Banjo Build

[S. Heslop]

Wasn't a whole lot I could do today. Redid the truss rod since the part where the screw bulged out just meant id have to route more material out the neck, right at the part where I feel i'm cutting it close on how much i've already routed out.

Also thicknessed the fingerboard to 6mm.

For planing the back of the headstock I was at first gonna use a router with some rails to ride it on, but that'd require sticking the thing to the table... but I ran out of carpet tape. So plan B was to try using the drum sander. I needed something smooth to slide the neck on, and the ideal thing I thought would be a bit of glass. I had a bit that was just ever so slightly too wide. Not a big deal to trim a bit off.


Except it was reinforced glass. I should've figured, considering where it came from. What I thought was neat was that it kept crackling after it'd initially shattered, with new cracks appearing. Like a bowl of rice crispies.


Anyways a bit of MDF worked fine. I'm not too keen on this idea though, it worked out okay but when removing the part it had a tendency to catch and get thrown out faster than expected. I wont't do it again if I can avoid it.


Smooth enough.  I'm not too worried about it looking ugly.

What i'm waiting on is a bearing to match a router bit i've got, to try make one of those bottom bearing follow routers. Almost all the rest of the tasks before carving require use of one of those.

[S. Heslop]

The stuff arrived today. Got fretwire and bearings.


Transmuted bottom bearing to top bearing, but squashed the top of it by mistake so it's irreversible.


Also made a template for the peghead but I figured it'd probably be better to route that after getting the fingerboard stuck on. And there's a few things to do with that before then.


For cutting the fret slots I'm using a hacksaw blade. It's set in a wooden block to give it more of a handle and to make it easier to keep it on target. I've got a whole thing planned but i'm finding it awkward to explain, so I guess i'll wait till i've got photos.

Anyways, not a whole lot done today. Spent most of it outside, and the first thing I did when I got back was epoxy that hacksaw blade. But I got the slow setting kind of epoxy (to make the brass tube stuff later easier, hopefully) and it'll probably be an overnight thing.

[S. Heslop]

It exploded.




I'm lucky the lid didn't hit me in the face because I was right over it, i'm lucky that the charcoal powder inside hadn't gotten hot enough to burn me, and i'm lucky I had my goggles on. But despite all that i'm still disappointed I wasn't recording it.

[NormanV]

Simon, you are very honest with your posts, even if they make you look silly. That's a great portrait of you, worth keeping.
I have kept my silliness to myself but in order to redress the balance I will divulge some of my own stupidity. (Not that I am trying to imply that you are stupid.)
After pouring an aluminium casting I had poured the surplus into a loaf tin to make an ingot. In tidying up I picked up a firebrick to put it in a safe place and managed to drop it onto the edge of the loaf tin, molten aluminium flew in all directions, a large dollop falling on my shoe. Fortunately it was leather and didn't melt or burst into flames, I was able to flick it off and no harm was done, not even to the shoe. But this is where my stupidity comes in, I was wearing shorts, I was so lucky. I will wear proper protective clothing in future.

[AdeV]

Are you sure you're not the Batman?

Seriously - I'm with Norman on this one - thanks for sharing, it's a timely reminder that some of the stuff we do is quite dangerous...

Speaking of which, what actually were you doing? I must have missed the post where you were making a charcoal bomb?

[Lew_Merrick_PE]

Hi Simon,

A couple of question/comments:  (1) Banjo pegheads are traditionally cut with the "sides" perpendicular to the fretboard face (unlike guitar pegheads).  (2) What size fret wire are you using that allows you to use a hacksaw blade to cut the slots?  The wire I use requires a .026 to .030 (inch) slot width in ebony.  As your fretboard is made of softer woods, I would postulate a narrower slot requirement.

[nrml]

I've been silently following this thread all along. I am glad you came through that unscathed . Thanks for posting the pictures as a reminder to everyone not to cut corners where safety is concerned. We are all guilty of it from time to time.

