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Discussion in 'The Small Company Luthiers' started by DEMENTED, Feb 7, 2011.
yeeeeaahhhh! One of my favorite threads! Just love when this gets updated!
Heh, wasn't so much a suggestion as trying to fulfill curiosity.
Guess one of the reasons I asked was that I've read that UF dries nearly as hard as hide glue, has zero creep and the added benefit of longer open time. Just surprised me to see someone using polyurethane is all. I've used PU for furniture on other types of joints but it never occurred to me that it might be just as capable for scarfs. I think my best bet at this point is to make several test pieces and determine which one works best for me. Thanks for the answer.
oh-ho! He's in the know.
Aw shucks, thanks Doug. I figured you might be lurking around. Thanks for speaking up.
BTW, I have been lurking on your facebook page and am loving the stuff you've been doing. Some of the custom paint jobs I see are real killer, keep it up.
Yeah, not a lot of guys working with polyurethane in the instrument field. I don't know why that is though. When used properly(not too much) in tight fitting joints, It dries hard and crystalline(comparable to UF), much more so than white or yellow glues, and is incomparably stronger than any other glue I have worked with. There are applications where it isn't the best choice, due to the expansion. The joint must be tight fitting and clamped well. I only use it on joints where the wood is oversized and will be cut or carved to final dimension after the glue has cured.
Back to this for a moment. I was thinking about this some more and thought I might mention that when it comes to glues and finishes we can never stop learning, we can all also benefit from the experience of others. Please keep me in the loop with any of the findings in your experimentation. Thanks.
OK, sorry for the delay in posting this but here goes. This is how I cut and inlay the pieces for the Maguire trinity logo.
This is the jig that the pieces are cut on. In the foreground is the underside of the jig with the brass trinity templates epoxied to a plexiglass jig plate that is screwed on to the bottom of the jig. A brass pin on the table of the milling machine rides the templates to form the shape in the blanks being cut. The blanks are seen above the jig, CA glued to a lexan jig plate that will screw onto the top of the jig.
Here is the pin table setup on the milling machine. In essence this table converts the milling machine to a miniature pin router. The pin and the endmill are both .041".
Here is the jig in action. This photo should say it all as far as how this system works.
You can also see surgical tubing attached to the back of the jig. The tubing is attached to a vacuum and mates with slots milled in the bottom of the jig. These vacuum slots act as a hold down of sorts and stabilize the jig while in action, making for smoother cutting. There is also a surgical tubing that suspends just behind the bit for dust extraction and bit cooling, also making for smoother cutting but mostly to keep the carcinogenic pearl dust out of the air(it also captures a little bit of the cigar smoke that is constantly looming in my shop).
The cutting is done. Now I remove the topside lexan jig plate, give it a good flex(which is why I chose lexan) and the pieces pop off and are ready to meet the rings that were cut earlier.
After a little finessing of the tips with a small grinding stone, setup on the milling machine, the trinity pieces meet the ring.
Now for the inlaying. I made a surrogate ring out of UHMW plastic that snaps right into the ring pocket to aid in perfectly locating the woven trinity logo in the center of the ring with the points just barely touching the ring itself. With the pieces snug in the surrogate ring I put a single drop of CA glue in the center of the weave and that's just enough to hold it in place for scribing around the perimeter.
Surrogate ring removed and ready for scribing. Oops, I think this one got 2 drops of CA glue.
After the scribing is done I soak the pieces with CA solvent for a minute or 2 and gently lift the pieces off the headstock and its time for routing.
Here's the inlay router in action.
I don't go right for the final dimension with the router. I like a snug fit with no filler and just can't seem to get that kind of control with the router(at least not in the tight corners), so I leave a little bit to be done by hand.
The final perimeter cuts are made with miniature carving tools. Several swift pushes of properly radiused carving tools gets me the tight fit I am looking for. The points where the trinity pieces meet the ring are sort of nibbled away with a modified x-acto knife blade that is also used for the scribing step above.
Gentle thumb pressure brings the pieces home into the cavity. Nice and tight(but not too tight) and no need for filler.
Ca glue is the glue of choice here.
Here's, Brian's in MOP on Brz. r/w
This one is Obelio's in mammoth ivory on Mad. RW.
And here's the lot.
Tardy, but not absent.
Here are some shots of how I do electronics control cavities.
The jig is made of 3/8" plexi, as are most of my jigs. Very durable, and see thru helps. Double stick carpet tape holds them down just right. Holes are drilled in the jig, perpendicular to the inner perimeter, screws are slipped into the holes with the heads protruding slightly. These protruding screw heads create the little bumps in the cavity necessary for the cover plate screws.
The first main cavity is cut with a 3/8" endmill and a 3/4" bushing installed in the baseplate of the router. This is where I get to see the wiring chase created earlier.
The coverplate recess is created by changing to a 1/2" bushing, setting the endmill to a 1/8" depth and removing the screws from the jig
Here's the cavity, all set.
Same procedure as above with the selector switch cavity on the upper bout. In the photo below I had pulled the screw-bump screws out before taking the pic. Here's where I get to see the other side of that wire chase.
Here are the guitars front and back, as of now.
junior Certified 7
Tony's Certified 7
Brian's Certified 7
Brian's guitar gets some body binding, then it's time to carve some tops!
You may notice Tony's semi-hollow Meridian is missing. That model is on a different schedule and it will catch up later in the process.
