Tag: Wood

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Ready for ribs

Well, the work bench is cleared off — well, at least enough to get both jigs on it.  I’ve got a couple dozen sticks of geodetic brace stock shaved down.  The epoxy syringes are filled.  All I need now is a razor saw and a steam setup.

Yes, I have a razor saw.  Somewhere.  I pulled it out during the kitchen remodel, and I remember seeing it in a box of tools we were using, but now I can’t find it.  It’s a Zona, good quality but inexpensive.  A new one is on the way.  Two, in fact; one medium and one fine tooth.  I also have a steam box that I built for the capstrips, but I’m unsure whether I’ll use it in the basement.  It takes bench space (which I now don’t have down there), and drips water out the end by design.  I’m thinking about ways I can use it vertically.  I had looked at rigging up a piece of pipe or something with a heating element for hot water, but it looked like an awful lot of extra work considering I’m over halfway through the ribs.  I’ll probably need it for the tail and wingtip bows as well, but I’m not entirely sure yet how I’m going to steam 6 to 9 foot long strips of wood.  Tonight I tried soaking half a dozen capstrips in a bucket of hot water for an hour — we’ll see how well that worked. 

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Back at it…

Well, I thought it had been a lot longer since I did any construction, but I see it was only back in February.  I really wouldn’t have been surprised to find that I’d gone an entire year without building anything.  But, I’m getting ready for winter and more building.  To be honest, I’d had second thoughts recently about even continuing with this project.  Sometimes it seems like such a massive undertaking, especially when I see pictures of guys attaching the wings and getting flying wires made and rigging done…  only to tear it all apart again and then start covering.  Covering!!  How the hell an I ever going to cover this beast?  But then I decide that maybe I’ll keep at it after all.  Hey, it’s relatively cheap…  so far…  as hobbies go.  It keeps me occupied for as long as I care to work on it, and nothing bad happens if I let it sit idle for a while.  Even a long while. 

Over the past few days I’ve been working on getting my absolute pit of a basement workshop cleaned up at least enough to be able to move around and use the workbench.  A new water softener installation, a kitchen remodel and a few other household projects meant there was a lot of mess left over, and a whole lot lot of crap got just piled everywhere.  Most of it’s cleaned up.  Not enough, really, but at least enough for me to be able to take stock of where I am.  In hindsight, I suppose I could have, you know, looked at my blog posts, but where’s the fun in that?

I need 26 normal wing ribs, and they are all done.  I need 16 aileron ribs — the same as the normal ribs, but just missing a couple of cross pieces.  Of those, I have built ten, so there are six left to build.  Then there are 34 false ribs — just stubs from teh leading edge back to just behind the main spar.  I’ve built one of them, so 33 left to build.  Those should be quicker to build, since there are only about a quarter of the geodetic braces to cut and glue.  Unfortunately, each will still occupy a full rib jig — so two at a time is still the limit.  Unless…  maybe after the aileron ribs are done, I can tear down one of the rib jigs and rebuild it to do several false ribs at a time.  I think keeping one rib jig intact would be good, just in case I should ever need to build more ribs for a repair or whatever. 

I’ve got a bunch of geodetic brace stock sanded down to the correct thickness.  Enough for sure to do the rest of the aileron ribs and get a good start on the false ribs.  I’ll probably do half a dozen more, then put the oscillating sander away and maybe knock out a few ribs.  I’m starting to get a little fired up again. 

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Slow progress

I’ve knocked out a few more aileron ribs, two at a time.  I’m about halfway through them and trying to speed things up a little, so I don’t die of old age with a half finished airplane.

Yesterday I decided to use up a piece of obviously bad capstrip Aircraft Spruce saw fit to ship me.  This piece has a large chunk missing out of one edge, part of a knothole or pitch pocket or something.  Part of it is in no way suitable for aircraft use or much else for that matter.  But – there’s enough good wood there to use it for false ribs, so I made one of those.  That went OK, but it’s apparent that I will need to soak the top capstrip in HOT water for the false ribs.