[S. Heslop]

Are you sure you're not the Batman?

Seriously - I'm with Norman on this one - thanks for sharing, it's a timely reminder that some of the stuff we do is quite dangerous...

Speaking of which, what actually were you doing? I must have missed the post where you were making a charcoal bomb?

I was trying to case harden. The idea is to seal the thing in a canister packed with charcoal and get it hot. Obviously gasses will probably be released, and internal pressures would increase. To try deal with this I only sealed the canister with some fire cement, since bolting it down would make a quite literal bomb. I suppose the fire cement did what it was supposed to, but I didn't imagine it'd be so sudden and dramatic.

I think if I were to do it again, i'd probably either drill a pinhole into the top of the canister, or i'd leave a small gap in the fire cement seal. Although if I was to really do it again, i'd go about building an electric furnace. The big reason I avoided doing so is because I just don't have the space.

Hi Simon,

A couple of question/comments:  (1) Banjo pegheads are traditionally cut with the "sides" perpendicular to the fretboard face (unlike guitar pegheads).  (2) What size fret wire are you using that allows you to use a hacksaw blade to cut the slots?  The wire I use requires a .026 to .030 (inch) slot width in ebony.  As your fretboard is made of softer woods, I would postulate a narrower slot requirement.

Don't quite know what you mean with the banjo peghead sides.

For the fretwire the tang is about 0.8mm wide. The hacksaw blade is a junior hacksaw blade and is about 0.6mm wide, measured from the teeth (to account for the set, hopefully). It probably cuts a wider slot, but I did a test slot to see if it was suitable and it took alot of force to remove the fret wire. Enough that it teared the wood out from the sides of the slot. I've heard that putting a slight bevel on the fret slots can help prevent that from happening if you ever need to re-fret the instrument.

[tom osselton]

Glad your ok! That is the last thing I would expect to happen!

[Lew_Merrick_PE]

Don't quite know what you mean with the banjo peghead sides.

Normally (at least on this side of the pond) a banjo's peghead is cut with the fretboard face held to the jigsaw or bandsaw table as the contour is cut.

For the fretwire the tang is about 0.8mm wide. The hacksaw blade is a junior hacksaw blade and is about 0.6mm wide, measured from the teeth (to account for the set, hopefully). It probably cuts a wider slot, but I did a test slot to see if it was suitable and it took alot of force to remove the fret wire. Enough that it teared the wood out from the sides of the slot. I've heard that putting a slight bevel on the fret slots can help prevent that from happening if you ever need to re-fret the instrument.

I normally make classic or flamenco guitars and frailing banjos.  It sounds as if you have fret wire for an electric guitar.  ???

[S. Heslop]

Normally (at least on this side of the pond) a banjo's peghead is cut with the fretboard face held to the jigsaw or bandsaw table as the contour is cut.

I normally make classic or flamenco guitars and frailing banjos.  It sounds as if you have fret wire for an electric guitar.  ???

Yeah I was considering cutting the peghead that way, I didn't know it was traditional I just thought it'd look cool. But with my bandsaw I think it would've been a difficult cut. Also usually banjos have funky heads but i'm going for something fairly basic here.

I was very tempted to go for this style of headstock.



It's one of those 'so stupid it's cool' sorts of things. Pompadour banjo. I think i'd only be allowed to play rock n roll with it.

But yeah following a template seems like it'd probably work out better. I'm a little concerned about routing endgrain though. I'll have to take it very slow.

As for the fret wire, I did buy it from a guitar place at about the same width as what my current (cheap) banjo has. But I can't imagine it'd make much of a difference. I imagine you could probably go a bit thinner with the stuff on a banjo, with the lighter strings. But my old banjo's frets are surprisingly worn after not a huge amount of playing, so I didn't want to take any chances.

Anyways I got the thing slotted.


