Replacing all the brackets

I thought I was almost done, having reattached the tailpiece and neck to the pot I went to insert the head and found it wouldn't fit. :-o I'd previously fitted it into the pot before reassembling it. It'd been a squeeze but had been doable. Now it was all reassembled it wasn't going in at all. Two of the brackets were 2 or 3mm over the edge of the pot. Levering it into place would've probably damaged the pot and maybe even buckled or broken the tension ring. I was going to have to make eight new slightly smaller brackets for an easier fit. Luckily I still had most of the flat rod I'd used to make the first two brackets from. As before the first thing I needed to do was thin it down.

Clamping it in two tiny vices I started making a cut right along the length to give the rod a width of just over 5mm. The first Dremel cutting disc fell apart not very long after starting, the rest managed a few inches before they were too small to continue.

After cutting the width of the rod I then cut out nine 7-8 cm lengths. They were longer than I needed but as before I planned to cut them down after bending them. I only needed 8 brackets but decided to make a spare just in case I made an error on one.

With the rough blanks cut I then used a grinding cylinder thing to finish getting them the right size and smooth off the cut edges.

That done I bent the brackets in the vices using one of the old brackets to measure the distance between each bend.

That done I trimmed the brackets to size then drilled the holes and countersinks into each bracket. I used the same drill bits as before but using two vices and two brackets in each sped things up compared to when I made the first two brackets. To make the head a better fit into the pot I moved the hole the hex bolts screwed into 1mm towards the outer edge of the bracket.

I tapped new 3/16" threads in the the hole at the bottom of each brackets where the hexbolts will screw in.

The shiny new brackets were cut to size. I used a lot of metal cutting lubrication for the whole process.

The brackets were attached to the hexbolts and the head tested for fit in the pot. It was spot on, although the edges of the bracket heads protruded beyond the edge of the pot in some places.

I marked the protruding edges in blue ink then removed the head again. To remove the head I threaded a string below two of the brackets and pulled it up.

I filled the bracket tabs down to size with the Dremel. The new brackets were very shiny. Not the kind of lustre you'd expect on an instrument of it's age so I decided to force a patina on the new brackets.

 I left them for a few hours with some vinegar soaked tissues paper on the metal then gave them a rinse and dried them before lightly sanding them with 2000 grit paper. In the picture below the thee brackets on the left are my new ones, the shiny one is the spare one I made and the one on the right is the original bracket.

The patina only mattered in the top visible part of the brackets, the lower part would be hidden by the metal hoops and vellum. Having got the patina I wanted I gave the brackets a spray with clear acrylic sealer to protect it and stop it ageing further. I used the same satin finish I'd used for the pot. I gave the a couple of coats then set them aside to dry.

Reattaching Neck and Tailpiece

Having painted and sealed the pot it was time to reattach the neck, tailpiece and the stud at the back which nobody seems to know the purpose of.

I wound up having to use a hammer to get the stud back into place, this damaged some of the woodfiller on the inside so I had to stop and fix that then spray over that. Next up as the tailpiece.

I'd've liked to have electroplated the tailpiece again as the presumably nickel was rather worn but finding a couple of pieces of pure nickel to use as anode and cathode proved impossible locally and too expensive to order online so I gave up on that. The tailpiece is in two parts, the piece the strings attach to which is all the majority of Zither Banjos and Zither Mandolin Banjos I've sen online have and a second piece of metal which goes between this and the wooden pot. The large metal bracket appears to be there to maintain the shape of the pot against the poll of the strings. I've seen this on one other banjo I've seen on the net. Using a small flat headed screwdriver and an adjustable wrench I replaced both parts. They still fitted the original screw holes despite my having reglued the pot. There's a gap of almost 1mm between the top of the pot and the edge of the tailpiece from when I sanded the rim flat again.

Using a  right angled torque screwdriver I reattached the neck. Messing about with difficult to reach slotted screws gives you a new appreciation for the crosshead screws.

Watching paint dry

Having reglued, woodfilled and sanded the pot it was time to repaint the thing. The pot's original black painted finish was pretty worn but I think the finish was closer to satin than gloss or matt -whilst it was havily scuffed on the outside on the inside surface of the pot it will've been protected from contact so I was able to tell it wasn't a heavily scuffed gloss or worn matt surface. I wanted to come up with something close tothe original but without the unpleasant lead content. I opted for a can of Plastikote Satin Black spray paint. It should be pretty durable and protect the aged wood for a long time to come.

