Building banjo #44, part 4

On  the evening of the 24th I had a bit over 2 hours of time to spend in the shop.  My first priority was to make the dowel stick and glue it into the neck mortise.  I found a piece of leftover cherry that was about 1 inch square and had minimal grain runout.  I ripped it down to just over 3/4″ square on the bandsaw and marked an X from corner to corner on both ends.  I have a handy plastic doodad for this that was in a box lot I got at an auction, but I forgot to take a picture of it.  I used to do it with a ruler too.  Then I cut about 1/8″ into the tenon end of the X on both arms, using the bandsaw.  I stand behind the saw to do this so I can see exactly where I’m cutting.  Then I drill a hole to accommodate the spike on the drive spur.  I lined up the X on the tailpiece end with the dead center in the tailstock on the Shopsmith and tapped it in a little way with a mallet, and then scooted the headstock up to the X with the cuts and lined it up so each arm of the spur was in its slot.  I thumped the headstock toward the tailstock briskly and tightened the clamp so it would stay in place.

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The pencil mark on the side shows where the shoulder of the tenon should be, approximately.  I began to turn the tenon down, aiming for 5/8″

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The caliper is hard to read but it says .624, which is about ideal for me.  I like the dowel stick to require both hands and some force to install dry, but not to be so tight that is has to be tapped into place as that could crack the heel.  I have found that anywhere between .615 and .625″ will work fine, though the lower end of that is a little less than ideal.  The next step was to take the dowel stick off the Shopsmith and cut the square end off the tenon.  Then I cut a very small channel with a knife to allow glue to escape when I put tenon into the mortise.  I hope it will show up in the picture.

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Then I put glue in the mortise, all around the edge in a thick bead.  I want to make sure that as I push the tenon in it will be pushing glue ahead of it all the way around, and this should make a good joint.  I put the channel on the bottom of the neck and with the neck in my left hand and the dowel stick in my right I pushed it in and a small stream of glue came out of the channel and fell on the floor.  I adjusted the rotation of the stick till it looked parallel to the fretboard from both ends, to my eye.  I set the neck on the treble side to dry so that if any drooping happened it would be to the treble side, since when I had dry fitted the dowel stick it had looked like if it was not perfectly lined up it might have been angled to the bass side a bit.  I have not developed a jig to ensure perfect centering, but I think it might be a good idea.  I get pretty close by sighting from both ends but it could be better, I’m sure.

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I left the neck to dry and moved on to working on the tension hoop.  It is made from a piece of 360 brass, 1/2″x 1/8″ in cross section and long enough to go around.  My first dozen were made with what was described as soft 360 brass from Speedy Metals, which was easier to bend and came in 4 foot lengths.  I later found that I could get a better price from Online Metals and their 360 brass is described as ‘half hard’.  I am not up enough on metals to understand that, but it is stiffer to bend for sure.  I bought 10 of their 7 foot pre-cut pieces and each on will make two 12″ hoops with 6 or 7 inches left over.  The first picture shows the brass with one end held in the vise.  This is the second hoop from this 7 foot piece so it is extra long.

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Next I bent the brass by hand into a sort of spiral shape.  In the picture I show it being about 1-3/4 turns, but in order to get it to end up near where I want it I have to make about 2-1/4.  I was afraid I would not be able to hold that with one hand while I took the picture.

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The next picture shows how far it sprang back when I gradually released the tension.

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Once I had bent it tightly enough to spring back close to where I wanted it I began to tweak it in or out as needed here and there.  I use the rim as a reference point to see what it needs.  In the next picture I am ready to cut it to length.

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The next picture is cutting it to length with the hacksaw.  I also cut brass on the bandsaw sometimes but I had just put a nice new blade in last week and didn’t want to accelerate the wear on it, and it takes less time to make a cut with the hacksaw than to put a different blade in the bandsaw.  If I was making a bunch of cuts I would use the band saw.

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Then I sanded the ends square and clean on the little belt sander, fluxed the ends and clamped the hoop to the bandsaw table with the ends butted up tight to each other.  I think there must be a better way to do this, as it can be hard to get the end to stay perfectly aligned as I tighten the clamps.  Some sort of fixture seems called for and I have a couple of ideas but have not tried to make them yet.  I used Harris Stay-Silv flux and 15% silver solder, and a regular Bernzomatic torch with MAPP gas.

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After it cooled I cleaned up the soldered are with the belt and spindle sanders and some hand sanding.

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Then I did some more tweaking of the roundness of the hoop and test fit it with a head.

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It still is not perfectly round but it’s pretty close.  Then I used a sewing tape measure to mark 1-1/8″ on each side of the brazed joint and then used some clothespins to hold the tape on the hoop so I could make 9 markson each side,  spaced at 2-1/8″ apart, starting at  the marks by the joint.  This leaves the space between the marks at the neck at 2-3/4″

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Then I put the table back on the Shopsmith and put a short 11/64 drill bit in the chuck.  I clamped a stop block to the table and set the height so that the holes are just slightly higher than centered.  I had a hard time at first with regular drill bits bending as I tried to drill brass, but I got a 10 pack each of 11/64 and 9/64″ short drills on eBay (I think they’re called “screw machine length” or something like that) and they drill so easily through the brass that it’s become a fun job.  I am still on the first one of each size, so I think a 10 pack will last me for many years to come.

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Then I used a Dremel tool with one of those little carving bits to cut a crescent away on the inside of each hole, on the bottom side.  This is to accommodate the end of the hook.  I am still using this same carving bit that I got with my first Dremel tool when I was 14 or so, but one of these days I will buy a new one.  The brass carves pretty easily.

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Then I sanded the hoop with 220 paper to remove the pencil marks, burrs, and bits of brass that stuck out where the drill bit came through on the inside.  The last photo is a close-up of a hole to try to show the shape.

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Then I did a little vacuuming and putting away of things and quit for the night.

 

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