Being the most critical part of the banjo i'd naturally not given it alot of thought and came up with most of this stuff as I went along. I figured i'd use paper templates since they tend to be more accurate than a tape measure. But I wasn't sure how to attach it. Usually i'd use spray adhesive but I don't really want to have to sand it all off, since I was clever enough to get the fingerboard to exactly the final thickness before slotting it. I also didn't want to use the double sided tape since it'd probably gum up the saw blade and tear off while cutting. So I went with putting a few spots of tape to lightly adhere the template, then marking each slot with a chisel.


Was pleased the lines came out so visible. It's stuck to a bit of MDF to keep it lined up properly in the miter box.


Got a sort of junk miter box that the saw butts up against. The cut is lined up by eye, by stooping down and getting the sawblade in line with my eye I could see the reflection on the wood below to line the cut up pretty well. A light backwards stroke with the saw also confirmed if I was on line or not.

Now if this is accurate or not, i'm not sure. There's probably an error in lining up the paper templates (that were in 3 parts for this), there's an error in marking the chisel line, and an error in lining up the sawblade to the mark. It could be a considerable ways off by the end of all that. But I think that, for the first 10 or so frets, being within 1mm of the intended position will probably be fine. I don't think i'd be that far out.


I had a hell of a time separating the MDF from the fretboard. The old carpet tape I had was more like duct tape and didn't stick all that well, but this new stuff is intense. Opened it a bit to begin with using a chisel then slipped this steel ruler in and hammered it down.


Then used it like a knife to get the rest off. I flexed the fingerboard well past what i'd assumed it would've been able to survive, but i'm glad it didnt break.


Before glueing it to the rest of the neck I need to put the 5th string in. I'm not entirely sure if I got the 5th string pip in the right place, and i'm a bit concerned about it really. It doesn't have to be exactly in line with the rest of the strings but hopefully its not so far over it interferes with the 4th string. Here i'm drilling the angled hole for the tube.


A slot was routed out on the other side. Rather than route it deeper I decided to squash the tube a bit in the vise. Checked it still guided the string, then fit it to the recess and fit the recess to the tube. It was then epoxied in. More of the slow stuff, so it'll be a while till it sets.

This epoxy sets very flexible. Usually that'd be a good thing but it might make it harder to trim flush.

[vtsteam]

I was trying to case harden. The idea is to seal the thing in a canister packed with charcoal and get it hot. Obviously gasses will probably be released, and internal pressures would increase. To try deal with this I only sealed the canister with some fire cement, since bolting it down would make a quite literal bomb. I suppose the fire cement did what it was supposed to, but I didn't imagine it'd be so sudden and dramatic.

Glad you're okay, Simon. That must have been a shock. I always wear a welding helmet with a clear lens when working with the furnace, and lull length leather welders cape and leather apron for cast iron, even if it's hot out. I'll remember to do the same if I ever pack harden.

BTW I've heard "fire clay" for luting, not "fire cement" The first is water mix would be fairly porous and have low adhesion to the steel. Fire cement on the other hand is fire clay mixed with sodium silicate -- is much harder, non-porous and a strong binder to steel. It would bake into a hard plug.

[SwarfnStuff]

I too am glad you survived to tell the tale Simon. As I understand things forget the pin-hole If you try again. Go with at least 1/4" AKA 6mm hole. You will be generating gas and the air inside will be expanding rapidly with your furnace heat. Atmospheric air will not be in a rush to get in there until things cool down when it won't matter as I understand it.
John B

[S. Heslop]

I was trying to case harden. The idea is to seal the thing in a canister packed with charcoal and get it hot. Obviously gasses will probably be released, and internal pressures would increase. To try deal with this I only sealed the canister with some fire cement, since bolting it down would make a quite literal bomb. I suppose the fire cement did what it was supposed to, but I didn't imagine it'd be so sudden and dramatic.

Glad you're okay, Simon. That must have been a shock. I always wear a welding helmet with a clear lens when working with the furnace, and lull length leather welders cape and leather apron for cast iron, even if it's hot out. I'll remember to do the same if I ever pack harden.

