Scott Hiser wrote:
I'm prepping the surface and edges for my empennage. Some of the surface scratches and general aluminum has some dents and scratch lines in it. According to the instructions, these must be removed with 400 grit sandpaper or whatever will take it out. I've prepped the metal but may need to continue further if these marks are beyond acceptable tolerance.
Could somebody with experience take a look at these image links and let me know if these require more surface removal? It seems like some of it would be significant if so. This is how they came from the factory.
I have 2 horizontal stabilizer reinforcement bars I'm currently working on.
https://drive.google.com/file/d/0Bwx62FIsvFPmQVREYlBlQmp2SFU/view?usp=sharing
https://drive.google.com/file/d/0Bwx62FIsvFPma1poZE9TUkE5VUk/view?usp=sharing
Bar ends, were blunt squared edges with burrs.
https://drive.google.com/file/d/0Bwx62FIsvFPmQXRSM0NyUFNDNjA/view?
usp=sharing
Round impression from factory, fairly smooth impression but it would require a lot of material removal to blend out.
https://drive.google.com/file/d/0Bwx62FIsvFPmcE11aTVMVG1xWFk/view?usp=sharing
General edge rounded.
https://drive.google.com/file/d/0Bwx62FIsvFPmVmF3a0dTdElXdFE/view?usp=sharing
This is the 2nd reinforcement bar. One the first bar I spent an initial 15 minutes using a vixen file to round the edges before using the deburring wheel on my bench grinder. That seemed overkill so on this one I skipped the vixen file and went direct to the deburring wheel.
These went from rough and gray to smooth and satin finished.
Scott,
I'd prefer looking at some of those first hand, but for the most part I think you are fine. As long as you don't have any sharp edges where stress risers can form, you should be fine, particularly on these thicker bars. Where you really have to be careful is on the thinner skins, where vibrations will be more prevalent and can cause cracks to form and propagate. Your rounded edges are good. I did the same thing, initially using a vixen file then going to the scotchbrite wheels. THEN I started just using the scotchbrite wheels only and skipped the vixen file for almost everything and never looked back. Much quicker and smooth as a baby's butt. The vixen file is good for taking a lot of material down quickly, but using the maroon 6 inch scotchbrite wheel on a bench grinder, you can take quite a lot of aluminum off an edge too. A word of caution though, it is surprising how much very fine aluminum dust and dust from the scotchbrite wheel you will create over time with all the aluminum you will deburr. I'd suggest using a dust mask when using the scotchbrite wheel, just as a precaution. No sense breathing that dust into your lungs when a simple cheap disposable dust mask can prevent it!
Anytime you want a second set of eyeballs to look at something, I'll be happy to stop over and take a look.
Regards,
Mike Whitescarver