Here's a fun little tool

Went over to Mike's for a BBQ after work. When showing me some of the cool parts for the Stewart S-51 (works of art by the way!!) A cool little tool caught my eye.

What is it. Well...I picked it up and noticed right away that the 'hole' was about the same size as my mushroom head rivet set, but I couldn't figure out how or where it was used/placed.

Well with a big grin Mike showed my what it is used for.


It's used to keep the rivet gun in place when bucking solo.

What a cool little tool!!! Now I want one!!!!

And just a little more debur and countersink - 3.5 hours

Well this morning I found myself really questioning the dimpling of the inboard ribs. I had dimpled all the holes on the rib yesterday. The plans on drawing #12 to leave certain holes un-riveted for future attachment of the wing root fairing. Well of course I interpret this as dimple it all and not rivet some holes.

So after I did some checking on the forums this are seems to be a bit of a tricky area for some builders. First off the holes noted to be left open do not match between drawing #12 and #38. Next issue is do you not dimple these areas, or do you drill and dimple them now. Well...more reading on the forums and a message sent to Wirejock (Larry Larson) I think I have it figured out.

I've decided that drawing #38 is the correct drawing for locations. Everyone says "about every third hole". Ok...That's settled. Next Wirejock recommended leaving the hole undimpled and keep the #40 pilot hole. He said that I will use these holes to cleco on the fairing later.  Good enough for me!

So...Of course I had to flatten out the necessary dimpled holes on the left wing rib that I had done yesterday. Not a big deal as you typically can flatten a small dimple without structural issue. Better yet, down the road I will have to drill open these holes to a larger diameter anyway so its totally fine in the end no mater what.

Once I had the left wing fixed up. I needed to complete the few countersink holes and rib dimples that where left on the right wing. I then cleaned, masked off the front and rear spar and primed.

While I waited for the primer to dry, I prep'd the right leading edge skin (debur, edge roll, and dimpled) same as yesterday.

Little more debur, countersink, and dimpling - 4.5 hours

I had finished the majority of deburing and counterskinking however there is just a handful of places where I just couldn't reach the end (inside) ribs where my wing stand structure blocks access. I've built a slightly smaller wing stand structure than indicated on the plans to maximize space in the garage. It works, but I have to make some concessions to make it work. ie. I have to climb under the structure to access between the wings. I will have to rivet the skin on the wing, with one wing at a time. And of course in today's work session, I have to take the wing structure off the stand to access a few locations. Not the most efficient setup, but given that I need the space in the garage, this is a totally workable situation.

So I had pulled the left wing off the stand and finished the 6 or so holes that needed to be countersunk, as well as the handful of holes that needed to be dimpled.

Now it was time to countersink the rear spar (top) holes. The bottom ones are very easy to do with the pneumatic squeezer. The top side is another story due to the angle and interference with the rear spar. I've been giving this area some thought for a while, and I figured that my vice grip 3/32" dimpler would do the trick. I tested a couple of holes first and checked with a rivet. The dimple is not as nice as the pneumatic squeezer, but it works.



Once I was complete I pulled out my microstop countersink (having it set up for the main spar I just did) and I started to check the holes. Of course the holes that are dimpled with the vice-grips take some material off. I then checked the bottom of the rear spar that was done with the pneumatic squeezer and little to no material is removed. I decided that this is the correct setting and went to work cleaning up the top side holes on the rear spar.

Next order of business is to clean an prime the spar where the countersink holes are made. The manual indicates that this can be done as a spot prime while countersinking (i.e. when doing the tank screw countersinks) buy I opted to prime the whole face as some builders choose to do. I masked off the front spar and primed it. I had also primed the top of the rear spar where the machine countersink had removed the primer (and where the dimpling operation flakes off the paint).


As I let the primer dry...I moved on to starting to de-vinyl the wing walk doubler. Next operation was to debur. Now at the back of my mind, I had to keep my dimpling operation correct. I had chose to dimple the ribs for the wing walk doubler with tank dimple dies. The idea is that if I dimple the ribs/doubler skin with tank dies, and then dimple the skins with regular dies this will provide slightly better nesting. However....months ago when I dimpled the rear spar....I didn't use this thinking and I dimpled with regular dies. Confusing I know but basically when it comes to the doubler the bottom line for my build was this;

Dimple the rear spar line with regular dies, dimple the rest with tank dies. So...to make sure I mitigate the risk of messing this up at a later date. I dimpled the rear line.
 