BTW I've heard "fire clay" for luting, not "fire cement" The first is water mix would be fairly porous and have low adhesion to the steel. Fire cement on the other hand is fire clay mixed with sodium silicate -- is much harder, non-porous and a strong binder to steel. It would bake into a hard plug.

I've got a face shield I'd usually break out, but it's that running around getting everything set up, and then trying to keep on top of it all that makes me forget stuff like that. I forgot the welding gloves at first too. Also I did wonder with the fire clay/ cement thing. I couldn't find fire clay anywhere nearby so I went with the cement.

[S. Heslop]

Looks pretty good, but what's that?


Oh...

I raised the router table so high that the collet nut was above the table and it took me a while to figure out why it wasn't cutting so easily, and why I could smell wood burning. I thought that maybe the router bit had gotten dull.

I had some important words to say after seeing that, thinking I might've irreversibly wrecked the project. But I think I might be able to get away with some edge binding. I'll need to get a new router bit though.

Really thought I was on course for getting this finished by Sunday, at least without the finish.

[vtsteam]

Simon I always seem to have bad luck with a router! I remember once rounding over the sheer clamp on a dory skiff i had built -- the topsides were painted, this rail was going to be finished bright -- I just needed to round it.

As I was going along, the bit raised a splinter, in a split second the router bit pin followed it in diagonally across the whote rail, pulling through the planking and all. The rail relieved of tension split and snapped out away from the topsides for a couple feet forward of the cut. What a mess! My new boat looked like somebody had taken a sledgehammer to the side!

I've had many router mishaps since, though none so serious, just ruined a lot of work -- I just don't trust the damn things. And they'e probably one of the most unpleasant tools to run ever invented. Loud and lookin for trouble! I'd ten times rather run a chainsaw than a router. Well I know many people use them every day with little problem. I just don't get along with them.

re. fire clay for luting: since case hardening temps aren't iron melting temps and the luting is temporary , I would guess that ordinary clays other than fireclay might work as well. But I don't think furnace cement is a good idea.

[S. Heslop]

Yeah I know what you mean. I'm still hesitant to use a hand router. I bought a fairly fancy one a while back, the kind with a cylindrical body (that are hard to get ahold of in the UK), for another project that probably won't go anywhere. But I can't see myself getting a whole load of use out of it as is.

The router table though has made it much more controllable. But of course you can only route what you can fit onto the table...

[S. Heslop]

Too many pictures in this post. I got carried away.

Put holes in the peghead using the template to locate.


Plenty of tearout though. The trick is to never drill all the way through with forstner bits, but drill from the other side (if possible) once the point of it starts poking through. I forgot though. Plus with the extra thickness of the burl face the peghead was too thick for the tuning machines. So I trimmed it further in the drum sander like before, in the way I said I wouldn't do again... but I did this right after id mucked the neck up so I figured it wouldn't be a big loss if it got flung out through the window or something.


Anyways that didn't happen.


Onto fixing yesterdays mistake. I decided edge binding would be the way to go, but didn't want to go searching for suitable plastics at a reasonable price, or wait for delivery on the 'proper' stuff.
 

So I cut this black ABS pipe I had bought for dust collection but never actually used.


Then got it soft with the brand new iron (hence the wax paper).


Clamped a flat board on it.


And it came out surprisingly flat with no curling back.


For routing the recess I made a... ring I guess you'd call it, for the bearing. To give about a 2.5mm depth of cut. I forget what the router bit originally was but I bought it for the drum sander.

I was originally going to try increasing the thickness of the ABS pipe material (which was about 2mm thick) by superglueing two bits together, but that didn't quite work out so well (it delaminated easily in a test), so I decided to rout to a lesser depth by putting a few layers of masking tape on the side of the wood where the bearing rides.


I don't often use superglue but I quite like how it waits for you. As far as I know it sets when no air can get to it. So it wasn't a problem gluing this much at a time.


Masking tape holds it on as it dries. It dries pretty fast but my fingers couldn't cover the whole thing.