Here are some shots of the copy carver I recently built. Nothing revolutionary here, many similar machines can be bought and others have been seen built by some of the talented luthiers here on TGP. The main material used on this jig is known as "The scientific erector set", made by 80/20 inc. It is a system of t-slot aluminum tubing with countless connectors and mending plates. Easy to work with, very adjustable for prototyping and stiff as the dickens.
The following are shots of the carving of the master template for my double cut body style
Notice the contours at present. These are routed with a big panel raising bit, with a bearing that rides 4 different contoured patterns at different depths. The pre-routing not only removes a large portion of the waste, it also provides some carving guidelines. The black spray paint keeps me in check in regards to where I have and haven't carved.
In the above shot you can see the fiddle planes used to do the heavy stock removal. Also seen is a small french curve scraper I made from a big french curve scraper, this is what really smoothes the surface
more carving gets me closer...
...until there isn't a flat spot left
Here is the master for the offset double cut.
And the single cut.
mmmmmmm ... build thread update ...... mmmmmmm ...
More progress shots for those who are interested. Below are shots of the single cut bodies being carved in my duplicarver. The machine works great and I can't believe I went without one for so long!
Here is obelio's body registered in the carver ready to kick up some router shavings.
Same guitar in the middle of the rough out pass.
I do a rough out pass at full depth minus a 1/16" or so at roughly 1/4 " spacing followed by a finish pass at full depth at roughly 1/16" spacing. This extra pass takes a little extra time but it minimizes tearout and just makes for more accurate, predictable and consistent results. Extra time on the carver is paid off with less time sanding and that's more than an even trade any day.
Here is Obelio's body all carved up!
obelio's body carved up with some naptha applied.
Obelio's body carved and sanded with naptha applied. I love this top! Lots of interesting things happening in this piece of wood.
This is a shot of Tony's C7. Very clear depiction here of the difference in cleanliness between the rough and final passes.
Tony's top all carved up.
Tony's top carved and sanded with naptha applied.
Brian's top all carved up.
Brian's top carved and sanded with naptha applied.
Stunning work obviously done with great care. Tony is a lucky guy!
I really love that single cut shape! Would like to see a semi-hollow body version!
Drools. Thanks for sharing, keep them coming!
Amen brother ... these updates are a slow torture for me.
Thanks for the compliments guys.
Semi-hollow single cut might happen on the next batch, what flavor would you like?
That which does not kill us...
Yeah, I know, I'm feeling it a bit too.
Very glad I came across this thread. Awesome!
Rick I compliment you on your methods and especially the outcome.
Can I ask you a question about your duplicarver. I see that your passes are very even. Do you have a brake or some way to prevent the bit from wandering?
a-ha, another compliment from a true great! Those 59's you put out are stunning, truly stunning! Being a member of the Gibson camp myself, I must applaud you on the purity of your guitars and their origins. Quite the portfolio, indeed!
I did put a brake on the carver. I felt it was essential to do so. I can only imagine the wandering bit syndrome I have seen with other carvers, w/o a brake, would lead to inaccuracies and extra time chasing missed spots. In steadying the y-axis toolpath, it also steadies the router itself, eliminating any possible "bouncing" around in the x and more importantly the z-axis.
The added accuracies save time in the actual carving operation, but moreover in the sanding. With even, consistent toolmarks across the entire guitar, the sanding becomes much less of a chore, almost a dream. When the toolmarks are gone, that's it.
Here are some shots specific to the brake system. I used the cheapest Shimano bike brakes I could find and a single bike brake lever set-up to accept 2 brake cables. After some tension adjustment I got it so I can stop the y-axis without much effort on the squeeze. The brakes are attached to the y-axis trams and the brake pads simply capture the y-axis bar. Overall I am pleased with how it works.
That is what I thought. Excellent!
Thanks for the compliment also. You make beautiful guitars yourself.
More photos. These are of Tony's Meridian semi-hollow getting caught up with the rest.
Here is Tony's top registered in the duplicarver getting ready to have the underbelly carved.
Here it is after the first pass and part way through the finish pass.
Finish pass complete and ready to come off the duplicarver.
Off the duplicarver and ready to be sanded.
All sanded up. Man that ebony takes a nice sheen all on it's own.
This is the back after routing the mating hollow recess. I use a bowl and tray bit for this. This style of bit leaves a nice flat bottom and a gentle radius at the corner. Perfect for this application.
I will be installing a Graph-tech piezo bridge pickup in this guitar. This requires a little room for extra wiring, a pre-amp and a battery. Since Tony didn't want any access covers on the back, I had to get creative. With some input from Tony we came up with a cavity that will be under the bridge and inbetween the humbucker cavities, accessible from the bridge pickup cavity. Half the thickness of the cavity will be taken from the back and half the thickness will be taken from the top. This is a shot of the back being routed for this cavity. I'll be darned if I can find the photo of the top being routed but you can see the results in the next photo.
Here are the top and back carved, routed, sanded and sealed, ready to be glued together. The sealer is Tru-Oil. I seal any surfaces I possibly can. Keeping balance is important to maintaining long term stability.
Here it is all glued, shaped, carved and sanded. I didn't take any shots of the carving process, because it's really the same as the earlier carves. The only difference is that these are a deeper carve and I do it in 3 passes instead of 2.
I put the fretboard on there to inflict some more torture on Tony....Brazilian style.
And here is my tiger myrtle Meridian glued, shaped, carved and sanded.
jeeeeze Rick if there was anyway I could own that Ebony topped one I would in a heartbeat. The owner is one lucky fellow.