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  #1  
Old 08-30-2013, 01:47 PM
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mill2978 mill2978 is offline
 
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Default Counter sink area scratches, are they a problem, will they buff out?

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?



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

I may be over analyzing some of this...
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Old 08-30-2013, 04:28 PM
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Default 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.

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Old 08-30-2013, 06:21 PM
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Quote:
Originally Posted by mill2978 View Post
I suspect that this is removed material being spun around by the bit.
Yes

Quote:
Originally Posted by mill2978 View Post
I hope to polish my plane
Recommend budgeting for psychotherapy............
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Old 08-30-2013, 06:47 PM
aerhed aerhed is offline
 
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Turning REALLY slow seems to help, and yes you'll scuff those away. But, does anyone have a trick for preventing this?
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Old 08-30-2013, 09:43 PM
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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
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Old 08-30-2013, 09:46 PM
aerhed aerhed is offline
 
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That helps with the cage marks, but it doesn't stop the cuttings from cutting.
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  #7  
Old 08-30-2013, 10:03 PM
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BLittleton BLittleton is offline
 
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Default 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.
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Old 08-31-2013, 12:07 AM
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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
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  #9  
Old 08-31-2013, 07:22 AM
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Are you letting the cage spin?
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  #10  
Old 08-31-2013, 11:48 AM
Echo Tango Echo Tango is offline
 
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dont know if it would work, but perhaps some masking tape over the holes before c/s'ing them?
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