Of course it wasn't midnight yet and I was still wide awake...why not do a little more I thought. So whats a little more deburing and dimpling? I took the left leading edge out and debured. Now...most important for me to remember. I used the edge forming tool and ran through to two edges. Next I dimpled.

More deburring and countersinking the wing - 3.5 hours

I decided to use 3/32" tank dies on the ribs and wing walk doubler (with regular dies for the skin). As such I double checked the countersink needed and came to the conclusion that it is the same depth of countersink that is needed for the thicker 0.035" skin. (As the wing walk doubler is 0.025" thick).

I ended up completing all the wing spar countersinks. Wow...what a lot of work. It's fun a first, but becomes very repetitive. I decided to re-tackle deburring for a bit before calling it a night.

Deburring/dimpling/countersink the wing - 5 hours

Well finally to the point where I can get working back on the wings. Earlier in the day I put in an order to aircraft spruce for some cherry rivets to attach the leading edge (also sent an email to vans support to ask about my options) but before I can get that I have a ton of work that can be done.

I need to remove the top skins and go to work deburring all holes, dimpling all ribs and the skins and countersinking the spar for all the dimples.

After I removed the top skins, I started in on deburring. Once I was done with the left wing/top. I dimpled the ribs. I then climbed in between the wings and kept deburring, and deburring and deburring.

Once I had my fill, I decided to do a little dimpling just to see how it was going to work out with dimpling the rear spar and the rib together. Not bad.



Then I moved onto some countersinking on the spar for all the #40 holes. I made absolute sure of what holes need a rivet to sit flush (the top row that connect the ribs but sit under the tank skin) all the holes that need to accept a 3/32 dimple for 0.025" skin (outboard skin) and those that need to accept a 3/32 dimple for 0.035" (inboard skin). After check, check and re-check I settled on a countersink diameter around 0.193" for the inboard skin dimples and then added a couple of clicks for the thicker inboard skins which ended up around 0.202" (give or take).

Countersinking works best and consistent if you go slow... Grrr.

Finished riveting the leading edge skin - 2 hours

My buddy Mike dropped by in the evening to lend a hand riveting the last few rivets that remain on the leading edge skin. These are a bit tricky to do by yourself (even though I managed to do it on the fuel tanks) it can be done by yourself, I just chose to get some help and make it easier.

Well.....what a pain the butt. Straight outta the gate we were batting 50% on the first few rivets. Had to drill some out and re shoot. One in particular was MURDER. Must have drilled it out 6 times. Well very frustrating. The rivet just did not want to sit flush. After much frustration we re grouped. I drilled it out to #30 and installed and oops rivet. After that order Mike had the gun a bit different and I held the bar a bit different, and we nailed every rivet after. Sheesh...it is true. Riveting is very much a feel and it takes a few to get it back again.

Started assembling the flaps - 4 hours

I had a little bit of edge finishing to do on the flap ribs so I started the day by taking care of those outstanding items. Once I was satisfied with all the ribs and the spars. I clecoed the assembly together and clecoed the bottom skin on.

Right away I noticed that I was not getting a good fit with respect to the rear spar. The plans want you to first drill the rear spar into the ribs, but I felt uncomfortable with this as there is a bit of play in the skin as the rearmost hole is not drilled. After much thought, I decided to remove the plastic from the skin to ensure a proper fit before drilling anything. I disassembled, used the soldering iron and removed the plastic. Then I re-assembled everything.

I gave it all a good look over. I was still uncomfortable with the fit at the rear. Just a bit of play on the skin/rib. My fear was that if I followed the plans and drilled the rear spar first, I risked poor fitment with the skin and the edge distance for the #30 rear hole is a bit sketchy. So I decided to drill and cleco the rearmost hole on the rib/skin to ensure a good fit. I then drilled the rear spar to the ribs. Now, the plans warns about the possible use of shims between the rib and rear spar. I made some out of 0.025" material, and sure enough it was very tight. I decided to go with a 'liquid shim' as I only needed 0.010" or so. (The Stewart S-51 plans have you use 3m structural epoxy as a liquid shim in places - so I think I can use this method on my project). 
 
 

Next order of business was to fabricate the spacers that get placed on the underside of the ribs. 
 
Simple enough to do but the trick was to match drill them with the holes in the rib. After a bit of head scratching I figured my best bet was to use the fan spacer and clecod 'do according to the holes that I could and that allowed me to use the last hole in the fan spacer as a drill guide for the hole I needed. Worked like a charm.

Lots of monkeying around and I spent more time than really needed, but oh well....it's a Sunday.