u/PGHNeil

When building acoustic guitars it’s necessary to sand the tone woods for the sides thin enough to where they’ll bend and for the top to vibrate freely when you play the finished instrument. The tool required for that is not a thickness planer (which would shred thin stock) but instead a drum sander. Even the cheapest one on the market (by my research the Jett 16/32) can cost over $800 to purchase and aren’t available for sale in brick and mortar stores my area.

This is my attempt to DIY a solution using materials that are a little more accessible from general hardware stores like Home Depot, Lowes, Ace Hardware and Harbor Freight. It’s far from perfect (it makes a LOT of dust, vibrates a lot and has stripped out the chuck on my drill) but for someone doing just a few of these as a hobbyist it’s a good alternative. I didn’t use plans and the design does have limitations that cause wear via vibrations and misalignment.

Materials:

2x4 lumber (1) for the sides cut into two 24” long sections. They cost less than $5 from Lowes or Home Depot

(2) 2’ x 4’ x 3/4” birch plywood board cut in two to serve as the base and the adjustable shelf to vary the thickness of your project. I like to use the furniture grade stuff because it’s stable and true (resistant to delaminating.) $42 apiece from Lowe’s

2’ x 4’ x 3/4” birch plywood board or MDF board to use to create at least 12 circular cutouts to create the drum which should be at least 18” long - because the biggest guitar I’ve built is 16” wide. MDF is very stable and resistant to warping. It can be heavy to work with though. MDF is cheaper (about half the price; $24)

Stainless Steel Lab Rods Monkey Bars.5 Diameter, Round rods (24") purchased from Amazon for $24. This serves as the axle for the drum

2 Pack UCP201-8 Pillow Block Bearing - 1/2" Mounted Pillow Block Bearings Solid Cast Iron Base - Self Alignment (UCP201) purchased from
Amazon for $14.99. These are bolted to the two 2x4 sides, have the same diameter bore as the axle and allow the drum to rotate freely.

Two door hinges to mount the shelf to the base

BAUER 7.5 Amp, 1/2 in. Variable-Speed Hammer Drill purchased from
Harbor Freight for $44. I chose this model because it has a locking activation trigger that allows me to freely use both hands to guide my projects under the drum.

WARRIOR 2-3/4 in. x 25 ft., 80-Grit Sandpaper Roll purchased from Harbor Freight for $9. I cut an end at an angle so that I can wrap it tightly around the drum and use Gorilla glue to attach it permanently to the plywood drum. It has held adequately but I’m sure there are better methods. It doesn’t seem to want to melt from the friction.

That’s just basic parts, so figure around $200 for that (counting hardware and glue to assemble)

Assembly:

The most intensive part of assembly is cutting out the circular cutouts. For this I use a 4” hole saw ($30) on a bench top drill press ($90 from Harbor Freight.) This creates a rough outline but also a center hole which I then widen with a reamer ($5 from Harbor Freight, also on the drill press.) Total cost: $125.

Other tools mentioned:

YUKON 60 in., 3-Drawer Hardwood Workbench. $160 from Harbor Freight. I modified it by mounting 4 light duty polyurethane caster wheels with brakes ($6 apiece; $24 total) to allow me to roll it from my basement to my garage and also into my driveway to work in open air and natural lighting and cut down on dust contamination inside my house. $184 total cost.

PITTSBURGH 12 in. Quick-Release Bar Clamp ($4.49 from Harbor Freight) is a good cheap clamp to secure projects together and to the workbench. I have 4 of these ($18 for the set) in addition to 4 of the 6” version ($3.50; $14 fur the set) and 4 of the 24” ones ($6.99 apiece; $28 for the set.) clamps are a must for luthiery and this has been my go to source.

I also have a Ridgid 16gal Shop Vac ($90) from Home Depot for clean ip and dust control. It’s not ideal but I use it for general household use.

Design flaws:

1: height adjustment. Right now I just slip the rubber sandpaper cleaning stick under the adjustable shelf which doesn’t want to move around despite the vibrations. I have seen videos of DIY sanders on YouTube that feature elaborate threaded rod mechanisms to give finer control but I’m sure the vibration is a major issue.

2: alignment with the drill. Again, I’ve seen videos where the drill sits in a cradle but I rely on using the clamp on my workbench to hold it in place. Even still, I’ve ruined a couple of chucks on the drill and rounded off the end of the axle. I just found a possible work around though: a shaft coupler with the ability to absorb vibrations between the axle and the drill. I found one on Amazon for $20 and have some more length of the 1/2” stainless steel rod to marry it to.

3: there is no self feeding mechanism/conveyor so I’ve sanded my knuckles a few times.

All told, It would definitely be cheaper in the long run to order the Jett but I’m only 4 builds in and haven’t sold anything yet. Maybe once I have a dozen builds under my belt and can sell a decent product for several thousand dollars apiece but for now I like that the DIY tool can sit on one end beneath my permanent workbench; the Jett would require a permanent location in my cluttered garage and my cars would be perpetually covered with sawdust, drawing more ire from my wife.

I know it doesn’t look much different than my last post, but I’ve been focusing on the fine details:

- I installed the rest of the frets over the body. I actually did it with the neck taken off and on a cradle so that I could use a clamp to process them in without risking damaging the body

- I did a quick level and dressing of the fret ends - but will have to fine tune things once the neck is permanently attached

- I got the neck set so that it compression fits firmly enough to handle and hang from a String Swing, but I’m still on the fence on whether the is still a bit shallow.

- I had an oversized and unbleached bone saddle that I needed to cut it to width and round the ends off to slip them in the ebony bridge which I bought directly from Martin. I also did a preliminary plotting/masking of the top.

- I’ve also been working on the shaft/heel profiles on the neck and cut an end cap out of spare ebony from the headplate.

Now it’s on to final sanding and gap filling. After that it’s pore filling with ebony and epoxy followed by rattle can nitrocellulose lacquer. That’s new territory for me; I French polished my first 3.

This is an acoustic related question but could just as easily to electric as it has to do with neck construction. For my first couple of builds I made laminated necks with bolt on mortise/tenon neck joints, but I’ve been having trouble with backbow. My questions are:

1: has anyone else experienced this on their builds?

2: did the use of carbon fiber rods help solve this problem in future builds, and/or

3: is it more a problem of a poorly fit neck joint or was it solved by tweaking the truss rod?

I admit, I’m leaning toward #3 but there’s no gap between the neck and body at the heel despite paying close attention to the neck angle during an attempt to reset the neck angle - and yes, I’m using Stewmac 2 way truss rods. I think my issue may be the way I oriented the grain.

Neck construction is as follows:
-5 ply with flat sawn stock (mahogany/maple/walnut)

- threaded brass insert into tenon

- Stewmac Hot Rod double action truss rod.

Anyway, I was a complete newbie when I made these blanks over 15 years ago. I have another that I rejected because it twisted. Now I’m thinking my next one would be made with a quartersawn blank made with a scarf joint and stacked heel. I’ve seen builders on YouTube just cut them in half along the length and ad the central laminate after gluing up the blank. I haven’t seen them using carbon fiber rods but have seen boutique builders use them to prevent twisting. I may do this with the first build (on the right.)