It was then scraped down. Masking tape is there to prevent me from gouging the surface like I did on the test piece.


The final bit was sanded flush since I needed to slightly flatten the neck a bit anyways. Had a tiny bit of an S curve.


Looks pretty good for something that's just covering up a stupid mistake.


With the slightly lesser rout depth there's two spots that didn't get totally removed. I'm considering filling them, but I don't think they're particularly noticeable and they're far enough up the neck that i'm not worried about trying to bend strings into the divots.


I also removed the material to get access to the truss rod adjustment. I'll probably make a truss rod cover out of more ABS pipe, but i'm still deciding on the shape. I'm also going to edge bind the headstock since I bungled the cut and went into it a bit. I'll have to be careful to not bungle it backwards into the stuff I just did.

[S. Heslop]

Decided to do the headstock tonight too.


Lost my lighter and the blowtorch packed in.


Just passing it through the flame to warm it.


So it's flexible enough to hold the shape. Whatever this plastic is, it holds its shape beautifully as it cools. No spring back at all.


Also cut the nut slot, perhaps a little too deep. I might glue a bit of wood back in.


Gonna go with a brass nut, part because it's what I have, but i'm also interested to see how much a difference it makes. I'd imagine it'd probably wear faster than more traditional materials.

[vtsteam]

I like the ironed flat ABS technique!

I've flattened 4" PVC pipe before in an electric utility oven with plenty of ventilation. Heating slowl is the key, but never thought of an iron.

I'm thinking a homemade solar oven might be interesting to try for that, since slow and relatively low temp would seem to suit.

The banjo is coming along great and I like all the setbacks and watching them overcome towards a beatuiful instrument.

[S. Heslop]

I'd heard that carving the neck is probably the easiest part of making any stringed instrument, and i'm happy to say that it's indeed true.


Rasp worked well, but I probably would've done fine with just the coarse crosscut file.


There's alot of methods for carving necks it seems, but I liked the idea of this one; faceting the neck until it approximates the profile then smoothing it.


Although after the first facets I started to think 'who cares about getting it to the plan' and just carved away at it till it seemed about right. I'd say the faceting probably helped keep it even though.

This is also the first time i've gotten a scraper sharpened so well and it really pulled off a surprising amount of material. It's such a goofy tool in principle yet it works so well.


After less than an hour I had it shaped and sanded. I didn't time myself but i'd guess it took about 30-40 minutes. It's kinda funny considering how much effort I put into assembling the whole gamut of carving tools.


It's also hard to take a photo that shows the shape. I guess ideally i'd find somewhere with strong lighting from one direction, which I was trying to do in this photo with it down by the side of the router table.

Anyways, being an idiot I thought this would take up the whole day. So now i'm kinda sitting around trying to think of what to do next. Maybe figure out how to put the frets in. It's trickier now that i've got the edge binding in the way. I tried nipping the tangs off with some small side cutters but it bent the wire pretty bad and was tough getting it back. Everywhere I look online seems to recommend either fancy pants tooling or just carefully filing the tangs away, but I'm hoping to find something easier and cheaper.

They sell a fret tang nipper from stewmac that everyone seems to get real excited about, and it took a while to find a close-up video in action and it just seems to be a regular old hand nibbler. So i'm considering trying to make something like that.

[AdeV]

Suddenly that's really starting to look like a lovely instrument... I'm sure it'll play as well as it looks.

Question - the frets, are they just a piece of relatively thick wire, or a specifically shaped extrusion? Like a thin flat bar? Either way, I'm assuming you cut them over-length, glue them in place, then file the hanging ends off? Or do you cut them, file them to length & glue them in that way? If the latter, then careful "filing" with a flap disk on an angle grinder would seem to be the obvious, and much faster, method of sizing them to length. I'd be tempted to make a jig - a simple block of wood with an accurately drilled hole, which traps the fret to the exact right depth; then simply angle grind flush to the block. A pair of small pliers might be needed to extract the finished fret, which is now the perfect length to glue in place.

