Fuselage - Bulkheads
I finished deburring the F-704A/B/C/D parts. I spent some more time deburring the spar web for a few more of the small close tolerance bolts. I know these are supposed to be precision match-drilled by Van's, but I don't think they were precision assembled. If you do not ream out the spar web around the holes, the bolts rub against the spar web when they are inserted. Individually, this is not a big problem, but when you go through several holes (like when you install the wing), this all adds up.
I, also, fabricated the F-633 control column mounts. This is where you drill the brackets to match the holes in the rear center bulkhead, and then you get to remove some unneeded aluminum for "weight savings." I spent several hours on this, and the net savings was 2 oz. You decide whether this is worth it or not. Basically, I did it because it's expected, and, the brackets look really cool when you're done.
|When you are all done match-drilling the center section, it is a good idea to try and blow out the metal chips. Don't really want that stuff stuck between the spar web and the heavy bars.|
|First hole marked on F-633, ready to be drilled.|
|After the first hole has been drilled, you need to back-drill the second hole. Good idea to make sure it is square.|
|You have to clamp the F-633 to the center section to drill it. When I was done drilling, I was off by half a millimeter--close enough.|
|If you did the first part right, you should be able to just clamp the second part to the first, and drill them. Anyway, that's what I did, and it came out ok.|
|Both parts drilled, ready to be lightened.|
|I tried to cut this with my band saw, but the blade drifts really badly. I think I need a finer blade, and some adjustment on the band saw. Anyway, this is an excuse to use the Smithy. Worked great, and it really doesn't take that long to cut this out.|
|Looks like the part sifted in the vice a little. I used masking tape to protect the part, but that allowed the part to slide. Just do the last few inches again.|
|After the Smithy, the part was pretty rough, so I got to use my belt sander to finish the part. I'm really starting to like that tool a lot. I bought a really cheap combination 1" belt sander/6" disk sander from Harbour Freight (I think it was on sale for $30). I am using a very coarse belt and disk, so the part is still a little rough after the sander. This requires a combination of filing, deburring, and Scotch-brite wheel to finish.|
|When you are done, they look like this.|
|BTW, for those of you who are interested, each part weighed 6 oz when I started.|
|When you are done, they each weigh 5 oz. You can either view this as a 20% savings in weight, or two ounces of wasted effort. Either way, I think they look better.|