Author: dale

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Back to working in pairs

I finally went out and got the second rib jig from the garage and brought it down to the basement.  Ribs 24 & 25 are now curing, they will be ready to pull tomorrow evening.  My new routine:

  • Put the first jig on the bench.  Cut all the pieces fro one rib and set the geodetic pieces above and below the rib caps, ready to glue.
  • Stack the second jig on top of the first, cut all the pieces for it.
  • Mix up enough glue for both ribs (14cc seems about right)
  • Glue up the rib in the top jig and set it aside.
  • Glue up the rib in the bottom jig.

Double the completion rate.  I’m out of pre-cut geodetic pieces, so now I”m marking and cutting them individually with a razor saw.  It doesn’t take much longer, really, and each one is cut exactly to fit.

I’m almost out of pre-curved top capstrips.  The comments on the plans say you can bend the spruce dry and glue the ribs.  I don’t like the idea of having that much tension on the wood.  The nice thing about working indoors, though, is that I can keep hot water hot longer.  When I run out of pre-bent pieces, I’ll try the hot water bend method again.  In the garage the water cooled off far too quickly.  In the basement, I can get REALLY hot water in a capped length of PVC, and keep it hot long enough to soften the capstrip.  System 3 says T-88 works fine on damp wood…  I’ll try that and see how it goes.

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Got rib #22 done…

I finally took a minute to go out and count the ribs hanging in teh garage today.  Combined with the ones in the basement, I have 22 of the 26 required full ribs.  Four more and I can start on the 16 aileron ribs — they are identical to the full ribs, but missing one geodetic brace.  After that will come 34 false ribs.  I’m considering (maybe) using 1/16″, 2mm or 3/32″ birch plywood for those, just to speed up the process.  Haven’t decided yet, and probably won’t do it because of weight.  We’ll see once I get to that point.

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Six down.

Progress has been slow, much slower than I planned, but really — building ribs is a pretty low priority.  I have knocked out half a dozen in the basement, to add to the I-forget-how-many in the garage.  I’ll need to count them up soon, but I know I’m not at 26 yet, which is the count of full ribs I will need.

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Back at it – more ribs

Got the basement workbench cleared off enough to move rib production indoors.  So far I’m only using one jig, but I’ve knocked out two ribs now.  I need to get the second jig set up.  One rib per day isn’t going to cut it.  Sure is nice working in the basement instead of the garage though.

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It’s damn cold outside!

I’ve been wanting to get back to building ribs.  The garage bench has been piled too deep to get anything done, and now it’s been below zero for over a week solid.  Insulation or no, it’s damned cold out in the garage.  Too cold for epoxy to cure, and too cold to work.

So…  there’s a perfectly good work bench down in the basement.  8′ long and rock solid, built by Dad back in the 1960s.  It’s been pretty much completely covered up for the past several years with a collection of parts, partially-disassembled or -assembled prototype projects and assorted debris from the side business I was running, plus a CNC router that took up about 3′ of it.  I have cleared most of it off (much of it into a trash can).  The CNC machine is shelved for now; I’ll maybe resurrect it when needed at a later date.  It will probably come in handy for cutting the instrument panel and/or nose ribs.

The next issue is containers for the geodetic rib braces.  There are 24 braces used in each rib, all of which are of course slightly different.  Just enough so that none are interchangeable.  I was using paper cups to hold them in the garage, but it’s a completely unsatisfactory solution.  In the basement I think I’m going to try stapling taller plastic cups along the back edge of the bench and see how that works.

I’m not moving power tools down there from the garage, so new geodetics will be cut with a razor saw.  We’ll see how that works out…  it’s one of those jobs I wish I could set up a machine or fixture to do.  It’s 24 different lengths with over 40 different angle cuts, so I’m not sure how I’d make that work.  Even cutting them out in batches on the band saw meant fine-tuning each one with a sanding block before assembly.  It’s fiddly work and tedious as hell.  Classic gusseted ribs would be a whole lot faster and easier to build.  If I were starting this over I’d probably just depart from the plans and build them all that way; I’d probably have them all done by now.

 

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Getting ready for winter…

It’s only late August, but I’m trying to get started on cleaning up the garage / workshop for the winter.  I can’t build in its current state.  Too many other projects, too much clutter.  I’ve got to get stuff put away, thrown away, stowed, etc.  Then I want to get the rest of the geodetic strips shaved down for assembly, so I’m not out there all winter miserable as I run them through the sander.

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Another rib

Just so I could feel like I’m not totally stalled, I built rib #15 this weekend.  6cc of glue turned out to be just about right, with no skimping and very little excess.  The new method of mixing and applying the epoxy with an acid brush worked out well.  I think I will go back to an earlier idea I had, of pre-wetting the groove with glue before putting the top and bottom capstrips into the jig.  It will be easy to do with the brush, and will save some assembly time.  I have a template with pencil marks defining where the glue should go; I think I’ll mark the glue lines along the bottom and top of the jigs to make it easier to apply the glue.

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Mixing epoxy

I’ve been mixing epoxy in the little plastic medicine cups using “craft sticks” (think Popsicle stick).  I thought I was doing a pretty good job of stirring, spending some time scraping the sides and swiping along the bottom corners of the cup to ensure everything was mixed up.

Last night I mixed up about 2 cc of epoxy, mostly just to try out my new syringe dispensers.  I let it sit in the cup with the stick propped up in the center.  Today I popped the slug of glue out of the cup.  Lo and behold, there are sticky spots around the edge!  Nearly all of the glue is perfectly hard and cured, but there is just a tiny little bit of uncured epoxy right around the bottom edge.  Apparently the stir stick is not a good tool for making sure ALL of the material gets mixed together.

In light of that discovery, today I did another 2 cc sample.  This time I did the mixing with an acid brush with the bristles trimmed down to about 1/4″ to 3/8″.  After mixing I cleaned the brush out with a little MEK, just to see if that would be worth doing or not.  We’ll see how that one turns out after the epoxy has had a chance to cure.  Acid brushes are pretty cheap, so even if the MEK cleanup doesn’t work out it’s not a big deal.  You can buy the brushes by the gross for around $0.12 to $0.15 each.  But what will I do with about 950 craft sticks?  Good thing I have grandkids.

 

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Prep work

I’ve been away from building for a while dealing with a remodeling project, the annual condition inspection on the RV-12, Oshkosh and few other odds & ends.  At Oshkosh I discovered that the wood shop guys had actually saved my miniature wing rib from last year (2016).  I brought it home with me, of course.  Last night I pulled the staples, cleaned it up and sanded it, and gave it a coat of clear polyurethane.  I figure it will make a nice wall decoration for my office.

Last night I also started cleaning up some of the enormous mess in the garage so I can get back to building.  I’m not quite there yet, but tools are slowly making their way back into drawers and onto pegs.  It may take a few more days, but it will be nice to get back out to a garage that’s not a complete disaster.  There are 14 wing ribs hanging on the wall, and the guy on the Biplane Forum is catching up with 11 finished.  He can work faster, since he can pull his ribs out of the jigs as soon as they are stapled.  I need to step up my game!

I did pick up a good idea from that discussion — using cut down acid brushes to mix & apply the epoxy.  They’re cheap, and it looks like I might be able to get more precise application of the glue where it’s needed, in the amount needed, with good penetration into the wood grain.  I’m anxious to try that, I have a handful of brushes here.  And, I got some of the epoxy  into 60 cc syringes so I can dispense exactly the same amount of each component.  I know it’s not terribly critical with T-88, but I still want to be as accurate as I can.