If you glue them in then file them, I'd do it exactly the same way, except I'd probably put some masking tape on that plastic edging, to prevent scuffing.

Edit to add: A slightly modifed version of the above: Make the hole big enough to contain ALL of your frets (+ 2/3 spares); angle grind all to length, then either tap out or split the block to release them. Same result, but only one operation instead of a dozen or so...

[S. Heslop]

Suddenly that's really starting to look like a lovely instrument... I'm sure it'll play as well as it looks.

Question - the frets, are they just a piece of relatively thick wire, or a specifically shaped extrusion? Like a thin flat bar? Either way, I'm assuming you cut them over-length, glue them in place, then file the hanging ends off? Or do you cut them, file them to length & glue them in that way? If the latter, then careful "filing" with a flap disk on an angle grinder would seem to be the obvious, and much faster, method of sizing them to length. I'd be tempted to make a jig - a simple block of wood with an accurately drilled hole, which traps the fret to the exact right depth; then simply angle grind flush to the block. A pair of small pliers might be needed to extract the finished fret, which is now the perfect length to glue in place.

If you glue them in then file them, I'd do it exactly the same way, except I'd probably put some masking tape on that plastic edging, to prevent scuffing.

Edit to add: A slightly modifed version of the above: Make the hole big enough to contain ALL of your frets (+ 2/3 spares); angle grind all to length, then either tap out or split the block to release them. Same result, but only one operation instead of a dozen or so...

Thanks. The fret wire is like an extrusion, somewhat of a mushroom cross section. The 'stalk' aka tang also has little barbs all the way down that grip into the wood. They're also made from fairly soft metal, German silver I think. And they are filed to length after sticking them in.

Also the problem isn't cutting them to length, but cutting out the tang where the edge-banding is. Since there's not a slot there, but the fret still needs to hang over it.


Here's a picture to illustrate. It'll probably be easy enough to just file the tang away by hand in all honesty. But I've got an idea for a kind of block that could hold them, with tape over half of the file so it doesn't wear away the block where it contacts.

[nrml]

The little gouge marks still left can be easily made invisible with those bits of coloured wax that are made for that purpose.

[S. Heslop]

Got some brass today. Couldn't get the size I wanted at a reasonable price so I got another shape that still fit the parts. The original idea was that id be able to grind away part of the stuff with a burr in the router table but after what I learned today i'm not sure if that would've worked anyways.


Made a little test shoe with the hacksaw and files. It has that hand-made charm~

Took way too long that way and is fairly ugly despite all the effort, and I wasn't so hot on the idea of doing 28 like that, so i'm definitely going to try doing it in an overly complicated but more entertaining way.

I first tried cutting it on the tablesaw but the cut was getting narrower, and I was blaming blade deflection. So I tried bandsawing it and had similar problems against a fence. Worked out better free-hand, but you can see the offcut curling away.


The bar itself was also curling away. Internal stresses I suppose. This was pulling it away from the fence and making the cut get narrower. I'd heard that this could happen but I always imagined it being a matter of a few thousandths, and nothing quite as dramatic as this. It also stayed fairly cool during the bandsaw cut so I don't think it was bending from heat expansion on one side.


I straightened it by pulling on it in the vise a bunch and sent it through the drum sander, but it bowed again while doing that and I didn't notice until i'd overshot the 10mm mark I was aiming for. Straightened it again and kept an eye on it, and it's now at about 9mm but still useable.


Then I hacksawed it off. Was originally going to use the tablesaw but the metal cutting blade didn't raise high enough, and the bandsaw didn't produce anywhere near a straight cut. Then I ganged them up in 5s (got away with 10 for the last... 10) to file a flat side to them, mostly just for referencing and to make drilling a hole easier.

It was alot of work and there's more to go. I'm still going to try using the burrs, by clamping them into a stack like in the above picture. Chances are the stack will explode and fling them all everywhere, but it's something I really want to try out regardless.