Saturday, December 27, 2008

right tank catch up

6 hours
I picked up a set of crows feet to torque the aluminum pipe fittings in the tank and put them to use on the left tank, then moved on to the right tank and set all of the interior ribs in two proseal sessions.

Measuring proseal is much simpler and far less messy when using an actual scale rather than my make shift 10 to 1 balance.

crows feet and a torque wrench... whoo hoo!
riveting the anti-rotation bracket is a bit tricky since the torqued fitting and fuel pickup tube need to be in place when setting the rivet... at least i could not figure an alternative.

this simple working jig was very helpful
outboard end rib and fuel access panel

anti-rotation bracket for the fuel pick-up
fresh rivets and a ghostly reflection 
measure pro seal with a real scale ;) 
just about ready for the baffle

Friday, December 26, 2008

back on track

9 hours
A very good shop day.  I picked up some more rags, regrouped and cleaned for a fresh start.  I sanded down some high rivets at the tank fill flange... very nice, cleaned proseal and began final preparations of the right tank for the first proseal session.

By the end of the day the left tank is only lacking the inboard rib and baffle and the right tank is ready for a rib proseal session.  Tomorrow I plan to knock out two proseal sessions to bring the right tank to the same status and rivet the last rib in the left tank.  At that point I should have a clear idea if I will need more proseal for the baffles.

So far I have done all of my proseal spreading, dabbing, and filet work with different ‘popsicle’ sticks; for the flange this may not work out, I will experiment with squeezing through a freezer baggie.

The right tank is ready to go into the jig for final rib assembly.

right tank skin prepping for proseal
bring on the proseal! 
starting to like the smell... 
tank ghost...
proseal madness!
stiffeners buttered with proseal and clecoed in position for riveting
filler flange riveted and dressed with proseal
tank drain ready for proseal to encapsulate the rivets

Thursday, December 25, 2008

Ho Ho... Doh!

6 hours

Most of the day was spent on final preparation of parts for the right tank... duburring, dimpling, scuffing, and cleaning.

I used my robo flaring and parker bending tools for the first time on the vent line, I need to pick up a set of crow’s feet to torque the fittings and finish the inboard rib.

What seemed like a great shop day turned a bit sour as I realized that I drilled the right tank access reinforcement ring without regard to its orientation to the access panel... after much head scratching to come up with an acceptable fix; modify the access plate to orient the sender correctly, fabricate a new pickup tube, replace the access plate, replace the rib, fabricate a new plate, order a blank plate...

...since I have finalized my planning for landing lighting on a pair of duckworks for wig-wag function and I have a small list of miscellaneous items to order from vans anyway, I have decided to simply order a new rib and plate from the ‘big list’.

I had hoped to break out some proseal... at the end of the day there remains a significant amount of prep to complete though... tomorrow...

The access plate is shown in the correct orientation, you can see the reinforcing ring is offset by 20 degrees or so... doh!

inboard rib on the left tank with access panel ring in place
bulkhead fitting for the vent line
vent line at the tank high point near the filler flange
ready to start the right tank... clean! 
cutting the access panel
Error!  I misaligned the ring when drilling it to the rib...
getting ribs and parts ready to start fitting the tank together
access panel misalignment
As it turned out I ended up fitting the right tank with a flop tube fuel pickup and could have just fabricated up a new blank plate here rather than replacing the rib...

Wednesday, December 24, 2008

proseal is less messy each time

6.5 hours

Cleaned up the shop.  After the last proseal session I left things a bit tossed about and started the day by restoring order to the shop.

I spent some time working out the inboard end rib details for the fuel level sensor, vent line, and access plate.  I need to enlarge the rib opening slightly to accommodate the edge of the anti-rotation bracket for the fuel pickup.

The outboard end rib has a couple of tooling holes that need to be covered.  The leading edge has a reinforcing plate that takes care of the one, for the other I fabricated a small plate and prosealed it in with some rivets.

For this session I mixed the same quantity with my makeshift balance scale... one cleco, by weight, of part A.  I set the balance up for mixes of 1, 2, 3, and 4 clecos of part A.  As it turned out 1 cleco worth is plenty of proseal for a full session and will cover 3 ribs.  This is a pretty crappy way to mix proseal... it works but it is messy and time consuming.  I have a nice grain / gram scale that I need to get a hold of.