Typically I'd've taken it outside, sprayed it, left it to dry, resprayed it and repeated until completed. Unfortunately the best temperature to apply Plastikote is 15-20 degress Ceclius and as we're approaching the tailend of January the temperature is hovering at about zero. Knocking a few nails into a piece of wood to use as handles and sitting the pot on a plastic tub I took it outside, sprayed it then brought it inside to dry.

It looked pretty smart but the paint didn't seem to be properly drying properly. It was sticky and I was able to mark it with finger prints. Not quite the protective coating I'd been hoping for. It may've been because I was spraying in such cold temperatures I suppose. Anyway looking online a few people suggested addressing that by spraying an acrylic sealer the top. So that's what I did. Although to try and speed up drying times I let it dry in the utility room with a fan heater running and the window slightly open so the paint fumes had some place to go other than the rest of the house.

However when it was finally dry I decided the indentations from where I'd filled cracks in the wood were too blatant and needed a bit more work. Roughening the surface with 400 grit sandpaper and wiping it down with cotton wool and naptha I applied some more woodfiller, it was a lot easier having finally found an old sculpting tool that'd been knocking about the house for years.

That done I went through the sanding it again, spraying it, waiting for it to dry, respraying it, waiting for it to dry, and so on. After a few coats of paint I sprayed a couple of coats of sealer on it and called it a day.

With a little more filing and filler I could get the surface even better but I don't want to completely lose the instruments age. Spraying the last few coats of black and sealer indoors seems to have made a difference to to the paint drying. Just needs a little work on the tailpiece then I can look at putting it back together and adding some strings and a bridge.

Cracked Tone Ring

I'd initially noticed one of the bolt holes in the tone ring had been over tightened causing a piece of the pot metal edge to break off. At the time I decided to just leave it be but yesterday whilst I was using a little vice to try and straighten out each of the warped brackets as best I could I noticed the edge of another bolt hole was cracked. The crack extended from both sides of the hole and it needed addressing because if the instrument ever gets played the crack may rattle and even worse left unchecked may grow and render the instrument useless.

Normally you'd dissemble the head and weld the crack but I don't know how to weld and don't have access to a welder. I also didn't want to fully dissemble the head as I suspect the vellum might not survive removing and refitting the tone ring. Luckily these days there's some alternatives to welding. I popped to Halfords and returned with a pack of Plastic Padding Super Steel Epoxy Weld, a metal filled two component adhesive. The blurb said it could be used to replace lost metal and showed a propellor wth a blade missing so I figured it was probably up to repairing a crack in a pot metal tone ring. As it could replace missing metal I decided to fix the other broken bolt hole too.

To avoid blocking the bolt holes I inserted round skewers bound with cling film. Mixing up some epoxy I pushed it into the crack and built it up above and below to provide extra support. To repair the missing piece of metal I used masking tape to form a gantry which I then filled with the epoxy. It's meant to dry in five minutes according to the blurb but it didn't where I was rebuilding lost metal -possibly because of the thickness. After a half hour I removed the skewers, cling film and masking tape and filled back the excess epoxy. There were a few places I thought it should be thicker so I mixed a little more and positioned it with a skewer. Then I went swimming. Well who's going to sit about watching glue dry? Returning, better for some exercise, I got out a few files andonce again tidied up the epoxy.

The dried epoxy had a dark shiny surface but once filled became matt and matched pretty closely to the colour of the tone ring. I think the tone ring is most likely some sort of pot metal basically a cheap mix of metals but mostly zinc, melted at low heat. Looking at the edge of the head I could see the hex bolts had quite visibly been overtightened in the past. This has buckled the tone ring and quite likely contributed to bending the brackets.

The Tension Ring (top metal bit) was a bit grotty so I wiped it down with naptha on cotton wool as I went round removing and straightening the z brackets one at a time. I also gave the surface of the vellum a rub down with a soft rubber eraser although I'm not convinced it had any effect. As you can see in the above images below the vellum is a sirt of dry excess vellum which should've been trimmed back once fitted. Over the years it's hardened to the point it fels like plastic. It probably effects the sound on the instrument possibly acting as a dampener so  I tried trimming it back with a scalpel but it was far too hard to cut. I could probably do it with the Dremmel but didn't want to risk damaging the main disc of vellum so for now I'm leaving it in place.

Threading the new brackets

Having cut and bet some steel to make new brackets fo the head I neeed to cut screw holes and tap a thread. Apart from not knowing how to tap a thread my initial problem was identifying what thread I actually needed to cut. There's a load of complex maths and confusing measurements involved in working out a screw thread, more so if it's imperial or you can just do it the easy way using a thread guage.

Each of the guage leaves matches a screw thread. You just hold the screw thread to the stencil till you find the one that fits. It's that simple. This one had fiftytwo imperial and metric threads.