I’m looking forward to starting work on the tail surfaces.  I’m planning to get out to the garage and clear off the workbench this week, lay out the plans and see exactly what I will need to get started.  The wood called out is white pine, so I’ll start checking the local places for suitable pieces of white pine or Douglas fir…  a little heavier, but I know Menard’s sells some good boards from which I can cut suitable pieces for the laminations.

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Plugging along on aileron ribs

Five down, eleven to go.  Cutting the geodetic braces individually is really not as much of a chore as I thought it would be.  I am finding that I’m going through the 6′ lengths of stock quickly, though — I figure I have enough shaved down for the next 3 ribs, maybe 4, then I’ll have to fire up the drum sander again and make some more.  Not that it’s stupidly tedious work or anything, mind you.

In hindsight, it would have been a whole lot less work and actually less expensive to have bought 3/8″ thick spruce spar stock and just ripped it down to 3/32 strips, losing half the board to saw kerf.  I am at a loss to explain why that little bit of math didn’t make itself obvious.  Of course, I thought at the time that shaving 1/32″ off those strips would be quick and easy.  Not so much.  So…  if you’re building a Celebrity from plans, you’d be better off doing that.

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What next?

It’s a little early for this debate, but given the long lead times for ordering wood…  not too early.  I could possibly be done building the wing ribs in a month or two, if I get on it with a purpose.  If I’m going to need a bunch of spruce, I probably need to get the order in now.  So the question becomes — what next?

  • I could build the wings.  It looks like the wood for the spars will cost me around $8-900, plus substantial shipping.  I’d also need to extend my workbench by at least 4 feet, so that’s another project in itself.  But I’d have wings, man, which would look bitchin’ cool hanging in the garage or hangar.
  • I could start on the fuselage.  It’s a big piece that would be a huge leap forward.  I haven’t calculated the wood cost yet, but it’s a significant amount of birch ply and spruce.  Again, I’d have to build another workbench to extend what I have by 8 feet or so (and rearrange the garage).
  • I could start on the tail feathers.  I could do all the work on my existing workbench.  After looking at the parts list, most of the wood specified is pine; I’d need some aircraft ply as well.  The elevator & stab. spars are specified as spruce, but I could source suitable quality Douglas fir locally and substitute that.  I’ve seen boards at Menard’s with growth rings and grain slope that meet specs, with enough defect-free wood to be usable.  That means all I would need to ship from Aircraft Spruce or Wick’s would be a couple sheets of plywood.  Plus, building the tail would give me some valuable experience with large/long glue-ups that I’ll need to do for the wing spars, and if I screw it up it’s relatively cheap pine instead of very expensive spruce.

So…  tail feathers it is.  Now I just need to consult the plans and see what size sheets of plywood I will need to order.

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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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Bending more capstrip, and glue efficiency

Last night I tested out the upgraded steam box door with an hour of steam.  While that was going on I grabbed a chunk of scrap 2×4 and cut a second bending form.  I wasn’t happy with only being about to bend three lengths per run of the steam box.  I really need a better blade for that band saw…  this one is cheap, and while it will claw its way through a 2×4 it’s not something I would want to do regularly.

But — I have two bending forms, which means I can now do six lengths of capstrip at a time, so I won’t run out as often.  The steamer seems to work pretty well.  It’s not quite as perfect as if I had attacked it with a planer, jointer and an attitude of complete professionalism…  but I don’t have a jointer or planer, and even if I did what that steam would do to cheap flat sawn boards would be a real downer.  It works.

On the last several ribs I’ve been taking a different approach to gluing.  Early on I found that trying to glue up two ribs in one night meant working with epoxy that was starting to get a little stiffer than I would have liked.  I was using a popsicle stick to carefully spread glue in the groove, then on the braces, and assembling.  I was also having to fit each brace piece as I went along.  Each rib seemed to want about 10cc of glue, but I was getting a fair amount of it running down onto the plastic on the jig.

