Category Archives: bandsaw

Tank attach brackets

I finished up countersinking the fuel cap brackets and moved on to the tank attach brackets. These have a bearing, some shims, and three different kinds of nutplates that need to be attached.

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As always, first I had to find everything.  I had put the shims by the brackets themselves when I was hunting up everything at the start of the chapter, but it took a while to dig out all the nutplates.  The MS21051-L08’s in particular were a bear to find.  They are in bag #3015.  They are the only nutplates in there.  The spreadsheet of parts was very helpful! I separated the shims on the bandsaw and carefully deburred the holes (the instructions note to do a good job with this, particularly on the #8 screw holes).

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The shims have to be trimmed to match the ends of the attache bracket.  The narrow shim in particular has a very slim edge clearance to the outer nutplate hole.  I carefully sanded them down on my sanding disk to get the a close clearance.

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I marked the “primer line” on the attach brackets and started clecoing the nutplates in as I found them.  I’m substituting K1100-08 for the K1100-08D because I’m going to use “oops” rivets instead of dimpling the tiny shims.  I’m afraid that the shims will warp badly in the dimpler.  The hole on the end, in particular, is way too close to the edge for my to think about dimpling.

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I filed the cut marks off of the brackets before running them through the Scotch  Brite wheel.  The initial edge was a little sharp.  So I donated a few more drops of “Blood, toil, tears, and sweat” to the project.

The RV-12 was feeling a bit neglected.  The early low clouds had finally risen.  My son Ryan came down for the afternoon, so we fired up 3EN and did some pattern work.  He is getting ready to start his flying lessons, so I let him do one of the takeoffs and one of the landings.  He did a great job!

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I primed up the external parts of the brackets and shims and countersunk the brackets.  The picture shows a test fit.  The bracket lays tight to the skin and the shims have sufficient clearance.

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The final step for the day was to rivet the flange bearings onto the brackets.  This is where I really like working both right and left together.  I’m able to make sure I’ve got everything set up correctly.  The nice mirror image gives me some assurance that dyslexia didn’t bite me here.  I don’t show the riveting, but it came out pretty nice.

I have a few more things to finish up before diving into the Proseal.  I have to rivet some nutplates to the shims and then the shims (with more nutplates) to the brackets. I’m using the NAS 1097 rivet trick here rather than dimpling to avoid warping the shims.  I got the light countersinks done, but then had to jet to meet my wife for BBQ at Killen’s.

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The spar is finally done….

The work on the spar really dragged on.  Section 13 is another one of those nasty little sections that just drag on and on…  It is only 3 pages of instructions, but oh, there are so many holes!

I had a long break in the work as I was off in Houston helping my brother out.  He was starting a new job (actually returning to an old one after a few years of trying a startup). He needed some help watching his family while he went to Chicago (in the midst of the Polar Vortex) and followed that with a week in frosty Delaware.  The long and the short of it is that I lost 3 weeks in the aircraft factory (but earned the love of my brother).

It was pretty cold in the shop, a pretty hash 18 degrees.  My torpedo heater brought the temperature up to almost 60, but with the high roof it just kept sliding back to freezing.

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I finally got to the point where I could install the 120 some odd nut plates.  This went pretty smoothly.

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I did mess one up when I didn’t have the squeezer set when I hit the trigger.  I managed to drill it out (with a small bit of my finger).   This is a plane building right of passage, apparently, glad to get that out of the way.

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While I was doing that, I put my son to work deburring and smoothing the lightening holes in the many, many ribs.  I had a little Scotch-brite flap wheel installed on the drill press.  It made pretty quick work of the task.

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He did some nice work!

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I was still in nut plate hell, so I let him head home to warm up. I kept plugging away at the nut plates.  Eventually, you do get to the end of it.  Yay!  All the flange nut plates are in place.  The blue tape is there to (1) keep the aluminum chips out of the gap between the flange and spar web and (2) mask it off when I spot prime all the countersinks.

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With the nut plates in place, it is time to countersink the fuel tank screw holes and the inspection plate screw holes.   There’s a couple hundred of those to do as well.  Van’s provides specs for the max hole size.  The bottom of the spar went really great.  My holes were all smooth and consistent.

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A quick hit of primer, and I wrapped up for the day.

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The top countersinks did not go as well.  I chipped my countersink bit which made very rough holes.  I ordered new ones Sunday night from Brown Aviation.  They were delayed a day (FedEx wouldn’t deliver in the blizzard), I still got them Friday.  Saturday, I finished the top screw countersinks (much easier with a good, sharp bit) and spot primed the spar as well.  With that, I finally finished the first two pages (it took a full month of build sessions, sigh).  The last page covered another dozen nut plates on the spar face, 10 final AN470 4-6 rivets at the end of the spar, and the aileron bellcrank bracket.  The hardest part of the bellcrank bracket was finding all the parts.  The W823-1 brackets were hard to dig up (they are in one of the small parts bags).

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I had to mentally put myself back into part prep mode — I really hadn’t done any deburring and priming since before Christmas. It was nice to install some green parts on the spar.

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At last, Section 13 is done!

I got started on Section 14.  It begins with some part prep.  I had to replace my bandsaw blade since some of the teeth had gotten bent and were messing with the cut.  This meant a trip to the aviation department of my local Home Depot (I was breaking for lunch and ice skating lessons anyway).  I deburred and primed the parts for the whole section.  You have to be careful because some of the left and right parts are nearly indistinguishable.  There are many cautionary notes in the instructions and the blogs to mark them before separating them.  I added the markings to drop paper so that I could keep them all straight (important since the acetone wipes off all the marks).    I put them far apart on the paper (left parts on the left side, right parts on the right side naturally!).

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The parts were rough from the bandsaw cuts, so they needed some filing before moving to finish on the Scotch-brite wheel.  The aileron brackets are very hefty chunks of aluminum.  They appear to be cut with a water jet and are very rough.  They needed some serious work in the vice with the bastard file.

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I made a lot of magic pixie dust!  They polished up very nicely though.

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That gave me a nice pile of parts to end a solid day at the shop.  I’ve got all the parts for Section 14 ready to go (including the two bearings).

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Sunday was a lot warmer than Saturday —  The mid-40’s seemed almost tropical.  It was the first day in months that I could work in the shop without running the heater.  I even left my jacket in the car!  I did have to shovel a foot and a half of snow to make a path to the shop door though 😦

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The first real step in Section 14 is to square the rib flanges.  I made a little tool from the end of a paint stir stick to check them.  Most were pretty square and didn’t need any adjustment.  My seaming pliers fixed the rest. Not hard, but there are 28 ribs to check!

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The ribs also needed fluting.  They look pretty straight, but if you lay them along a straight edge you’ll see a pronounced bow.  Three or four flutes on each side of each rib took care of that.  But with 28 ribs, that’s 150 flutes!

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Lastly, I reamed the #40 skin holes, deburred them with some Scotch-brite, and dimpled them.  I now have two piles of ribs.  After I dress the flange edges and prime, they’ll be ready for assembly.

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Back to the grind… Wing inventory and the rear fuselage

Sunday, 30 November

inventory only took about 3 hours.  Lots of new rivet types.  So many nut plates that it made sense to sort them into their own bins.  Many of the drawers that were almost empty are now full again!  These are all the new rivets ready to go back in the organizer.

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Most of the parts are actually in the smaller spar crate.  It is packed very tightly.  The spars are truly beautiful.  Individually numbered too!

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And, the wings are officially a “project.”  As anyone knows, you need at least 3 trips to the hardware store and, in my house at least, a blood sacrifice.  I snagged my knuckle on one of the crate staples to satisfy the later requirement.

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With the wing parts unwrapped and cached in my cabinets, it was time to get cracking on the rear fuselage.  Right now, the wing crates are along the back wall (where the empennage crate sat) and the empennage crate is uncomfortably situated between the far wall and the work tables.  I’m hoping that I’ll get the crate emptied soon and recover the floor space.

The first part of section 10 is cutting out parts.  It feels weird to do this after such a long hiatus.  It seems like months since I deburred and primed parts (because it was months ago!).

I went to cut the parts on my bandsaw since that is so convenient (one of the helpers I met during the EAA workshop told me that a bandsaw was absolutely required… he was right!). The lead counterweights for the elevator, in addition to being cut wrong, also dulled my blade, so it will be (another) trip to the Home Depot Aviation Supply Store.  Meanwhile, I cut the j-channel and other parts using my metal snips.  You also have to modify the F-1037B part to have a little chunk out of one end.  I marked it up and drilled the hole (just used my electric drill as it was not worth the effort to fire up the compressor).  The plan is to rough cut the notch and then file the edges to ease up on the nice round corner. I’ll get a new saw blade and finish the rest of the cuts later.