The hex bolts seem to have a Whitworth 55 degree thread with 24 threads to the inch and a size of 3/16" which according to Wikipedia gives them a core diameter of 0.1341". I guess when Whitworth developed his threads in the 1840's people really hated round numbers, but they must've liked Whitworth's threads as they eventually became a standard.

I'd ordered a job lot of thread taps and dies from eBay and there was a 3/16" 24 thread tap amongst the rest. According to the chart on Wikipedia I needed a 3.7mm drill to make the hole for this sized screw, just to keep in confusing a 3.7m drill is apparently called Number Drill 26. As luck would have it nowhere I tried sold 3.7mm drill bits. I opted for a 3.5mm bit and figured the thread tap could probably cut out the extra diameter.

A brief look at a WikiHow post told me how to tap a thread. It also left me wondering why I never learnt this sort of basic stuff in metal work at school, I've never felt the need to make a crappy pen holder from a bent piece acrylic but how to cut a thread seems a really useful (and easy) thing to know.

Working in daylight, unlike when I initially cut them, I secured a bracket in my cheap but adequate unbranded chinese made vice and gave it a squirt with Metal Cutting Lubricant. A week ago I didn't know Metal Cutting Lubricant existed, thanks WikiHow. I then drilled a hole using the 3.5mm drill bit. That done I sprayed the bracket with more lube and put the thread cutting tap into a handle. Never used one before but it's basically a handle with a little vice type arrangement in the middle, one of the handle is threaded counter clockwise which is a bit confusing but means you don't loosen a handle whilstcutting the thread.

The tap is tapered at the start so had no trouble getting it into the 3.5mm hole. Basically you just press and twist the tap clockwise with an occassional counter clockwise twist to break off the shavings. The challenge is keeping it vertical at the start. It's surprisingly easy to be honest. at one point I gave it a little more lube but once the tap was a quarter of the way  into the bracket the thread was cut so cleanly that with a flick of the handle it was able to rotate freely.

I then tested it with a bolt. Perfect. At the other end of the bracket I cut a hole for the smaller screw to attach the bracket to the pot and using a larger drill bit countersunk the hole. These didn't need a thread as they were for wood screws which were going straight into the pot. I did the same with the other bracket.

Repairing the pot

I'd been fairly successful in correcting the warped back edge of the pot by rebending and regluing the strip that made up the sides but still needed to reattach the base. Wood glue adheres best to smooth surfaces so using a piece of sandpaper taped to the worktop I sanded the top and bottom edges of the pot sides smooth

Examining the pot sides there were a few hairline cracks visible so I put a little wood glue into them to hopefully stop them spreading. Hardly surprising to find a few cracks really.

Once the glue was dry I worked a little woodfiller into the crack and also used a bit more to tidy up the join on the pot side and fill another crack. I kept the filler to a minimum.

The base wasn't flat so I gave it a soak in boiling water and clamped it to a piece of aluminium. so it'd dry flat. It didn't work though. The disc cracked across the middle so I wound up soaking it and clamping it again as two different halves. Looking at the grain I'm pretty sure it's made up from two pieces of wood glued together.

In the end I got it flat as two separate halves and tested the fit.

Gluing the sides to the three parts of the base (two halves and a tiny piece) proved tricky because the wet glue was so slippery. eventually using a few clamps and a piece of wood below the pot for them to press against I got the thing in place although the edges of the split down the middle weren't married up
as close as I'd've liked. I used a bit much glue so once again there was a lot of run off. I figure it's better to scrape off the excess later than have a joint that starved.

 
I left the glue till the next day to reach full strength. As the halves of the pot base were flush to each other there were areas where it protruded beyond the pot sides. The holes where there had been nails from a previous repair were also clearly visible.

I pushed some wood filler into the cracks and nail holes and also right around the edge of the sides inside and outside of the pot. I suspect the white stuff I'd originally found below the black paint was some sort of filler rather than a primer.

As well as pushing the filler into the gaps I applied so it was proud of the wood surface. After giving it a couple of hours to dry I then set about filing the edges of the pot base so they were level with the sides and sanded the filler down to the level of the wood -or as close as I could get it anyway. This meant removing most of the filler visible from the picture above. Using the file and sandpaper I also rounded off the new edge of the pot base as it'd been rounded originally.

 I wasn't so worried about finishing the inside as it'd been pretty poorly finished originally and would be hidden under the vellum. Using a few different grades of sand paper I once again removed most of the wood filler. Whilst the outside of the pot is curved the inside is actually flat.