Now I pre-fit all the braces and mark them with their location.  I mix up the glue, dip the ends in the glue and put them in place.  I can work a lot faster and make less mess.  I’ve been seeing more left-over glue than I would like, as much as half what I mixed up.  I think about 7.5cc of glue per rib is more than enough.  I mixed 15cc for one pair of ribs and only had a little left over.  I’ve also been more careful about the glue mixing.  I had the ratios close enough to work well, since T-88 is not too critical.  Still, the darker B component was getting used faster than the A, and that tells me I’m not getting it completely right.  The stuff is pretty viscous, B much more so than A, and it takes a while to level out in the mixing cup.  Now I’ve been squeezing the B part into the mixing cup and walking away for a few minutes while it levels out.  Then I add the A component, walk away again, check back in a couple of minutes.  I can get it dead on 50/50 that way.  I may see about building a 100:83 balance scale to get it even closer.

 

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Fixing up the steamer

I built two more ribs last night and took them out this morning; I’m up to 14 now.  I’m trying to 3D print some clamps too use on one of the jigs that has locating blocks too thick to use the small red sprig clamps I bought.  of course first I have to fix the 3D printer…

When I used the steam box, the door warped — no, curled outward.  I flattened it out, but because everything isn’t perfectly square it really only fits on one way so I can’t just flip it over.  Tonight I cut a couple of 3/4″ square stiffeners and epoxied them to the outside of the door.  I need to bend some more pieces of capstrip, and I can’t do that until the door is usable.  We’ll see if this is enough or not, should be interesting at least.

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Trying out the steam box

The other night I finished up the steam box and made a set of little standoffs for the bottom.  I wanted to keep the wood off the bottom of the box to allow air circulation, but also allow water to run back to the low point at the rear.   I got a little lazy and didn’t put in dowels like most plans show.

Tonight I loaded it up with eight cap strips and let it run for 45 minutes while I went out and hung some outdoor lights on the deck.  When I came back I found that the door had developed a pretty good curl — concave from the outside – and was venting a lot of the steam past the door seal.  The spruce inside was fairly pliable, so I clamped three pieces in my bending form and put four more in the rib jigs.  They would only fit partway down in the jigs, since the wood is swollen.  While the wood cooled down I got all of the geodetic braces ready to install.  I’ll glue these two ribs up tomorrow night.

I did email System 3 about their epoxy.  Some of the ribs were assembled with the capstrips not pre-bent.  They’re fine, but the wood will spring out of shape if it gets hot enough for the epoxy to soften.  I don’t want that to happen. so I was thinking about clamping them in their current shape and steaming them to relieve some of the stress in the capstrip.  Of course that will soften the epoxy, and I wanted to know what that would do.  Their answer is that T-88 will begin to soften at around 120 degrees, but once returned to room temperature will be at full strength.  That’s great news.

I’m definitely not in love with the geodetic rib bracing design.  24 braces, no two alike, and I’m having to hand-fit them all.  It takes for-freaking-ever.  I have to wonder how much heavier 3/32 plywood would be with suitable lightening holes.  A guy could pop sets of them out on a CNC router in no time, save a ton of time and effort on the ribs, and probably end up with much stronger ribs too.   But, I don’t think I’m going to re-engineer the ribs right now.

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Built a steam box

Last night I built a steam box out of 1×6 boards.  All that remains to be done is to put some foam weatherstrip on the door and run a few dowels through it to get the wood off of the bottom of the box for steam circulation.  The steam generator arrived a few days ago, so once I get the box finished up it will be ready to go.  I found that the Wagner steamer hose will mate with 1/4″ pipe fittings.  I spent a little extra for brass rather than galvanized iron.  I also re-worked my bending form with a gentler curve, providing a fairly close match for the rib shape.  It won’t give me a perfect fit, but will get the capstrip close to the curvature needed.