Glue for colored veneer marquetry in spruce top

[Chuck Tweedy]

OK - now i'm just trolling for compliments. Thanks guys - you are too kind.
Randy, this guitar is for a young lady in the Bay Area who commissioned it - how _dare_ you imply that i only make guitars for family and friends!! OK her father-in-law was my best friend in middle school
The design (drawn by my AMAZINGLY talented daughter) is above the soundhole - only "stem" goes around the bottom arc. So I have options for scratchguard - not sure what it will be.

Barry - the veneer is all 1mm thick dyed poplar from Atlas Billiard Supplies. I've found that the best selection of inlay materials is now through billiard guys. I think some of the old sources that we used to throw around here have dried up.

Full disclosure - I've cheated like hell to make all the inlay bits - they are laser cut from the sheet based on vector graphics that I generated from the hand drawing. So cutting the scores of veneer pieces did not take skill, only technology. They are ridiculously complex, and they fit together perfectly so ... I'm good with that

[Bob Orr]

Don't say it is only technology there is a skill, that I don't possess, in doing the CAD drawings etc to get the cutter to work in the first place.

[Karl Wicklund]

Hand cut or CNC? Going to be stunning either way.

[Barry Daniels]

Chuck, I appreciate your humble nature. I also realize that you have not actually invented anything here. But, you are in the process of presenting (at least here for the first time) an accumulation of new materials and technology that, dare I say, represents a true Game Changer in our craft. I think that I have been around long enough to make that claim.

Inquiring minds would appreciate a few more details, like specific laser cutter and vector software.

[Alan Carruth]

One of the local luthiers does laser cut inlays on tops. He uses the cutter at the local makers space, and does the cuts into the top at the same time. The fit is perfect, but the edges are charred. I imagine that there are CNC milling setups that could cut the pockets using the same art work. A little char on the inlay pieces would not show as much, particularly if they're sand shaded.

[Barry Daniels]

Exactly what I was thinking. This would be one of the best reasons for buying a small CNC.

[Clay Schaeffer]

CNC is coming to the crafty crowd - cricut machines are cutting paper, cloth, leather, vinyl and wood veneers as well as drawing. Small CNC machines will soon sit next to the 3D printers people are using in the home. Like computers, if you dumb things down enough, many people will use them, although only a few people will go much beyond point and click.

https://www.google.com/search?q=cutting ... PpdWWmAM35

[Chuck Tweedy]

Hey Guys, I'm back from the weekend.
Ok, some specifics. Buckle-up-buttercup - here we go into TLA soup...
My daughter drew the original image on paper with pen - she is the art-eest.
I took that image and scanned it to a digital format (PNG), and imported that into CAD so that it was 1:1 in the drawing units.
For CAD I use QCAD. It works on Linux & Mac - which is a requirement for my home computing needs. It is a pretty simple 2D CAD that I've jelled with - I can work pretty quickly in it now.
With the image as a background layer, I use splines and lines to trace the image. Judicious use of layers makes it so that I can separate out different pieces of the image. I do need to be very careful to make closed paths that I know can be cut by the laser system. E.g. Inside corners are going to get rounded, the edges are going to get singed, etc. There is some skill in doing the tracing so it will work - that I will take credit for.
The CAD gets saved as DXF.

With the image traced, I can then export the file directly to SVG (vector graphics) from QCAD. It preserves color and linewidth, so that export looks exact-a-mundo like the CAD. Now I have an SVG file.
That SVG imports into 2 other tools that I use. One is Inkscape, the other is GIMP.

I scanned the veneers to get an idea of the color they are, and made a specific color palette with the colors, and then imported the SVG to created a GIMP image that I can have my daughter to do a color-by-numbers exercise - then I use the colors she picks to more forward with.

I use Inkscape to copy and paste and re-orient the pieces onto "coupons" that are about 2x6" - each coupon has a specific "part" of the image. In this case they are the the petals, stems, leaves and "hubs", all of which are different color in the inlay.
Another file type change - I export each of the coupon drawings to PDF (path not raster), for the laser cutter - It consumes PDF's. Sorry. The cutter is in the lab at work, and I have to get an operator to run it for me, I don't know the brand/model - but I do know, that it is not as "industrial" as we would like for our real engineering work. Luckily, my workplace allows any engineer to submit "G-jobs" to the machine shop, 3D printers, water jet, or laser cutter - we pay cost + a bit. Which means, I can get pretty much anything mechanical fabricated from a color 3D print of my bust, to a motorcycle frame (both of which have been done at work - so far).

Veneers are Elmers School Glued down to a hardboard substrate (backer), and cut up. The 2x6" coupons go to the laser cutter and get burned up - then I make a second set of coupons, and they get cut at 50% power . The pieces come off the backer pretty easily.
Next is what you see in the original image - me routing the cavities to put them in there.

