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Counter sink area scratches, are they a problem, will they buff out?

mill2978

mill2978

Well Known Member
I started to countersink the fuel tank skins. I am ending up with lots of scuff marks from the tool. Is this normal? I hope to polish my plane, will they buff out?

20130830_131444.jpg


I suspect that this is removed material being spun around by the bit.

I may be over analyzing some of this...
 
better example

Here is a better example. I know the large ring is from the cage, I am concerned about the middle ring and the oval shaped scratches at edge of the CS.

20130830_161425.jpg
 
Turning REALLY slow seems to help, and yes you'll scuff those away. But, does anyone have a trick for preventing this?
 
The way I do it is to pull the cage back to the set stop, and then insert the cutter in the hole, I then start to c/ sink until the cage come in contact with the skin. Hope this makes sense
 
First Post

I've been lurking for about a year now...first post.

I put a piece of duct tape on the end of my countersink and cut away the hole in the middle. The bit of tape on the leading edge of the coutnersink seams to prevent scratches. It will get fouled with shavings at some point...a new piece of tape will fix it.
 
These scratches are more of a problem with single flute countersinks, the kind where the flute is a single hole bored at an angle through the body of the tool. I found that clearing this flute hole of stringy chips after each operation cuts down on scratching. 3-flute countersinks have open flutes so the chips clear from the tool and are less likely to cause scratches. However, these countersinks are more prone to "chatter" if not run at the correct speed and pressure. Practice on scrap will help you figure out the best method for you!

Stewart Willoughby
6, finishing
 
Just thought of something. I do not recall countersingking the fuel tank skins anywhere except the trailing edge (rivets to rear baffle). Are these supposed to be dimpled?
 
AltonD said:
Just thought of something. I do not recall countersingking the fuel tank skins anywhere except the trailing edge (rivets to rear baffle). Are these supposed to be dimpled?
Click to expand...

I am working on the four baffle lines and fuel cap, you are correct, the rest of the tank gets dimpled.
 
BLittleton said:
I've been lurking for about a year now...first post.

I put a piece of duct tape on the end of my countersink and cut away the hole in the middle. The bit of tape on the leading edge of the coutnersink seams to prevent scratches. It will get fouled with shavings at some point...a new piece of tape will fix it.
Click to expand...

Welcome to VAF!

That works well for the cage marks. My issue seems to be the chips getting caught by the blade and dragged around the hole.

Turning the tool slower helps, I am also going to try putting an air nozzle next to the work and see if that moves the chips away before they can get caught.
 
Tape it up!

I tried the air, it couldn't eject the metal fast enough because of the cage on the CS.

However the suggestion from Echo Tango to use masking tape made all the difference.

Here is a hole after I laid down a piece of masking tape. Most ended up this good, the worst using the method was as good or better than the best without.

IMG_9623.JPG
 
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