project for next weekend.  I will let you know how it really went.


    

Lattice Jig

Granddaughter and kids went home yesterday.  We went to Lowe's where Lora bought a white Christmas tree (something she has always wanted) and I bought a quarter sheet of birch ply (something I can always use).  I adjusted the platen on my thickness sander, and put a coat of poly on the drum.  I will put another coat on today, then during the week, I'll install the sandpaper, and all is for the good.

The lattice jig is really a rather simple affair, though it is somewhat ingenious, and I don't know who to credit for that ingenuity.   I took my design from LMI, and simplified it.   It is used for joining the plates for the back and soundboard.  I'll picture its work when I get to joining the plates for my next guitar,

It consists of two lattices, each of which consists of two rails (thinking of the rail road analogy again) and three ties (with a bad pun on ties).  It is assembled using standard wood-working techniques.  I cut 2 inch strips to length, then set up my dado blade to cut over-lapping notches.  I cut them slightly deep, at about an inch and an eighth, so I could keep it all perfectly flat during glue up.

The bottom lattice required the most work.  Between the notches for the two rails, I removed enough material to accommodate 1/4 inch MDF and some sheet plastic.  It provides the base against which the top rails bear, keeping the plates flat at the seam.

On one side, the rope is knotted into a single hole, and on the other, once it is crossed back and forth over the plates, it is snaked through the three holes pictured.  Drill the holes before assembly.  I glued and pinned it on my table saw, so it would be perfectly flat, threaded the rope and tested it on some scrap 1/8th ply.  It worked as advertised, so I can actually begin work on the guitar.  I will need to dig through my wood, but I believe I salvaged the mahogany for the back and sides, along with a book-matched piece of redwood for the soundboard.

If not, I will need to wait for the pieces needed to repair my band saw come from the manufacturer, and there is another project that I can tackle -- a circle cutter to define the rosette channel.  For that, I need a 1/4 inch brass rod (about 12 inches).  I have the necessary screws and inserts -- those I did salvage from the flood -- and the body I can make from oak off-cuts left over from the bench.  I could also continue making my shop cabinets.  I have in mind a router cabinet and another to hold my hand held power tools.  Never a lack of things to do.         

Thickness Sander and Lattice Jig

I have given this some thought on and off over the holiday, between games with my granddaughter, and remembered something that was implicit in my design for the thickness sander all along, though I wasn't completely cognizant of it. The cross member that holds the hinge is not structural and was unintentionally, or perhaps intentionally behind the white noise that usually fills my head, set up to allow for adjustment. Consequently, I have resolved on the plan to withdraw the screws that hold the hinge support in place on the out-feed side. With the adjustment screw fully extended, I will then bring the hinge end of the platen up until it touches all the way across the drum, and screw the hinge support back into place. I've taken a straight edge to the drum, and it reasonably flat along its length all the way around its diameter, so to continue down my current path would simply distort the drum, making the radius smaller on one side than on the other. I will do this Saturday, when the kids and granddaughter return to Boise.

Also, in the meantime, I have been giving some thought to the first step in actually building the guitar, the plate joining for the soundboard and back. I have used the method that Sloane describes. After getting a good light-tight joint, on a work-board, one places a dowel or metal rod under the plates, taps nails along the two edges of the plates (not into the plates, but abutting them), removes the nails and presses the plates flat against the work-board, places a caul over the joint, and then weights that down. For weight, I used edger bricks wrapped in duct tape, but about anything suitably heavy would do. This works reasonably well -- that is to say, it works -- but I wouldn't necessarily recommend it. A couple of reasons, the most important being that you can't really see the joint as it is coming together and its difficult to get even pressure along the length of the joint with the caul, so there have been occasions where plates, perfectly thicknessed, have not come together sufficiently flat at the seam. I have had to cut them apart, re-joint the plates, and go through the steps again.

Consequently, I have been thinking about jigs to join the plates, and the one that holds the most promise is the lattice jig. I call it that for lack of a better term, but it is the jig sold by LMI. Though it has nice features, the price is a bit steep, and I think LMI, in particular, sets prices on such things as if to say, "look, if you're too lazy or impatient to build your own jigs, then you shouldn't be building guitars." Regardless, my next project will be the lattice jig. I will build it from birch ply, cutting strips about 2.5 inches in width and about 22 inches long. It will consist of basically two lattices (think a section rail road tracks with three ties) put together with interlocking notches. On the bottom lattice, on the ties, between the notches for the rails, I plan to remove about 3/8ths. This will accommodate 1/4 MDF and sheet plastic, that will provide a solid flat surface. On each end of the rails, I plan to drill three holes, large enough to thread rope. The three holes should provide enough friction to lock the rope in place, but if not, the exposed loop can be clamped to hold it. To use it, the plates are sandwiched between the two lattices, rope is crossed over the rails, locked into place, and then to provide clamping pressure, a wedge is tapped under the crossed ropes. The lattice holds the plates flat while the ropes provide pressure not only against the edges of the plates, but also to lattice. The trick to this will be keeping the lattice perfectly flat during construction.

A quarter sheet of birch ply should provide enough to build the lattice jig, with enough left over to build the jig that will build the radius dishes for sanding and gluing the braces on the sound board and backs.

Thickness Sander Continued

I was able to accomplish more than I had anticipated, in part because my wife and granddaughter took longer than expected to travel from Boise. The almost finished sander is pictured from the in-feed side, and you can see the simple adjustment that raises and lowers the platen. The eye-screw is threaded through an insert and pushes against a mending plate, which helps prevent the screw from digging into the MDF.

I say, "almost finished," for a couple of reasons. The drum still needs to be rounded over completely and adjusted to the platen. Viewed from the in-feed side, it is between 1/32 and 1/64th of an inch higher on the right side. I am rounding and making the adjustment by running a sheet of sandpaper attached to a piece of scrap ply through the sander as it turns. It may be quicker to back the screw out and tap up the right side of the platen, but we will see where my patience takes me.

Also, of course, once adjusted, I will need to attach the sandpaper to the drum. I have ordered adhesive back sandpaper from Amazon, and I think it will do the trick, but here again, we shall see. It hasn't arrived yet, perhaps to my benefit, because I would have been tempted to put it on before rounding and adjusting the drum. If not, I have a back-up plan for a pair of hold downs on either side of the drum, but I am hoping they will not be necessary.



A couple of problems did emerge. Pictured is the power-train for the drum. The belt runs between two pullies, the one attached to the arbor of my table saw is a one inch diameter, the one attached to the drum is a two inch. The rotational speed of the drum seems about right -- not sure what it is exactly -- but the bottom pully had to be modified to fit on my saw arbor. I had to cut away the set screw. Since it was aluminum, it cut away easily.

Also, on the right side, during the trail run, the bearing on the right side grew very hot -- literally smoking hot. The problem was a small set screw that holds the interior sleeve of the bearing firm against the arbor. It is visible in the photo. There were two on each bearing, and on the right, one of the set screws wouldn't remain set. It had backed out and was turning against the housing generating the heat. I removed it, and now things seem to be fine.

Finally, when the bearing over-heated, the drum came loose on the arbor. The two events were most likely not connected. It is held firm to the arbor by two bolts on either end which are cranked in against either end of the drum. It seems to be holding fine now, but if necessary, I will pin the drum through the arbor. Here again, I am reluctant to do so, because that too will require dis-assembly, but will do so if necessary.