Coming up with a Better Mousetrap for Deburring Rib Flanges

Tonight I set out to debur the inner rib flange holes of all 7 tank ribs, and reassemble the tank with the baffle plate. After suffering through yet another trip to the dentist where they had to shoot me up 3 times to refill a cracked filling, and then biting my tongue pretty bad in the process, when the drug finally wore off I was not feeling quite 100%. So I decided to keep the plan activity to a minimum by only deburring the rivet holes in the rib flanges.

However, this seemingly small task re-opened another nagging problem that I have encountered before, but never really managed to solve. That task is trying to find a tool with a 90 degree angle that has a small enough profile to be able to insert a deburring bit and properly debur the holes in the inner rib flanges. The problem is that there is only about 5/16ths of an inch clearance from the rib web to the rivet hole, and although this task must be performed a rather significant number of times, nobody seems to make a custom tool specifically for this purpose. So everyone seems to come up with their own creation to try to accomplish this task.

In my case, I was simply going to take my deburring bit in my fingers and clean each rivet hole manually, and then spend the next several days recovering from the pain in my fingers, just like I did for the similar rivet holes in the main wing ribs a long time ago. Then, just as I got started on the first rib, I had a moment of clarity. For some reason I was thinking about back riveting the rib flange holes and the top main wing skins, and the fact that I still needed to order a 12 inch extended shaft back rivet set in order to do this.

That's when I had the brilliant idea that could use a similar extended shaft with a hex insert for the deburring bit. There would still be a slight angle of the bit against the rivet hole, but the low angle still allowed the holes to be deburred adequately. I taped the bit in place in the extension to keep it from falling out:

Before I settled on the above solution, I was also pondering a couple of other ideas. The first one was to use my drill-driven 90 degree angle drill attachment that I ordered with my tool kit when I started this crazy project. It has a fitting that will accept the screw shaft of that 3 flute deburring bit on the end of the yellow-handled tool I reviewed in my previous post. Unfortunately, just as I had mentioned at the beginning of this post, the width of the tool is just too wide to allow the bit to reach the hole properly:

And then I had another thought. I had also ordered a set of quick disconnect bits with a chuck that was designed to replace the chuck in my air drill. I have never used any of them because I never got around to deciding to remove the standard chuck from the air drill. These last two pics are of the bits that came with the 90 degree drill attachment shown above, and then the quick disconnect bits. The quick disconnect chuck and collets have a design that is very similar to my edge deburring tool. The collet shaft has a set of divets in it that fit the ball bearings inside the chuck and locks the collet in place. the pic below shows the 1/4 inch collet with one of my 1/4 inch drill bits inserted and secured with the collet nut. Think of it as a big Dremel tool attachment with a special shaft insertion and locking design with multiple collets of different sizes for different sizes of commonly used drill bits.

These would certainly be easier and quicker to change out than having to use the manual chuck key to change bits each time. The only problem is that they use a specialized chuck, and once you remove the standard chuck and replace it with this chuck you pretty much have to use the collets for that chuck from that point on. Luckily I now have two air drills, so I can keep the standard chuck in one of them and the quick disconnect chuck in the other one:

Unfortunately the quick disconnect set does not come with a deburring bit, nor does the 90 degree angle drill set. Anyway, it had been way too long since I had even looked at these other tools so I decided to break them out to "refresh" my memory about them. I may decide to get brave and figure out how to replace the standard chuck in one of my air drills with the quick disconnect chuck. I seem to recall that I have instructions for that lying around somewhere - I'll have to look.

So I managed to get the inner rib flange holes deburred, and I also manged to use my edge deburring tool to smooth the edges of the remaining tooling holes in each rib. Apparently I discovered that I had deburred the larger holes in the inner ribs that are designed to allow fuel to pass through from each bay of the tank as it empties from the most outboard bay near the fuel cap toward the inboard bay where the fuel pick up tube resides.