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I’m toying with the idea of a cut away on this build. But I’ve never done one.
What advise is out there for making it a success?
Also does the neck block need to travel the length of the cutway on the side?



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Do you you cut a rough profile into your sides before bending? If so, you have to modify the profile of the bottom edge in the section that goes through the cutaway. You have to add a bulge in the profile on the bottom edge of the treble side to account for the fact that the body is thicker in the middle of the cutaway than it would be without a cutaway due to the radius of the back.

My neck block is the same thickness with or with out a cutaway.

Here's an example. The upper side in the photo has a bulge for the cutaway. The bulge on this particular set is a bit exaggerated over what is actually needed just to be sure.



Here's a photo of the guitar those sides were used so you can see the cutaway shape.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Yes I generally do profile as much as I can when I cut out the sides
I’ll let what you said sink in haha


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Here's what I'm doing

To make it easier to bend the tight bends of the cutaway like the ones in your plan, people often make the side a bit thinner than usual through the cutaway section. You have to be careful though about how thin you go if you're using some figured woods which may ripple during bending making it hard to level sand them later without making some spots dangerously thin or even sand through.

One other thing, I saw the photo of the body mold you bought in the "Gibson L-1 plan" thread. You'll need to add a notch to the mold (like the one in the mold in Michael's photo above) for the end of the treble side to fit into where it initially runs past the side of the neck block. Leaving the end of the side a bit long before gluing the side to the neck block allows you to nicely flush the end of the cutaway side to the surface of the bass side that runs over the neck block face after they are glued together.

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

Fortunately this is sapelle with nice strait grain


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So many great clues for the beginning builder!

Are those ebony bindings?. Ebony can be problematic and prone to breaking especially on a cutaway as the grain runout is hard to see.
Even more so on a first cutaway. If not ebony, disregard and forge ahead:) IMO it would be best to do a few practice bends on some disposable
wood to get a feel for bending the cutaway before going at the one on the bench.

Ken... it is ebony yes



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That’s not bad advise. I’m plenty comfortable doing sides, but the sharp bends I haven’t done. I do use a vending machine and have the cut away ram ready, so it won’t be on a pipe


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Good idea on the notch!!! Thanks


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When you are gluing the sides to the neck block, be especially careful about having the neck block squared up to the plane of the soundboard. Normally when you glue sides to the blocks it makes a rim which can still be flexed a bit to make everything square when the back and soundboard get glued up. You normally don't need to fuss too much about how square everything is until you are actually closing up the box. With a cutaway you are gluing to the side of the block as well as the end. This means there is no flex to rotate it later if the neck block was a bit off square. If you don't pay attention to it at the time of gluing up the sides you can later find it has thrown your neck angle off. Do you wonder how I know this?

We use macasser ebony bindings quite often, and Gabon now and again. Both woods bend well in the Fox bender if done with sufficient water (we use wet kraft paper in the stack as the water reservoir, versus just wetting the wood). Hand-bending can be done, but you'll certainly want a bending strap to support the side in tension. If you don't already have SuperSoft II in the shop, worth having for those sometimes difficult to bend woods like anigre, and just about any highly figured stock that is more prone to blow out in the tighter cutaway bends.

Mr. De Rocher's notched mold is the only modification to our outside molds we use for cutaways. A 1/4" wide by 3/8" deep notch allows enough adjustment to handle any variations in fretboard width at the body fret, with MDPE (really, scraps of take-away food containers) and green tape shimming the side until the neck block is in. If the top of the side is kept unprofiled until the blocks go in, the bench surface and sides of the mold will keep the neck and tail blocks dead square for glue-up. For Florentines, we do the point block in the mold as well.

_________________
For the times they are a changin'

- Bob Dylan

Jet black ebony bindings look great - so smooth and black and sleek under finish that they are indistinguishable from black plastic. Now, you can buy black plastic bindings which are perfectly flexible and will never snap on you in tight curve, and which probably protect the edges of the instrument even better than wood does. Can you see where I am going with this? But you say "I would never put plastic on my guitar". I say "why not"?