Barry - I really appreciate your kind words. I'm not the best at marketing my skills and abilities, I know this well. To me the true test is the product. I can babble on all day about the tools, tricks, techniques (see above), but that generally causes eyes to roll back into peoples heads and I get a blank stare. I, therefore, have to let the guitars speak for themselves. I can say that I have never been turned away at any retail shop - I've had guitars in some of the best shops in Southern CA and sold several. But all that has dried up - lucky me!

More pictures coming. I'm too tired to reformat pix tonight (wish this forum would take a 3MB image )
did that kill anyone?

[Barry Daniels]

Running to get my fret saw and clutch it close to my luddite chest.

I've been looking at Clay's Cricut machine. It looks like a more DIY, straight forward solution. And it should leave a clean CUT edge instead of burned. It would be nice to see someone using one on real veneer.

[Chuck Tweedy]

See now, I saw the text and read "circuit" CNC - I thought it was a machine for printed circuit boards. Got it now, that is cute.
It would make a clean edge, but it would not work on my 1mm thick veneer.

I discussed CNC routing the cavities with people at work, and that is definitely the way to go. It would be a clean edge cavity, to exact dimensions and pieces would drop in. I can't do it at work, since the machines are all for metal and plastic and covered in cutting fluid. I may look into it for future projects, but it would have to be outsourced, and I'd need to be sure they can do what i need before jumping in with a good piece of wood.

[Barry Daniels]

I can send you some mismatched spruce tops if you want to experiment. Yep, a small CNC machine could do both parts.

[Chuck Tweedy]

Thanks for the offer Barry, but I'm not ready to go on that yet. Need to go back to the Luddite shop to finish this build.

[Barry Daniels]

Let me know if and when you need some. I got a big stack of them that I may never use.

[Clay Schaeffer]

Here is a CNC setup I am tempted to buy:
https://www.youtube.com/watch?v=Y5nyjvytlBk
It has a spindle and I believe can also take a laser. It is a relatively small machine (300 X 180 X 45mm, 11.8 X 7.1 X 1.8 ins.) but could do rosettes and fretboards, headplates, and other small stuff (ukuleles anyone?).

The library where my wife works has a cricut (cricket) machine and I have been tempted to send in some veneer and see what they can do with it.
The machine retraces the tool path several times to cut wood veneer, so if you do enough repetitions it may cut through 1 mm stuff

[Chuck Tweedy]

I finally got everything together and fit. Been a lot of distractions since I started... Oye!
The second picture is the complete inlay, all installed and the epoxy is setting as I type.
I test fit everything before sealing, then again after and had to fix a few too-tight pieces. Once the epoxy was in the cavity, all the pieces fit in better than dry, so I'm real happy I did all the test fits and prep, because the real thing was a snap - 15 min or so.
After trying a few things to color the epoxy, I found that I only have a few spots where there will be any gap at all, so I just went with natural System 3 T-88.

For the T-88 epoxy, I really wanted to de-gas it properly, because it looks good clear/natural. Not so good fizzy. SO, I worked out a way to de-gas similar to how it would be done industrially. In the lab, we would mix up a big batch and put it in a deep container, then into a vacuum bell jar. Once it has foamed up and fell, it would be good an clear. The second picture below, shows the result of my de-gas technique. Here's what I did:
Mix epoxy in a silicone glue tray
Hit it with a heat gun to make it flow and loose some of the big bubbles
Pour it into a 30mL syringe and expel out all the "bulk" air
Then cap the opening and pull the plunger back
This creates a very strong vacuum which causes the material to expand like foam and the bubbles rise and pop

Its not perfect, but it is FAR better than freshly mixed epoxy. You can see how clear it is in the first pic

[Barry Daniels]

I have had good results with removing bubbles by simply passing a propane torch over the laid in place epoxy. Quick and easy.

The T-88 epoxy has quite an amber color to it. Does it cure that color? I use West Systems which is colorless.

[Barry Daniels]

I love the design. And the different colored flowers is very nice. Can't wait to see it under finish.

[Chuck Tweedy]

Hey Barry, the T-88 will cure with an amber tint, and I'm good with that for this application. Its about the color of most hide glue.

[Bryan Bear]

That looks great so far. I can’t wait to see it when it is done.

Thanks for the tip about degassing in a syringe. That is a great idea. I don’t have a vaccine pot or enough justification to get/make one. Every now and then I need to do a small pour of epoxy and wish I had a good way to get the bubbles out. I hope I remember this tip next time I need it.

[Alan Carruth]

I just remembered something: test any dyed veneers with whatever glue you plan on using by inlaying pieces into some scrap spruce. I once used epoxy and ebony dust to make a mastic for inlaying some pearl around a rosette. The problem was that that the color in the black dyed veneer I used for the BW line around it dissolved in the slow curing epoxy, and wicked out into the end grain of the spruce top. Not pretty.......