It has been almost a month since my last blog post, but work continued on the slats over that time. No real need to blog about it as the process was the same for all four with the exception that the outboard slats were slightly longer externally. The internal skeleton and assembly steps were the same.
A pciture of the last slat on the bench awaiting trailing edge bend before debur, prime and rivet.
Also in the last couple of weeks I played a bit more with the 3D printer. It seems I've run into an issue with the filament jamming in the extruder. Very frustrating stepping away to do other things while the printer works on something, just to come back and find nothing coming from the nozzle!
I took the extruder apart and it was clear it wasn't feeding correctly as evidenced by the "knot" of melted filament between the extruder and the hot end.
I spoke to a work colleague who is very invested in 3D printing as a side business and showed him some pictures. There are two things that most commonly cause this are a gap between the hot end feeder tube and the extruder, or worn extruder parts. As the extruder parts are 3D parts themselves from the manufacturer, his suggestion was to spend some money to upgrade to an all metal extruder and hot-end.
Looking further into this, I decided to not to proceed any further with using this printer. The printer is not mine (it belongs to the local library) and I'm not quite ready to invest the time or money to upgrade something that is already esentially obsolete. I still plan on printing parts for the airplane eventually, but this printer is has become a bit of a distraction from the airplane itself. Also, newer model printers are getting cheaper by the minute and easier to use with built in functionality that makes printing exactly what I need more sense, so I'll look at investing in one of my own eventually. I've accomplished what I set out to do - proof of concept and making it functional again for the library. 3D scanning is also functionally feasible, but it too needs more time to getting it working the way I want it so it too will be shelved for the meantime.
A question came up from another builder on the forum on how I've managed to bend the trailing edges so cleanly. The entire procedure of assembling the slats can be seen on a previous blog post but for the sake of explanation, I used a small diameter rod along the inside of the fold held in place with some spacers Ron and I came up with. The are scrap strips of 0.016 aluminum with a a small curled up end.
I used wide painters tape to hold the strips in place, the curl of the strip against the rod. The picture make sit look like the curl is taller than the rod, but it is not. If it were, it would leave a mark on the inside of the skin so caution is warranted here
Strips and tape are cheap, good to have several across the entire width of the slat skin:
The inboard slats (the shorter ones) eventually tuck inside the outboard slat enough to be riveted together once they are mounted on the wings. Here they are back to back and upside down on the bench lined up but not yet tucked together - this really gives the idea how long and wide the wings will be!
Looking at my "completed sections" drawing, I'm pleased to be "mostly done" the control surfaces.....
.... and happy to see an empty bench, even for a few minutes! Now to begin one of the bigger sections both in size and number of parts - the WINGS!
I brought a fresh roll of 0.032 (on the bench) and 0.042 (coiled beside the bench) down from the storage barn, to start laying out the components for the wings. Like everything else, I want all the parts made and ready to use in assembly to minimize the time on the bench.
First up, the wing spar webs from 0.032. The two spar webs are almost a full length section of a sheet and requires accurate cutting so the spar assembly is straight and true. They make up the centre part of the spar between to 6061-T6 angles on the top and bottom (more on later).
I cut the first web using a plunge saw with metal cutting wheel and it turned out fairly decently. The saw isn't as accurate or clean cutting as I would like leaving me some extra work with a hand file to clean up the cut edge by hand before deburring and sanding smooth. With a bit of work, it eventually cleaned up nice and straight. I cut the second spar web by hand using the large hand shears - it took longer to cut, but I found that if I was careful I could be more accurate cutting by hand and it took a lot less time to debur and clean up the cut. I used each side of the factory edges of the sheet to be and edge for each spar web giving me a perfect factory edge to measure from..
With the spar webs cut to size, I measured and cut out the tapers at the inboard ends of the spars where they will meet the wing (the bottom of the spar web faces the ruler in the picture below)
The thickness of the 0.032 and 0.040 sheet make them awkward to roll/unroll, so it makes sense to cut the other pieces out while the sheet is on the bench.
In the picture below you can see the remaining 0.032 sheet after cutting out the spar webs (coiled at top of picture), the spar root doublers (bottom of picture) and the four rear spar channel blanks (middle of picture). The two thinner strips on the right at 0.040 blanks that will be bent into angles as inboard rear channel doublers.
The 0.032 rear spar channels and the 0.040 doublers are too long to bend at our shop, so I've taken them to the same shop who bent the flapperon spars for me previously. I'll get them back this week.
I also needed to cut out the left and right 0.063 strut support brackets (bottom right in photo below). So while I had the sheet on the bench I also cut out some of the other 0.063 parts for the fuselage - the fuselage parts will be put into storage until I need them, but at least they are done. I ran out of space on the 0.063 sheet I had to layout/cut the spar web doublers, so I'll have to get some more from storage to get these done.
So despite no blog updates, I have been working away. Control surfaces are "done" and work on the wings is underway. Looking at the completed parts picture I posted above I'm very pleased how far I've come since starting. I'm not sure I can put a concrete answer on how much I've got done, but of the approximately 275 aluminum parts to make, I've got about 145 done which is very roughly 53%. Understand that's just parts made, not bent, assembled, drilled, debured, primed, riveted.
As always, thanks for following along.
Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.