Mandolins in progress

[Kip Carter]

Is that a rosette you're going to use in the last pic? These will be interesting to see completed!
Kip...

[Steve Sorensen]

Quilt lovers unite!



Steve

[Kip Carter]

Quilt lovers unite!

Steve

Nice quilt to cozy up to!

Kip...

[Marty Jacobson]

Is that a rosette you're going to use in the last pic? These will be interesting to see completed!
Kip...

Kip, that's a vacuum fixture. All the air is pumped out from underneath the top and back plates, so atmospheric pressure holds the parts down while they are roughed out at very high speeds and to very tight tolerances. The parts come off the machine (homemade CNC) looking exactly as you see them... no sanding or scraping done to any of these parts yet.

[Jim Garber]

Very interesting, Martin, but it is unclear to me how the sides are attached. Is the rim made of one piece?

[Marty Jacobson]

Very interesting, Martin, but it is unclear to me how the sides are attached. Is the rim made of one piece?

The rim is a 3-piece bent lamination. Mahogany, Maccassar Ebony (which is really stiff), and Mahogany. They are pre-formed and then glued around the top and back plates. Since they cover up all the end grain, no binding is necessary. Gives it a really clean look and is much faster than traditional bending, kerfing, gluing, and binding. Now it's just two steps instead of 4. At least, now that I have built the machine that does it. Which wasn't easy.
I think it has an elegant look, too. Not for everyone, of course. But traditional is not what I'm going for with this particular instrument.

[billhay4]

Martin,
This is fascinating and innovative stuff. What's missing here is a picture of the sides so we can see how this goes together. Your work is really creative.
One thing that will interest me is the weight the finished instrument will come in at.
Bill

[Dobe]

I love that neck joint Martin. In fact the whole design is a thing of beauty !

[hank]

Steve your definitely into some good wood. Martin I used to do aerospace composite blade repair and some plastic interior parts with self made vacuum tools. We used an old refrigerator pump with wooden fixtures similar to yours. Am I correct in assuming you cut the back or front on a band saw to the outer edge pattern that fits within the outer fixture cutout. The actual vacuum is pulled in the center area within your inner caulk ring sucking the wood down firmly in your fixture. As long as your top or bottom fits tightly in your fixture all twisting forces are prevented by the wooden cut out. Are you also using a similar vacuum fixture and Mylar sheeting to pull the rim tightly against the top and bottom without clamps when bonding?

[billhay4]

Martin,
Since this is all CNC, is there a reason for a neck joint at all. Couldn't you just make the neck and block as one piece?
Bill

[hank]

Wow, I like that idea Bill. There would be more room for error with defects and grain consideration, higher cost of larger wood slabs but what a beautiful notion! An instrument made almost entirely of one continuous piece of wood. Only the upper tap tuned plate and the rim vacuum close tolerance bonded. This would be as close as you could get to one continuous piece of wood. Even if the results (tone and sound wise) were only marginal improvement think of the advertising and sales pitches that could be generated from this kind of precision building!

[billhay4]

Hank,
I wish it was my idea, but classical instruments have been made that way for centuries.
The big drawback is that it creates issues if you have to take the neck off the instrument.
BTW, I'm thinking laminated necks is the way to go in the future. Much stronger than single pieces. some of the guitar manufacturers are doing it now and it doesn't look bad, different, but not bad IMHO. It certainly allows the use of much smaller pieces of wood for the neck construction.
Bill
Bill

[Marty Jacobson]

Bill and Hank,
Orville Gibson was doing that with his early instruments, remember? The neck heel, back plate, and rim were all one piece.

Making the back and rim all one piece is fine to do, since you tune the back plate attached to the rim anyway. Peter Mix did this with the Rigel mandolins, with great success.

I personally wanted to make the neck separate so that I could french-polish the top without the neck attached yet. I really hate finishing around that fretboard extension. Additional material cost is not an issue, it actually would be less wasteful than making a separate neck block.

Hank, the parts are 100% roughed out on the CNC machine. So all the tedium is automated, leaving me with the voicing and tuning which is done traditionally. Compressed air is used to pull the sides into a good glue joint with the top and back.
I will post a detailed step-by-step process probably next week. Need to prove the concept works first, though!

Yeah, there's a lot of cool stuff to do. Let me tell you, though, that getting the CNC machined parts working right is not a shortcut. Having built a dozen or so instruments with the traditional techniques, I can definitely say that it is harder. It's taken me a year to get this instrument to this point, and am only now refining the details. But once it's set up, it's repeatable. So my goal is to fill that hole in the market for a luthier-made instrument at a price that can compete with the Chinese-made brands. We'll see if it works.

[billhay4]

Martin,
I see your reason for a separate neck, especially if you're going to fp. You could fp before the fretboard went on, though. Another pain.
You are going great guns here, and I can appreciate just how much work you've put into this. Let me know when you're ready to produce instruments. I'd like to try one.
Bill

[hank]

A channel precision cut down the center of the neck/back could give the strength and warp resistance of laminates or carbon fiber while retaining the energy transfer qualities of a continuous piece of wood. The channel could also be used to adjust the mass at the peghead if wanted. Most of us would agree a perfect fitting neck to body glue joint held together correctly in a controlled environment is fine and much more practical but I can't help but wonder how no breaks or stiffness changes across the grain from nut to tail piece would affect the energy transmission and node locations in the wood itself. In rotorwing airframes and blades changes in stiffness from repairs often shifts the antinodes to new location causing new stress locations with potential for future cracking. I know primarily our acoustic sound comes from the energy of vibrating strings with their shifting nodes and antinodes as we fret them but how well this energy is transmitted to the amplifying effect of the vibrating tone plates is the difference between average tonal and response charateristics and stellar. Sustain could be affected as well with this hypothetical junctionless neck but then again it may not have much effect at all to any of these characteristic.

[hank]

I wrote the above before reading your last post in reference to Bill's laminate suggestion. I think the point is moot now.

[Marty Jacobson]

Thanks for the comments, everyone. I'm glad I'm not the only one excited about this stuff... :-)

Got the top machining process dialed in today! First instruments are being assembled next week!

[Eric Foulke]

Making the back and rim all one piece is fine to do, since you tune the back plate attached to the rim anyway. Peter Mix did this with the Rigel mandolins, with great success.

Just a point of clarification and to give credit where it is due, the Rigel mandolin was wholly designed by Pete Langdell, Peter Mix was his business partner when Rigel became a production shop.

[pickngrin]

Here's a little clip of the four mandos shown above out for a little test-drive before pulling off the hardware.



Many thanks to Randy Torno for helping me wring-out these babies before final tweaks and finishing.

Steve

You do beautiful work, Steve. Love your modern take on the curve, headstock and those sound holes! That F8's gonna be a monster.

[Steve Sorensen]

Here's the other side of the story.



Steve

[Steve Sorensen]

Four coats of oil varnish and many more to go . . .



Steve

[Skip Kelley]

Steve, that mandolin is looking awesome!

[Londy]

Wow Magnus, that is one awesome looking mando! Can you tell me more about it? Did you build it yourself? Your design?

[pjlama]

I keep trying to find reasons not to buy a Sprite, that design just kills. I hate this thread, way too much eye candy.

[pjlama]

Thanks for the comments, everyone. I'm glad I'm not the only one excited about this stuff... :-)

Got the top machining process dialed in today! First instruments are being assembled next week!

I'm just dying to see one finished. I have great respect for guys coming from that industrial design background. I worked for Ned Steinberger for a couple years and was blown away by his ingenuity. Clearly you're throwing out the tried and true and blazing a new path here, awesome, very exciting! Do you have a pic of a completed prototype?