Days 7 (11-30) and 8 (12-1): Final Planing, Gluing, and Sanding – Part 2

As mentioned before, his resin is Epon 828 and hardened with Epikure 3140, which he uses normally in 1:1, but can go up to 2 parts epoxy to 1 part hardener (which is pretty close to 1:1 stoichiometry, or 100g to 198.4g epoxy).  So, first measure out the hardener for how much you think you’ll need, then get to that amount or just over with the epoxy; it’ll be dialed right in simply by your process so you won’t have anything to worry about.  That’s a convenient trick.  There are other epoxy systems that work well too – I’m exploring those right now (hint: DER 671-X75 or -T75).

 His batches were about 200-250 GRAINS total, but I only got through my butt and 1 tip with that before my cup was about dry.  Because that was too little, and my scale is a gram scale (not grains), I’m going to show you the math for converting:

Per Google, 1 gram = 15.432584 grains.  So Jerry’s batch size would have been about 15-16 grams.  THAT WAS TOO LITTLE.  Bear in mind I needed to make 2 batches to get through my rod, I used about 20-25 grams of glue, and I thought I was going rather sparingly with the glue despite being sure to obviously coat everything well.  In short, my rod wasn’t dripping – really thin coats are hard with that stuff at it’s full viscosity. Doing a rod any bigger and I would have wanted to have a 40-50g batch for myself.

 Mixing: this epoxy system (828 and 3140) turns a light, milky caramel color when mixed.  You have to be careful to get all the stuff off the sides and bottom since you can’t really see what you missed.  I also noticed it tacked up quite a bit in the 10 minutes or so following mixing and application.  I really thought a few drops of some solvent – acetone, denatured alcohol, etc – would have been nice to cut the viscosity, but then you would have to air dry the rod a bit to let the solvent flash off, then bake it lightly after binding to drive the solvent out of the rod.  Otherwise the potential for the solvent to affect your finish is there.  (I don’t think it would have much effect, if anything visible, but still – potential is there).

 ((PS – if you want to extend the shelf life of your adhesive materials to nearly infinitely long, keep them sealed and in the freezer.))

 Glue was applied with a cheap toothbrush.  The most “critical” sides to get were the two outside faces, because the natural tendency is to focus on the center strips, which leaves the junction of the two outside faces weaker due to having less glue.  Be sure to wet them well – the reflection in the light will be a good reference for your glue coverage.  The faster you can mix up your glue the faster it can be applied to the rod before it tacks up.  Frankly I would have preferred something like a 1″ white china “chip” brush or even a real bristle brush for better pickup and spreading (read: not so many dips in the cup for more to spread) and either way, white china brushes will allow themselves to be cleaned with acetone, mineral spirits, or some other thinner allowing them to be reused at least a couple times.  Preserving a nice WC brush will take a little work cleaning though.  Chip brushes can be tossed out if desired.

 If you haven’t been wearing them already, put on some cheap latex or nitrile gloves for this.  Pick up the section from the paper (it will be stuck by the adhesive’s tackiness) by the butt, gently teasing it up an inch or so. Then guide your fingers from the other hand slowly along to lift the entire piece bit by bit, eventually lifting the entire section up.  Now you have to prep it for the binder: once up, hold on to the butt and let it hang freely – that was very important and is how the sections should always be held while the glue is still uncured.  Guide the outside edges back together, taking care to make sure again that all of the enamel sides are facing outwards.  Squeeze (don’t slide your fingers!!) the section together; the glue’s tackiness will hold it nicely.  Work your way down the section and press the strips together all the way down.  Support the section (no bends if possible, minimal otherwise) and move it to the binder.  Then run it through the binder and move on to another section.  Don’t press the strips together and then set the section down before running it through the binder; sliding can occur.  That’s bad.

 After binding was done, a loop of binding thread was attached to the tip end of the section.  Then the section was grasped at both ends (or as near as reasonable) and pulled, almost stretched, to prevent sagging and bending. Then it was hung up to let the glue set up enough to allow sanding. It is important to note that the section was NEVER BENT, not even by gravity. We did sight down the section by supporting it in the middle, though, to check straightness.  It was most important not to let it sag as the tip and butt were held (especially on the tip sections).  If straightening needed to happen, we rolled the blank under a board to nudge it in the right direction.  Final straightening will happen after the glue cures, if it is still needed.

 Sanding occurred within 24 hours before the glue set up too much.  It was of a “hard rubber” consistency when taken off with 220 grit sandpaper.  Cooler temperatures will draw out the time before sanding is safe, and warmer temps will shorten it due to the different times in which the adhesive will set up.  Correct pressure for sanding is about the weight of the sanding block, or about 8 ounces.  Doing the tips gently also meant decreasing the pressure a bit to avoid rolling the tip as the third, fourth, and fifth flats were done (explained below).  The block must also be kept flat as in planing to maintain the apexes, otherwise they’ll round off and the hex shape will be greatly decreased.  This is also why soft-bottom blocks are a bad idea – a very flat, hard surface needs to be behind the paper to keep it flat.  Change paper frequently to avoid having to work at it too hard and risking injury (tendonitis is a big danger here) – one strip of 220 did about 2 flats on the butt and 3 flats on the tips.  By the time sanding has become work, the paper is dead.

It was suggested, and also found, that doing the tips of each section first was beneficial in keeping the hex shape.  This was, of course, most obvious on the tip of the tip section.  Moving down the blank toward the butt about 10 inches (more or less, depending on your particular taper) to find each flat where it was first well-defined, place the butt of your hand to hold the rod and keep it from rolling.  Start sanding with light strokes in the direction of the rod tip ONLY to slowly remove the glue and reveal the flat.  Work your way down until the tape, glue, and pencil marks are gone.  Then flip the rod 180 degrees and do the opposite flat.  I found it easiest to then do a third flat by moving another 4 or 5 inches down the rod and repeating the process of cleaning up the tip.  Moving further down the blank allowed better stability. It’s not necessary but I found it convenient with my little rod.  Work the tip gently to avoid twisting it.  The problem with the tip is that its small diameter doesn’t correct for the excess glue forming concave drips on the outside of the rod blank, so it leads to a round rod.  Be very careful not to round out the tip.  Remember to be sanding in only one direction – the paper tends to grab the tacky adhesive and you don’t want to rip the rip back that sharply.  It will either put a nasty set in right at the tip, or break.  Not worth the few extra minutes it takes doing it right.  This isn’t an issue with mid-sections nearly as much or with butt sections at all due to the extra rigidity of all the wood in the blank at that point.

Once the tip is done and the rod is sanded back at least 10-15 inches from the tip (finer rods need to be sanded further back), begin really sanding the glue off by doing 6-8″ sections at a time, sanding back and forth using the full weight of the block.  It goes surprisingly fast – don’t push down on the block despite the temptation to go even faster.  It’s not worth it, and it’s not needed.  It is very exciting to see the rod this close to being finished but relax, take it easy, the best is yet to come – ferruling and finishing.

Hang it back up (clamps are fine now that everything has been sanded off; string doesn’t have anything to stick to anymore) and let it cure for a week.

 

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