I completed the interior ribs along with the outboard end rib.  There are twice as many rivets in the outboard ribs but they can be squeezed.  I contemplated just bucking them since bucking had gone so well but I just squeezed them; the proseal makes the surface very slick and you need to take extra care when squeezing.  Drilling out rivets with wet proseal is to be avoided.

Tomorrow I plan to prepare the right tank for riveting and make a batch of proseal to set the stiffeners, touch up some rivet heads on the last rib where I ran out of proseal, and finish the last rib on the left tank...

The tooling holes in the outboard rib are covered with a small plate that i fabricated and with a stiffener plate at the tip.

fitting a small plate to seal up the tooling hole along with a backing plate for the tank hard attach point
after rivets and proseal
level sender, fuel pickup and vent fittings
pretty close to finishing this tank up

proseal... good to the last drop ;)
finished outboard rib

Monday, December 22, 2008

proseal... a right of passage

6.5 hours

An unexpected day in the shop... over the past couple of days Seattle has received nearly a foot of snow, the town is simply not equipped to address significant snow fall and our office building, along with many downtown, is closed.  The mighty Subaru thought nothing of the conditions ;)

I started the day making some changes to the flange and drain work from yesterday.  On the drain I did not seal the outside contact points with proseal and decided that that was an error; no issue in drilling out the rivets, cleaning everything, and riveting again.  On the fill flange I was not happy with how the rivets set... they were short and did not have enough grab on the thick flange.  The load is very light on the flange and it is not a structural point so -3 rivets are technically fine but they just do not have much pull on the thick material.  I drilled them out, cleaned the flange, and contersunk for -4 rivets... I probably should have just left it all alone... oh well, it is done and I think that it actually looks better balanced visually.

Then on to the ribs with proseal.  After buttering a rib it really slides in easily.  Finishing three ribs and feeling pretty good I noticed a couple of dings on the leading edge... I dropped my bucking bar inside of the tank while riveting the second rib and it banged the skin from the inside... the dings are really pretty small, but anything short of perfection on the skin jumps right out to the eye.  Oh well...  I plan to use a wooden form on the inside and tap the skin with the rivet gun set very low and see if that will clean things up enough to disappear with paint...

My chemical resistant gloves and respirator have been put to good use... until today... with proseal everywhere I pretty much gave up and ended up nearly bathing in MEK to clean it all up... I hope that experience with the stuff will reduce the mess and casual use of MEK...

quick build kits don’t get the chance to build tanks... they really miss out on a critical right of passage in building.  
proseal is the messiest, stickiest, yuckyiest, stuff i have ever seen... but it is kind of fun.  
I am glad to be doing a ‘slow’ build.

fuel tank drain rivets sealed with proseal leaving channels for the fuel to drain
fuel cap flange sealed up 
finished flange with -4 rivets
rib buttered with proseal ready to fit to the tank
this is a tricky shot with proseal everywhere ;)
just riveted in
another rib in
each rivet is set with a dab of proseal
debris path to cleanup...
starting to get a nice fillet and encapsulating each rivet in proseal
pretty slow going to get a good fillet and make sure that every rivet gets fully sealed
the stand worked great during the process
nicely finished
a good work day... I still have my proseal shirt :)

Sunday, December 21, 2008

proseal begins

7 hours

I finished all of the tank preparation on the left tank, deburring, dimpling, scuffing, cleaning, more cleaning with MEK, and set everything up to begin sealing all rivet penetrations and attachments with proseal.

The homemade balance worked okay but it is very awkward scooping the muck into cups on the long balance arms without spilling out.

I must have gone through 20+ gloves in mixing, frosting parts, forming fillets, coating rivet heads and so on.  Lots of MEK to clean parts prior to using proseal and after to get it off of tools and anything that it comes close to... proseal will stick and string to everything!

proseal is fun... ha!  mixing the two parts to a 10 to 1 ratio is quite a bugger with a home made balance... I need to retreive my digital scale.

the mess from my first proseal session 
deburring holes with a long reach extension.
just a firm half turn with the three flutes to knock off any burrs on the hole before dimpling
my two primary tools for duburring small holes
in the driver is a single flute bit 
fitting up the fuel cap flange with the cap
the small clip will hold the end of the vent line at the tank high point
on the underside of the tank is the drain flange and fitting
getting ready to scrub and clean for proseal
all contact points for proseal are scrubbed and cleaned vigorously
mixed proseal with rivets soaking in MEK ready to start buttering the pieces and riveting together
with proseal, every rivet is sealed and all contact points are carefully filleted smooth

fill flange from inside the tank
finished tank filler flange