Ken's Sonex 1243

[dtwolcott]

Ken
I think you will find if you haven't made at least one part three times during your build you haven't learned what building your own plane means. This will make most builders a little more humble. Keep up the good work
Don

[Sonex1243]

You guys are so right! Thanks :mrgreen:

[Sonex1243]

Back at it, F9 passes on the flaps finished. Ailerons start tomorrow.




Not sure I like the polka dot area's on the skin from the "dabbing" of polish. I can't remember if it comes out with the "C" grade?

[ScottM-Sonex1629]

Ken
You shouldn't see the polish dots after each pass of the F9. Are you sure you're applying enough polish and thoroughly spreading it around in small sections, then removing it with the machine/wool pads before moving to next section? Don't take this the wrong way but your F9 should be a pretty decent shine albeit with the polishing swirls. The C grade then begins removing the swirls and refining the shine and depth. Your photos don't like like your done with F9 yet. Here is an example of one pass with F9 on my wing.



I generally end up with 4-5 passes of F9 with film pressure on the aluminum (will slightly heat the surface)...then 2-3 passes of C.

[wlarson861]

Before you move on from the F-9 you should have a very high shine, very mirror like. It looks like its done until you get it in the sun and see all the swirls.

[Bryan Cotton]

When I do my F9 polishing I am really beating up and heating up the metal. Nuvite may say we are healing the metal, but I say it is an abrasive. The finger I use to dab and smear ends up raw. The sharp triangle of aluminum scrap I use to clear the buffer pad ends up rounded and smooth. It is an abrasive. Show that metal no mercy with the F9.

The material properties of 6061-T6 won't change below its aging temerature. I forget what the actual temperature is but it is well above what you are going to get with a buffer and F9. I still occasionally forget to not touch it right after I stop and though it is hot I have not gotten as much as a first degree burn, and my plastic table does not melt.

[Sonex1243]

Are you sure you're applying enough polish and thoroughly spreading it around in small sections, then removing it with the machine/wool pads before moving to next section?

Scott; I think you are correct, I was breaking the skin into 1/4 sections, if that makes sense, and trying to cover too large an area. How did you get the stuff to come off with the pads? I keep the same speed and never got the skins to be free of polish residue, albeit small black specks everywhere that came off with the mineral spirits.

Show that metal no mercy with the F9.

Bryan; I was always afraid of overheating the metal! I'll get those skins back on the table and try smaller sections and a lot more pressure and more time in smaller area's


The compounding pad I use. Do you have to remove the markings from the metal before F9?


Macro photo, the grain is starting to close up some from the first passes, should be smoother?

[ScottM-Sonex1629]

Ken:

I highly recommend watching the video (again if you've already seen it) on the Sonex video tips page which Kerry Fores created. When I apply the F9 (and C) I use small dabs on my finger every 6-8" apart in a grid. Use slow rpm and spread it out (not sling it around), then increase the RPM and go at it. The metal should be evenly covered in Nuvite and the surface will be dark gray (smeared around polish). The build up on your pad will need to be removed frequently (many ways to do this including the spur method).

Keep moving the polisher around slowly with pressure and the polish will work its way off and the polished metal will remain. Once you figure out the process you will have an Ah ha moment!

http://www.eaavideo.org/video.aspx?v=25190150001

[wlarson861]

I found that the f-9 was the hardest polish to use. I worked in about a 1 foot square and the buffer would grab on the first pass quite a bit. The subsequent passes were much better and went much better. I put dabs of polish about 4 inches apart and smeared them around with the pad without turning on the buffer, then I started at low rpm and worked up to the polish speed. The first pass is not very productive bur the 2nd and 3rd pass get a much better shine. I used 4 to 5 passes on the F_9 on each area before moving onto the c grade. Your last photo shows a lot of grain in the metal, that should be all polished out before you move on to the C-grade. The initial polish is a lot more time consuming than the maintenance polish you will do later.

[DCASonex]

My best results were obtained working maximum of about 2 square feet (not 2 ft. square), using very small amount of polish and spreading that about with polisher set at its lowest speed, then increasing speed to about 1,500 -2,000 RPM to polish, finish with a quick once over at maximum speed to throw off any remaining polish. Last step throws it everywhere, including on you. Work outside and wear old clothes.

If working with flat sheets on a table, you can use quite a bit of pressure and two passes with the F9 seems sufficient. If starting with finished assembly, must use lighter pressure to keep from deforming skins leaving ribs etc showing, and more passes with be required before moving on to grades C and S.

Experiment to find minimum amount of polish required. Will be surprised at how little it takes. Also throwaway 1/2" paint brushes or the like will keep your dirty fingers from contaminating the polish which becomes more important with the finer grades, and saves your finger from messing up (and getting into) the trigger on your grinder.

When advancing to finer grades, be sure to keep all pads, bushes etc. used for that completely separated. Zip lock bags are good for storing the pads and their associated brushes.

David A. Sonex TD, with lazy man's polish. (Undersides of wings and tail and all moving control surfaces painted.)