Headstock question

[Verne Andru]

For those that have done some building I have a question about the difference between slotted and unslotted headstocks; I'm wondering if there is a significant weight difference between the two.

I note that while the slotted approach requires a thicker headstock to accommodate the side mounted machines there is a considerable amount of wood removed to create the slots, so I'm wondering if they end up being close to the same weight-wise or not.

[sunburst]

I believe Dave Cohen recently reported that a slotted a headstock is indeed lighter than a solid headstock. Of course, the weight of the tuners can vary.

[Verne Andru]

Thanks John - that's kinda what I was thinking.

I have a Selmer-ish styled mandolin with a solid headstock and I'm looking at it as a bit of a missed opportunity. I thought the builder went solid to save weight but looking at how much material is removed from the slots that just doesn't feel right...

[sunburst]

...I thought the builder went solid to save weight but looking at how much material is removed from the slots...

I don't know how many slotted pegheads you've done, but I would assume the builder went solid to save work and time!

[Marty Jacobson]

Do you have CAD software? You can model these up quickly, plug in the density values for the woods you're using, and get the weight calculated for you automagically. If you don't, I highly recommend Fusion360, which is comparable in functionality to $10,000 solid modeling software, but with an easy learning curve and with a free version that imposes some inoffensive limitations.

[Verne Andru]

Do you have CAD software? You can model these up quickly, plug in the density values for the woods you're using, and get the weight calculated for you automagically.

I did CAD back in the stone-age (Autodesk Autocad V1 was my first computer aided drawing system) but now work in Maya. It does make files that drive CNC but I don't think it has a weight calculator. It's more for modeling and animation than CAD.

[Marty Jacobson]

You actually can calculate the volume of an object in Maya, then multiply by the density to get the mass.
Guess I can't post links anymore? Forums dot autodesk dot com then /t5/maya-forum/calculate-the-volume-of-an-object/td-p/60228811

If you have the Bonus Tools installed, you can select an object and click Bonus Tools->Display->Poly Volume.

Note: Make sure you have the "Measure" plugin enabled. (It's in the Bonus Tools section of the plugin manager. If it doesn't work after you first enable the plugin, restart Maya.

[Dave Cohen]

A slotted headstock isn't necessarily lighter than o post-through headstock, but you CAN say that for a given headstock outline, a slotted headstock can generally be made to be lighter than a post-through headstock. Otoh, there are other ways to decrease headstock mass. One of the OPs drawings (top row, third from left) has already been used. Luthier Harry Fleischman made some guitars (and basses?) with that basic headstock idea. And, there are still more ways to get to less headstock mass. In the recent tuner mass thread, the "Fronkeenshteen" mandolin that I showed has a partially hollow CF composite neck+headstock. Seems to me that you don't need CF cloth to make a partially hollow headstock. You could do something very similar with wood.

If you don't have CAD software, a piece of graph pape or quadrille paperr can be used to give you an estimate of headstock mass at far less cost than a CAD package. Trace your proposed headstock outline on the graph paper, count the squares within the tracing to get the area, then multiply that by the thickness of the headstock to estimate the volume, and finally multiply the estimated volume by the density of your wood sample to get an estimate of the mass.

[Richard500]

Or, an elegant mechanical planimeter, a planimeter app, or for the already constructed shape, Archimedes’ dunk in water.
For some reason, nobody likes my previously suggested way of finding mandolin body volume by filling with water.

[sunburst]

For some reason, nobody likes my previously suggested way of finding mandolin body volume by filling with water.

I'll have to remember to ask the Troublesome Creek guys if they thought to measure the volume of flood water that came out of the mandolin I'm fixing for them.

[sunburst]

Or, an elegant mechanical planimeter,

I had a summer job in my college days working for ASCS (agricultural stabilization and conservation service) measuring corn fields, set aside land and so forth. There was plenty of time spent pulling a chain (tape, in reality) through the hot summer sun, but using aerial photography and a planimeter felt almost like magic and was amazingly accurate. It would indeed be a handy tool for the shop.