In the middle of the back of the pot there's a metal stud. I'm not sure what it's for. Suggestions on Banjo Hangout have suggested on a regular banjo a stud may be in the back to hold a resonator although on a zither banjo the pot is the resonator. It may be for protection or possibly just for decoration. Anyway rather than try whacking a nail through the pot I'd just repaired, pulling it out and inserting the stud again I located the centre of the pot and drilled a small hole to put the stud back in once the pot is painted.

Shaping new Brackets

Normally banjo's have a skin stretched over a wooden pot, but the zither banjo has a skin suspended on metal brackets within the wooden pot which acts as a resonator. The 'zither' part of the name comes from sounding similar to a zither apparently -the stringed instrument not the African wooden thing of the same name you rubbed with a stick at primary school.

On this instrument two of the metal brackets appear to have been replaced with brackets from another instrument which didn't really fit and seem to have contributed to warping the pot. When I removed the head I could see some of the brackets were slightly bent and the replacement two were thicker than the rest. The two replacement brackets were going to need replacing.

It looks like Zither Banjos like this haven't been made for about 70 years, having fallen out of favour as with a budget instruments like this one the strings can pull up the lower edge of the pot ruining the instrument. To get a couple of replacement brackets my choice was to either find another instrument with the same size brackets to cannibalise or make them myself. The chances of locating an identical 120ish year old instrument are a bit slim, and unless it was wrecked I wouldn't want to ruin it by taking parts from it anyway so I decided to make some brackets from scratch.

I popped to B&Q and picket up a metre of 10x2mm steel rod and a Dremmel. Measuring the brackets roughly they're length was about 55mm but have two bends in so I cut some 70mm lengths from the rod as I wasn't sure how they right angles would affect the length. Thanks to the early sunset I was working by torchlight, made things a bit awkward but the Dremmel sparks looked impressive :)

The brackets are 7mm across so I needed to trim the width too. I measured it all by sight instead of marking measurements as my pen wouldn't mark the metal and the Dremmel made quite a wide cut anyway. Each bracket used up one cutting disc completely, I also used a cylinder shaped sanding bit to finish the cut edges

With the pieces more or less cut to size I clamped the metal in a vice and bent it to as near to a right angle as I could manage before giving it a wallop with a little 3lb sledgehammer. Seemed to do the trick. The important thing was the distance between the two bends which I measured by holding an existing bracket to the one I was making when figuring out where to bend it. Once bent I trimmed the ends to the right length, again gauging the length by holding an existing bracket to the new one.

I got the brackets pretty close to the size of the originals. The thickness wasn't spot on but I'm learning as I go. The picture below shows my two new brackets needing to be drilled and one of the original brackets which is a little buckled.

The top hole is just a hole straight though for a countersunk screw but the lower one is threaded for the bolt. I'll need to find out how to cut a thread and identify the thread of the bolts at some point too.

Test fitting the head

Having stripped the pot back to bare wood I decided to check the fit of the head before gluing the base back on. After all this antique piece of wood has just undergone a lot of punishment with steaming, bending, regluing and having the old paint stripped. When I first took out the banjo head it had taken me about an hour to prise out as the fit was so tight.

Good job I checked it first. The head wouldn't go in at all. I'd removed the two oversized replacement brackets so in theory the head should've been a far loser fit than it had been. I'm also pretty sure I'd glued it correctly at the sides, the black paint marked the edges of the glued section so I was pretty certain I hadn't made it any smaller.

I'm starting to suspect that the 6 remaining brackets may also be from another instrument and be a millimetre so too big. They're all a little bent anyway. The brackets were all a little bent out of shape and but I don't think that accounted for the poor fit, more likely the other way round. At some point I'll need to try to straighten them before I properly reassemble the instrument, but that's a while off yet.

Giving the brackets the benefit of the doubt I decided to see if I could soften the wood and get the head back in then let it dry out with it in place.

Into a bath of warm water the pot sides went. Being wood of course it floated so I weight it down with a couple of skewers and a jar. I gave it a little over half an hour to soak then pulled it out gave it a quick once over with a towel as I didn't want to get any water on the vellum and managed to persuade the head into the pot.

The pot sides bowed in where the two brackets were missing, so I took apart a wood clamp and reassembled it reversed so it pushed out instead of clamping together then placed it where the missing brackets would've been. The diameter from the outside edges seems to be 18.6mm across with the head inserted so I jacked the clamp to the same distance and left it to dry again. I'd intentionally not placed the head in it's original orientation because whilst it was far rounder than when it'd arrived part of the rear of the pot was still a bit flattened where the strings had pulled it in I'm hoping the reorient ed brackets will help push the pot back into shape.