Axiom carries a nice black cellulose nitrate binding, and it is a good replacement for black binding on modern Style 18 and 21 guitars, but ebony - especially macasser with lovely dark chocolate undertones - is just so luscious when under a gloss finish...it's a toss-up as to whether I prefer cocobolo or macasser more. As to wood versus plastic, after the Style 42 guitars and a 00 rebinding, I believe it's actually harder to do a good, clean job with plastic than with wood, and specially ivoroid, but also for the other cellulose nitrate color and pattern options (we don't do ABS...too many ABS binding repairs to have any faith in the material!).

_________________
For the times they are a changin'

- Bob Dylan

So is it best NOT to profile the side with the cut away and let the dish do the work later on??


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Not sure if there is really a best practice here, so much as different practices with associated advantages and disadvantages. As mentioned, one way to ensure that the blocks go in square and true is to hold off on any profiling of the top edge of the sides until they are bent, trimmed, and the end blocks in, then profile the top of the rim while in the dish. With most builders using something between 25' and 60' radius, there is not nearly as much time to be saved by pre-profiling the top edge as the back edge.

To summarize: the advantage to keeping the top edges of the sides flat is the ability to block up the mold at the ends and waist and use the bench as a reference surface when milling the neck and tail blocks and getting them in. The disadvantage to the approach is the need to profile the top after assembly of the rim. For us, getting a straight, true rim with squared blocks takes precedence over any slight time savings, but there are other approaches which might work as well for you. Our main bench top (mostly quartered to rift hard maple assembled some 15 years ago or so) is leveled every year or two, and is quite stable; if your bench tends to less than flat and cannot be easily leveled (e.g., plywood or melomine), another reference surface - such as a known flat auxiliary bench or top of a cabinet saw - might serve as well.

_________________
For the times they are a changin'

- Bob Dylan

Quick question regarding the mold picture above with the notched treble side. Does the base side stop short of the neck block cutout? And will there be a separate piece added to the other side of the neck block to meet the treble side cutout? There's currently no side wood on that left side of the neck block and that's where my question focuses.

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Thank You and Best To All

Actually the bass side is installed first and extends past the neck block mortise and makes contact with the treble side rim. The bass side rim is trimmed back to allow the treble side rim to run by, hence the need for the notch. Here is a picture of the same guitar which is almost ready to level and buff.

Thanks Michael, I can now that piece I thought was missing. Beautiful guitar...

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Thank You and Best To All

Hey Woodie,
Specifically what happened? The ABS somehow failed or the adhesive let go?

Sorry for the hijack.
Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

We see a steady parade of 1970s - 2010s Martins coming in the door with Bolteron (an ABS/PVC alloy) bindings pulling away in the waist, shedding finish from bindings, and entire pieces of binding letting go from the purflings. The issues appear to be rooted in poor adhesive choices, high shrinkage rates on some binding materials (particularly the early versions of the binding material), and Martin's finishing materials and schedules - especially in the 1990s. Combine high shrinkage and poor adhesion, and we see Martins with loose bindings on guitars that range in age from a few years to nearly 50 years, as well as finish which fails in sheets, but only on the bindings.

Rather than attempting to fix someone else's problems, we avoid ABS, ABS/PVC, and similar materials in our own work and instruments.

_________________
For the times they are a changin'

- Bob Dylan

Trying not to start a new thread but also want to start a new cut away guitar and associated molds. I currently have both inside (for bending) and outside (for construction) molds and can easily add the cutaway shape (Venetian in this case) to the outside mold as an additional piece but the inside mold which is 5 or 6 layers of 3/4" mdf either requires cutting the shape out perfectly with a band saw (ain't gonna happen) or hacking away at it until it's shaped up correctly, then shaping a new caul for the bending process.

OR, building both the inside and out side molds from scratch as cutaway mold sets.

Recommendations?

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Thank You and Best To All

A third option is to use the molds you have now and free hand bend the cutaway on a hot pipe. The builder I learned from did it that way and that's how I made the Venetian cutaway on my first steel string guitar. The treble side was bent in his bending machine using his standard mold and then I reshaped the upper bout into a cutaway on a hot pipe. Even though that was my first time bending anything on a hot pipe, it worked fine. This approach saves you from having to modify your mold or make separate molds and it gives you the option of varying the cutaway shape from one guitar to another since you are not locked into one shape by a mold. Here's what the cutaway looked like:

_________________
Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter