4.5 Hours -

Four and a half hours of dimpling and deburring today and I’m still not done with the rudder final prep.  The skins are done, but there are a few holes on the ribs that I can’t dimple yet.  When my order from onlinemetals.com arrives, I’ll make a thin bucking bar that will also have #30 and #40 female dimple dies drilled into it.  Using these female dies, I’ll be able to dimple the aft few holes on the tip and bottom ribs.

4.6 Hours -

Nothing too exciting today.

I spent 2 hours finishing the edges of the right stiffeners, 15 minutes dimpling all sixteen stiffeners with the squeezer, 30 minutes removing protective vinyl from the rudder skins, 45 minutes dimpling the skins with the c-frame, and 66 minutes prepping and priming all these pieces.  I’m exhausted!

Tomorrow, my Dad is coming over to help.  We’ll back rivet the stiffeners to the skins and start the rudder skeleton.

Another one for the FAA...me dimpling the rudder skins with a c-frame.

A fresh line of dimples in the rudder skin.

16 primed rudder stiffeners.

I primed the inside of the rudder skins where the stiffeners will attach.

1.1 Hours -

It took me just over an hour to finish the edges and deburr the holes on half of the rudder stiffeners (the eight stiffeners for the left skin).  After cutting them, the edges were pretty rough.  To smooth the edges and radius the corners, I used the Scotch-Brite wheel.  This wasn’t difficult, but it took some time to even out the taper cut on the aft end of each stiffener.  Once all of the edges were cleaned up, the holes were deburred with my Avery Deburring Tool. 

I’m probably going a little overboard with finishing these pieces, but they look nice!  The pictures below compare finished stiffeners with unfinished one.

The forward ends of the rudder stiffeners don't have a taper. The two on the right are finished, the two on the left are not.

The aft ends of the rudder stiffeners are tapered so they don't interfere with the skin or each other. The two on the right are finished, the two on the left still have some work to be done.

2.1 Hours -

After two more hours of tedious work, the vertical stabilizer parts are all ready for assembly.  Tonight, I finished prepping the VS rear spar.

First, I deburred the edges and holes of the rear spar and the rear spar doubler.  The spar was simple, but the double is quarter-inch thick aluminum and takes considerable more effort to deburr.  The holes are simple enough, but the edges have to be broken with a file as opposed to a dove tail deburr tool or directly on the Scotch-Brite wheel.  I’m still trying to get used to using a file.  I just don’t feet that it is very precise and it seems to make a mess of the part at first.  However, by breaking the edge with the vixen file and then finishing with the Scotch-Brite, I still seem to end up with a nice looking part.  Maybe I’m worrying about nothing!

After deburring the parts, I had to dimple and counter sink where appropriate.  The lower, forward portion of the aft spar needs to lay flush with a fuselage bulkhead, so flush rivets are used.  However, universal head rivets are still used in the upper portion.  Fortunately, the plans are very clear as to which rivets go where.  Anywhere flush rivets are used, the spar has to be dimpled and the spar double has to be countersunk.  The only challenge is to make sure you dimple/counter sink the correct side.

The lower, forward portion of the VS rear spar is dimpled so that it can lay flush against a fuselage bulkhead.

The lower, forward portion of the VS rear spar doubler is dimpled so that it can lay flush against a fuselage bulkhead

After dimpling/counter sinking, I scuffed both parts with a Scotch-Brite pad, then wiped them off with MEK.  Finally, they received a coat of primer.

After deburring the parts, they are scuffed in preparation for primer.

The VS rear spar doubler primed.

Now that all the VS parts are prepped, it’s time to pull the rivet gun back out of the tool chest.

1.1 Hours -

Nothing exciting on the RV today.  Just an hour of deburring, dimpling and priming VS parts.  All the VS ribs and the VS front spar are now primed and ready for assembly.  The rear spar is not ready yet as it will take a little more time.  Several of the holes on the rear spar have to be countersunk and I didn’t want to spend the time setting up my countersink tonight.

2.5 Hours -

Another one of those tedious days.

I started by final drilling the VS skin to the skeleton.  That took about 20 minutes.  The next two hours were spent deburring and dimpling the VS skin…just the skin…all the pieces of the skeleton still need to be deburred!

For the FAA, a picture of me deburring.

Dimpling the VS skin with a c-frame.

Finally, I wrapped up the day by priming the inside of the VS skin.  Again, nothing fancy with the primer.  Just a quick scuffing along the rivet line with a Scotch-Brite pad, followed by a MEK wipe down and then NAPA 7220 self-etching rattle can primer.

The VS skin is prepped, primed and ready to be riveted.

I quit for the day because I was starving.  However, before going upstairs, I disassembled the VS skeleton and marked all the pieces for proper orientation.  Tomorrow, I’ll deburr, dimple and prime them.

The parts of the VS skeleton are ready to be prepped for final assembly.

3.8 Hours -

I woke up today with the goal of smashing some rivets.  For me, getting to a step where some rivets go in would feel like a huge accomplishment. Plus, I wanted to see how well the pneumatic squeezer worked on some 4- rivets.  Yes, I’m one of those people that loves the little things in life!

My work was broken up into two shifts.  Unfortunately, I had non-airplane related stuff that had to get done too. 

In the morning, I started by cleaning and priming all the HS ribs.  Once the primer was on, I moved over to the HS skins and started to deburr the holes and edges.  This was a time consuming process and I only managed to deburr the holes in one skin before I decided it was time to break for lunch and go get my other stuff done.

The HS ribs are primed and ready for assembly.

More tedium...deburring the HS skin drill holes.

In the afternoon, I returned to my HS skin deburring task.  It probably took me another hour to finish the holes and edges of both skins.

Using a dove-tail deburring tool to break the edges of the skins.

Using a swivel style deburring tool in the tough to reach areas.

After deburring the HS skins, I began dimpling all the holes.  I dimpled as many holes as I could with my pneumatic squeezer and then switched to a c-frame dimpler.

This was the first time I used my c-frame.  Fortunately, I checked it’s alignment before whacking away on it with a hammer.  The bottom plate, which held my male dimple die, was slightly out of alignment.  If I would have used it this way, it likely would have dimpled fine.  However, it would have put a lot of stress on my die, eventually causing the male die to break (ouch!). Fixing the alignment was simple, and it actually took me longer to find the right sized Allen wrench than it did to get everything into alignment.

Once the c-frame was set-up, I slid one of the HS skins in and started to dimple the easy to reach holes.  After a few holes, I realized I either needed another hand or I needed to build some sort of dimpling table.  It was difficult to hold these large skins thanks to the bend they have.  I couldn’t find an easy way to hold the skin on the die, hold the bend open enough to allow space for the hammer, and swing the hammer with enough force to get a good dimple.  This was starting to frustrate me and my goal for the day was to set some rivets, so I sat the HS skins aside and reassembled the HS rear spar for riveting.  Maybe holding the skin sideways will simplify this…skins without bends should be much easier.

I dug out the two HS-603PP rear spar channels and the two HS-609PP rear spar reinforcement bars.  After figuring out the correct orientation (my markings weren’t very helpful), I clecoed them together.  As per the instructions, I taped over the holes that will be used to attach the ribs so that I wouldn’t accidentally rivet them.  I also re-attached the elevator attachment brackets so that I wouldn’t rivet those with the wrong sized rivets.

With everything clamped together and marked, I was ready to smash some AN470A4-6 rivets!  I grabbed a rivet from the bin and tried to place it in the center hole on the bottom of the spar.  It wouldn’t go all the way through both pieces.  After double checking that I had the right rivet size, I took a close look at the rear spar.  Even though the channels and reinforcements were clecoed together on every other hole, the holes were slightly off and not perfectly aligned.  At first, I wondered if I had oriented the reinforcement piece the wrong way, but I quickly determined that was not the case.  Before getting too frustrated, I realized that the clecoes are smaller than the actual holes and could be the source of my problem.  So, I removed all the clecoes from the lower reinforcement piece and placed rivets in the holes instead.  Using this method, everything lined up perfectly.  Relieved that I hadn’t made a major screw-up, I removed every third rivet and put the clecoes back in those holes in order to keep the pieces tightly clamped for riveting.

Finally, it was time to rivet!  Setting up the squeezer on the first rivet was surprisingly simple.  After a couple of progressively shorter squeezes, my rivet gauge said I had the appropriate sized shop head.  With the squeezer set-up, I proceeded down the rivet line, checking every two or three rivets with the rivet gauge to make sure the squeezer was still set-up correctly.  The entire row of rivets took about 15 minutes.  I’m guessing that the same number of rivets would have taken me about an hour with a hand squeezer (if I didn’t get tired and quit half way through).  I left the second row for another day…dinner time!

A perfect shop head according to my rivet gauge.

Riveting using the pneumatic squeezer yields more consistent results.

3.7 Hours -

My Dad came over today to help with the airplane for the first time.  Fortunately, there was a lot to do.  Unfortunately, it was all deburring and dimpling, so he got a taste of the tedium involved with building an airplane.

All of the holes in the HS needed to be deburred, as well as the edges of all pieces except the ribs and reinforcements.  I gave my Dad a quick lesson on how to deburr holes and let him at it.  After he finished a small rib, I checked his work.  The holes were deburred and no extra materials were removed, so I let him run with it while I worked on deburring the edges.  Usually, while I’m working, I listen to aviation themed podcasts on my IPod.  It was a nice change to have someone to talk to.

My Dad's job for the day was to deburr the holes in the HS skeleton.

I finished deburring all the edges, except for those on the skins, before deciding to switch tasks and dimple the HS skeleton with my new-to-me pneumatic squeezer.  Using the pneumatic squeezer, I could dimple a rib in less than half the time it took me with my hand squeezer.  I think the squeezer could be my new favorite tool!

Dimpling with the pneumatic squeezer...so simple!

First dimples squeezed using a pneumatic squeezer.

Once my dimpling caught up to my Dad’s deburring, I sat the squeezer aside and started to remove the vinyl coating from the HS skins.  I’m going to only remove strips of vinyl along the rivet lines.  Since I’m planning to leave the majority of the airplane unpainted, I want to protect the skins as much as possible from scratches during construction.

Using a soldering iron and straight edge, I quickly melted lines in the vinyl and then easily peeled off the strips.  Whoever came up with this little trick was one smart dude.

Lines in the protective vinyl are made with a soldering iron.

Left: Once lines are cut with the soldering iron, nice strips can be easily removed. Right: My Dad still deburring away.

As I finished removing the vinyl strips from the two skins, my Dad finished his deburring task and we decided it was time for a lunch break.  My Dad, my girlfriend and I all walked over to Gourmet Burger Grill for burgers, sweet potato fries and onion rings.  If you are in the San Antonio area and you haven’t been there yet, you are seriously missing out!

After lunch, my Dad headed back to Kerrville and I headed back into the garage.  Before leaving the airplane for the day, I wanted to finish dimpling the skeleton and prime the front and rear spars.  With this done, I still need to prime the ribs, as well as deburr, dimple and prime the skins.  However, with the spar pieces all primed, I’m ready to rivet together the rear spar tomorrow.  Yes, I’ll be using my pneumatic squeezer for that too!

The last 3 nights I’ve been fabricating, matching drilling, prepping and  the parts for the bellcrank rib substructure that attaches to the 706 bulkhead. I’ve had to pay close attention to drawing #26 for this structure as there are many intersecting parts; virtually each one with it’s own special way to attach to the other. Also after cursing Van’s for some apparently misaligned predrilled holes in F730, I discovered that the holes are actually asymmetrical in their layout and yours truly had cleco’d it on backwards. The holes aligned perfectly now. A little more drilling tonight and this bad boy gets thrown into the ever growing “To Be Primed” pile. I swear I am gonna spray paint this weekend. Sorry for the crappy photos. I only had the iphone with me this morning.

Notice the missing hole on the upper right of 730.

Here's the backside of the F730 intersections

Triangle Home Products Medicine Cabinet
The door frame on this medicine cabinet is made of steel U-channel. The corners are formed by punching V-notches into the channel, then bending it 90 degrees. The punching process leaves sharp burrs, which are inadequately (or not at all?) deburred. These burrs are made worse by the forming process. I find it especially ironic that a medicine cabinet, to which we turn to help heal injuries, itself inflicts injuries. Well, at least the bandaids are close at hand

Lesson Learned/Solution:
Sharp edges are to the metal-working world what flash is to the injection-molding world, and they’re just as often an offender. Again, deburring sharp edges doesn’t cost that much. Shame on you, Triangle Metal Products.

Yesterday and today we Deburred some parts of the Horizontal Stabilizer, tomorrow we will assembly alittle bit together….

- Deburring ?
Deburring is, to put it simply, a finishing method used in industrial settings and manufacturing environments. Metal is frequently machined using many processes in order to create pieces of specific shape and size. For example, metal may be welded, molded, cast, trimmed, slit or sheared. These procedures often create ragged edges or protrusions. The raised particles and shavings that appear when metal blanks are machined are referred to as burrs, and the process by which they are removed is known as deburring.

Deburring

I’ve tried a few different methods over the the years to reduce my hands-on time in getting rid of those razor-sharp fresh-cut titanium edges. I started doing this with essentially no tools or money to buy any. I first bought tin snips, and then a small bench shear something like the one pictured.

The merciless edges on fresh cut titanium encouraged me to buy leather gloves. To remove those edges, I first used emery paper (wet/dry sand paper) to smooth them. But the tedium soon urged me to learn that a motor, a couple of taper spindles, and Cratex wheels (rubberized carbide) were much faster and spit few sparks. I put my grinder/polisher together from a salvaged ¼ horse motor and parts from a mail-order catalog (this was around 1980). Now there is website: www.RioGrande.com and you can get everything there. But grinding small parts ended up using up finger tips; both gloves and my own.

On a whim, I tried out my childhood rock tumbler. I just cut up a bunch of pieces, and threw them in with some rocks, and let them go for a week, then three weeks. There was some rounding of the sharp edges, but not much nor fast. I then ordered abrasive ceramic media from RioGrande, and tried that in place of the rocks. After a couple of weeks, nice, smooth edges. The ceramic media lasts for many uses (I have yet to reorder). You can also get it cheaply from HarborFreight, here or at your local Harbor Freight shop. You can also try rock shops, craft stores, or online.

But, c’mon! Weeks? So (many years later) I went to eBay to find a vibratory polisher. I wasn’t ready to spend $500 on a name-brand one at RioGrande. So I found one specified to clean shotgun shell casings for about $60 delivered. It has a clear top, so I could watch the pieces and media do their thing. It reduced the time to about 4 days. I ran it with a dry load, with no water or agents. Amusingly, the dust that grinds off from the media is hydophobic! Water runs right off of it, like mercury on glass. I found that adding tap water at the end and vibrating for another hour suspended the dust in the water and didn’t darken the titanium too much. Anyway, I etch after I tumble.

But I never did manage to get a shine with this machine. I tried ceramic media and porcelain media, I used polishing compounds, ran it wet, ran it dry, and still my best was a matte finish. My worst was that the titanium turns almost black in water with porcelain.

So I thought I’d try another type of vibrator. I got it from eBay, and then found that I could have driven across town to HarborFreight and gotten the exact same unit for about $25 less. I first tried running it wet with porcelain. Blackish titanium, eww. I etched the titanium clean, and then tried dry with ceramic media: Shine! Trumpets and doves and a beam of light from above. The gray ceramic media turned dark and shiny in 24 hours, as the titanium deburred and gleamed.

Had this not worked, I would have finally bought a professional (expensive) circulating fluid vibrator assembly (Raytech). But I’ll hold off on those.