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So not a bad afternoon!  Inventory done (no parts missing) and a few parts rough cut!2014-11-30 16.38.43

Tuesday, 2 December

Well, my contract job ended on Monday and, while I have a new job in the works, I’m gainfully unemployed for a week or two.  So, I got to work on the plane mid-week!  I’m hoping to get most of the rear fuselage done by Christmas when I can get my kids to help with the riveting.

I got a new propane space heater for the garage.  I worked last winter when the temps got down to single digits and that is just too cold.  My garage space is way underpowered, so electric heating is out of the question.  I can run this new heater for just a few minutes to bring the temps up to the mid-40’s or 50’s.  Warm enough to work, short enough to avoid CO poisoning.

I also ran to Home Depot to get a new bandsaw blade.  It was the wrong size!  So I had to go back and exchange it.  Finally got to work much later than I hoped.

I started by reworking the trim tab push/pull arm.  Van’s issued a service bulletin about the arm (the original design was a little too short).  I didn’t like the way the original one turned out anyway (and was planning on re-ordering), but I got a new one tucked into the wing kit!  The photo makes it look much longer, but it is only a tiny bit bigger.2014-12-02 16.46.47

Page 10-04 is quite daunting!  I have to fab two parts from (not quite) raw angle.  It’s not as bad as a scratch built because the angle is all cut to length and there are predrilled holes.  Not too much to go wrong.  Also, the plans have full size drawings to allow you to check the part easily.  Good thing too as I cut the top too shallowly on my first try.  I used a piece of 2×4 to run the part through the bandsaw (with a new blade!).  I read that the wood helps clear the soft aluminum off the blade teeth.  The cut went pretty easily (even the tight bend at the bottom wasn’t that hard.

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The cuts were very rough.  WAY to rough to run through my Scotchbrite wheel.  I clamped the piece to my bench and used a bastard file to dress the edges (and work my way up to the cut lines).  I did the raw ends on my belt sander disk.  I got nice sharp, shiny, smooth edges out of that.

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In the end, I got a part that very closely matched the drawings.

 

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Giving me a pile of un-deburred parts to deal with later.

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Tuesday, 3 December

I got another late start on the day as I had to hang around in case the contractors actually showed up (they didn’t) to finish our remodel work.  Nothing much to show for the morning, but a couple of small deposits in the bank of marital bliss.

So, it’s back to page 10-04 and fabricating the two rudder stops. These may eventually get swapped out (some builders complain that the default stops don’t work well), but it is at least a more interesting fab than the horizontal stabilizer attach bar.  I tried printing out a full size template, but I found that it was actually easier to mark the angle directly from the full size drawing on the page. I then used the wood block trick to make the angle easier to cut squarely.  Conveniently, the round corner of the angle fit nicely into the rounded corner of the 2×4.

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A few passes through the bandsaw and I had some (very) rough cut parts

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These needed some serious filing (I accounted for that in my cuts).  So I clamped the parts on my bench and went to work.  I did some final polish with the disk on my belt sander.

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Unlike the horizontal stabilizer attach bar, these holes also need to be reamed and countersunk.  The rear holes are much to close to the back to get my countersink cage in.  In fact, they are too close to even get the countersink bit in!  Luckily, my deburring bit is a touch smaller and it fit nicely.

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This gave me two parts that match the spec very nicely.

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After a stop at the scotchbrite wheel, these parts were done.  So I shot some rattle can primer to finish them up.

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I had skipped a step on page 10-02 previously.  You need to straighten the F-01411C attach bars to within 1/16″.  They start out with a distinct rounding (maybe 1/4″).  The plans (which are normally written in spare engineering terms) have the most amusing illustration to show you how to straighten them out.  It looks like it is straight out of a Batman comic.

whang

It is actually very helpful!  I brought along my rubber mallet from home (that’s why I previously skipped this step) and tried to do it just like the drawing.  I think I succeeded!  At least the parts where straight to within 1/32″ when I finished.

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Then the parts needed some serious filing.  The machining work is very rough.  There are about a dozen tags on each piece and even the straight parts need a lot of work. Again, it would be lunacy to attack these with a scotchbrite wheel.  The bastard file did a great job shining up these edges.

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This made a lot of magic pixie dust!

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With the hard work done, I ran all the small parts through filing, deburring, and polish on the wheel.  A nice new pile of parts ready for priming!.

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