Friday, August 26, 2016

Progress



So I have completed the sample wing section practice kit from Vans. This practice kit uses all the tools so is very helpful in getting to know my way around cleco pliers and such.

A word about reamers and drill bits; the holes in the parts are prepunched on a very precise CNC machine so everything lines up. If things don't line up, something is wrong. I found the clecos from Brown Tools are professional grade and line up the holes precisely. The prepunched holes are slightly undersized and need to be enlarged to final size. This can be done with a standard drill bit or a reamer bit. The reamer looks like a drill bit but the flutes are straight up and down. I use the reamer just like a drill bit and enlarge the holes to final size. The reamer produces a nice clean hole that is perfectly round and others say less prone to cracking; reamers also tend to leave smaller burrs so deburring seems to be minimal.

Deburring was a challenge. Most of the tools I tried for deburring the holes were too aggressive. I found what works best was a 120 degree counter sink on the end of a tapped rod. And for the skin edges, the old tried and true butterfly deburring tool works great (red handle on bench). For drilling out bad rivets, the drill press was invaluable. I can lock the piece down to the table and use an end mill to knock off the head. It turns out the heads of a squeezed rivet are pretty hard and it is easy to bugger the flight piece if not careful. All the more reason to make the rivets right the first time, quality is never having to say rework. I also made a holder for the clecos. This was suggested by a mechanic friend and was a great idea.

I thought I would get away without having a belt sander, then I realize the reinforcing strips of the practice kit didn't fit without heavy mods. I tried to trim with snips and files, but was not  happy with the results, so I broke down and bought a belt sander and added it to my lazy Susan in the background. What a difference. I also tried to rivet with the DRDT2 in the foreground and that was hopeless; there was no way to secure the part and operate the handle while keeping everything aligned. My best rivets were with the Cleveland Main Squeeze shown in the corner of the bench; what a nice tool. I used the close edge dimpling tool attached to the bench in the corner with the rivet gun to dimple the ribs; this was noisy and brutal. The results were good, but it is still too out of control for my liking. So next time I will either use the Main Squeeze or I will make a top guide for the rivet tool to keep everything lined up. The less I rely on my holding things straight, the better the results seem to be. Jigs are our friends. Also, having the work well secured seems to make it much easier to add a little English to the tools to keep everything lined up as the rivets are formed.

The practice kit came out fine with errors that are easily corrected. I feel confident that the skills I have tested are good enough for real parts.

So I am making progress. Who needs sleep, there is plenty of time to sleep when I am not building.


Tuesday, August 16, 2016

Learn by Doing

So tools are at critical mass and I have started the practice kits. First impression are the tools from Cleveland Tools and Brown Tools are first rate; they are high quality and reasonably priced. I bought the professional  surplus tools whenever I could and that worked out well. Sorry to say, but most of the hand tools I bought at Harbor Freight I ended up returning and reinvesting on similar items from Cleveland and Brown.

First discovery is that those machinists scales are hard to read; the 1/32 of an inch graduations must have gotten smaller over the years because when I was 18, I could read them no problem. So it IS true the world is getting smaller.

I found using the dial calipers as a measuring tool works much better than the machinist's scale. Also, the 10 year old Craftsman drill press was a score. Small, precise and nice to work with. What I did not expect is the trouble with deburring. I Invested in several different kinds of debuting tools for the small rivet holes, but still not happy with any of them. The best I found is a countersink threaded into a handle. But the alclad is soooo soft I am still way over deburring. The so called " deburring" bits left too many chatter marks in the soft aluminum. The best was the 100 degree countersink in the handle. Interesting that this produces a flat spot the rivet will sit on when dimpled to accept a 100 degree rivet. But this flat spot exists in the first place because the hole was over deburred. My last attempt is to try a 120 degree counter sink for deburring since the hole burrs are mostly normal to the surface and not inside the diameter. For the prepunched kit parts, I plan to enlarge the holes using  reamers, rather than drills, which should minimize the amount of deburring.

The best tool is the Main Squeeze rivet squeezer from Cleveland. Very precise, light and accurate. I bought a used DRDT2 and it need a but of filing to get aligned, but once set works well too. The slow dimpling speed makes for precise work, as opposed to using a hammer and c frame, and the Wack-A-Mole technique. The aluminum skin is soft and thin, so a fast dimpling force doesn't seem to be needed. But alignment is critical.



Thursday, August 4, 2016

Tools and Tools


After the great big learning curve on airplane tools, I think it is time to begin. The tools were not really more expensive than I anticipated, but just mind numbing with all the options. I think this is where a weekend course or the guidance of an experience builder would come in handy; before buying having tried the tools on a sample project, or helping another builder and learning the tools, would probably have saved some grief. But I do want to thank my friends who have stepped up and helped me out with tools they no longer use.

I started looking at the practice kit, and realized one of the first tools I need, is not one I had anticipated buying right away; that is a close quarters dimple die set. But the practice kit needs this for the ribs. So that is on the way. These tools are not really expensive in terms of dollars, but are in terms of time waiting to get started.

Next stop on this journey is completion of the practice kit, to see if I feel good enough to start on things that will leave this earth (and I don't mean being flung across the yard in a desperate rage)

I made the standard EAA workbench... except I used 3/4 melamine, made a 2 inch lip all around for clamping, and added inserts to hold the DRDT2. I also made a lazy susan for the drill press, grinder and belt sander (not shown) so that I can put this up against the wall and minimize wall space for these tools. Notice the tail feathers on the shelf with the earthquake safety straps around the boxes ;-)  Next to the band saw is the real estate for the compressor. Hopefully I can wire it for 220V to minimize the light flicker when it turns on. Besides the compressor, the only thing left to do is add the retractable power cord and retractable air hose, both mounted on the ceiling.