The Shop > Wood & Stuff
Banjo Build
S. Heslop:
--- Quote from: Lew_Merrick_PE on March 22, 2015, 02:11:46 PM ---Simon,
I have been making 5-string banjos for 51 years now. One of the things that makes the job a lot easier is to cut your "shell wood" into thin (call it 2-2.5 mm thick) strips and laminate them inside of a (hollow) circular jig. Here in the U.S. nearly all banjo heads are 11 inches in diameter -- making 10.950/10.900 inches the correct OD for the shell. The circular clamping jig I use has the OD set to 15 inches -- which means that I can use it in my table saw to "trim off" the (inevitable) "mismatch" at the top and bottom edges. I "wax" the ID of the jig to keep glue from sticking to it.
My "ID Clamp" is an inner tube from a hand truck (5 inch hub, as I recall) that fits on an inner (about 7.5 inches OD) piece with an extension that allows me to inflate it to clamp each "layer" as I laminate the shell. I find that (about) 30 psi works really well.
I normally make my shells 3.5 inches tall, so I start off with a piece of wood that is 3.75 inches wide and 34.75 inches long. I "dress" the face of the stock on my joiner and slice off a piece on my bandsaw, take it back to the joiner, and repeat until I have all my strips. I then use my thickness sander to finish each "layer" to thickness (.090 inches for my approach). I cut them to length, steam them, and insert them into my jig and force them to round using the "ID Clamp." The "outer joint" of the shell gets located under the heel of the neck, so the slight "mismatch" is (virtually) never seen.
I make my frailing banjos with a (roughly) 10 mm thick shell. Bluegrass banjos get a (roughly) 20 mm thick shell. After the slightly over-tall shell is complete, I return it to the "circular jig" and use that to trim it to length. I then glue "strips" to the bottom of the shell and trim them flush using a trim-router. I can then, if so desired, route a "perfling rabit" for final clean-up trim.
--- End quote ---
That's some good information. Thanks!
The reason i'm going with the segmented construction is because I was hoping to be able to make some fancy segmented bowl style patterns from the wood. Although i'm just trying to get anything working right now.
My current banjo is cobbled together from a banjo neck, some hardware, and a wooden box that had paints. Kinda like a cigar box banjo but not at all solidly constructed. The whole thing can flex too easily and it goes in and out of tune. I'm long overdue a replacement.
I've all but finished that rubbish lathe. Apologies for the busy photos, it's hard to see whats what.
Turned the faceplate round without any issues so i'm fairly convinced it should work.
Also I'm pretty pleased with that router base. It's just screwed into the side of the headstock to hold the drill in place. It's a pretty cheap and flimsy thing, but i've been finding all kinds of uses for it since it grips regular drills. The router/ laminate trimmer itself also works as (and is pretty much built exactly the same as) a die grinder. I found it in a second hand shop.
S. Heslop:
Didn't get anything done yesterday since I needed some 9mm plywood. I usually buy it from a builders merchants in full sized boards, quartered so I can get them home, but without a car it's a weekend thing. Had a while to wait for the bus up in Consett today so I decided to head to the hardware store and see if maybe they sold some. And sure enough, they did. For a fair price too. £6 for a quarter board.
The hardware store is called Gralands and it's well worth checking out if you're in the area. It's amazing what they fit into a small place. I keep thinking I might take some photos of the place but it's a bit of a dorky thing to do, but afaik hardware stores like that (the sort that sell screws by weight) are a rare thing.
Anyways it's now pissing it down with rain so I've got everything up on the benches in case the garage floods, so there's not alot to do till it stops.
S. Heslop:
Here's what happens when I try be clever. Instead of just clamping a bit of plywood to the table I thought i'd put some threaded inserts into the table to bolt a fancy thing to. I put the first threaded inserts in the wrong place, down at the bottom of those slots, and then realised that the banjo pot would cover them so I couldn't use that to screw it down, so I put a couple further up. Which I put too high so I had to sand the middle part longer.
I also made a mess of trying to make the thing. You can see all the lines where I kept bungling it up, and the slots are terribly long (and cut roughly with a jigsaw) since I kept putting them in the wrong place too.
I also bungled up transferring the banjo pot from the 18mm ply to the 9mm ply, by forgetting to first draw a circle on it so I could find the center again. So I'm probably going to print out a circle and try find a place to fit it, then use that to find the center. At least the paper thing worked and it was possible to remove it from the plywood, although now i'm worried it wont be able to survive the force of being turned on that lathe.
vtsteam:
Trial and error has a great friend in me, Simon. Keep up the exploration of your ideas! :thumbup: :clap:
S. Heslop:
Spent the last couple days doing other things for the most part. I'm having trouble again with the sanding sleeves on the spindle sander. I'm mostly going through each half-assed idea I can think of to avoid doing the best solution and copying commercial sanders (that use a rubber block that gets compressed down with a nut, to expand out and grip the sleeve).
Another vaguely interesting thing i've been doing is editing a clip show for some sort of conference (I don't know what to expect but I was asked to do it). Condensing 4 projects into a 5 minute video turned out to be a difficult task. I really expected it to be a quick job but since I can't use the rendered files (they've got baked-in commentary) i've had to sort through all the source clips. So it was almost equivalent to editing 4 videos back to back. I didn't have to record commentary at least.
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